nearby: snapshot of cl/304428753

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: I0023ac6e40456fc4a8169c3173bcbff3b5ccc476

cpp/platform/BUILD

@@ -26,7 +26,6 @@ cc_library(
         ":types",
         "//platform/api",
         "//platform/port:string",
-        "//strings",
         "//absl/strings",
         "//absl/time",
     ],
@@ -34,15 +33,11 @@ cc_library(
 
 cc_library(
     name = "types",
-    srcs = [
-        "ptr.cc",
-    ],
     hdrs = [
         "byte_array.h",
         "callable.h",
         "cancelable.h",
         "container_of.h",
-        "exception.cc",
         "exception.h",
         "ptr.h",
         "runnable.h",
@@ -113,6 +108,15 @@ cc_test(
     ],
 )
 
+cc_test(
+    name = "exception_test",
+    srcs = ["exception_test.cc"],
+    deps = [
+        ":types",
+        "//testing/base/public:gunit_main",
+    ],
+)
+
 cc_test(
     name = "pipe_test",
     timeout = "short",

cpp/platform/api/BUILD

@@ -20,23 +20,28 @@ cc_library(
         "hash_utils.h",
         "input_file.h",
         "input_stream.h",
+        "listenable_future.h",
         "lock.h",
         "multi_thread_executor.h",
         "output_file.h",
         "output_stream.h",
         "scheduled_executor.h",
+        "server_sync.h",
         "settable_future.h",
         "single_thread_executor.h",
         "socket.h",
         "submittable_executor.h",
         "system_clock.h",
         "thread_utils.h",
+        "webrtc.h",
         "wifi.h",
+        "wifi_lan.h",
     ],
     deps = [
         "//platform:types",
         "//platform/port:down_cast",
         "//platform/port:string",
+        "//webrtc/files/stable/webrtc/api:libjingle_peerconnection_api",
     ],
 )
 

cpp/platform/api/ble_v2.h

@@ -39,7 +39,7 @@ struct BLEAdvertisementData {
   std::set<std::string> service_uuids;
   // Maps service UUIDs to their service data.
   // Ownership of the map values is tied to ownership of BLEAdvertisementData.
-  std::map<std::string, ConstPtr<ByteArray> > service_data;
+  std::map<std::string, ConstPtr<ByteArray>> service_data;
 };
 
 // Opaque wrapper over a BLE peripheral. Must be able to uniquely identify a
@@ -217,7 +217,8 @@ class GATTServer {
   // about this descriptor, please go to:
   // https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.descriptor.gatt.client_characteristic_configuration.xml
   virtual Ptr<GATTCharacteristic> createCharacteristic(
-      const std::string& service_uuid, const std::string& characteristic_uuid,
+      const std::string& service_uuid,
+      const std::string& characteristic_uuid,
       const std::set<GATTCharacteristic::Permission::Value>& permissions,
       const std::set<GATTCharacteristic::Property::Value>& properties) = 0;
 
@@ -384,7 +385,9 @@ class BLEMediumV2 {
   //   HIGH:
   //     - Connection interval = ~100ms - 125ms
   virtual Ptr<ClientGATTConnection> connectToGATTServer(
-      Ptr<BLEPeripheralV2> peripheral, MTU mtu, PowerMode::Value power_mode,
+      Ptr<BLEPeripheralV2> peripheral,
+      MTU mtu,
+      PowerMode::Value power_mode,
       Ptr<ClientGATTConnectionLifecycleCallback>
           connection_lifecycle_callback) = 0;
 

cpp/platform/api/bluetooth_classic.h

@@ -60,7 +60,7 @@ class BluetoothServerSocket {
   //
   // The returned Ptr will be owned (and destroyed) by the caller. Returns
   // Exception::IO on error.
-  virtual ExceptionOr<Ptr<BluetoothSocket> > accept() = 0;
+  virtual ExceptionOr<Ptr<BluetoothSocket>> accept() = 0;
 
   // https://developer.android.com/reference/android/bluetooth/BluetoothServerSocket.html#close()
   //
@@ -116,8 +116,9 @@ class BluetoothClassicMedium {
   //
   // The returned Ptr will be owned (and destroyed) by the caller. Returns
   // Exception::IO on error.
-  virtual ExceptionOr<Ptr<BluetoothSocket> > connectToService(
-      Ptr<BluetoothDevice> remote_device, const std::string& service_uuid) = 0;
+  virtual ExceptionOr<Ptr<BluetoothSocket>> connectToService(
+      Ptr<BluetoothDevice> remote_device,
+      const std::string& service_uuid) = 0;
 
   // https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#listenUsingInsecureRfcommWithServiceRecord
   //
@@ -129,8 +130,9 @@ class BluetoothClassicMedium {
   //
   // The returned Ptr will be owned (and destroyed) by the caller. Returns
   // Exception::IO on error.
-  virtual ExceptionOr<Ptr<BluetoothServerSocket> > listenForService(
-      const std::string& service_name, const std::string& service_uuid) = 0;
+  virtual ExceptionOr<Ptr<BluetoothServerSocket>> listenForService(
+      const std::string& service_name,
+      const std::string& service_uuid) = 0;
 };
 
 }  // namespace nearby

cpp/platform/api/executor.h

@@ -1,6 +1,9 @@
 #ifndef PLATFORM_API_EXECUTOR_H_
 #define PLATFORM_API_EXECUTOR_H_
 
+#include "platform/ptr.h"
+#include "platform/runnable.h"
+
 namespace location {
 namespace nearby {
 
@@ -12,6 +15,9 @@ class Executor {
 
   // https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ExecutorService.html#shutdown--
   virtual void shutdown() = 0;
+
+  // https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executor.html#execute-java.lang.Runnable-
+  virtual void execute(Ptr<Runnable> runnable) = 0;
 };
 
 }  // namespace nearby

cpp/platform/api/future.h

@@ -1,6 +1,8 @@
 #ifndef PLATFORM_API_FUTURE_H_
 #define PLATFORM_API_FUTURE_H_
 
+#include <cstdint>
+
 #include "platform/exception.h"
 
 namespace location {
@@ -16,6 +18,11 @@ class Future {
 
   virtual ExceptionOr<T>
   get() = 0;  // throws Exception::INTERRUPTED, Exception::EXECUTION
+
+  // throws Exception::INTERRUPTED, Exception::EXECUTION
+  // throws Exception::TIMEOUT if |timeout_ms| is exceeded while waiting for
+  // result.
+  virtual ExceptionOr<T> get(std::int64_t timeout_ms) = 0;
 };
 
 }  // namespace nearby

cpp/platform/api/input_file.h

@@ -16,7 +16,7 @@ class InputFile {
   // The returned ConstPtr will be owned (and destroyed) by the caller.
   // When we have exhausted reading the file and no bytes remain, read will
   // always return an empty ConstPtr for which isNull() is true.
-  virtual ExceptionOr<ConstPtr<ByteArray> > read(
+  virtual ExceptionOr<ConstPtr<ByteArray>> read(
       std::int64_t size) = 0;  // throws Exception::IO when the file cannot be
                                // opened or read.
   virtual std::string getFilePath() const = 0;

cpp/platform/api/input_stream.h

@@ -18,9 +18,9 @@ class InputStream {
   virtual ~InputStream() {}
 
   // The returned ConstPtr will be owned (and destroyed) by the caller.
-  virtual ExceptionOr<ConstPtr<ByteArray> > read() = 0;  // throws Exception::IO
+  virtual ExceptionOr<ConstPtr<ByteArray>> read() = 0;  // throws Exception::IO
   // The returned ConstPtr will be owned (and destroyed) by the caller.
-  virtual ExceptionOr<ConstPtr<ByteArray> > read(
+  virtual ExceptionOr<ConstPtr<ByteArray>> read(
       std::int64_t size) = 0;            // throws Exception::IO
   virtual Exception::Value close() = 0;  // throws Exception::IO
 };

cpp/platform/api/listenable_future.h

@@ -0,0 +1,28 @@
+#ifndef PLATFORM_API_LISTENABLE_FUTURE_H_
+#define PLATFORM_API_LISTENABLE_FUTURE_H_
+
+#include "platform/api/executor.h"
+#include "platform/api/future.h"
+#include "platform/exception.h"
+#include "platform/ptr.h"
+#include "platform/runnable.h"
+
+namespace location {
+namespace nearby {
+
+// A Future that accepts completion listeners.
+//
+// https://guava.dev/releases/20.0/api/docs/com/google/common/util/concurrent/ListenableFuture.html
+template <typename T>
+class ListenableFuture : public Future<T> {
+ public:
+  ~ListenableFuture() override {}
+
+  // Executor is shared among multiple runnables. It is not owned by any future.
+  virtual void addListener(Ptr<Runnable> runnable, Executor* executor) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API_LISTENABLE_FUTURE_H_

cpp/platform/api/multi_thread_executor.h

@@ -11,8 +11,8 @@ namespace nearby {
 //
 // https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executors.html#newFixedThreadPool-int-
 template <typename ConcreteSubmittableExecutor>
-class MultiThreadExecutor :
-    public SubmittableExecutor<ConcreteSubmittableExecutor> {
+class MultiThreadExecutor
+    : public SubmittableExecutor<ConcreteSubmittableExecutor> {
  public:
   ~MultiThreadExecutor() override {}
 };

cpp/platform/api/server_sync.h

@@ -0,0 +1,64 @@
+#ifndef PLATFORM_API_SERVER_SYNC_H_
+#define PLATFORM_API_SERVER_SYNC_H_
+
+#include <string>
+
+#include "platform/byte_array.h"
+#include "platform/ptr.h"
+
+namespace location {
+namespace nearby {
+
+// Abstraction that represents a Nearby endpoint exchanging data through
+// ServerSync Medium.
+class ServerSyncDevice {
+ public:
+  virtual ~ServerSyncDevice() {}
+
+  virtual std::string getName() = 0;
+
+  virtual std::string getGuid() = 0;
+
+  virtual std::string getOwnGuid() = 0;
+};
+
+// Container of operations that can be performed over the Chrome Sync medium.
+class ServerSyncMedium {
+ public:
+  virtual ~ServerSyncMedium() {}
+
+  // Takes ownership of (and is responsible for destroying) the passed-in
+  // 'endpoint_info'.
+  virtual bool startAdvertising(const std::string& service_id,
+                                const std::string& endpoint_id,
+                                ConstPtr<ByteArray> endpoint_info) = 0;
+  virtual void stopAdvertising(const std::string& service_id) = 0;
+
+  class DiscoveredDeviceCallback {
+   public:
+    virtual ~DiscoveredDeviceCallback() {}
+
+    // Called on a new ServerSyncDevice discovery.
+    virtual void onDeviceDiscovered(Ptr<ServerSyncDevice> device,
+                                    const std::string& service_id,
+                                    const std::string& endpoint_id,
+                                    ConstPtr<ByteArray> endpoint_info) = 0;
+    // Called when ServerSyncDevice is no longer reachable.
+    virtual void onDeviceLost(Ptr<ServerSyncDevice> device,
+                              const std::string& service_id) = 0;
+  };
+
+  // Returns true once the Chrome Sync scan has been initiated.
+  virtual bool startDiscovery(
+      const std::string& service_id,
+      Ptr<DiscoveredDeviceCallback> discovered_device_callback) = 0;
+  // Returns true once Chrome Sync scan for service_id is well and truly
+  // stopped; after this returns, there must be no more invocations of the
+  // DiscoveredDeviceCallback passed in to startScanning() for service_id.
+  virtual void stopDiscovery(const std::string& service_id) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API_SERVER_SYNC_H_

cpp/platform/api/settable_future.h

@@ -1,7 +1,7 @@
 #ifndef PLATFORM_API_SETTABLE_FUTURE_H_
 #define PLATFORM_API_SETTABLE_FUTURE_H_
 
-#include "platform/api/future.h"
+#include "platform/api/listenable_future.h"
 
 namespace location {
 namespace nearby {
@@ -10,11 +10,13 @@ namespace nearby {
 //
 // https://google.github.io/guava/releases/20.0/api/docs/com/google/common/util/concurrent/SettableFuture.html
 template <typename T>
-class SettableFuture : public Future<T> {
+class SettableFuture : public ListenableFuture<T> {
  public:
   ~SettableFuture() override {}
 
   virtual bool set(T value) = 0;
+
+  virtual bool setException(Exception exception) = 0;
 };
 
