Fix crash: Scan plugins on message thread via Timer (one per tick), not background thread"

Source/PluginBridgeProcessor.cpp

@@ -1,6 +1,5 @@
 #include "PluginBridgeProcessor.h"
 #include "PluginBridgeEditor.h"
-#include <thread>
 
 PluginBridgeProcessor::PluginBridgeProcessor()
     : AudioProcessor(BusesProperties()
@@ -14,6 +13,7 @@ PluginBridgeProcessor::PluginBridgeProcessor()
 PluginBridgeProcessor::~PluginBridgeProcessor()
 {
     mcpServer.stop();
+    stopTimer();
 }
 
 void PluginBridgeProcessor::prepareToPlay(double sampleRate, int samplesPerBlock)
@@ -90,43 +90,69 @@ void PluginBridgeProcessor::startPluginScan()
 
     scanning.store(true);
 
-    // Detached thread is safe here because Processor outlives Editor
-    // and scannedPlugins is only written by this thread, read by message thread after scanComplete=true
-    std::thread([this]()
+    // Initialize scanner on message thread
+    scanFormatManager = std::make_unique<juce::AudioPluginFormatManager>();
+    #if JUCE_PLUGINHOST_VST3
+    scanFormatManager->addFormat(new juce::VST3PluginFormat());
+    #endif
+    #if JUCE_PLUGINHOST_AU
+    scanFormatManager->addFormat(new juce::AudioUnitPluginFormat());
+    #endif
+
+    scanList = std::make_unique<juce::KnownPluginList>();
+
+    // Build file list to scan
+    for (int i = 0; i < scanFormatManager->getNumFormats(); ++i)
     {
-        juce::AudioPluginFormatManager formatManager;
-        #if JUCE_PLUGINHOST_VST3
-        formatManager.addFormat(new juce::VST3PluginFormat());
-        #endif
-        #if JUCE_PLUGINHOST_AU
-        formatManager.addFormat(new juce::AudioUnitPluginFormat());
-        #endif
+        auto* format = scanFormatManager->getFormat(i);
+        auto paths = format->getDefaultLocationsToSearch();
+
+        // Use a temporary scanner just to get the file list
+        juce::PluginDirectoryScanner tempScanner(
+            *scanList, *format, paths, true, juce::File());
+
+        // We'll use the scanner directly — start it
+        scanners.add(new ScannerState{
+            std::make_unique<juce::PluginDirectoryScanner>(
+                *scanList, *format, paths, true, juce::File()),
+            false
+        });
+    }
 
-        juce::KnownPluginList pluginList;
+    currentScannerIndex = 0;
 
-        for (int i = 0; i < formatManager.getNumFormats(); ++i)
-        {
-            auto* format = formatManager.getFormat(i);
-            auto searchPaths = format->getDefaultLocationsToSearch();
-
-            juce::PluginDirectoryScanner scanner(
-                pluginList,
-                *format,
-                searchPaths,
-                true,
-                juce::File()
-            );
-
-            juce::String pluginName;
-            while (scanner.scanNextFile(false, pluginName)) {}
-        }
+    // Use Timer to scan one file per tick on the message thread
+    startTimerHz(30); // 30 files per second — responsive UI
+}
 
-        // Copy results (safe — Editor only reads after scanComplete is true)
-        scannedPlugins = pluginList.getTypes();
+void PluginBridgeProcessor::timerCallback()
+{
+    if (currentScannerIndex >= scanners.size())
+    {
+        // All scanners done
+        stopTimer();
+        scannedPlugins = scanList->getTypes();
         scanning.store(false);
         scanComplete.store(true);
+        scanners.clear();
+        scanFormatManager.reset();
+        scanList.reset();
+        return;
+    }
+
+    auto* state = scanners[currentScannerIndex];
+    if (state->done)
+    {
+        currentScannerIndex++;
+        return;
+    }
 
-    }).detach();
+    juce::String pluginName;
+    if (!state->scanner->scanNextFile(true, pluginName))
+    {
+        state->done = true;
+        currentScannerIndex++;
+    }
 }
 
 // JUCE plugin entry point