Restart audio after ALSA stall.

src/AlsaDriver.cpp

@@ -1657,7 +1657,7 @@ namespace pipedal
                 Lv2Log::error(e.what());
                 Lv2Log::error("ALSA audio thread terminated abnormally.");
             }
-            this->driverHost->OnAudioStopped();
+            this->driverHost->OnAlsaDriverStopped();
 
             // if we terminated abnormally, pump messages until we have been terminated.
             if (!terminateAudio())

src/AlsaDriverTest.cpp

@@ -212,7 +212,7 @@ public:
         
     }
 
-    virtual void OnAudioStopped() {
+    virtual void OnAlsaDriverStopped() {
     }
     virtual void OnProcess(size_t nFrames) {
         if (testType == TestType::NullTest) return;

src/AudioDriver.hpp

@@ -48,7 +48,7 @@ namespace pipedal {
     public:
         virtual void OnProcess(size_t nFrames) = 0;
         virtual void OnUnderrun() = 0;
-        virtual void OnAudioStopped() = 0;
+        virtual void OnAlsaDriverStopped() = 0;
         virtual void OnAudioTerminated() = 0;
 
 

src/AudioHost.cpp

@@ -183,7 +183,8 @@ namespace pipedal
                             reader.read(&vProperty);
                             if (!vProperty.is_null())
                             {
-                                try {
+                                try
+                                {
                                     vProperty = pluginHost.MapPath(vProperty);
 
                                     // now to atom format (what we want on the rt thread0)
@@ -194,7 +195,8 @@ namespace pipedal
                                     pathPatchProperty.atomBuffer.resize(atomValue->size + sizeof(LV2_Atom));
                                     memcpy(pathPatchProperty.atomBuffer.data(), atomValue, pathPatchProperty.atomBuffer.size());
                                     this->pathPatchProperties.push_back(std::move(pathPatchProperty));
-                                } catch (const std::exception &e)
+                                }
+                                catch (const std::exception &e)
                                 {
                                     Lv2Log::info(SS("IndexedSnapshotValue: Failed to map path property " << pathProperty.first << ". " << e.what()));
                                 }
@@ -207,7 +209,7 @@ namespace pipedal
         void ApplyValues(IEffect *effect)
         {
 
-            effect->SetBypass(this->enabled);            
+            effect->SetBypass(this->enabled);
             if (effect != pEffect)
             {
                 throw std::runtime_error("Wrong effect");
@@ -907,7 +909,7 @@ private:
 
     bool onMidiEvent(Lv2EventBufferWriter &eventBufferWriter, Lv2EventBufferWriter::LV2_EvBuf_Iterator &iterator, MidiEvent &event)
     {
-        //eventBufferWriter.writeMidiEvent(iterator, 0, event.size, event.buffer);
+        // eventBufferWriter.writeMidiEvent(iterator, 0, event.size, event.buffer);
 
         this->realtimeActivePedalboard->OnMidiMessage(event.size, event.buffer, this, fnMidiValueChanged);
         if (listenForMidiEvent)
@@ -1100,10 +1102,12 @@ private:
     {
         return this->active && (!this->audioStopped) && !this->isDummyAudioDriver;
     }
-    virtual void OnAudioStopped() override
+    virtual void OnAlsaDriverStopped() override
     {
+
         this->audioStopped = true;
         Lv2Log::info("Audio stopped.");
+        this->realtimeWriter.AudioTerminatedAbnormally();
     }
     virtual void OnAudioTerminated() override
     {
@@ -1256,12 +1260,14 @@ public:
         return this->sampleRate;
     }
 
-    void OnAudioComplete()
+    void HandleAudioTerminatedAbnormally()
     {
-        // there is actually no compelling circumstance in which this should ever happen.
-
         Lv2Log::error("Audio processing terminated unexpectedly.");
-        realtimeWriter.AudioStopped();
+
+        if (pNotifyCallbacks)
+        {
+            pNotifyCallbacks->OnAlsaDriverTerminatedAbnormally();
+        }
     }
     std::vector<uint8_t> atomBuffer;
     std::vector<uint8_t> realtimeAtomBuffer;
@@ -1271,7 +1277,7 @@ public:
     {
         SetThreadName("rtsvc");
         SetThreadPriority(SchedulerPriority::AudioService);
-        
+
         int underrunMessagesGiven = 0;
         try
         {
@@ -1456,7 +1462,7 @@ public:
                                             {
                                                 LV2_URID propertyUrid = ((LV2_Atom_URID *)property)->body;
                                                 this->pNotifyCallbacks->OnPatchSetReply(instanceId, propertyUrid, value);
-                                                //this->pNotifyCallbacks->OnNotifyMaybeLv2StateChanged(instanceId);
+                                                // this->pNotifyCallbacks->OnNotifyMaybeLv2StateChanged(instanceId);
                                             }
                                         }
                                     }
@@ -1492,11 +1498,11 @@ public:
                                 hostReader.read(&buffer);
                                 OnPathPropertyReceived(buffer);
                             }
-                            else if (command == RingBufferCommand::AudioStopped)
+                            else if (command == RingBufferCommand::AudioTerminatedAbnormally)
                             {
                                 AudioStoppedBody body;
                                 hostReader.read(&body);
-                                OnAudioComplete();
+                                HandleAudioTerminatedAbnormally();
                                 return;
                             }
                             else if (command == RingBufferCommand::
@@ -1621,7 +1627,7 @@ public:
         if (jackServerSettings.IsDummyAudioDevice())
         {
             this->isDummyAudioDriver = true;
-            this->audioDriver = std::unique_ptr<AudioDriver>(CreateDummyAudioDriver(this,jackServerSettings.GetAlsaInputDevice()));
+            this->audioDriver = std::unique_ptr<AudioDriver>(CreateDummyAudioDriver(this, jackServerSettings.GetAlsaInputDevice()));
         }
         else
         {
@@ -1927,7 +1933,7 @@ public:
     }
 