 }  // namespace nearby

cpp/platform/api/single_thread_executor.h

@@ -11,8 +11,8 @@ namespace nearby {
 //
 // https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executors.html#newSingleThreadExecutor--
 template <typename ConcreteSubmittableExecutor>
-class SingleThreadExecutor :
-    public SubmittableExecutor<ConcreteSubmittableExecutor> {
+class SingleThreadExecutor
+    : public SubmittableExecutor<ConcreteSubmittableExecutor> {
  public:
   ~SingleThreadExecutor() override {}
 };

cpp/platform/api/submittable_executor.h

@@ -6,7 +6,6 @@
 #include "platform/callable.h"
 #include "platform/port/down_cast.h"
 #include "platform/ptr.h"
-#include "platform/runnable.h"
 
 namespace location {
 namespace nearby {
@@ -29,12 +28,9 @@ class SubmittableExecutor : public Executor {
   ~SubmittableExecutor() override {}
 
   template <typename T>
-  Ptr<Future<T> > submit(Ptr<Callable<T> > callable) {
+  Ptr<Future<T>> submit(Ptr<Callable<T>> callable) {
     return DOWN_CAST<ConcreteSubmittableExecutor*>(this)->submit(callable);
   }
-
-  // https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executor.html#execute-java.lang.Runnable-
-  virtual void execute(Ptr<Runnable> runnable) = 0;
 };
 
 }  // namespace nearby

cpp/platform/api/webrtc.h

@@ -0,0 +1,46 @@
+#ifndef PLATFORM_API_WEBRTC_H_
+#define PLATFORM_API_WEBRTC_H_
+
+#include <vector>
+
+#include "platform/byte_array.h"
+#include "platform/ptr.h"
+#include "webrtc/files/stable/webrtc/api/peer_connection_interface.h"
+
+namespace location {
+namespace nearby {
+
+class WebRtcSignalingMessenger {
+ public:
+  virtual ~WebRtcSignalingMessenger() = default;
+
+  /** Called whenever we receive an inbox message from tachyon. */
+  class SignalingMessageListener {
+   public:
+    virtual ~SignalingMessageListener() = default;
+
+    virtual void onSignalingMessage(ConstPtr<ByteArray> message) = 0;
+  };
+
+  class IceServersListener {
+   public:
+    virtual ~IceServersListener() = default;
+
+    virtual void OnIceServersFetched(
+        std::vector<Ptr<webrtc::PeerConnectionInterface::IceServer>>
+            ice_servers) = 0;
+  };
+
+  virtual bool registerSignaling() = 0;
+  virtual bool unregisterSignaling() = 0;
+  virtual bool sendMessage(const string& peer_id,
+                           ConstPtr<ByteArray> message) = 0;
+  virtual bool startReceivingMessages(
+      Ptr<SignalingMessageListener> listener) = 0;
+  virtual void getIceServers(Ptr<IceServersListener> ice_servers_listener) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API_WEBRTC_H_

cpp/platform/api/wifi.h

@@ -58,7 +58,7 @@ class WifiMedium {
     // owned (and destroyed) by the recipient of the callback methods (i.e. the
     // creator of the concrete ScanResultCallback object).
     virtual void onScanResults(
-        const std::vector<ConstPtr<WifiScanResult> >& scan_results) = 0;
+        const std::vector<ConstPtr<WifiScanResult>>& scan_results) = 0;
   };
 
   // Does not take ownership of the passed-in scan_result_callback -- destroying
@@ -69,7 +69,8 @@ class WifiMedium {
   // WifiConnectionStatus::CONNECTED on success, or the appropriate failure code
   // otherwise.
   virtual WifiConnectionStatus::Value connectToNetwork(
-      const std::string& ssid, const std::string& password,
+      const std::string& ssid,
+      const std::string& password,
       WifiAuthType::Value auth_type) = 0;
 
   // Blocks until it's certain of there being a connection to the internet, or

cpp/platform/api/wifi_lan.h

@@ -0,0 +1,94 @@
+#ifndef PLATFORM_API_WIFI_LAN_H_
+#define PLATFORM_API_WIFI_LAN_H_
+
+#include "platform/api/input_stream.h"
+#include "platform/api/output_stream.h"
+#include "platform/byte_array.h"
+#include "platform/exception.h"
+#include "platform/port/string.h"
+#include "platform/ptr.h"
+
+namespace location {
+namespace nearby {
+
+// Opaque wrapper over a WifiLan service which contains encoded service name.
+class WifiLanService {
+ public:
+  virtual ~WifiLanService() = default;
+
+  virtual std::string GetName() = 0;
+};
+
+class WifiLanSocket {
+ public:
+  virtual ~WifiLanSocket() = default;
+
+  // Returns the InputStream of the WifiLanSocket, or a null Ptr<InputStream>
+  // on error.
+  //
+  // The returned Ptr is not owned by the caller, and can be invalidated once
+  // the WifiLanSocket object is destroyed.
+  virtual Ptr<InputStream> GetInputStream() = 0;
+
+  // Returns the OutputStream of the WifiLanSocket, or a null
+  // Ptr<OutputStream> on error.
+  //
+  // The returned Ptr is not owned by the caller, and can be invalidated once
+  // the WifiLanSocket object is destroyed.
+  virtual Ptr<OutputStream> GetOutputStream() = 0;
+
+  // Returns Exception::IO on error, Exception::NONE otherwise.
+  virtual Exception::Value Close() = 0;
+
+  // The returned Ptr is not owned by the caller, and can be invalidated once
+  // the WifiLanSocket object is destroyed.
+  virtual Ptr<WifiLanService> GetRemoteWifiLanService() = 0;
+};
+
+// Container of operations that can be performed over the WifiLan medium.
+class WifiLanMedium {
+ public:
+  virtual ~WifiLanMedium() = default;
+
+  virtual bool StartAdvertising(const std::string& service_id,
+                                const string& wifi_lan_service_info_name) = 0;
+  virtual void StopAdvertising(const std::string& service_id) = 0;
+
+  // Callback for WifiLan discover results.
+  class DiscoveredServiceCallback {
+   public:
+    virtual ~DiscoveredServiceCallback() = default;
+
+    virtual void OnServiceDiscovered(Ptr<WifiLanService> wifi_lan_service) = 0;
+    virtual void OnServiceLost(Ptr<WifiLanService> wifi_lan_service) = 0;
+  };
+
+  virtual bool StartDiscovery(
+      const std::string& service_id,
+      Ptr<DiscoveredServiceCallback> discovered_service_callback) = 0;
+  virtual void StopDiscovery(const std::string& service_id) = 0;
+
+  class AcceptedConnectionCallback {
+   public:
+    virtual ~AcceptedConnectionCallback() = default;
+
+    // The Ptr provided in this callback method will be owned (and
+    // destroyed) by the recipient of the callback methods (i.e. the creator of
+    // the concrete AcceptedConnectionCallback object).
+    virtual void OnConnectionAccepted(Ptr<WifiLanSocket> socket,
+                                      const string& service_id) = 0;
+  };
+
+  virtual bool StartAcceptingConnections(
+      const std::string& service_id,
+      Ptr<AcceptedConnectionCallback> accepted_connection_callback) = 0;
+  virtual void StopAcceptingConnections(const std::string& service_id) = 0;
+
+  virtual Ptr<WifiLanSocket> Connect(Ptr<WifiLanService> wifi_lan_service,
+                                     const std::string& service_id) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API_WIFI_LAN_H_

cpp/platform/api2/BUILD

@@ -0,0 +1,65 @@
+package(default_visibility = [
+    "//core:__subpackages__",
+    "//platform:__subpackages__",
+    "//location/nearby/setup/core:__subpackages__",
+])
+
+cc_library(
+    name = "api2",
+    hdrs = [
+        "atomic_boolean.h",
+        "atomic_reference.h",
+        "ble.h",
+        "ble_v2.h",
+        "bluetooth_adapter.h",
+        "bluetooth_classic.h",
+        "condition_variable.h",
+        "count_down_latch.h",
+        "executor.h",
+        "future.h",
+        "hash_utils.h",
+        "input_file.h",
+        "input_stream.h",
+        "listenable_future.h",
+        "multi_thread_executor.h",
+        "mutex.h",
+        "output_file.h",
+        "output_stream.h",
+        "scheduled_executor.h",
+        "server_sync.h",
+        "settable_future.h",
+        "single_thread_executor.h",
+        "socket.h",
+        "submittable_executor.h",
+        "system_clock.h",
+        "thread_utils.h",
+        "webrtc.h",
+        "wifi.h",
+    ],
+    deps = [
+        "//platform:types",
+        "//absl/strings",
+        "//absl/time",
+        "//webrtc/files/stable/webrtc/api:libjingle_peerconnection_api",
+    ],
+)
+
+cc_library(
+    name = "mutex",
+    hdrs = ["mutex.h"],
+    visibility = [
+        "//platform:__subpackages__",
+    ],
+)
+
+cc_library(
+    name = "condition_variable",
+    hdrs = ["condition_variable.h"],
+    visibility = [
+        "//platform:__subpackages__",
+    ],
+    deps = [
+        "//platform:types",
+        "//absl/time",
+    ],
+)

cpp/platform/api2/atomic_boolean.h

@@ -0,0 +1,21 @@
+#ifndef PLATFORM_API2_ATOMIC_BOOLEAN_H_
+#define PLATFORM_API2_ATOMIC_BOOLEAN_H_
+
+namespace location {
+namespace nearby {
+
+// A boolean value that may be updated atomically.
+//
+// https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/atomic/AtomicBoolean.html
+class AtomicBoolean {
+ public:
+  virtual ~AtomicBoolean() {}
+
+  virtual bool Get() = 0;
+  virtual void Set(bool value) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_ATOMIC_BOOLEAN_H_

cpp/platform/api2/atomic_reference.h

@@ -0,0 +1,22 @@
+#ifndef PLATFORM_API2_ATOMIC_REFERENCE_H_
+#define PLATFORM_API2_ATOMIC_REFERENCE_H_
+
+namespace location {
+namespace nearby {
+
+// An object reference that may be updated atomically.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/atomic/AtomicReference.html
+template <typename T>
+class AtomicReference {
+ public:
+  virtual ~AtomicReference() {}
+
+  virtual T Get() = 0;
+  virtual void Set(const T& value) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_ATOMIC_REFERENCE_H_

cpp/platform/api2/ble.h

@@ -0,0 +1,111 @@
+#ifndef PLATFORM_API2_BLE_H_
+#define PLATFORM_API2_BLE_H_
+
+#include "platform/api2/bluetooth_classic.h"
+#include "platform/api2/input_stream.h"
+#include "platform/api2/output_stream.h"
+#include "platform/byte_array.h"
+#include "absl/strings/string_view.h"
+
+namespace location {
+namespace nearby {
+
+// Opaque wrapper over a BLE peripheral. Must contain enough data about a
+// particular BLE device to connect to its GATT server.
+class BlePeripheral {
+ public:
+  virtual ~BlePeripheral() {}
+
+  // The returned Ptr is not owned by the caller, and can be invalidated once
+  // the corresponding BLEPeripheral object is destroyed.
+  virtual BluetoothDevice& GetBluetoothDevice() = 0;
+};
+
+class BleSocket {
+ public:
+  virtual ~BleSocket() {}
+
+  // Returns the InputStream of the BleSocket.
+  // On error, returned stream will report Exception::kIo on any operation.
+  //
+  // The returned object is not owned by the caller, and can be invalidated once
+  // the BleSocket object is destroyed.
+  virtual InputStream& GetInputStream() = 0;
+
+  // Returns the OutputStream of the BleSocket.
+  // On error, returned stream will report Exception::kIo on any operation.
+  //
+  // The returned object is not owned by the caller, and can be invalidated once
+  // the BleSocket object is destroyed.
+  virtual OutputStream& GetOutputStream() = 0;
+
+  // Conforms to the same contract as
+  // https://developer.android.com/reference/android/bluetooth/BluetoothSocket.html#close().
+  //
+  // Returns Exception::kIo on error, Exception::kSuccess otherwise.
+  virtual Exception Close() = 0;
+
+  // The returned object is not owned by the caller, and can be invalidated once
+  // the BleSocket object is destroyed.
+  virtual BlePeripheral& GetRemotePeripheral() = 0;
+};
+
+// Container of operations that can be performed over the BLE medium.
+class BleMedium {
+ public:
+  virtual ~BleMedium() {}
+
+  virtual bool StartAdvertising(absl::string_view service_id,
+                                const ByteArray& advertisement) = 0;
+  virtual void StopAdvertising(absl::string_view service_id) = 0;
+
+  class DiscoveredPeripheralCallback {
+   public:
+    virtual ~DiscoveredPeripheralCallback() {}
+
+    // The BlePeripheral* is not owned by callbacks.
+    // It is passed to give access to its non-const methods.
+    // It is guaranteed to be valid for the duration of call.
+    virtual void OnPeripheralDiscovered(BlePeripheral* ble_peripheral,
+                                        absl::string_view service_id,
+                                        const ByteArray& advertisement) = 0;
+    virtual void OnPeripheralLost(BlePeripheral* ble_peripheral,
+                                  absl::string_view service_id) = 0;
+  };
+
+  // Returns true once the BLE scan has been initiated.
+  virtual bool StartScanning(
+      absl::string_view service_id,
+      const DiscoveredPeripheralCallback& discovered_peripheral_callback) = 0;
+
+  // Returns true once BLE scanning for service_id is well and truly stopped;
+  // after this returns, there must be no more invocations of the
+  // DiscoveredPeripheralCallback passed in to StartScanning() for service_id.
+  virtual void StopScanning(absl::string_view service_id) = 0;
+
+  // Callback that is invoked when a new connection is accepted.
+  class AcceptedConnectionCallback {
+   public:
+    virtual ~AcceptedConnectionCallback() {}
+
+    virtual void OnConnectionAccepted(std::unique_ptr<BleSocket> socket,
+                                      absl::string_view service_id) = 0;
+  };
+
+  // Returns true once BLE socket connection requests to service_id can be
+  // accepted.
+  virtual bool StartAcceptingConnections(
+      absl::string_view service_id,
+      const AcceptedConnectionCallback& accepted_connection_callback) = 0;
+  virtual void StopAcceptingConnections(const std::string& service_id) = 0;
+
+  // BlePeripheral* is not owned by this call;
+  // it must remain valid for the duration of a call.
+  virtual std::unique_ptr<BleSocket> Connect(BlePeripheral* ble_peripheral,
+                                             absl::string_view service_id) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_BLE_H_

