Use shared memory to update the renderer's view of the command buffer state.

gpu/command_buffer/common/command_buffer_shared_test.cc

Index: gpu/command_buffer/common/command_buffer_shared_test.cc
diff --git a/gpu/command_buffer/common/command_buffer_shared_test.cc b/gpu/command_buffer/common/command_buffer_shared_test.cc
new file mode 100644
index 0000000000000000000000000000000000000000..327533a40d5f9b9c91ffd8652c2a56f0ef6b40ad
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+++ b/gpu/command_buffer/common/command_buffer_shared_test.cc
@@ -0,0 +1,97 @@
+
+// Copyright (c) 2011 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 CommandBufferSharedState class.
+
+#include "gpu/command_buffer/common/command_buffer_shared.h"
+#include "base/bind.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace gpu {
+
+class CommandBufferSharedTest : public testing::Test {
+ protected:
+
+  virtual void SetUp() {
+    shared_state_.reset(new CommandBufferSharedState());
+    shared_state_->Initialize();
+  }
+
+  scoped_ptr<CommandBufferSharedState> shared_state_;
+};
+
+TEST_F(CommandBufferSharedTest, TestBasic) {
+  CommandBuffer::State state;
+
+  shared_state_->Read(&state);
+
+  EXPECT_LT(state.generation, 0x80000000);
+  EXPECT_EQ(state.get_offset, 0);
+  EXPECT_EQ(state.put_offset, 0);
+  EXPECT_EQ(state.token, -1);
+  EXPECT_EQ(state.error, gpu::error::kNoError);
+  EXPECT_EQ(state.context_lost_reason, gpu::error::kUnknown);
+}
+
+static const int kSize = 100000;
+
+void WriteToState(int32 *buffer,
+                  CommandBufferSharedState* shared_state) {
+  CommandBuffer::State state;
+  for (int i = 0; i < kSize; i++) {
+    state.token = i - 1;
+    state.get_offset = i + 1;
+    state.generation = i + 2;
+    state.error = static_cast<gpu::error::Error>(i + 3);
+    // Ensure that the producer doesn't update the buffer until after the
+    // consumer reads from it.
+    EXPECT_EQ(buffer[i], 0);
+
+    shared_state->Write(state);
+  }
+}
+
+TEST_F(CommandBufferSharedTest, TestConsistency) {
+  scoped_array<int32> buffer;
+  buffer.reset(new int32[kSize]);
+  base::Thread consumer("Reader Thread");
+
+  memset(buffer.get(), 0, kSize * sizeof(int32));
+
+  consumer.Start();
+  consumer.message_loop()->PostTask(
+      FROM_HERE, base::Bind(&WriteToState, buffer.get(),
+                            shared_state_.get()));
+
+  CommandBuffer::State last_state;
+  while (1) {
+    CommandBuffer::State state = last_state;
+
+    shared_state_->Read(&state);
+
+    if (state.generation < last_state.generation)
+      continue;
+
+    if (state.get_offset >= 1) {
+      buffer[state.get_offset - 1] = 1;
+      // Check that the state is consistent
+      EXPECT_LE(last_state.token, state.token);
+      EXPECT_LE(last_state.generation, state.generation);
+      last_state = state;
+      EXPECT_EQ(state.token, state.get_offset - 2);
+      EXPECT_EQ(state.generation,
+                static_cast<unsigned int>(state.get_offset) + 1);
+      EXPECT_EQ(state.error, state.get_offset + 2);
+
+      if (state.get_offset == kSize)
+        break;
+    }
+  }
+}
+
+}  // namespace gpu
+