 private:
-    //virtual bool UpdatePluginStates(Pedalboard &pedalboard) override;
+    // virtual bool UpdatePluginStates(Pedalboard &pedalboard) override;
     virtual bool UpdatePluginState(PedalboardItem &pedalboardItem) override;
 
     class RestartThread
@@ -2051,7 +2057,7 @@ public:
 
         result.msSinceLastUnderrun_ = (uint64_t)dt;
 
-        result.temperaturemC_ = (int32_t)(std::round(cpuTemperatureMonitor->GetTemperatureC()*1000));
+        result.temperaturemC_ = (int32_t)(std::round(cpuTemperatureMonitor->GetTemperatureC() * 1000));
 
         result.active_ = IsAudioRunning();
         result.restarting_ = this->restarting;
@@ -2065,7 +2071,9 @@ public:
         if (result.hasCpuGovernor_)
         {
             result.governor_ = GetGovernor();
-        } else {
+        }
+        else
+        {
             result.governor_ = "";
         }
 
@@ -2110,7 +2118,7 @@ void AudioHostImpl::SetSystemMidiBindings(const std::vector<MidiBinding> &bindin
         else if (i->symbol() == "prevBank")
         {
             this->prevBankMidiBinding.SetBinding(*i);
-        } 
+        }
         else if (i->symbol() == "nextProgram")
         {
             this->nextPresetMidiBinding.SetBinding(*i);

src/AudioHost.hpp

@@ -170,6 +170,8 @@ namespace pipedal
         virtual void OnNotifyLv2RealtimeError(int64_t instanceId, const std::string &error) = 0;
         virtual void OnNotifyMidiRealtimeEvent(RealtimeMidiEventType eventType) = 0;
         virtual void OnNotifyMidiRealtimeSnapshotRequest(int32_t snapshotIndex,int64_t snapshotRequestId) = 0;
+
+        virtual void OnAlsaDriverTerminatedAbnormally() = 0;
     };
 
     class JackHostStatus

src/CMakeLists.txt

@@ -343,6 +343,7 @@ target_link_libraries(pipedal_kconfig
   PRIVATE ftxui::dom
   PRIVATE ftxui::component  # Not needed for this example.
   PRIVATE PiPedalCommon
+  systemd
 )
 
 #################################

src/PiLatencyMain.cpp

@@ -350,7 +350,7 @@ public:
     Oscillator oscillator;
     LatencyMonitor latencyMonitor;
 
-    virtual void OnAudioStopped()
+    virtual void OnAlsaDriverStopped()
     {
     }
     virtual void OnAudioTerminated()

src/PiPedalModel.cpp

@@ -138,6 +138,8 @@ void PiPedalModel::Close()
         }
         closed = true;
 
+        CancelAudioRetry();
+
         if (avahiService)
         {
             this->avahiService = nullptr; // and close.
@@ -1301,6 +1303,10 @@ void PiPedalModel::RestartAudio(bool useDummyAudioDriver)
 {
     try
     {
+        if (useDummyAudioDriver)
+        {
+            CancelAudioRetry();
+        }
         if (this->audioHost->IsOpen())
         {
 
@@ -1380,6 +1386,8 @@ void PiPedalModel::SetJackChannelSelection(int64_t clientId, const JackChannelSe
         this->storage.SetJackChannelSelection(channelSelection);
 
         this->pluginHost.OnConfigurationChanged(jackConfiguration, channelSelection);
+
+        CancelAudioRetry();
     }
 
     RestartAudio(); // no lock to avoid mutex deadlock when reader thread is sending notifications..
@@ -1791,6 +1799,8 @@ void PiPedalModel::SetJackServerSettings(const JackServerSettings &jackServerSet
 