cpp/platform/api2/ble_v2.h

@@ -0,0 +1,390 @@
+#ifndef PLATFORM_API2_BLE_V2_H_
+#define PLATFORM_API2_BLE_V2_H_
+
+#include <cstdint>
+#include <limits>
+#include <map>
+#include <memory>
+#include <optional>
+#include <set>
+#include <string>
+
+#include "platform/byte_array.h"
+#include "platform/exception.h"
+#include "absl/strings/string_view.h"
+
+namespace location {
+namespace nearby {
+namespace v2 {
+
+// https://developer.android.com/reference/android/bluetooth/le/AdvertiseData
+//
+// Bundle of data found in a BLE advertisement.
+//
+// All service UUIDs will conform to the 16-bit Bluetooth base UUID,
+// 0000xxxx-0000-1000-8000-00805F9B34FB. This makes it possible to store two
+// byte service UUIDs in the advertisement.
+struct BleAdvertisementData {
+  using TxPowerLevel = int8_t;
+
+  static const TxPowerLevel kUnspecifiedTxPowerLevel =
+      std::numeric_limits<TxPowerLevel>::min();
+
+  bool is_connectable;
+  // When set to kUnspecifiedTxPowerLevel, TX power should not be included in
+  // the advertisement data.
+  TxPowerLevel tx_power_level;
+  // When set to an empty string, local name should not be included in the
+  // advertisement data.
+  std::string local_name;
+  // When set to an empty vector, the set of 16-bit service class UUIDs should
+  // not be included in the advertisement data.
+  std::set<std::string> service_uuids;
+  // Maps service UUIDs to their service data.
+  std::map<std::string, ByteArray> service_data;
+};
+
+// Opaque wrapper over a BLE peripheral. Must be able to uniquely identify a
+// peripheral so that we can connect to its GATT server.
+class BlePeripheral {
+ public:
+  virtual ~BlePeripheral() {}
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothDevice#getAddress()
+  //
+  // This should be the MAC address when possible. If the implementation is
+  // unable to retrieve that, any unique identifier should suffice.
+  virtual std::string GetId() const = 0;
+};
+
+// https://developer.android.com/reference/android/bluetooth/BluetoothGattCharacteristic
+//
+// Representation of a GATT characteristic.
+class GattCharacteristic {
+ public:
+  virtual ~GattCharacteristic() {}
+
+  // Possible permissions of a GATT characteristic.
+  enum class Permission {
+    kUnknown = 0,
+    kRead = 1,
+    kWrite = 2,
+    kLast,
+  };
+
+  // Possible properties of a GATT characteristic.
+  enum class Property {
+    kUnknown = 0,
+    kRead = 1,
+    kWrite = 2,
+    kIndicate = 3,
+    kLast,
+  };
+
+  // Returns the UUID of this characteristic.
+  virtual std::string GetUuid() = 0;
+
+  // Returns the UUID of the containing GATT service.
+  virtual std::string GetServiceUuid() = 0;
+};
+
+// https://developer.android.com/reference/android/bluetooth/BluetoothGatt
+//
+// Representation of a client GATT connection to a remote GATT server.
+class ClientGattConnection {
+ public:
+  virtual ~ClientGattConnection() {}
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#getDevice()
+  //
+  // Retrieves the BLE peripheral that this connection is tied to.
+  virtual BlePeripheral& GetPeripheral() = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#discoverServices()
+  //
+  // Discovers all available services and characteristics on this connection.
+  // Returns whether or not discovery finished successfully.
+  //
+  // This function should block until discovery has finished.
+  virtual bool DiscoverServices() = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#getService(java.util.UUID)
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGattService.html#getCharacteristic(java.util.UUID)
+  //
+  // Retrieves a GATT characteristic. On error, does not return a value.
+  //
+  // DiscoverServices() should be called before this method to fetch all
+  // available services and characteristics first.
+  //
+  // It is okay for duplicate services to exist, as long as the specified
+  // characteristic UUID is unique among all services of the same UUID.
+  virtual std::optional<GattCharacteristic> GetCharacteristic(
+      absl::string_view service_uuid,
+      absl::string_view characteristic_uuid) = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#readCharacteristic(android.bluetooth.BluetoothGattCharacteristic)
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGattCharacteristic.html#getValue()
+  //
+  // Reads a GATT characteristic. No value is returned upon error.
+  virtual std::optional<ByteArray> ReadCharacteristic(
+      const GattCharacteristic& characteristic) = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGattCharacteristic.html#setValue(byte[])
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#writeCharacteristic(android.bluetooth.BluetoothGattCharacteristic)
+  //
+  // Sends a remote characteristic write request to the server and returns
+  // whether or not it was successful.
+  virtual bool WriteCharacteristic(const GattCharacteristic& characteristic,
+                                   const ByteArray& value) = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#disconnect()
+  //
+  // Disconnects a GATT connection.
+  virtual void Disconnect() = 0;
+};
+
+// https://developer.android.com/reference/android/bluetooth/BluetoothGattServer
+//
+// Representation of a server GATT connection to a remote GATT client.
+class ServerGattConnection {
+ public:
+  virtual ~ServerGattConnection() {}
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGattCharacteristic.html#setValue(byte[])
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGattServer.html#notifyCharacteristicChanged(android.bluetooth.BluetoothDevice,%20android.bluetooth.BluetoothGattCharacteristic,%20boolean)
+  //
+  // Sends a notification (via indication) to the client that a characteristic
+  // has changed with the given value. Returns whether or not it was successful.
+  //
+  // The value sent does not have to reflect the locally stored characteristic
+  // value. To update the local value, call GattServer::UpdateCharacteristic.
+  virtual bool SendCharacteristic(const GattCharacteristic& characteristic,
+                                  const ByteArray& value) = 0;
+};
+
+// Callback for asynchronous events on the client side of a GATT connection.
+class ClientGattConnectionLifeCycleCallback {
+ public:
+  virtual ~ClientGattConnectionLifeCycleCallback() {}
+
+  // Called when the client is disconnected from the GATT server.
+  virtual void OnDisconnected(ClientGattConnection* connection) = 0;
+};
+
+// Callback for asynchronous events on the server side of a GATT connection.
+class ServerGattConnectionLifeCycleCallback {
+ public:
+  virtual ~ServerGattConnectionLifeCycleCallback() {}
+
+  // Called when a remote peripheral connected to us and subscribed to one of
+  // our characteristics.
+  virtual void OnCharacteristicSubscription(
+      ServerGattConnection* connection,
+      const GattCharacteristic& characteristic) = 0;
+
+  // Called when a remote peripheral unsubscribed from one of our
+  // characteristics.
+  virtual void OnCharacteristicUnsubscription(
+      ServerGattConnection* connection,
+      const GattCharacteristic& characteristic) = 0;
+};
+
+// https://developer.android.com/reference/android/bluetooth/BluetoothGattServer
+//
+// Representation of a BLE GATT server.
+class GattServer {
+ public:
+  virtual ~GattServer() {}
+
+  // Creates a characteristic and adds it to the GATT server under the given
+  // characteristic and service UUIDs. Returns no value upon error.
+  //
+  // Characteristics of the same service UUID should be put under one
+  // service rather than many services with the same UUID.
+  //
+  // If the INDICATE property is included, the characteristic should include the
+  // official Bluetooth Client Characteristic Configuration descriptor with UUID
+  // 0x2902 and a WRITE permission. This allows remote clients to write to this
+  // descriptor and subscribe for characteristic changes. For more information
+  // about this descriptor, please go to:
+  // https://www.bluetooth.com/specifications/Gatt/viewer?attributeXmlFile=org.bluetooth.descriptor.Gatt.client_characteristic_configuration.xml
+  virtual std::optional<GattCharacteristic> CreateCharacteristic(
+      absl::string_view service_uuid, absl::string_view characteristic_uuid,
+      const std::set<GattCharacteristic::Permission>& permissions,
+      const std::set<GattCharacteristic::Property>& properties) = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGattCharacteristic.html#setValue(byte[])
+  //
+  // Locally updates the value of a characteristic and returns whether or not it
+  // was successful.
+  // Takes ownership of (and is responsible for destroying) the passed-in
+  // 'value'.
+  virtual bool UpdateCharacteristic(const GattCharacteristic& characteristic,
+                                    const ByteArray& value) = 0;
+
+  // Stops a GATT server.
+  virtual void Stop() = 0;
+};
+
+// A BLE socket representation.
+class BleSocket {
+ public:
+  virtual ~BleSocket() {}
+
+  // Returns the remote BLE peripheral tied to this socket.
+  virtual BlePeripheral& GetRemotePeripheral() = 0;
+
+  // Writes a message on the socket and blocks until finished. Returns
+  // Exception::kIo upon error, and Exception::kSuccess otherwise.
+  virtual Exception Write(const ByteArray& message) = 0;
+
+  // Closes the socket and blocks until finished. Returns Exception::kIo upon
+  // error, and Exception::kSuccess otherwise.
+  virtual Exception Close() = 0;
+};
+
+// Callback for asynchronous events on a BleSocket object.
+class BleSocketLifeCycleCallback {
+ public:
+  virtual ~BleSocketLifeCycleCallback() {}
+
+  // Called when a message arrives on a socket.
+  virtual void OnMessageReceived(BleSocket* socket,
+                                 const ByteArray& message) = 0;
+
+  // Called when a socket gets disconnected.
+  virtual void OnDisconnected(BleSocket* socket) = 0;
+};
+
+// Callback for asynchronous events on the server side of a BleSocket object.
+class ServerBleSocketLifeCycleCallback : public BleSocketLifeCycleCallback {
+ public:
+  ~ServerBleSocketLifeCycleCallback() override {}
+
+  // Called when a new incoming socket has been established.
+  virtual void OnSocketEstablished(BleSocket* socket) = 0;
+};
+
+// The main BLE medium used inside of Nearby. This serves as the entry point for
+// all BLE and GATT related operations.
+class BleMedium {
+ public:
+  using Mtu = uint32_t;
+
+  virtual ~BleMedium() {}
+
+  // Coarse representation of power settings throughout all BLE operations.
+  enum class PowerMode {
+    kUnknown = 0,
+    kLow = 1,
+    kHigh = 2,
+    kLast,
+  };
+
+  // https://developer.android.com/reference/android/bluetooth/le/BluetoothLeAdvertiser.html#startAdvertising(android.bluetooth.le.AdvertiseSettings,%20android.bluetooth.le.AdvertiseData,%20android.bluetooth.le.AdvertiseData,%20android.bluetooth.le.AdvertiseCallback)
+  //
+  // Starts BLE advertising and returns whether or not it was successful.
+  //
+  // Power mode should be interpreted in the following way:
+  //   LOW:
+  //     - Advertising interval = ~1000ms
+  //     - TX power = low
+  //   HIGH:
+  //     - Advertising interval = ~100ms
+  //     - TX power = high
+  virtual bool StartAdvertising(const BleAdvertisementData& advertisement_data,
+                                const BleAdvertisementData& scan_response,
+                                PowerMode power_mode) = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/le/BluetoothLeAdvertiser.html#stopAdvertising(android.bluetooth.le.AdvertiseCallback)
+  //
+  // Stops advertising.
+  virtual void StopAdvertising() = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/le/ScanCallback
+  //
+  // Callback for BLE scan results.
+  class ScanCallback {
+   public:
+    virtual ~ScanCallback() {}
+
+    // https://developer.android.com/reference/android/bluetooth/le/ScanCallback.html#onScanResult(int,%20android.bluetooth.le.ScanResult)
+    //
+    // Called when a BLE advertisement is discovered.
+    //
+    // The passed in advertisement_data is the merged combination of both
+    // advertisement data and scan response.
+    //
+    // Every discovery of an advertisement should be reported, even if the
+    // advertisement was discovered before.
+    //
+    // Ownership of the BleAdvertisementData transfers to the caller at this
+    // point.
+    virtual void OnAdvertisementFound(
+        BlePeripheral* peripheral,
+        const BleAdvertisementData& advertisement_data) = 0;
+  };
+
+  // https://developer.android.com/reference/android/bluetooth/le/BluetoothLeScanner.html#startScan(java.util.List%3Candroid.bluetooth.le.ScanFilter%3E,%20android.bluetooth.le.ScanSettings,%20android.bluetooth.le.ScanCallback)
+  //
+  // Starts scanning and returns whether or not it was successful.
+  //
+  // Power mode should be interpreted in the following way:
+  //   LOW:
+  //     - Scan window = ~512ms
+  //     - Scan interval = ~5120ms
+  //   HIGH:
+  //     - Scan window = ~4096ms
+  //     - Scan interval = ~4096ms
+  virtual bool StartScanning(const std::set<std::string>& service_uuids,
+                             PowerMode power_mode,
+                             const ScanCallback& scan_callback) = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/le/BluetoothLeScanner.html#stopScan(android.bluetooth.le.ScanCallback)
+  //
+  // Stops scanning.
+  virtual void StopScanning() = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothManager#openGattServer(android.content.Context,%20android.bluetooth.BluetoothGattServerCallback)
+  //
+  // Starts a GATT server. Returns a nullptr upon error.
+  virtual std::unique_ptr<GattServer> StartGattServer(
+      const ServerGattConnectionLifeCycleCallback& callback) = 0;
+
+  // Starts listening for incoming BLE sockets and returns false upon error.
+  virtual bool StartListeningForIncomingBleSockets(
+      const ServerBleSocketLifeCycleCallback& callback) = 0;
+
+  // Stops listening for incoming BLE sockets.
+  virtual void StopListeningForIncomingBleSockets() = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothDevice.html#connectGatt(android.content.Context,%20boolean,%20android.bluetooth.BluetoothGattCallback)
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#requestConnectionPriority(int)
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#requestMtu(int)
+  //
+  // Connects to a GATT server and negotiates the specified connection
+  // parameters. Returns nullptr upon error.
+  //
+  // Both connection interval and MTU can be negotiated on a best-effort basis.
+  //
+  // Power mode should be interpreted in the following way:
+  //   LOW:
+  //     - Connection interval = ~11.25ms - 15ms
+  //   HIGH:
+  //     - Connection interval = ~100ms - 125ms
+  virtual std::unique_ptr<ClientGattConnection> ConnectToGattServer(
+      BlePeripheral* peripheral, Mtu mtu, PowerMode power_mode,
+      const ClientGattConnectionLifeCycleCallback& callback) = 0;
+
+  // Establishes a BLE socket to the specified remote peripheral. Returns
+  // nullptr on error.
+  virtual std::unique_ptr<BleSocket> EstablishBleSocket(
+      BlePeripheral* peripheral,
+      const BleSocketLifeCycleCallback& callback) = 0;
+};
+
+}  // namespace v2
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_BLE_V2_H_

