Merge branch 'master' into release.

Change-Id: Id627ceca5ef60281e024ff80fc1848b3ccb6c14d

cpp/platform_v2/base/medium_environment.h

@@ -0,0 +1,127 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef PLATFORM_V2_BASE_MEDIUM_ENVIRONMENT_H_
+#define PLATFORM_V2_BASE_MEDIUM_ENVIRONMENT_H_
+
+#include <atomic>
+
+#include "platform_v2/api/bluetooth_adapter.h"
+#include "platform_v2/api/bluetooth_classic.h"
+#include "platform_v2/base/listeners.h"
+#include "platform_v2/public/single_thread_executor.h"
+#include "absl/container/flat_hash_map.h"
+
+namespace location {
+namespace nearby {
+
+// MediumEnvironment is a simulated environment which allows multiple instances
+// of simulated HW devices to "work" together as if they are physical.
+// For each medium type it provides necessary methods to implement
+// advertising, discovery and establishment of a data link.
+// NOTE: this code depends on public:types target.
+class MediumEnvironment {
+ public:
+  using BluetoothDiscoveryCallback =
+      api::BluetoothClassicMedium::DiscoveryCallback;
+  MediumEnvironment(const MediumEnvironment&) = delete;
+  MediumEnvironment& operator=(const MediumEnvironment&) = delete;
+
+  // Creates and returns a reference to the global test environment instance.
+  static MediumEnvironment& Instance();
+
+  // Clears state. No notifications are sent.
+  void Reset();
+
+  // Waits for all previously scheduled jobs to finish.
+  // This method works as a barrier that guarantees that after it returns, all
+  // the activities that started before it was called, or while it was running
+  // are ended. This means that system is at the state of relaxation when this
+  // code returns. It requires external stimulus to get out of relaxation state.
+  //
+  // If enable_notifications is true (default), simulation environment
+  // will send all future notification events to all registered objects,
+  // whenever protocol requires that. This is expected behavior.
+  // If enabled_notifications is false, future event notifications will not be
+  // sent to registered instances. This is useful for protocol shutdown,
+  // where we no longer care about notifications, and where notifications may
+  // otherwise be delivered after the notification source or target lifeteme has
+  // ended, and cause undefined behavior.
+  void Sync(bool enable_notifications = true);
+
+  // Adds an adapter to internal container.
+  // Notify BluetoothClassicMediums if any that adapter state has changed.
+  void OnBluetoothAdapterChangedState(api::BluetoothAdapter& adapter,
+                                      api::BluetoothDevice& adapter_device,
+                                      std::string name, bool enabled,
+                                      api::BluetoothAdapter::ScanMode mode);
+
+  // Adds medium-related info to allow for adapter discovery to work.
+  // This provides acccess to this medium from other mediums, when protocol
+  // expects they should communicate.
+  void RegisterBluetoothMedium(api::BluetoothClassicMedium& medium,
+                               api::BluetoothAdapter& medium_adapter);
+
+  // Updates callback info to allow for dispatch of discovery events.
+  //
+  // Invokes callback asynchronously when any changes happen to discoverable
+  // devices, or if the defice is turned off, whether or not it is discoverable,
+  // if it was ever reported as discoverable.
+  //
+  // This should be called when discoverable state changes.
+  // with user-specified callback when discovery is enabled, and with default
+  // (empty) callback otherwise.
+  void UpdateBluetoothMedium(api::BluetoothClassicMedium& medium,
+                             BluetoothDiscoveryCallback callback);
+
+  // Removes medium-related info. This should correspond to device power off.
+  void UnregisterBluetoothMedium(api::BluetoothClassicMedium& medium);
+
+ private:
+  struct BluetoothMediumContext {
+    BluetoothDiscoveryCallback callback;
+    api::BluetoothAdapter* adapter = nullptr;
+    // discovered device vs device name map.
+    absl::flat_hash_map<api::BluetoothDevice*, std::string> devices;
+  };
+
+  // This is a singleton object, for which destructor will never be called.
+  // Constructor will be invoked once from Instance() static method.
+  // Object is create in-place (with a placement new) to guarantee that
+  // destructor is not scheduled for execution at exit.
+  MediumEnvironment() = default;
+  ~MediumEnvironment() = default;
+
+  void OnDeviceStateChanged(BluetoothMediumContext& info,
+                            api::BluetoothDevice& device,
+                            const std::string& name,
+                            api::BluetoothAdapter::ScanMode mode, bool enabled);
+  void RunOnMediumEnvironmentThread(std::function<void()> runnable);
+
+  std::atomic_int job_count_ = 0;
+  std::atomic_bool enable_notifications_ = false;
+  SingleThreadExecutor executor_;
+
+  // The following data members are accessed in the context of a private
+  // executor_ thread.
+  absl::flat_hash_map<api::BluetoothAdapter*, api::BluetoothDevice*>
+      bluetooth_adapters_;
+  absl::flat_hash_map<api::BluetoothClassicMedium*, BluetoothMediumContext>
+      bluetooth_mediums_;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_V2_BASE_MEDIUM_ENVIRONMENT_H_