     FireJackConfigurationChanged(this->jackConfiguration);
 
+    CancelAudioRetry();
+
     guard.unlock();
     RestartAudio();
 
@@ -2735,4 +2745,62 @@ std::map<std::string,std::string> PiPedalModel::GetWifiRegulatoryDomains()
         Lv2Log::warning(SS("Unable to query Wifi Regulatory domains. " << e.what()));
     }
     return result;
-}
+}
+
+void PiPedalModel::CancelAudioRetry() {
+    std::lock_guard<std::recursive_mutex> lock(mutex);
+    if (audioRetryPostHandle) 
+    {
+        // don't think this can ever happen, but if it did, it would be bad.
+        this->CancelPost(audioRetryPostHandle);
+        audioRetryPostHandle = 0;
+    }
+
+}
+void PiPedalModel::OnAlsaDriverTerminatedAbnormally() {
+    // notification from the realtime thread, via the audiohost that the 
+    // ALSA stream has broken. We want to restart.
+
+    // get off the service thread as promptly as possible
+    this->Post([&]() {
+        std::lock_guard<std::recursive_mutex> lock(mutex);
+        if (closed) return;
+
+        auto now = clock::now();
+        clock::duration timeSinceLastRetry = now-this->lastRestartTime;
+        this->lastRestartTime = now;
+        if (timeSinceLastRetry > std::chrono::duration_cast<clock::duration>(std::chrono::milliseconds(1000))) {
+            audioRestartRetries = 0;
+        }
+        CancelAudioRetry();
+
+        if (audioRestartRetries == 0)
+        {
+            this->audioRetryPostHandle = this->Post(
+                // No lock to avoid deadlocks!
+                [this]() {
+                    Lv2Log::info("Restarting audio.");
+                    this->RestartAudio();
+                });
+        } else if (audioRestartRetries < 3) 
+        {
+            this->audioRetryPostHandle = this->PostDelayed(
+                std::chrono::milliseconds(100 * audioRestartRetries),
+                [this]() {
+                    if (closed) {
+                        return;
+                    }
+                    Lv2Log::info(SS("Restarting audio. (retry " << audioRestartRetries << ")"));
+
+                    RestartAudio();
+                });
+        } else {
+            this->audioRetryPostHandle = this->Post(
+                // No lock to avoid deadlocks!
+                [this]() {
+                    Lv2Log::info(SS("Switching to dummy driver."));
+                    RestartAudio(true); // switch to the dummy driver.
+                });
+        }
+    });
+}

src/PiPedalModel.hpp

@@ -109,6 +109,12 @@ namespace pipedal
         using NetworkChangedListener = std::function<void(void)>;
 
     private:
+
+        void CancelAudioRetry();
+        clock::time_point lastRestartTime = clock::time_point::min();
+        int audioRestartRetries = 0;
+        PostHandle audioRetryPostHandle = 0;
+
         bool hasWifi = false;
 
         void SetHasWifi(bool hasWifi);
@@ -230,6 +236,7 @@ namespace pipedal
         virtual void OnPatchSetReply(uint64_t instanceId, LV2_URID patchSetProperty, const LV2_Atom *atomValue) override;
         virtual void OnNotifyMidiRealtimeEvent(RealtimeMidiEventType eventType) override;
         virtual void OnNotifyMidiRealtimeSnapshotRequest(int32_t snapshotIndex,int64_t snapshotRequestId) override;
+        virtual void OnAlsaDriverTerminatedAbnormally() override;
 
         void OnNotifyPathPatchPropertyReceived(
             int64_t instanceId,

src/RingBufferReader.hpp

@@ -38,7 +38,8 @@ namespace pipedal
         EffectReplaced,
         SetValue,
         SetBypass,
-        AudioStopped,
+        //AudioStopped,
+        AudioTerminatedAbnormally, // specifically for an ALSA loss of connection.
         SetVuSubscriptions,
         FreeVuSubscriptions,
 
@@ -507,10 +508,10 @@ namespace pipedal
             write(RingBufferCommand::ReplaceEffect, pedalboard);
         }
 
-        void AudioStopped()
+        void AudioTerminatedAbnormally()
         {
             AudioStoppedBody body;
-            write(RingBufferCommand::AudioStopped, body);
+            write(RingBufferCommand::AudioTerminatedAbnormally, body);
         }
 
         void EffectReplaced(Lv2Pedalboard *pedalboard)

src/kconfigMain.cpp

@@ -75,7 +75,7 @@ std::string spinnerText(const Clock::time_point &startTime)
 
     int64_t position = (ms * MAX_LENGTH / 3000) % (MAX_LENGTH + N_DOTS);
 
-    char result[MAX_LENGTH - 1];
+    char result[MAX_LENGTH + 1];
     for (int64_t i = 0; i < MAX_LENGTH; ++i)
     {
         if (i >= position && i < position + N_DOTS)