cpp/platform/api2/bluetooth_adapter.h

@@ -0,0 +1,55 @@
+#ifndef PLATFORM_API2_BLUETOOTH_ADAPTER_H_
+#define PLATFORM_API2_BLUETOOTH_ADAPTER_H_
+
+#include <cstdint>
+#include <string>
+
+#include "absl/strings/string_view.h"
+
+namespace location {
+namespace nearby {
+
+// https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html
+class BluetoothAdapter {
+ public:
+  virtual ~BluetoothAdapter() {}
+
+  // Eligible statuses of the BluetoothAdapter.
+  enum class Status {
+    kDisabled,
+    kEnabled,
+  };
+
+  // Synchronously sets the status of the BluetoothAdapter to 'status', and
+  // returns true if the operation was a success.
+  virtual bool SetStatus(Status status) = 0;
+  // Returns true if the BluetoothAdapter's current status is
+  // Status::Value::kEnabled.
+  virtual bool IsEnabled() = 0;
+
+  // Scan modes of a BluetoothAdapter, as described at
+  // https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#getScanMode().
+  enum class ScanMode {
+    kUnknown,
+    kConnectableDiscoverable,
+  };
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#getScanMode()
+  //
+  // Returns ScanMode::kUnknown on error.
+  virtual ScanMode GetScanMode() = 0;
+  // Synchronously sets the scan mode of the adapter, and returns true if the
+  // operation was a success.
+  virtual bool SetScanMode(ScanMode scan_mode) = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#getName()
+  // Returns an empty string on error
+  virtual std::string GetName() const = 0;
+  // https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#setName(java.lang.String)
+  virtual bool SetName(absl::string_view name) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_BLUETOOTH_ADAPTER_H_

cpp/platform/api2/bluetooth_classic.h

@@ -0,0 +1,124 @@
+#ifndef PLATFORM_API2_BLUETOOTH_CLASSIC_H_
+#define PLATFORM_API2_BLUETOOTH_CLASSIC_H_
+
+#include <memory>
+#include <string>
+
+#include "platform/api2/input_stream.h"
+#include "platform/api2/output_stream.h"
+#include "platform/byte_array.h"
+#include "platform/exception.h"
+#include "absl/strings/string_view.h"
+
+namespace location {
+namespace nearby {
+
+// https://developer.android.com/reference/android/bluetooth/BluetoothDevice.html.
+class BluetoothDevice {
+ public:
+  virtual ~BluetoothDevice() {}
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothDevice.html#getName()
+  virtual std::string GetName() = 0;
+};
+
+// https://developer.android.com/reference/android/bluetooth/BluetoothSocket.html.
+class BluetoothSocket {
+ public:
+  virtual ~BluetoothSocket() {}
+
+  // Returns the InputStream of the BluetoothSocket.
+  virtual InputStream& GetInputStream() = 0;
+
+  // Returns the OutputStream of the BluetoothSocket.
+  virtual OutputStream& GetOutputStream() = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothSocket.html#close()
+  //
+  // Returns Exception::kIo on error, Exception::kSuccess otherwise.
+  virtual Exception Close() = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothSocket.html#getRemoteDevice()
+  virtual BluetoothDevice& GetRemoteDevice() = 0;
+};
+
+// https://developer.android.com/reference/android/bluetooth/BluetoothServerSocket.html.
+class BluetoothServerSocket {
+ public:
+  virtual ~BluetoothServerSocket() {}
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothServerSocket.html#accept()
+  //
+  // returns Exception::kIo on error.
+  virtual ExceptionOr<std::unique_ptr<BluetoothSocket>> Accept() = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothServerSocket.html#close()
+  //
+  // Returns Exception::kIo on error, Exception::kSuccess otherwise.
+  virtual Exception Close() = 0;
+};
+
+// Container of operations that can be performed over the Bluetooth Classic
+// medium.
+class BluetoothClassicMedium {
+ public:
+  virtual ~BluetoothClassicMedium() {}
+
+  class DiscoveryCallback {
+   public:
+    virtual ~DiscoveryCallback() {}
+
+    // BluetoothDevice* is not owned by callbacks.
+    // Pointer is guaranteed to remain valid for the duration of a call.
+    virtual void OnDeviceDiscovered(BluetoothDevice* device) = 0;
+    virtual void OnDeviceNameChanged(BluetoothDevice* device) = 0;
+    virtual void OnDeviceLost(BluetoothDevice* device) = 0;
+  };
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#startDiscovery()
+  //
+  // Returns true once the process of discovery has been initiated.
+  //
+  // Does not take ownership of the passed-in discovery_callback -- destroying
+  // that is up to the caller.
+  virtual bool StartDiscovery(const DiscoveryCallback& discovery_callback) = 0;
+  // https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#cancelDiscovery()
+  //
+  // Returns true once discovery is well and truly stopped; after this returns,
+  // there must be no more invocations of the DiscoveryCallback passed in to
+  // startDiscovery().
+  virtual bool StopDiscovery() = 0;
+
+  // A combination of
+  // https://developer.android.com/reference/android/bluetooth/BluetoothDevice.html#createInsecureRfcommSocketToServiceRecord
+  // followed by
+  // https://developer.android.com/reference/android/bluetooth/BluetoothSocket.html#connect().
+  //
+  // service_uuid is the canonical textual representation
+  // (https://en.wikipedia.org/wiki/Universally_unique_identifier#Format) of a
+  // type 3 name-based
+  // (https://en.wikipedia.org/wiki/Universally_unique_identifier#Versions_3_and_5_(namespace_name-based))
+  // UUID.
+  //
+  // On success, returns a new BluetoothSocket, wrapped in a ExceptionOr object.
+  // On error, returns Exception object.
+  virtual ExceptionOr<std::unique_ptr<BluetoothSocket>> ConnectToService(
+      BluetoothDevice* remote_device, absl::string_view service_uuid) = 0;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#listenUsingInsecureRfcommWithServiceRecord
+  //
+  // service_uuid is the canonical textual representation
+  // (https://en.wikipedia.org/wiki/Universally_unique_identifier#Format) of a
+  // type 3 name-based
+  // (https://en.wikipedia.org/wiki/Universally_unique_identifier#Versions_3_and_5_(namespace_name-based))
+  // UUID.
+  //
+  //  Returns Exception::kIo on error.
+  virtual ExceptionOr<std::unique_ptr<BluetoothServerSocket>> ListenForService(
+      absl::string_view service_name, absl::string_view service_uuid) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_BLUETOOTH_CLASSIC_H_

cpp/platform/api2/condition_variable.h

@@ -0,0 +1,26 @@
+#ifndef PLATFORM_API2_CONDITION_VARIABLE_H_
+#define PLATFORM_API2_CONDITION_VARIABLE_H_
+
+#include "platform/exception.h"
+
+namespace location {
+namespace nearby {
+
+// The ConditionVariable class is a synchronization primitive that can be used
+// to block a thread, or multiple threads at the same time, until another thread
+// both modifies a shared variable (the condition), and notifies the
+// ConditionVariable.
+class ConditionVariable {
+ public:
+  virtual ~ConditionVariable() {}
+
+  // https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#notify--
+  virtual void Notify() = 0;
+  // https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--
+  virtual Exception Wait() = 0;  // throws Exception::kInterrupted
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_CONDITION_VARIABLE_H_

cpp/platform/api2/count_down_latch.h

@@ -0,0 +1,29 @@
+#ifndef PLATFORM_API2_COUNT_DOWN_LATCH_H_
+#define PLATFORM_API2_COUNT_DOWN_LATCH_H_
+
+#include <cstdint>
+
+#include "platform/exception.h"
+#include "absl/time/time.h"
+
+namespace location {
+namespace nearby {
+
+// A synchronization aid that allows one or more threads to wait until a set of
+// operations being performed in other threads completes.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CountDownLatch.html
+class CountDownLatch {
+ public:
+  virtual ~CountDownLatch() {}
+
+  virtual Exception Await() = 0;  // throws Exception::kInterrupted
+  virtual ExceptionOr<bool> Await(
+      absl::Duration timeout) = 0;  // throws Exception::kInterrupted
+  virtual void CountDown() = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_COUNT_DOWN_LATCH_H_

cpp/platform/api2/executor.h

@@ -0,0 +1,26 @@
+#ifndef PLATFORM_API2_EXECUTOR_H_
+#define PLATFORM_API2_EXECUTOR_H_
+
+#include <memory>
+
+#include "platform/runnable.h"
+
+namespace location {
+namespace nearby {
+
+// This abstract class is the superclass of all classes representing an
+// Executor.
+class Executor {
+ public:
+  virtual ~Executor() = default;
+  // https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executor.html#execute-java.lang.Runnable-
+  virtual void Execute(std::unique_ptr<Runnable> runnable) = 0;
+
+  // https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ExecutorService.html#shutdown--
+  virtual void Shutdown() = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_EXECUTOR_H_

cpp/platform/api2/future.h

@@ -0,0 +1,30 @@
+#ifndef PLATFORM_API2_FUTURE_H_
+#define PLATFORM_API2_FUTURE_H_
+
+#include "platform/exception.h"
+#include "absl/time/time.h"
+
+namespace location {
+namespace nearby {
+
+// A Future represents the result of an asynchronous computation.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Future.html
+template <typename T>
+class Future {
+ public:
+  virtual ~Future() = default;
+
+  // throws Exception::kInterrupted, Exception::kExecution
+  virtual ExceptionOr<T> Get() = 0;
+
+  // throws Exception::kInterrupted, Exception::kExecution
+  // throws Exception::kTimeout if timeout is exceeded while waiting for
+  // result.
+  virtual ExceptionOr<T> Get(absl::Duration timeout) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_FUTURE_H_

cpp/platform/api2/hash_utils.h

@@ -0,0 +1,20 @@
+#ifndef PLATFORM_API2_HASH_UTILS_H_
+#define PLATFORM_API2_HASH_UTILS_H_
+
+#include "platform/byte_array.h"
+#include "absl/strings/string_view.h"
+
+namespace location {
+namespace nearby {
+
+// A provider of standard hashing algorithms.
+class HashUtils {
+ public:
+  static ByteArray Md5(absl::string_view input);
+  static ByteArray Sha256(absl::string_view input);
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_HASH_UTILS_H_

