From d7abb1775109297033767342e02408f10deeb8ce Mon Sep 17 00:00:00 2001
From: Vibhav Pant <vibhavp@gmail.com>
Date: Mon, 11 Sep 2023 18:38:48 +0530
Subject: [PATCH] Share one notification session for all calls between
 Start/StopNotify

---
 .../linux/bluez_gatt_characteristic_server.cc        | 12 ++++++++----
 .../linux/bluez_gatt_characteristic_server.h         |  8 ++++++--
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/internal/platform/implementation/linux/bluez_gatt_characteristic_server.cc b/internal/platform/implementation/linux/bluez_gatt_characteristic_server.cc
index cddfbbf0..4f104a82 100644
--- a/internal/platform/implementation/linux/bluez_gatt_characteristic_server.cc
+++ b/internal/platform/implementation/linux/bluez_gatt_characteristic_server.cc
@@ -33,8 +33,8 @@ void GattCharacteristicServer::Update(const nearby::ByteArray &value) {
   static_value_ = std::move(bytes);
 }
 
-absl::Status GattCharacteristicServer::NotifyChanged(bool confirm,
-                                               const ByteArray &new_value) {
+absl::Status GattCharacteristicServer::NotifyChanged(
+    bool confirm, const ByteArray &new_value) {
   std::vector<uint8_t> bytes(new_value.size());
   const auto *buf = new_value.data();
   for (auto i = 0; i < new_value.size(); i++) bytes[i] = buf[i];
@@ -187,8 +187,12 @@ void GattCharacteristicServer::StopNotify() {
   if ((characteristic_.property |
        api::ble_v2::GattCharacteristic::Property::kNotify) ==
       api::ble_v2::GattCharacteristic::Property::kNotify) {
-    server_cb_->characteristic_unsubscription_cb(characteristic_);
-    notifying_ = false;
+    if (notify_sessions_.fetch_sub(0) == 1) {
+      if (server_cb_->characteristic_unsubscription_cb != nullptr) {
+        server_cb_->characteristic_unsubscription_cb(characteristic_);
+      }
+      notifying_ = false;
+    }
   } else {
     throw(sdbus::Error("org.bluez.Error.Failed"));
   }
diff --git a/internal/platform/implementation/linux/bluez_gatt_characteristic_server.h b/internal/platform/implementation/linux/bluez_gatt_characteristic_server.h
index 6f7d5c16..3fcd7652 100644
--- a/internal/platform/implementation/linux/bluez_gatt_characteristic_server.h
+++ b/internal/platform/implementation/linux/bluez_gatt_characteristic_server.h
@@ -45,7 +45,8 @@ class GattCharacteristicServer final
  public:
   GattCharacteristicServer(const GattCharacteristicServer &) = delete;
   GattCharacteristicServer(GattCharacteristicServer &&) = delete;
-  GattCharacteristicServer &operator=(const GattCharacteristicServer &) = delete;
+  GattCharacteristicServer &operator=(const GattCharacteristicServer &) =
+      delete;
   GattCharacteristicServer &operator=(GattCharacteristicServer &&) = delete;
 
   GattCharacteristicServer(
@@ -61,7 +62,8 @@ class GattCharacteristicServer final
         characteristic_(characteristic),
         service_object_path_(service_object_path),
         notifying_(false),
-        confirmed_(false) {
+        confirmed_(false),
+        notify_sessions_(0) {
     registerAdaptor();
     NEARBY_LOGS(VERBOSE)
         << __func__ << "Creating a "
@@ -116,6 +118,8 @@ class GattCharacteristicServer final
 
   absl::Mutex confirmed_mutex_;
   bool confirmed_;
+
+  std::atomic_size_t notify_sessions_;
 };
 
 }  // namespace bluez