Fix Bug in RingBuffer

gpu/command_buffer/client/ring_buffer_test.cc

 // Copyright (c) 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.
 
 // This file contains the tests for the RingBuffer class.
 
 #include "gpu/command_buffer/client/ring_buffer.h"
 #include "base/at_exit.h"
 #include "base/callback.h"
 #include "base/message_loop.h"
@@ skipping 143 matching lines @@
 
 // Tests GetLargestFreeSizeNoWaiting
 TEST_F(RingBufferTest, TestGetLargestFreeSizeNoWaiting) {
   EXPECT_EQ(kBufferSize, allocator_->GetLargestFreeSizeNoWaiting());
 
   RingBuffer::Offset offset = allocator_->Alloc(kBufferSize);
   EXPECT_EQ(0u, allocator_->GetLargestFreeSizeNoWaiting());
   allocator_->FreePendingToken(offset, helper_.get()->InsertToken());
 }
 
+TEST_F(RingBufferTest, TestFreeBug) {
+  // The first and second allocations must not match.
+  const unsigned int kAlloc1 = 10;
+  const unsigned int kAlloc2 = 20;
+  RingBuffer::Offset offset = allocator_->Alloc(kAlloc1);
+  EXPECT_EQ(kBufferSize - kAlloc1, allocator_->GetLargestFreeSizeNoWaiting());
+  allocator_->FreePendingToken(offset, helper_.get()->InsertToken());
+  offset = allocator_->Alloc(kAlloc2);
+  EXPECT_EQ(kBufferSize - kAlloc1 - kAlloc2,
+            allocator_->GetLargestFreeSizeNoWaiting());
+  allocator_->FreePendingToken(offset, helper_.get()->InsertToken());
+  offset = allocator_->Alloc(kBufferSize);
+  EXPECT_EQ(0u, allocator_->GetLargestFreeSizeNoWaiting());
+  allocator_->FreePendingToken(offset, helper_.get()->InsertToken());
+}
+
 // Test fixture for RingBufferWrapper test - Creates a
 // RingBufferWrapper, using a CommandBufferHelper with a mock
 // AsyncAPIInterface for its interface (calling it directly, not through the
 // RPC mechanism), making sure Noops are ignored and SetToken are properly
 // forwarded to the engine.
 class RingBufferWrapperTest : public BaseRingBufferTest {
  protected:
   virtual void SetUp() {
     BaseRingBufferTest::SetUp();
 
@@ skipping 73 matching lines @@
   void* pointer1 = allocator_->Alloc(kSize);
   EXPECT_EQ(buffer_start_, static_cast<int8*>(pointer1));
 
   // Check that the token has indeed passed.
   EXPECT_LE(tokens[0], GetToken());
 
   allocator_->FreePendingToken(pointer1, helper_.get()->InsertToken());
 }
 
 }  // namespace gpu