cpp/platform/api2/input_file.h

@@ -0,0 +1,24 @@
+#ifndef PLATFORM_API2_INPUT_FILE_H_
+#define PLATFORM_API2_INPUT_FILE_H_
+
+#include <cstdint>
+
+#include "platform/api2/input_stream.h"
+#include "platform/byte_array.h"
+#include "platform/exception.h"
+
+namespace location {
+namespace nearby {
+
+// An InputFile represents a readable file on the system.
+class InputFile : public InputStream {
+ public:
+  ~InputFile() override = default;
+  virtual std::string GetFilePath() const = 0;
+  virtual size_t GetTotalSize() const = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_INPUT_FILE_H_

cpp/platform/api2/input_stream.h

@@ -0,0 +1,27 @@
+#ifndef PLATFORM_API2_INPUT_STREAM_H_
+#define PLATFORM_API2_INPUT_STREAM_H_
+
+#include <cstdint>
+
+#include "platform/byte_array.h"
+#include "platform/exception.h"
+
+namespace location {
+namespace nearby {
+
+// An InputStream represents an input stream of bytes.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/io/InputStream.html
+class InputStream {
+ public:
+  virtual ~InputStream() {}
+
+  virtual ExceptionOr<ByteArray> Read(
+      size_t size) = 0;           // throws Exception::kIo
+  virtual Exception Close() = 0;  // throws Exception::kIo
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_INPUT_STREAM_H_

cpp/platform/api2/listenable_future.h

@@ -0,0 +1,29 @@
+#ifndef PLATFORM_API2_LISTENABLE_FUTURE_H_
+#define PLATFORM_API2_LISTENABLE_FUTURE_H_
+
+#include <memory>
+
+#include "platform/api2/executor.h"
+#include "platform/api2/future.h"
+#include "platform/exception.h"
+#include "platform/runnable.h"
+
+namespace location {
+namespace nearby {
+
+// A Future that accepts completion listeners.
+//
+// https://guava.dev/releases/20.0/api/docs/com/google/common/util/concurrent/ListenableFuture.html
+template <typename T>
+class ListenableFuture : public Future<T> {
+ public:
+  ~ListenableFuture() override = default;
+
+  virtual void AddListener(std::unique_ptr<Runnable> runnable,
+                           Executor* executor) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_LISTENABLE_FUTURE_H_

cpp/platform/api2/multi_thread_executor.h

@@ -0,0 +1,23 @@
+#ifndef PLATFORM_API2_MULTI_THREAD_EXECUTOR_H_
+#define PLATFORM_API2_MULTI_THREAD_EXECUTOR_H_
+
+#include "platform/api2/submittable_executor.h"
+
+namespace location {
+namespace nearby {
+
+// An Executor that reuses a fixed number of threads operating off a shared
+// unbounded queue.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executors.html#newFixedThreadPool-int-
+template <typename ConcreteSubmittableExecutor>
+class MultiThreadExecutor
+    : public SubmittableExecutor<ConcreteSubmittableExecutor> {
+ public:
+  ~MultiThreadExecutor() override {}
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_MULTI_THREAD_EXECUTOR_H_

cpp/platform/api2/mutex.h

@@ -0,0 +1,22 @@
+#ifndef PLATFORM_API2_MUTEX_H_
+#define PLATFORM_API2_MUTEX_H_
+
+namespace location {
+namespace nearby {
+
+// A lock is a tool for controlling access to a shared resource by multiple
+// threads.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/locks/Lock.html
+class Mutex {
+ public:
+  virtual ~Mutex() {}
+
+  virtual void Lock() = 0;
+  virtual void Unlock() = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_MUTEX_H_

cpp/platform/api2/output_file.h

@@ -0,0 +1,20 @@
+#ifndef PLATFORM_API2_OUTPUT_FILE_H_
+#define PLATFORM_API2_OUTPUT_FILE_H_
+
+#include "platform/api2/output_stream.h"
+#include "platform/byte_array.h"
+#include "platform/exception.h"
+
+namespace location {
+namespace nearby {
+
+// An OutputFile represents a writable file on the system.
+class OutputFile : public OutputStream {
+ public:
+  ~OutputFile() override = default;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_OUTPUT_FILE_H_

cpp/platform/api2/output_stream.h

@@ -0,0 +1,25 @@
+#ifndef PLATFORM_API2_OUTPUT_STREAM_H_
+#define PLATFORM_API2_OUTPUT_STREAM_H_
+
+#include "platform/byte_array.h"
+#include "platform/exception.h"
+
+namespace location {
+namespace nearby {
+
+// An OutputStream represents an output stream of bytes.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/io/OutputStream.html
+class OutputStream {
+ public:
+  virtual ~OutputStream() {}
+
+  virtual Exception Write(const ByteArray& data) = 0;  // throws Exception::kIo
+  virtual Exception Flush() = 0;                // throws Exception::kIo
+  virtual Exception Close() = 0;                // throws Exception::kIo
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_OUTPUT_STREAM_H_

cpp/platform/api2/scheduled_executor.h

@@ -0,0 +1,29 @@
+#ifndef PLATFORM_API2_SCHEDULED_EXECUTOR_H_
+#define PLATFORM_API2_SCHEDULED_EXECUTOR_H_
+
+#include <cstdint>
+#include <memory>
+
+#include "platform/api2/executor.h"
+#include "platform/cancelable.h"
+#include "platform/runnable.h"
+#include "absl/time/time.h"
+
+namespace location {
+namespace nearby {
+
+// An Executor that can schedule commands to run after a given delay, or to
+// execute periodically.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ScheduledExecutorService.html
+class ScheduledExecutor : public Executor {
+ public:
+  ~ScheduledExecutor() override = default;
+  virtual std::unique_ptr<Cancelable> Schedule(
+      std::unique_ptr<Runnable> runnable, absl::Duration duration) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_SCHEDULED_EXECUTOR_H_

cpp/platform/api2/server_sync.h

@@ -0,0 +1,60 @@
+#ifndef PLATFORM_API2_SERVER_SYNC_H_
+#define PLATFORM_API2_SERVER_SYNC_H_
+
+#include <string>
+
+#include "platform/byte_array.h"
+#include "absl/strings/string_view.h"
+
+namespace location {
+namespace nearby {
+
+// Abstraction that represents a Nearby endpoint exchanging data through
+// ServerSync Medium.
+class ServerSyncDevice {
+ public:
+  virtual ~ServerSyncDevice() = default;
+
+  virtual std::string GetName() const = 0;
+  virtual std::string GetGuid() const = 0;
+  virtual std::string GetOwnGuid() const = 0;
+};
+
+// Container of operations that can be performed over the Chrome Sync medium.
+class ServerSyncMedium {
+ public:
+  virtual ~ServerSyncMedium() = default;
+
+  virtual bool StartAdvertising(absl::string_view service_id,
+                                absl::string_view endpoint_id,
+                                const ByteArray& endpoint_info) = 0;
+  virtual void StopAdvertising(absl::string_view service_id) = 0;
+
+  class DiscoveredDeviceCallback {
+   public:
+    virtual ~DiscoveredDeviceCallback() = default;
+
+    // Called on a new ServerSyncDevice discovery.
+    virtual void OnDeviceDiscovered(ServerSyncDevice* device,
+                                    absl::string_view service_id,
+                                    absl::string_view endpoint_id,
+                                    const ByteArray& endpoint_info) = 0;
+    // Called when ServerSyncDevice is no longer reachable.
+    virtual void OnDeviceLost(ServerSyncDevice* device,
+                              absl::string_view service_id) = 0;
+  };
+
+  // Returns true once the Chrome Sync scan has been initiated.
+  virtual bool StartDiscovery(
+      absl::string_view service_id,
+      const DiscoveredDeviceCallback& discovered_device_callback) = 0;
+  // Returns true once Chrome Sync scan for service_id is well and truly
+  // stopped; after this returns, there must be no more invocations of the
+  // DiscoveredDeviceCallback passed in to startScanning() for service_id.
+  virtual void StopDiscovery(absl::string_view service_id) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_SERVER_SYNC_H_

cpp/platform/api2/settable_future.h

@@ -0,0 +1,24 @@
+#ifndef PLATFORM_API2_SETTABLE_FUTURE_H_
+#define PLATFORM_API2_SETTABLE_FUTURE_H_
+
+#include "platform/api2/listenable_future.h"
+
+namespace location {
+namespace nearby {
+
+// A SettableFuture is a type of Future whose result can be set.
+//
+// https://google.github.io/guava/releases/20.0/api/docs/com/google/common/util/concurrent/SettableFuture.html
+template <typename T>
+class SettableFuture : public ListenableFuture<T> {
+ public:
+  ~SettableFuture() override = default;
+
+  virtual bool Set(const T& value) = 0;
+  virtual bool SetException(Exception exception) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_SETTABLE_FUTURE_H_

cpp/platform/api2/single_thread_executor.h

@@ -0,0 +1,23 @@
+#ifndef PLATFORM_API2_SINGLE_THREAD_EXECUTOR_H_
+#define PLATFORM_API2_SINGLE_THREAD_EXECUTOR_H_
+
+#include "platform/api2/submittable_executor.h"
+
+namespace location {
+namespace nearby {
+
+// An Executor that uses a single worker thread operating off an unbounded
+// queue.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executors.html#newSingleThreadExecutor--
+template <typename ConcreteSubmittableExecutor>
+class SingleThreadExecutor
+    : public SubmittableExecutor<ConcreteSubmittableExecutor> {
+ public:
+  ~SingleThreadExecutor() override {}
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_SINGLE_THREAD_EXECUTOR_H_

cpp/platform/api2/socket.h

@@ -0,0 +1,25 @@
+#ifndef PLATFORM_API2_SOCKET_H_
+#define PLATFORM_API2_SOCKET_H_
+
+#include "platform/api2/input_stream.h"
+#include "platform/api2/output_stream.h"
+
+namespace location {
+namespace nearby {
+
+// A socket is an endpoint for communication between two machines.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/net/Socket.html
+class Socket {
+ public:
+  virtual ~Socket() {}
+
+  virtual InputStream& GetInputStream() = 0;
+  virtual OutputStream& GetOutputStream() = 0;
+  virtual void Close() = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_SOCKET_H_

cpp/platform/api2/submittable_executor.h

@@ -0,0 +1,42 @@
+#ifndef PLATFORM_API2_SUBMITTABLE_EXECUTOR_H_
+#define PLATFORM_API2_SUBMITTABLE_EXECUTOR_H_
+
+#include <memory>
+
+#include "platform/api2/executor.h"
+#include "platform/api2/future.h"
+#include "platform/callable.h"
+
+namespace location {
+namespace nearby {
+
+// Each per-platform concrete implementation is expected to extend from
+// SubmittableExecutor and provide an override of its submit() method.
+//
+// e.g.
+// class XyzSubmittableExecutor
+//                      : public SubmittableExecutor<XyzSubmittableExecutor> {
+//  public:
+//   template <typename T>
+//   std::unique_ptr<Future<T>> submit(std::unique_ptr<Callable<T>> callable) {
+//     ...
+//   }
+// }
+template <typename ConcreteSubmittableExecutor>
+class SubmittableExecutor : public Executor {
+ public:
+  ~SubmittableExecutor() override {}
+
+  template <typename T>
+  std::unique_ptr<Future<T>> Submit(std::unique_ptr<Callable<T>> callable) {
+    static_assert(
+        std::is_base_of_v<SubmittableExecutor, ConcreteSubmittableExecutor>,
+        "Class template type is not derived from SubmittableExecutor");
+    return static_cast<ConcreteSubmittableExecutor*>(this)->submit(callable);
+  }
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_SUBMITTABLE_EXECUTOR_H_

cpp/platform/api2/system_clock.h

@@ -0,0 +1,22 @@
+#ifndef PLATFORM_API2_SYSTEM_CLOCK_H_
+#define PLATFORM_API2_SYSTEM_CLOCK_H_
+
+#include <cstdint>
+
+#include "absl/time/time.h"
+
+namespace location {
+namespace nearby {
+
+class SystemClock final {
+ public:
+  // Returns the time (in milliseconds) since the system was booted, and
+  // includes deep sleep. This clock should be guaranteed to be monotonic, and
+  // should continue to tick even when the CPU is in power saving modes.
+  static absl::Time ElapsedRealtime();
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_SYSTEM_CLOCK_H_

cpp/platform/api2/thread_utils.h

@@ -0,0 +1,22 @@
+#ifndef PLATFORM_API2_THREAD_UTILS_H_
+#define PLATFORM_API2_THREAD_UTILS_H_
+
+#include <cstdint>
+
+#include "platform/exception.h"
+#include "absl/time/time.h"
+
+namespace location {
+namespace nearby {
+
+class ThreadUtils final {
+ public:
+  // https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html#sleep(long)
+  // throws Exception::kInterrupted
+  static Exception Sleep(absl::Duration timeout);
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_THREAD_UTILS_H_

