cc: Enforce correct recycling in resource pool.

cc/gl_renderer.cc

 // Copyright 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/gl_renderer.h"
 
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 1264 matching lines @@
     setShaderOpacity(1, program->fragmentShader().alphaLocation());
     drawQuadGeometry(frame, drawMatrix, rect, program->vertexShader().matrixLocation());
 }
 
 void GLRenderer::finish()
 {
     TRACE_EVENT0("cc", "GLRenderer::finish");
     m_context->finish();
 }
 
+// TODO(epenner): This should probably be moved to output surface.
+namespace {
+// This implements a simple fence based on client side swaps.
+// This is to isolate the ResourceProvider from 'frames' which
+// it shouldn't need to care about, while still allowing us to
+// enforce good texture recycling behavior strictly throughout
+// the compositor (don't recycle a texture while it's in use).
+class SimpleSwapFence : public ResourceProvider::Fence {
+public:
+    SimpleSwapFence() : m_hasPassed(false) {}
+    virtual bool hasPassed() OVERRIDE { return m_hasPassed; }
+    bool setHasPassed() { m_hasPassed = true; }
+private:
+    bool m_hasPassed;
+};
+}

[piman, 2013/02/05 23:47:02]

nit: move to the top of the file instead of in the middle of the GLRenderer
implementation?

+
 bool GLRenderer::swapBuffers()
 {
     DCHECK(m_visible);
     DCHECK(!m_isBackbufferDiscarded);
 
     TRACE_EVENT0("cc", "GLRenderer::swapBuffers");
     // We're done! Time to swapbuffers!
 
+    scoped_refptr<ResourceProvider::Fence> lastSwapFence = m_resourceProvider->getReadLockFence();
+    if (lastSwapFence)
+        static_cast<SimpleSwapFence*>(lastSwapFence.get())->setHasPassed();
+    m_resourceProvider->setReadLockFence(new SimpleSwapFence());
+
     if (m_capabilities.usingPartialSwap) {
         // If supported, we can save significant bandwidth by only swapping the damaged/scissored region (clamped to the viewport)
         m_swapBufferRect.Intersect(gfx::Rect(gfx::Point(), viewportSize()));
         int flippedYPosOfRectBottom = viewportHeight() - m_swapBufferRect.y() - m_swapBufferRect.height();
         m_context->postSubBufferCHROMIUM(m_swapBufferRect.x(), flippedYPosOfRectBottom, m_swapBufferRect.width(), m_swapBufferRect.height());
     } else {
         // Note that currently this has the same effect as swapBuffers; we should
         // consider exposing a different entry point on WebGraphicsContext3D.
         m_context->prepareTexture();
     }
@@ skipping 486 matching lines @@
 
     releaseRenderPassTextures();
 }
 
 bool GLRenderer::isContextLost()
 {
     return (m_context->getGraphicsResetStatusARB() != GL_NO_ERROR);
 }
 
 }  // namespace cc