Cleanup DoubleBufferedTexture and SharedTexture classes.

The cleanup consisted of...
1. removing uneeded mutex calls
2. ensuring user's of the class fully initialize them before use
3. hiding protected variables to prevent potential misuse by subclasses

There will be a follow on CL focusing on cleaning up the use of mutexes
in BackedDoubleBufferedTexture.

Change-Id: Ia642d54d8a5b154ac287640a07d8b2c0e5d85334

1 files changed, 9 insertions, 25 deletions

diff --git a/WebCore/platform/graphics/android/DoubleBufferedTexture.cpp b/WebCore/platform/graphics/android/DoubleBufferedTexture.cpp
index ef261a0..bce230f 100644
--- a/WebCore/platform/graphics/android/DoubleBufferedTexture.cpp
+++ b/WebCore/platform/graphics/android/DoubleBufferedTexture.cpp
@@ -36,9 +36,6 @@ namespace WebCore {
 
 DoubleBufferedTexture::DoubleBufferedTexture(EGLContext sharedContext)
 {
-    // the mutex ensures that the variables are not used in any other thread
-    // until the constructor has the opportunity to initialize them
-    android::Mutex::Autolock lock(m_varLock);
     m_display = eglGetCurrentDisplay();
     m_pContext = EGL_NO_CONTEXT;
     m_cContext = sharedContext;
@@ -59,8 +56,6 @@ SharedTexture* DoubleBufferedTexture::getReadableTexture()
 
 EGLContext DoubleBufferedTexture::producerAcquireContext()
 {
-    // ensure that the constructor has completed and all values are initialized
-    android::Mutex::Autolock lock(m_varLock);
 
     if (m_pContext != EGL_NO_CONTEXT) {
         LOGV("AquireContext has previously generated a context.\n");
@@ -110,36 +105,26 @@ TextureInfo* DoubleBufferedTexture::producerLock()
 
 void DoubleBufferedTexture::producerRelease()
 {
-    producerReleaseTexture();
+    // get the writable texture and unlock it
+    SharedTexture* sharedTex = getWriteableTexture();
+    LOGV("Releasing P Lock (%d)", sharedTex->getSourceTextureId());
+    sharedTex->releaseSource();
 }
 
 void DoubleBufferedTexture::producerReleaseAndSwap()
 {
-    SharedTexture* sharedTex = producerReleaseTexture();
-
-    // swap the front and back buffers
-    m_varLock.lock();
-    m_writeableTexture = (sharedTex == &m_textureA) ? &m_textureB : &m_textureA;
-    LOGV("Released P Lock (%d)", sharedTex->getSourceTextureId());
-    m_varLock.unlock();
-}
+    producerRelease();
 
-SharedTexture* DoubleBufferedTexture::producerReleaseTexture()
-{
-    // get the front texture, unlock it, and return the id
-    SharedTexture* sharedTex = getWriteableTexture();
-    LOGV("Releasing P Lock (%d)", sharedTex->getSourceTextureId());
-    sharedTex->releaseSource();
-    return sharedTex;
+    // swap the front and back buffers using an atomic op for the memory barrier
+    android_atomic_acquire_store((int32_t)getReadableTexture(), (int32_t*)&m_writeableTexture);
+    LOGV("Released P Lock (%d)", m_writeableTexture->getSourceTextureId());
 }
 
 TextureInfo* DoubleBufferedTexture::consumerLock()
 {
-    m_varLock.lock();
     SharedTexture* sharedTex = getReadableTexture();
     LOGV("Acquiring C Lock (%d)", sharedTex->getSourceTextureId());
     m_lockedConsumerTexture = sharedTex;
-    m_varLock.unlock();
 
     TextureInfo* texInfo = sharedTex->lockTarget();
     LOGV("Acquired C Lock");
@@ -152,9 +137,8 @@ TextureInfo* DoubleBufferedTexture::consumerLock()
 
 void DoubleBufferedTexture::consumerRelease()
 {
-    android::Mutex::Autolock lock(m_varLock);
     // we must check to see what texture the consumer had locked since the
-    // producer may have swapped out the front buffer
+    // producer may have swapped out the readable buffer
     SharedTexture* sharedTex = m_lockedConsumerTexture;
     sharedTex->releaseTarget();
     LOGV("Released C Lock (%d)", sharedTex->getSourceTextureId());