cpp/platform/api2/webrtc.h

@@ -0,0 +1,46 @@
+#ifndef PLATFORM_API2_WEBRTC_H_
+#define PLATFORM_API2_WEBRTC_H_
+
+#include <vector>
+
+#include "platform/byte_array.h"
+#include "webrtc/files/stable/webrtc/api/peer_connection_interface.h"
+
+namespace location {
+namespace nearby {
+
+class WebRtcSignalingMessenger {
+ public:
+  virtual ~WebRtcSignalingMessenger() = default;
+
+  /** Called whenever we receive an inbox message from tachyon. */
+  class SignalingMessageListener {
+   public:
+    virtual ~SignalingMessageListener() = default;
+
+    virtual void OnSignalingMessage(const ByteArray& message) = 0;
+  };
+
+  class IceServersListener {
+   public:
+    virtual ~IceServersListener() = default;
+
+    virtual void OnIceServersFetched(
+        std::vector<webrtc::PeerConnectionInterface::IceServer>
+            ice_servers) = 0;
+  };
+
+  virtual bool RegisterSignaling() = 0;
+  virtual bool UnregisterSignaling() = 0;
+  virtual bool SendMessage(std::string_view peer_id,
+                           const ByteArray& message) = 0;
+  virtual bool StartReceivingMessages(
+      const SignalingMessageListener& listener) = 0;
+  virtual void GetIceServers(
+      const IceServersListener& ice_servers_listener) = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_WEBRTC_H_

cpp/platform/api2/wifi.h

@@ -0,0 +1,88 @@
+#ifndef PLATFORM_API2_WIFI_H_
+#define PLATFORM_API2_WIFI_H_
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include "absl/strings/string_view.h"
+
+namespace location {
+namespace nearby {
+
+// Possible authentication types for a WiFi network.
+enum class WifiAuthType {
+  // WiFi Authentication type; either none (non-secured a.k.a. open) link, or
+  // WPA PSK (WiFi Protected Access PreShared Key), or
+  //   see https://en.wikipedia.org/wiki/Wi-Fi_Protected_Access
+  // WEP (Wired Equivalent Privacy);
+  //   see https://en.wikipedia.org/wiki/Wired_Equivalent_Privacy
+  kUnknown = 0,
+  kOpen = 1,
+  kWpaPsk = 2,
+  kWep = 3,
+};
+
+// Possible statuses of a device's connection to a WiFi network.
+enum class WifiConnectionStatus {
+  kUnknown = 0,
+  kConnected = 1,
+  kConnectionFailure = 2,
+  kAuthFailure = 3,
+};
+
+// Represents a WiFi network found during a call to WifiMedium#scan().
+class WifiScanResult {
+ public:
+  virtual ~WifiScanResult() {}
+
+  // Gets the SSID of this WiFi network.
+  virtual std::string GetSsid() const = 0;
+  // Gets the signal strength of this WiFi network in dBm.
+  virtual std::int32_t GetSignalStrengthDbm() const = 0;
+  // Gets the frequency band of this WiFi network in MHz.
+  virtual std::int32_t GetFrequencyMhz() const = 0;
+  // Gets the authentication type of this WiFi network.
+  virtual WifiAuthType GetAuthType() const = 0;
+};
+
+// Container of operations that can be performed over the WiFi medium.
+class WifiMedium {
+ public:
+  virtual ~WifiMedium() {}
+
+  class ScanResultCallback {
+   public:
+    virtual ~ScanResultCallback() {}
+
+    virtual void OnScanResults(
+        const std::vector<WifiScanResult>& scan_results) = 0;
+  };
+
+  // Does not take ownership of the passed-in scan_result_callback -- destroying
+  // that is up to the caller.
+  virtual bool Scan(const ScanResultCallback& scan_result_callback) = 0;
+
+  // If 'password' is an empty string, none has been provided. Returns
+  // WifiConnectionStatus::CONNECTED on success, or the appropriate failure code
+  // otherwise.
+  virtual WifiConnectionStatus ConnectToNetwork(absl::string_view ssid,
+                                                absl::string_view password,
+                                                WifiAuthType auth_type) = 0;
+
+  // Blocks until it's certain of there being a connection to the internet, or
+  // returns false if it fails to do so.
+  //
+  // How this method wants to verify said connection is totally up to it (so it
+  // can feel free to ping whatever server, download whatever resource, etc.
+  // that it needs to gain confidence that the internet is reachable hereon in).
+  virtual bool VerifyInternetConnectivity() = 0;
+
+  // Returns the local device's IP address in the IPv4 dotted-quad format.
+  virtual std::string GetIpAddress() = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_WIFI_H_

cpp/platform/base64_utils.cc

@@ -1,6 +1,5 @@
 #include "platform/base64_utils.h"
 
-#include "strings/escaping.h"
 #include "absl/strings/escaping.h"
 
 namespace location {
@@ -25,7 +24,7 @@ std::string Base64Utils::encode(const ByteArray& bytes) {
   return base64_string;
 }
 
-std::string Base64Utils::encode(const std::string& input) {
+std::string Base64Utils::encode(absl::string_view input) {
   std::string base64_string;
   absl::WebSafeBase64Escape(input, &base64_string);
 
@@ -33,7 +32,7 @@ std::string Base64Utils::encode(const std::string& input) {
 }
 
 template<>
-Ptr<ByteArray> Base64Utils::decode(const std::string& base64_string) {
+Ptr<ByteArray> Base64Utils::decode(absl::string_view base64_string) {
   std::string decoded_string;
   if (!absl::WebSafeBase64Unescape(base64_string, &decoded_string)) {
     return Ptr<ByteArray>();
@@ -43,7 +42,7 @@ Ptr<ByteArray> Base64Utils::decode(const std::string& base64_string) {
 }
 
 template<>
-ByteArray Base64Utils::decode(const std::string& base64_string) {
+ByteArray Base64Utils::decode(absl::string_view base64_string) {
   std::string decoded_string;
   if (!absl::WebSafeBase64Unescape(base64_string, &decoded_string)) {
     return ByteArray();

cpp/platform/base64_utils.h

@@ -4,23 +4,24 @@
 #include "platform/byte_array.h"
 #include "platform/port/string.h"
 #include "platform/ptr.h"
+#include "absl/strings/string_view.h"
 
 namespace location {
 namespace nearby {
 
 class Base64Utils {
  public:
-  static std::string encode(const std::string& input);
+  static std::string encode(absl::string_view input);
   static std::string encode(const ByteArray& bytes);
   static std::string encode(ConstPtr<ByteArray> bytes);
 
   template <typename T>
-  static T decode(const std::string& base64_string);
+  static T decode(absl::string_view base64_string);
   template <>
-  Ptr<ByteArray> decode(const std::string& base64_string);
+  Ptr<ByteArray> decode(absl::string_view base64_string);
   template <>
-  ByteArray decode(const std::string& base64_string);
-  static Ptr<ByteArray> decode(const std::string& base64_string) {
+  ByteArray decode(absl::string_view base64_string);
+  static Ptr<ByteArray> decode(absl::string_view base64_string) {
     return decode<Ptr<ByteArray>>(base64_string);
   }
 };

cpp/platform/exception.cc

@@ -1,30 +0,0 @@
-#include "platform/exception.h"
-
-namespace location {
-namespace nearby {
-
-template <typename T>
-ExceptionOr<T>::ExceptionOr(T result)
-    : result_(result), exception_(Exception::NONE) {}
-
-template <typename T>
-ExceptionOr<T>::ExceptionOr(Exception::Value exception)
-    : result_(), exception_(exception) {}
-
-template <typename T>
-bool ExceptionOr<T>::ok() const {
-  return Exception::NONE == exception_;
-}
-
-template <typename T>
-T ExceptionOr<T>::result() const {
-  return result_;
-}
-
-template <typename T>
-Exception::Value ExceptionOr<T>::exception() const {
-  return exception_;
-}
-
-}  // namespace nearby
-}  // namespace location

cpp/platform/exception.h

@@ -1,21 +1,34 @@
 #ifndef PLATFORM_EXCEPTION_H_
 #define PLATFORM_EXCEPTION_H_
 
+#include <utility>
+
 namespace location {
 namespace nearby {
 
 struct Exception {
-  enum Value {
+  enum Value : int {
     NONE,
     IO,
     INTERRUPTED,
     INVALID_PROTOCOL_BUFFER,
     EXECUTION,
+    // New code should use the kConstants.
+    // Old CONSTANTS are deprecated, and should not be used.
+    kFailed = -1,  // Initial value of Exception; any unknown error.
+    kSuccess = NONE,  // No exception.
+    kIo = IO,  // IO Error happened.
+    kInterrupted = INTERRUPTED,  // Operation was interrupted.
+    kInvalidProtocolBuffer = INVALID_PROTOCOL_BUFFER,  // Couldn't parse.
+    kExecution = EXECUTION,  // Couldn't execute.
+    kTimeout,  // Operarion did not finish within specified time.
   };
+  Value value {kFailed};
 };
 
-// ExceptionOr models the concept of the return value of a function that might
-// throw an exception.
+// ExceptionOr provides experience similar to StatusOr<T> used in
+// Google Cloud API, see:
+// https://googleapis.github.io/google-cloud-cpp/0.7.0/common/status__or_8h_source.html
 //
 // If ok() returns true, result() is a usable return value. Otherwise,
 // exception() explains why such a value is not present.
@@ -36,22 +49,31 @@ struct Exception {
 template <typename T>
 class ExceptionOr {
  public:
-  explicit ExceptionOr(T result);
-  explicit ExceptionOr(Exception::Value exception);
+  ExceptionOr() = default;
+  ExceptionOr(T&& result) : result_{std::move(result)},  // NOLINT
+                            exception_{Exception::kSuccess} {}
+  ExceptionOr(const T& result) : result_{result},  // NOLINT
+                                 exception_{Exception::kSuccess} {}
+  ExceptionOr(Exception::Value exception) : exception_{exception} {}  // NOLINT
 
-  bool ok() const;
+  bool ok() const { return exception_.value == Exception::kSuccess; }
 
-  T result() const;
-  Exception::Value exception() const;
+  T& result() & { return result_; }
+  const T& result() const & { return result_; }
+  T&& result() && { return std::move(result_); }
+  const T&& result() const && { return std::move(result_); }
+
+  Exception::Value exception() const { return exception_.value; }
+
+  T GetResult() const;
+  Exception GetException() const;
 
  private:
   T result_;
-  Exception::Value exception_;
+  Exception exception_ {Exception::kFailed};
 };
 
 }  // namespace nearby
 }  // namespace location
 
-#include "platform/exception.cc"
-
 #endif  // PLATFORM_EXCEPTION_H_

cpp/platform/exception_test.cc

@@ -0,0 +1,76 @@
+#include "platform/exception.h"
+
+#include <vector>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+namespace location::nearby {
+
+TEST(ExceptionOr, Result_Copy_NonConst) {
+  ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
+  EXPECT_FALSE(exception_or_vector.result().empty());
+
+  // Expect a copy when not explicitly moving the result.
+  std::vector<int> copy = exception_or_vector.result();
+  EXPECT_FALSE(copy.empty());
+  EXPECT_FALSE(exception_or_vector.result().empty());
+
+  // Modifying |exception_or_vector| should not affect the copy.
+  exception_or_vector.result().clear();
+  EXPECT_FALSE(copy.empty());
+}
+
+TEST(ExceptionOr, Result_Copy_Const) {
+  const ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
+  EXPECT_FALSE(exception_or_vector.result().empty());
+
+  // Expect a copy when not explicitly moving the result.
+  std::vector<int> copy = exception_or_vector.result();
+  EXPECT_FALSE(copy.empty());
+  EXPECT_FALSE(exception_or_vector.result().empty());
+}
+
+TEST(ExceptionOr, Result_Reference_NonConst) {
+  ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
+  EXPECT_FALSE(exception_or_vector.result().empty());
+
+  // Getting a reference should not modify the source.
+  std::vector<int>& reference = exception_or_vector.result();
+  EXPECT_FALSE(reference.empty());
+  EXPECT_FALSE(exception_or_vector.result().empty());
+
+  // Modifying |exception_or_vector| should reflect in the reference.
+  exception_or_vector.result().clear();
+  EXPECT_TRUE(reference.empty());
+}
+
+TEST(ExceptionOr, Result_Reference_Const) {
+  const ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
+  EXPECT_FALSE(exception_or_vector.result().empty());
+
+  // Getting a reference should not modify the source.
+  const std::vector<int>& reference = exception_or_vector.result();
+  EXPECT_FALSE(reference.empty());
+  EXPECT_FALSE(exception_or_vector.result().empty());
+}
+
+TEST(ExceptionOr, Result_Move_NonConst) {
+  ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
+  ASSERT_FALSE(exception_or_vector.result().empty());
+
+  // Moving the result should clear the source.
+  std::vector<int> moved = std::move(exception_or_vector).result();
+  ASSERT_FALSE(moved.empty());
+}
+
+TEST(ExceptionOr, Result_Move_Const) {
+  const ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
+  ASSERT_FALSE(exception_or_vector.result().empty());
+
+  // Moving const rvalue reference will result in a copy.
+  std::vector<int> moved = std::move(exception_or_vector).result();
+  ASSERT_FALSE(moved.empty());
+}
+
+}  // namespace location::nearby

cpp/platform/impl/default/BUILD

@@ -1,8 +1,6 @@
 cc_library(
     name = "default",
     srcs = [
-        "default_condition_variable.cc",
-        "default_lock.cc",
         "default_platform.cc",
     ],
     hdrs = [
@@ -15,6 +13,8 @@ cc_library(
         "//core:__subpackages__",
     ],
     deps = [
+        ":condition_variable",
+        ":lock",
         "//platform:types",
         "//platform/api",
     ],
@@ -38,7 +38,7 @@ cc_library(
         "//platform:__subpackages__",
     ],
     deps = [
-        ":default",
+        ":lock",
         "//platform:types",
         "//platform/api:condition_variable",
     ],

cpp/platform/ptr.cc

@@ -1,13 +0,0 @@
-#include "platform/ptr.h"
-
-namespace location {
-namespace nearby {
-
-namespace ptr_impl {
-
-const std::int32_t RefCount::kInitialCount = 0;
-
-}  // namespace ptr_impl
-
-}  // namespace nearby
-}  // namespace location

cpp/platform/ptr.h

@@ -4,78 +4,15 @@
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
+#include <memory>
+#include <type_traits>
 
