Merge pull request #16106 from xARSENICx/fix/au-crash-backport-2.5

[2.5] Fix AudioUnit startup crash by loading out-of-process (macOS)

Author: acolombier

src/effects/backends/audiounit/audiounitmanager.h

@@ -39,9 +39,16 @@ class AudioUnitManager {
     /// want to e.g. block on a mutex.
     AudioUnit _Nullable getAudioUnit() const;
 
+    /// Blocks until the audio unit has been instantiated.
+    ///
+    /// Returns true if the audio unit was instantiated successfully and false if
+    /// the timeout was reached instead.
+    bool waitForAudioUnit(int timeoutMs) const;
+
   private:
     QString m_name;
     std::atomic<bool> m_isInstantiated;
+    dispatch_group_t _Nonnull m_instantiationGroup;
     AudioUnit _Nullable m_audioUnit;
 
     AudioUnitManager(AVAudioUnitComponent* _Nullable component);

src/effects/backends/audiounit/audiounitmanager.mm

@@ -1,15 +1,17 @@
 #import <AVFAudio/AVFAudio.h>
 #import <AudioToolbox/AudioToolbox.h>
-#include "util/assert.h"
+#import <dispatch/dispatch.h>
 
 #include <QString>
 
 #include "effects/backends/audiounit/audiounitmanager.h"
+#include "util/assert.h"
 
 AudioUnitManager::AudioUnitManager(AVAudioUnitComponent* _Nullable component)
         : m_name(component != nil ? QString::fromNSString([component name])
                                   : "Unknown"),
-          m_isInstantiated(false) {
+          m_isInstantiated(false),
+          m_instantiationGroup(dispatch_group_create()) {
 }
 
 AudioUnitManagerPointer AudioUnitManager::create(
@@ -56,6 +58,14 @@
     return m_audioUnit;
 }
 
+bool AudioUnitManager::waitForAudioUnit(int timeoutMs) const {
+    bool success =
+            dispatch_group_wait(m_instantiationGroup,
+                    dispatch_time(DISPATCH_TIME_NOW, timeoutMs * 1000000)) == 0;
+    DEBUG_ASSERT(!success || m_isInstantiated.load());
+    return success;
+}
+
 void AudioUnitManager::instantiateAudioUnitAsync(
         AudioUnitManagerPointer pManager,
         AVAudioUnitComponent* _Nonnull component,
@@ -75,17 +85,21 @@
     qDebug() << "Instantiating Audio Unit" << pManager->m_name
              << "asynchronously";
 
+    dispatch_group_enter(pManager->m_instantiationGroup);
+
     // TODO: Fix the weird formatting of blocks
     // clang-format off
     AudioComponentInstantiate(component.audioComponent, options, ^(AudioUnit _Nullable audioUnit, OSStatus error) {
         if (error != noErr) {
             qWarning() << "Could not instantiate Audio Unit"
                        << pManager->m_name << ":" << error
                        << "(Check https://www.osstatus.com for a description)";
+            dispatch_group_leave(pManager->m_instantiationGroup);
             return;
         }
 
         pManager->initializeWith(audioUnit);
+        dispatch_group_leave(pManager->m_instantiationGroup);
     });
     // clang-format on
 }

src/effects/backends/audiounit/audiounitmanifest.mm

@@ -1,6 +1,8 @@
 #import <AudioToolbox/AudioToolbox.h>
 #include "effects/backends/effectmanifestparameter.h"
 
+#include <QElapsedTimer>
+#include <QThread>
 #include <memory>
 
 #include "effects/backends/audiounit/audiounitmanager.h"
@@ -18,9 +20,17 @@
     setDescription(QString::fromNSString([component typeName]));
     setAuthor(QString::fromNSString([component manufacturerName]));
 
-    // Instantiate audio unit (in-process) to load parameters
-    AudioUnitManagerPointer pManager = AudioUnitManager::create(
-            component, AudioUnitInstantiationType::Sync);
+    // Instantiate audio unit (out-of-process) to load parameters
+    AudioUnitManagerPointer pManager = AudioUnitManager::create(component);
+
+    const int TIMEOUT_MS = 2000;
+    if (!pManager->waitForAudioUnit(TIMEOUT_MS)) {
+        qWarning() << name() << "took more than" << TIMEOUT_MS
+                   << "ms to initialize, skipping manifest initialization "
+                      "for this effect. This means this effect will not "
+                      "display any parameters and likely not be useful!";
+        return;
+    }
 
     AudioUnit audioUnit = pManager->getAudioUnit();