Fix TilesManager race condition

Change-Id: Ibbb8d6fa7565cf7d2205b28c8a9e870eb338ea14

4 files changed, 13 insertions, 29 deletions

diff --git a/Source/WebCore/platform/graphics/android/TexturesGenerator.cpp b/Source/WebCore/platform/graphics/android/TexturesGenerator.cpp
index 83e04dc..3279ec2 100644
--- a/Source/WebCore/platform/graphics/android/TexturesGenerator.cpp
+++ b/Source/WebCore/platform/graphics/android/TexturesGenerator.cpp
@@ -76,7 +76,7 @@ void TexturesGenerator::removeOperationsForFilter(OperationFilter* filter, bool
             // The solution is use this as a flag to tell Tex Gen thread that
             // UI thread is waiting now, Tex Gen thread should not wait for the
             // queue any more.
-            TilesManager::instance()->transferQueue()->interruptTransferQueue(true);
+            m_tilesManager->transferQueue()->interruptTransferQueue(true);
         }
 
         delete filter;
@@ -94,7 +94,6 @@ void TexturesGenerator::removeOperationsForFilter(OperationFilter* filter, bool
 
 status_t TexturesGenerator::readyToRun()
 {
-    TilesManager::instance()->markGeneratorAsReady();
     ALOGV("Thread ready to run");
     return NO_ERROR;
 }
@@ -165,7 +164,7 @@ bool TexturesGenerator::threadLoop()
             stop = true;
         if (m_waitForCompletion) {
             m_waitForCompletion = false;
-            TilesManager::instance()->transferQueue()->interruptTransferQueue(false);
+            m_tilesManager->transferQueue()->interruptTransferQueue(false);
             mRequestedOperationsCond.signal();
         }
         mRequestedOperationsLock.unlock();
diff --git a/Source/WebCore/platform/graphics/android/TexturesGenerator.h b/Source/WebCore/platform/graphics/android/TexturesGenerator.h
index b79baa7..35a3386 100644
--- a/Source/WebCore/platform/graphics/android/TexturesGenerator.h
+++ b/Source/WebCore/platform/graphics/android/TexturesGenerator.h
@@ -38,11 +38,14 @@ namespace WebCore {
 
 using namespace android;
 
+class TilesManager;
+
 class TexturesGenerator : public Thread {
 public:
-    TexturesGenerator() : Thread(false)
+    TexturesGenerator(TilesManager* instance) : Thread(false)
         , m_waitForCompletion(false)
-        , m_currentOperation(0) { }
+        , m_currentOperation(0)
+        , m_tilesManager(instance) { }
     virtual ~TexturesGenerator() { }
     virtual status_t readyToRun();
 
@@ -58,6 +61,7 @@ private:
     android::Condition mRequestedOperationsCond;
     bool m_waitForCompletion;
     QueuedOperation* m_currentOperation;
+    TilesManager* m_tilesManager;
 };
 
 } // namespace WebCore
diff --git a/Source/WebCore/platform/graphics/android/TilesManager.cpp b/Source/WebCore/platform/graphics/android/TilesManager.cpp
index e6577c6..1e9aee4 100644
--- a/Source/WebCore/platform/graphics/android/TilesManager.cpp
+++ b/Source/WebCore/platform/graphics/android/TilesManager.cpp
@@ -100,7 +100,7 @@ TilesManager::TilesManager()
     m_availableTextures.reserveCapacity(MAX_TEXTURE_ALLOCATION);
     m_tilesTextures.reserveCapacity(MAX_TEXTURE_ALLOCATION);
     m_availableTilesTextures.reserveCapacity(MAX_TEXTURE_ALLOCATION);
-    m_pixmapsGenerationThread = new TexturesGenerator();
+    m_pixmapsGenerationThread = new TexturesGenerator(this);
     m_pixmapsGenerationThread->run("TexturesGenerator");
 }
 
@@ -414,8 +414,9 @@ void TilesManager::setMaxLayerTextureCount(int max)
 
 TransferQueue* TilesManager::transferQueue()
 {
-    // To minimize the memory usage, transfer queue can be set to minimal size
-    // if required.
+    // m_queue will be created on the UI thread, although it may
+    // be accessed from the TexturesGenerator. However, that can only happen after
+    // a previous transferQueue() call due to a prepare.
     if (!m_queue)
         m_queue = new TransferQueue(m_useMinimalMemory);
     return m_queue;
@@ -446,9 +447,6 @@ TilesManager* TilesManager::instance()
     if (!gInstance) {
         gInstance = new TilesManager();
         ALOGV("instance(), new gInstance is %x", gInstance);
-        ALOGV("Waiting for the generator...");
-        gInstance->waitForGenerator();
-        ALOGV("Generator ready!");
     }
     return gInstance;
 }
diff --git a/Source/WebCore/platform/graphics/android/TilesManager.h b/Source/WebCore/platform/graphics/android/TilesManager.h
index 0640825..eed99c2 100644
--- a/Source/WebCore/platform/graphics/android/TilesManager.h
+++ b/Source/WebCore/platform/graphics/android/TilesManager.h
@@ -45,6 +45,7 @@ namespace WebCore {
 
 class TilesManager {
 public:
+    // May only be called from the UI thread
     static TilesManager* instance();
     static GLint getMaxTextureSize();
     static int getMaxTextureAllocation();
@@ -75,15 +76,6 @@ public:
 
     BaseTileTexture* getAvailableTexture(BaseTile* owner);
 
-    void markGeneratorAsReady()
-    {
-        {
-            android::Mutex::Autolock lock(m_generatorLock);
-            m_generatorReady = true;
-        }
-        m_generatorReadyCond.signal();
-    }
-
     void printTextures();
 
     // m_highEndGfx is written/read only on UI thread, no need for a lock.
@@ -170,13 +162,6 @@ public:
 private:
     TilesManager();
 
-    void waitForGenerator()
-    {
-        android::Mutex::Autolock lock(m_generatorLock);
-        while (!m_generatorReady)
-            m_generatorReadyCond.wait(m_generatorLock);
-    }
-
     void discardTexturesVector(unsigned long long sparedDrawCount,
                                WTF::Vector<BaseTileTexture*>& textures,
                                bool deallocateGLTextures);
@@ -206,8 +191,6 @@ private:
     sp<TexturesGenerator> m_pixmapsGenerationThread;
 
     android::Mutex m_texturesLock;
-    android::Mutex m_generatorLock;
-    android::Condition m_generatorReadyCond;
 
     static TilesManager* gInstance;