-#include "platform/impl/default/default_lock.h"
 #include "platform/logging.h"
 #include "platform/port/down_cast.h"
 
 namespace location {
 namespace nearby {
 
-namespace ptr_impl {
-
-class RefCount {
- public:
-  RefCount() : lock_(), count_(kInitialCount) {}
-
-  // Returns false if this operation doesn't make conceptual sense any more
-  // (for example, if it leads to bringing count_ back from the dead).
-  bool increment() {
-    bool result;
-
-    lock_.lock();
-    {
-      // Avoid coming back from the dead.
-      if (count_ < kInitialCount) {
-        result = false;
-      } else {
-        count_++;
-        result = true;
-      }
-    }
-    lock_.unlock();
-
-    return result;
-  }
-
-  // Returns true if after this operation, count_ is 0.
-  bool decrement() {
-    bool result;
-
-    lock_.lock();
-    {
-      // It's alright for count_ to go negative because it will only be exactly
-      // 0 once (since increment() makes sure that once you go negative, you
-      // can't come back from the dead).
-      count_--;
-      result = (count_ == 0);
-    }
-    lock_.unlock();
-
-    return result;
-  }
-
- private:
-  static const std::int32_t kInitialCount;
-
-  DefaultLock lock_;
-  std::int32_t count_;
-};
-
-}  // namespace ptr_impl
-
-template <typename T>
-class ObjectDestroyer {
- public:
-  static void destroy(T* t) { delete t; }
-};
-
-template <typename T>
-class ArrayDestroyer {
- public:
-  static void destroy(T* t) { delete[] t; }
-};
-
 // Forward declarations to make it possible for Ptr (a class template) to
 // declare ConstifyPtr, DowncastPtr, and DowncastConstPtr (function templates)
 // as friends.
@@ -85,7 +22,7 @@ class ArrayDestroyer {
 // Ptr (which is what one might reasonably expect).
 //
 // See https://isocpp.org/wiki/faq/templates#template-friends for more.
-template <typename T, template <typename> class Destroyer = ObjectDestroyer>
+template <typename T>
 class Ptr;
 template <typename T>
 class ConstPtr;
@@ -96,128 +33,74 @@ Ptr<ChildT> DowncastPtr(Ptr<BaseT> base_ptr);
 template <typename ChildT, typename BaseT>
 ConstPtr<ChildT> DowncastConstPtr(ConstPtr<BaseT> base_ptr);
 
-// A layer of indirection over a raw pointer, to buy flexibility in the
-// future to use, for instance:
-//
-// a) the in-built shared_ptr in modern implementations of C++,
-// b) a custom reference-counting mechanism, etc.
-//
-// , all without having to touch every line of our codebase that uses
-// pointers.
-//
-// Destroyer defines how the owned pointee should be destroyed, and is
-// expected to be a class template that provides at least a destroy()
-// method, like so:
-//
-// template <typename T>
-// class MyDestroyer {
-// public:
-//   static void destroy(T* t);
-// };
-//
-// It defaults to ObjectDestroyer<T>.
-template <typename T, template <typename> class Destroyer>
+// A layer of indirection over a raw pointer.
+// It is being deprecated in favor of standard c++ smart pointers.
+// For transion period, Ptr<T> will behave similar to shared_ptr<T>.
+// New code should use shrared_ptr<T> or unique_ptr<T> and not Ptr<T>.
+template <typename T>
 class Ptr {
  public:
   // Provide an alias for use as a dependent name.
   typedef T PointeeType;
 
-  Ptr() : pointee_(nullptr), ref_count_(nullptr) {}
-  explicit Ptr(T* pointee, bool is_ref_counted = false,
-               ptr_impl::RefCount* ref_count = nullptr)
-      : pointee_(pointee),
-        ref_count_(
-            is_ref_counted
-                ? (ref_count != nullptr ? ref_count : new ptr_impl::RefCount())
-                : nullptr) {
-    init();
-  }
-  Ptr(const Ptr& that) : pointee_(that.pointee_), ref_count_(that.ref_count_) {
-    init();
-  }
+  Ptr() = default;
+  explicit Ptr(T* pointee) : ptr_(pointee) {}
+  Ptr(const Ptr& that) = default;
 
-  Ptr& operator=(const Ptr& other) {
-    if (pointee_ != other.pointee_) {
-      // If we're not currently ref-counted, then an assignment shouldn't lead
-      // to any destruction of our past state -- that's the responsibility of
-      // whichever instance of Ptr believes it owns pointee_.
-      destroy(false);
+  Ptr(std::shared_ptr<T> ptr) : ptr_(ptr) {}  // NOLINT
 
-      pointee_ = other.pointee_;
-      ref_count_ = other.ref_count_;
-
-      init();
-    }
+  template <typename T2>
+  Ptr<T>& operator=(T2* ptr) {
+    Ptr<T> tmp(ptr);
+    this->ptr_.swap(tmp);
     return *this;
   }
 
+  Ptr& operator=(const Ptr& other) = default;
+
   // Conversion to Ptr<T2>, where T is trivially convertible to T2.  E.g.
   // conversion from derived to base class.
   template <typename T2>
-  operator Ptr<T2>() {
-    return Ptr<T2>(pointee_, isRefCounted(), ref_count_);
+  operator Ptr<T2>() {  // NOLINT
+    return Ptr<T2>(std::static_pointer_cast<T2>(this->ptr_));
+  }
+  operator Ptr() {  // NOLINT
+    return Ptr(*this);
   }
 
-  ~Ptr() {
-    if (isRefCounted()) {
-      destroy();
-    } else {
-      // Left empty on purpose.
-    }
-  }
+  explicit operator std::shared_ptr<T>() { return this->ptr_; }
+
+  ~Ptr() = default;
 
   bool operator==(const Ptr& other) const {
-    assert(!(this->isNull()));
-    assert(!(other.isNull()));
-
-    return ((*(this->pointee_) == *(other.pointee_)) &&
-            (this->isRefCounted() == other.isRefCounted()));
+    return *(this->ptr_) == *(other.ptr_);
   }
-
   bool operator!=(const Ptr& other) const { return !(*this == other); }
 
   bool operator<(const Ptr& other) const {
-    assert(!(this->isNull()));
-    assert(!(other.isNull()));
-
-    return *(this->pointee_) < *(other.pointee_);
+    return *(this->ptr_) < *(other.ptr_);
   }
 
-  // Calls Destroyer::destroy() to perform deallocation of pointee_.
-  void destroy(bool should_destroy_if_not_ref_counted = true) {
-    bool need_to_destroy = isRefCounted() ? ref_count_->decrement()
-                                          : should_destroy_if_not_ref_counted;
-    if (need_to_destroy) {
-      delete ref_count_;
-      Destroyer<T>::destroy(pointee_);
-    }
+  // No-op: refcounted objects will be destroyed correctly
+  ABSL_DEPRECATED("Use c++ smart pointers directly instead of Ptr<T>")
+  void destroy(bool = true) {}
 
-    ref_count_ = NULL;  // NOLINT
-    pointee_ = NULL;    // NOLINT
-  }
+  // No-op: refcounted objects will be destroyed correctly
+  ABSL_DEPRECATED("Use c++ smart pointers directly instead of Ptr<T>")
+  void clear() {}
 
-  // Use this function only when the ownership is held by someone else, and this
-  // Ptr object has no responsibility to destroy it.
-  void clear() {
-    if (isRefCounted()) {
-      NEARBY_LOG(FATAL, "Attempting to invoke clear() on a RefCounted Ptr.");
-    }
+  T& operator*() const { return *ptr_; }
 
-    pointee_ = NULL;  // NOLINT
-  }
+  T* operator->() const { return ptr_.get(); }
+  T* get() { return ptr_.get(); }
+  void reset() { return ptr_.reset(); }
 
-  T& operator*() const {
-    assert(pointee_ != NULL);  // NOLINT
-    return *pointee_;
-  }
+  ABSL_DEPRECATED("Use c++ smart pointers directly instead of Ptr<T>")
+  bool isNull() const { return !this->ptr_; }
 
-  T* operator->() const {
-    assert(pointee_ != NULL);  // NOLINT
-    return pointee_;
-  }
-
-  bool isNull() const { return pointee_ == nullptr; }
-  bool isRefCounted() const { return ref_count_ != nullptr; }
+  // used by pipe.cc; introduced by cr/295271652
+  ABSL_DEPRECATED("Use c++ smart pointers directly instead of Ptr<T>")
+  bool isRefCounted() const { return true; }
 
  private:
   template <typename PointeeT>
@@ -227,16 +110,7 @@ class Ptr {
   template <typename ChildT, typename BaseT>
   friend ConstPtr<ChildT> DowncastConstPtr(ConstPtr<BaseT> base_ptr);
 
-  void init() {
-    if (isRefCounted()) {
-      if (!ref_count_->increment()) {
-        NEARBY_LOG(FATAL, "Failed to increment RefCount.");
-      }
-    }
-  }
-
-  T* pointee_;
-  ptr_impl::RefCount* ref_count_;
+  std::shared_ptr<T> ptr_;
 };
 
 // Convenience wrapper for a read-only version of Ptr (in which the pointee
@@ -259,9 +133,9 @@ template <typename T>
 class ConstPtr : public Ptr<T const> {
  public:
   ConstPtr() {}
-  explicit ConstPtr(T* pointee, bool is_ref_counted = false,
-                    ptr_impl::RefCount* ref_count = nullptr)
-      : Ptr<T const>(pointee, is_ref_counted, ref_count) {}
+  explicit ConstPtr(const T* pointee) : Ptr<T const>(pointee) {}
+  explicit ConstPtr(T* pointee) : Ptr<T const>(pointee) {}
+  explicit ConstPtr(Ptr<T> ptr) : Ptr<T const>(ptr) {}
 };
 
 // RAII wrapper over Ptr and ConstPtr (hereon referred to by the PtrType
@@ -291,33 +165,29 @@ class ScopedPtr {
  public:
   explicit ScopedPtr(typename PtrType::PointeeType* pointee) : ptr_(pointee) {}
   explicit ScopedPtr(PtrType ptr) : ptr_(ptr) {}
-  ~ScopedPtr() { ptr_.destroy(); }
+  ScopedPtr(const ScopedPtr&) = delete;
+  ~ScopedPtr() = default;
+
+  ScopedPtr& operator=(const ScopedPtr&) = delete;
 
   // Shadow methods for the underlying Ptr.
-  typename PtrType::PointeeType& operator*() const { return ptr_.operator*(); }
+  typename PtrType::PointeeType& operator*() const { return *ptr_; }
   typename PtrType::PointeeType* operator->() const {
     return ptr_.operator->();
   }
   bool isNull() const { return ptr_.isNull(); }
 
   // Accessor for the underlying Ptr.
-  PtrType get() const { return ptr_; }
+  PtrType get() const { return this->ptr_; }
 
-  // Releases the underlying Ptr from the clutches of this ScopedPtr,
-  // effectively resetting this ScopedPtr (and making its destructor be a no-op)
-  // -- useful for transfer of ownership from one ScopedPtr to another across
-  // scopes.
+  // Does nothing;
+  // this is to avoid unintended destruction of a managed pointer.
+  // TODO(b/149938110): remove this completely.
   PtrType release() {
-    PtrType released = ptr_;
-    ptr_ = PtrType();
-    return released;
+    return ptr_;
   }
 
  private:
-  // Disallow copy and assignment.
-  ScopedPtr(const ScopedPtr&);
-  ScopedPtr& operator=(const ScopedPtr&);
-
   PtrType ptr_;
 };
 
