Fixing handshake stalls for Android devices

src/mesh/PhoneAPI.cpp

@@ -33,7 +33,6 @@
 
 // Flag to indicate a heartbeat was received and we should send queue status
 bool heartbeatReceived = false;
-
 PhoneAPI::PhoneAPI()
 {
     lastContactMsec = millis();
@@ -74,6 +73,9 @@ void PhoneAPI::handleStartConfig()
     nodeInfoForPhone.num = 0; // Don't keep returning old nodeinfos
     nodeInfoQueue.clear();
     resetReadIndex();
+    configStartMsec = millis();
+    configHandshakeRestarted = false;
+    onConfigHandshakeStarted();
 }
 
 void PhoneAPI::close()
@@ -101,8 +103,12 @@ void PhoneAPI::close()
         fromRadioNum = 0;
         config_nonce = 0;
         config_state = 0;
+        // Reset duplicate filter so each new connection starts clean
+        std::fill(std::begin(recentToRadioPacketIds), std::end(recentToRadioPacketIds), 0);
         pauseBluetoothLogging = false;
         heartbeatReceived = false;
+        configStartMsec = 0;
+        configHandshakeRestarted = false;
     }
 }
 
@@ -757,7 +763,35 @@ int PhoneAPI::onNotify(uint32_t newValue)
         onNowHasData(newValue);
     } else {
         LOG_DEBUG("Client not yet interested in packets (state=%d)", state);
+        checkConfigHandshakeTimeout();
     }
 
     return timeout ? -1 : 0; // If we timed out, MeshService should stop iterating through observers as we just removed one
 }
+
+bool PhoneAPI::isConfigHandshakeActive() const
+{
+    return !configHandshakeRestarted && state == STATE_SEND_MY_INFO && configStartMsec != 0;
+}
+
+uint32_t PhoneAPI::getConfigHandshakeElapsedMs() const
+{
+    if (configStartMsec == 0)
+        return 0;
+    return millis() - configStartMsec;
+}
+
+bool PhoneAPI::checkConfigHandshakeTimeout()
+{
+    if (!isConfigHandshakeActive())
+        return false;
+
+    uint32_t elapsedMs = getConfigHandshakeElapsedMs();
+    if (elapsedMs > kConfigHandshakeTimeoutMs) {
+        LOG_WARN("Config handshake stuck in state=%d for %u ms, forcing transport restart", state, elapsedMs);
+        configHandshakeRestarted = true;
+        onConfigHandshakeTimeout();
+        return true;
+    }
+    return false;
+}

src/mesh/PhoneAPI.h

@@ -91,6 +91,8 @@ class PhoneAPI
     /// Use to ensure that clients don't get confused about old messages from the radio
     uint32_t config_nonce = 0;
     uint32_t readIndex = 0;
+    uint32_t configStartMsec = 0;
+    bool configHandshakeRestarted = false;
 
     std::vector<meshtastic_FileInfo> filesManifest = {};
 
@@ -135,6 +137,7 @@ class PhoneAPI
     bool isConnected() { return state != STATE_SEND_NOTHING; }
 
   protected:
+    static constexpr uint32_t kConfigHandshakeTimeoutMs = 3000;
     /// Our fromradio packet while it is being assembled
     meshtastic_FromRadio fromRadioScratch = {};
 
@@ -144,12 +147,20 @@ class PhoneAPI
     /// Hookable to find out when connection changes
     virtual void onConnectionChanged(bool connected) {}
 
+    /// Invoked if the config handshake stalls long enough that we want to drop the BLE link.
+    virtual void onConfigHandshakeTimeout() {}
+    virtual void onConfigHandshakeStarted() {}
+
     /// If we haven't heard from the other side in a while then say not connected. Returns true if timeout occurred
     bool checkConnectionTimeout();
 
     /// Check the current underlying physical link to see if the client is currently connected
     virtual bool checkIsConnected() = 0;
 