@@ -358,19 +228,19 @@ ConstPtr<T> MakeConstPtr(T* raw_ptr) {
 // reference).
 template <typename T>
 Ptr<T> MakeRefCountedPtr(T* raw_ptr) {
-  return Ptr<T>(raw_ptr, true);
+  return Ptr<T>(raw_ptr);
 }
 
 // ConstPtr counterpart to MakeRefCountedPtr().
 template <typename T>
 ConstPtr<T> MakeRefCountedConstPtr(T* raw_ptr) {
-  return ConstPtr<T>(raw_ptr, true);
+  return ConstPtr<T>(raw_ptr);
 }
 
 // Use this function to convert a Ptr object to a ConstPtr object.
 template <typename T>
 ConstPtr<T> ConstifyPtr(Ptr<T> ptr) {
-  return ConstPtr<T>(ptr.pointee_, ptr.isRefCounted(), ptr.ref_count_);
+  return ConstPtr<T>(ptr);
 }
 
 // Use this function to downcast from a Ptr<BaseT> to a Ptr<ChildT>.
@@ -382,16 +252,16 @@ ConstPtr<T> ConstifyPtr(Ptr<T> ptr) {
 //         Ptr<MyChild> my_child_ptr = DowncastPtr<MyChild>(my_base_ptr);
 template <typename ChildT, typename BaseT>
 Ptr<ChildT> DowncastPtr(Ptr<BaseT> base_ptr) {
-  return Ptr<ChildT>(DOWN_CAST<ChildT*>(base_ptr.pointee_),
-                     base_ptr.isRefCounted(), base_ptr.ref_count_);
+  static_assert(std::is_base_of_v<BaseT, ChildT>);
+  return Ptr<ChildT>(std::static_pointer_cast<ChildT>(base_ptr.ptr_));
 }
 
 // ConstPtr counterpart to DowncastPtr().
 template <typename ChildT, typename BaseT>
 ConstPtr<ChildT> DowncastConstPtr(ConstPtr<BaseT> base_ptr) {
+  static_assert(std::is_base_of_v<BaseT, ChildT>);
   return ConstPtr<ChildT>(
-      const_cast<ChildT*>(DOWN_CAST<const ChildT*>(base_ptr.pointee_)),
-      base_ptr.isRefCounted(), base_ptr.ref_count_);
+      std::static_pointer_cast<const ChildT>(base_ptr.ptr_));
 }
 
 }  // namespace nearby

cpp/platform/ptr_test.cc

@@ -22,15 +22,6 @@ TEST(PtrTest, RefCountedPtr_MultipleReferences) {
   SUCCEED();
 }
 
-TEST(PtrTest, RefCountedPtr_IsRefCounted_Works) {
-  Ptr<int> ref_counted = MakeRefCountedPtr(new int(1234));
-  Ptr<int> manually_counted = MakePtr(new int(1234));
-  ScopedPtr<Ptr<int> > scoped_manually_counted(manually_counted);
-
-  ASSERT_TRUE(ref_counted.isRefCounted());
-  ASSERT_FALSE(manually_counted.isRefCounted());
-}
-
 TEST(PtrTest, RefCountedPtr_MultipleReferencesWithScoped) {
   Ptr<int> ref_counted = MakeRefCountedPtr(new int(1234));
   ScopedPtr<Ptr<int> > scoped_ref_counted_1(ref_counted);
@@ -51,60 +42,6 @@ TEST(PtrTest, AssignmentOperator_RefCountedToRefCounted) {
   ASSERT_EQ(1234, *ref_counted_2);
 }
 
-TEST(PtrTest, AssignmentOperator_ManuallyCountedToManuallyCounted) {
-  Ptr<int> manually_counted_1 = MakePtr(new int(1234));
-  Ptr<int> manually_counted_2 = MakePtr(new int(5678));
-  // Avoid leaks.
-  ScopedPtr<Ptr<int> > scoped_manually_counted_1(manually_counted_1);
-  ScopedPtr<Ptr<int> > scoped_manually_counted_2(manually_counted_2);
-
-  manually_counted_2 = manually_counted_1;
-
-  ASSERT_EQ(1234, *manually_counted_1);
-  ASSERT_EQ(1234, *manually_counted_2);
-  ASSERT_EQ(1234, *scoped_manually_counted_1);
-  ASSERT_EQ(5678, *scoped_manually_counted_2);
-}
-
-TEST(PtrTest, AssignmentOperator_RefCountedToManuallyCounted) {
-  Ptr<int> ref_counted = MakeRefCountedPtr(new int(1234));
-  Ptr<int> manually_counted = MakePtr(new int(5678));
-  // Avoid leaks.
-  ScopedPtr<Ptr<int> > scoped_manually_counted(manually_counted);
-
-  manually_counted = ref_counted;
-
-  ASSERT_EQ(1234, *ref_counted);
-  ASSERT_EQ(1234, *manually_counted);
-  ASSERT_EQ(5678, *scoped_manually_counted);
-}
-
-TEST(PtrTest, AssignmentOperator_ManuallyCountedToRefCounted) {
-  Ptr<int> manually_counted = MakePtr(new int(1234));
-  Ptr<int> ref_counted = MakeRefCountedPtr(new int(5678));
-  // Avoid leaks.
-  ScopedPtr<Ptr<int> > scoped_manually_counted(manually_counted);
-
-  ref_counted = manually_counted;
-
-  ASSERT_EQ(1234, *ref_counted);
-  ASSERT_EQ(1234, *manually_counted);
-  ASSERT_EQ(1234, *scoped_manually_counted);
-}
-
-TEST(PtrTest, AssignmentOperator_SelfAssignment_ManuallyCounted) {
-  Ptr<int> manually_counted_1 = MakePtr(new int(1234));
-  Ptr<int> manually_counted_2(manually_counted_1);
-  // Avoid leaks.
-  ScopedPtr<Ptr<int> > scoped_manually_counted_1(manually_counted_1);
-
-  manually_counted_1 = manually_counted_2;
-
-  ASSERT_EQ(1234, *manually_counted_1);
-  ASSERT_EQ(1234, *manually_counted_2);
-  ASSERT_EQ(1234, *scoped_manually_counted_1);
-}
-
 TEST(PtrTest, AssignmentOperator_SelfAssignment_RefCounted) {
   Ptr<int> ref_counted_1 = MakeRefCountedPtr(new int(1234));
   Ptr<int> ref_counted_2(ref_counted_1);
@@ -115,19 +52,6 @@ TEST(PtrTest, AssignmentOperator_SelfAssignment_RefCounted) {
   ASSERT_EQ(1234, *ref_counted_2);
 }
 
-TEST(PtrTest, EqualityOperator_ManuallyCounted) {
-  Ptr<int> manually_counted_1 = MakePtr(new int(1234));
-  Ptr<int> manually_counted_2(manually_counted_1);
-  // Avoid leaks.
-  ScopedPtr<Ptr<int> > scoped_manually_counted_1(manually_counted_1);
-
-  ASSERT_TRUE(manually_counted_1 == manually_counted_2);
-
-  manually_counted_1 = manually_counted_2;
-
-  ASSERT_TRUE(manually_counted_1 == manually_counted_2);
-}
-
 TEST(PtrTest, EqualityOperator_RefCounted) {
   Ptr<int> ref_counted_1 = MakeRefCountedPtr(new int(1234));
   Ptr<int> ref_counted_2(ref_counted_1);
@@ -139,16 +63,6 @@ TEST(PtrTest, EqualityOperator_RefCounted) {
   ASSERT_TRUE(ref_counted_1 == ref_counted_2);
 }
 
-TEST(PtrTest, EqualityOperator_ManuallyAndRefCounted) {
-  int* raw = new int(1234);
-  Ptr<int> manually_counted = MakePtr(raw);
-  Ptr<int> ref_counted = MakeRefCountedPtr(raw);
-  // No need for a ScopedPtr for manually_counted here because we know that
-  // ref_counted will take care of deallocating 'raw'.
-
-  ASSERT_FALSE(manually_counted == ref_counted);
-}
-
 namespace {
 
 class Base {
@@ -171,17 +85,6 @@ class Derived : public Base {
 
 }  // namespace
 
-TEST(PtrTest, DerivedToBaseConversion_ManuallyCounted) {
-  Ptr<Derived> derived = MakePtr(new Derived(1234));
-  Ptr<Base> base = derived;
-  // Avoid leaks.
-  ScopedPtr<Ptr<Derived> > scoped_derived(derived);
-
-  ASSERT_EQ(1234, base->getInt());
-  ASSERT_EQ(1234, derived->getInt());
-  ASSERT_EQ(1234, scoped_derived->getInt());
-}
-
 TEST(PtrTest, DerivedToBaseConversion_RefCounted) {
   Ptr<Derived> derived = MakeRefCountedPtr(new Derived(1234));
   Ptr<Base> base = derived;
@@ -193,17 +96,18 @@ TEST(PtrTest, DerivedToBaseConversion_RefCounted) {
   ASSERT_EQ(1234, base->getInt());
 }
 
-TEST(PtrTest, ScopedPtr_Release_ManuallyCounted) {
-  Ptr<int> manually_counted_1 = MakePtr(new int(1234));
-  ScopedPtr<Ptr<int> > scoped_manually_counted_1(manually_counted_1);
+TEST(PtrTest, DistinctValuesAreNotEqual) {
+  Ptr<int> value1 = MakePtr(new int(5));
+  Ptr<int> value2 = MakePtr(new int(6));
 
-  Ptr<int> manually_counted_2 = scoped_manually_counted_1.release();
-  // Avoid leaks.
-  ScopedPtr<Ptr<int> > scoped_manually_counted_2(manually_counted_2);
+  ASSERT_NE(value1, value2);
+}
 
-  ASSERT_TRUE(scoped_manually_counted_1.isNull());
-  ASSERT_EQ(1234, *manually_counted_2);
-  ASSERT_EQ(1234, *scoped_manually_counted_2);
+TEST(PtrTest, SameValuesAreEqual) {
+  Ptr<int> value1 = MakePtr(new int(5));
+  Ptr<int> value2 = MakePtr(new int(5));
+
+  ASSERT_EQ(value1, value2);
 }
 
 TEST(PtrTest, ScopedPtr_Release_RefCounted) {
@@ -212,20 +116,20 @@ TEST(PtrTest, ScopedPtr_Release_RefCounted) {
 
   Ptr<int> ref_counted_2 = scoped_ref_counted_1.release();
 
-  ASSERT_TRUE(scoped_ref_counted_1.isNull());
+  ASSERT_EQ(*scoped_ref_counted_1, *ref_counted_2);
   ASSERT_EQ(1234, *ref_counted_2);
 }
 
-TEST(PtrTest, ConstifyPtr_ManuallyCounted) {
-  Ptr<int> manually_counted = MakePtr(new int(1234));
-  // Avoid leaks.
-  ScopedPtr<Ptr<int> > scoped_manually_counted(manually_counted);
+TEST(PtrTest, ScopedPtr_Release_RefCounted_Stay_Valid) {
+  Ptr<int> ref_counted_1 = MakeRefCountedPtr(new int(1234));
+  Ptr<int> ref_counted_2 = ref_counted_1;
+  ScopedPtr<Ptr<int> > scoped_ref_counted_1(ref_counted_1);
 
-  ConstPtr<int> const_manually_counted = ConstifyPtr(manually_counted);
+  Ptr<int> ref_counted_3 = scoped_ref_counted_1.release();
 
-  ASSERT_EQ(1234, *const_manually_counted);
-  ASSERT_EQ(1234, *manually_counted);
-  ASSERT_EQ(1234, *scoped_manually_counted);
+  ASSERT_EQ(*scoped_ref_counted_1, *ref_counted_3);
+  ASSERT_EQ(1234, *ref_counted_2);
+  ASSERT_EQ(1234, *ref_counted_3);
 }
 
 TEST(PtrTest, ConstifyPtr_RefCounted) {
@@ -240,19 +144,6 @@ TEST(PtrTest, ConstifyPtr_RefCounted) {
   ASSERT_EQ(1234, *const_ref_counted);
 }
 
-TEST(PtrTest, DowncastPtr_ManuallyCounted) {
-  Ptr<Derived> derived = MakePtr(new Derived(1234));
-  Ptr<Base> base = derived;
-  // Avoid leaks.
-  ScopedPtr<Ptr<Derived> > scoped_derived(derived);
-
-  Ptr<Derived> derived_from_downcast = DowncastPtr<Derived>(base);
-
-  ASSERT_EQ(1234, base->getInt());
-  ASSERT_EQ(1234, derived->getInt());
-  ASSERT_EQ(1234, derived_from_downcast->getInt());
-}
-
 TEST(PtrTest, DowncastPtr_RefCounted) {
   Ptr<Derived> derived = MakeRefCountedPtr(new Derived(1234));
   Ptr<Base> base = derived;