+    bool checkConfigHandshakeTimeout();
+    bool isConfigHandshakeActive() const;
+    uint32_t getConfigHandshakeElapsedMs() const;
+
     /**
      * Subclasses can use this as a hook to provide custom notifications for their transport (i.e. bluetooth notifies)
      */

src/nimble/NimbleBluetooth.cpp

@@ -54,22 +54,39 @@ class BluetoothPhoneAPI : public PhoneAPI, public concurrency::OSThread
   protected:
     virtual int32_t runOnce() override
     {
-        std::lock_guard<std::mutex> guard(nimble_mutex);
-        if (queue_size > 0) {
-            for (uint8_t i = 0; i < queue_size; i++) {
-                handleToRadio(nimble_queue.at(i).data(), nimble_queue.at(i).length());
+        bool scheduledImmediate = false;
+        {
+            std::lock_guard<std::mutex> guard(nimble_mutex);
+            if (queue_size > 0) {
+                for (uint8_t i = 0; i < queue_size; i++) {
+                    handleToRadio(nimble_queue.at(i).data(), nimble_queue.at(i).length());
+                }
+                LOG_DEBUG("Queue_size %u", queue_size);
+                queue_size = 0;
+                // Reset our timer so any newly queued work is handled right away.
+                setIntervalFromNow(0);
+                scheduledImmediate = true;
+            }
+            if (!hasChecked && phoneWants) {
+                // Pull fresh data while we're outside of the NimBLE callback context.
+                numBytes = getFromRadio(fromRadioBytes);
+                hasChecked = true;
+                // Make sure we wake immediately to publish the prefetched data.
+                setIntervalFromNow(0);
+                scheduledImmediate = true;
             }
-            LOG_DEBUG("Queue_size %u", queue_size);
-            queue_size = 0;
         }
-        if (!hasChecked && phoneWants) {
-            // Pull fresh data while we're outside of the NimBLE callback context.
-            numBytes = getFromRadio(fromRadioBytes);
-            hasChecked = true;
+
+        bool timedOut = checkConfigHandshakeTimeout();
+        if (!timedOut && !scheduledImmediate && isConfigHandshakeActive()) {
+            uint32_t elapsed = getConfigHandshakeElapsedMs();
+            uint32_t remaining = elapsed >= kConfigHandshakeTimeoutMs ? 1 : (kConfigHandshakeTimeoutMs - elapsed);
+            // Keep nudging the thread while the config handshake is in flight.
+            setIntervalFromNow(remaining);
         }
 
         // the run is triggered via NimbleBluetoothToRadioCallback and NimbleBluetoothFromRadioCallback
-        return INT32_MAX;
+        return RUN_SAME;
     }
     /**
      * Subclasses can use this as a hook to provide custom notifications for their transport (i.e. bluetooth notifies)
@@ -92,6 +109,27 @@ class BluetoothPhoneAPI : public PhoneAPI, public concurrency::OSThread
 #endif
     }
 
+    virtual void onConfigHandshakeStarted() override { setIntervalFromNow(kConfigHandshakeTimeoutMs); }
+
+    virtual void onConfigHandshakeTimeout() override
+    {
+        LOG_WARN("Config handshake stalled; restarting BLE connection");
+        if (!bleServer) {
+            return;
+        }
+        auto peers = bleServer->getPeerDevices();
+        if (peers.empty()) {
+            LOG_WARN("No BLE peers to disconnect during restart");
+            return;
+        }
+        for (auto connHandle : peers) {
+            int rc = bleServer->disconnect(connHandle);
+            if (rc != 0) {
+                LOG_WARN("Failed to disconnect BLE handle %u (rc=%d)", connHandle, rc);
+            }
+        }
+    }
+
     /// Check the current underlying physical link to see if the client is currently connected
     virtual bool checkIsConnected() { return bleServer && bleServer->getConnectedCount() > 0; }
 };