GPU Program Caching

gpu/command_buffer/service/program_cache_lru_helper.cc

+// Copyright (c) 2012 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 "gpu/command_buffer/service/program_cache_lru_helper.h"
+
+namespace gpu {
+namespace gles2 {
+
+void ProgramCacheLruHelper::Clear() {
+  location_map.clear();
+  queue.clear();
+}
+
+bool ProgramCacheLruHelper::IsEmpty() {
+  return queue.empty();
+}
+
+void ProgramCacheLruHelper::KeyUsed(const std::string& key) {
+  IteratorMap::iterator location_iterator = location_map.find(key);
+  if (location_iterator != location_map.end()) {
+    // already exists, erase it
+    queue.erase(location_iterator->second);
+  }
+  queue.push_front(key);
+  location_map[key] = queue.begin();
+}
+
+const std::string& ProgramCacheLruHelper::PeekKey() {
+  static const std::string empty_queue_response = "";

[greggman, 2012/07/10 21:43:30]

statically initialized classes are not allowed. Maybe remove 'static' and put
inside the if? Honestly though I think you can just use 

  return "";  // empty queue response.

[dmurph, 2012/07/11 23:32:52]

Since I'm returning a reference, I'm pretty sure that will be bad.  I'll change
this to returning a pointer, so I can return NULL

+  if (queue.empty()) {
+    return empty_queue_response;
+  }
+  return queue.back();
+}
+
+void ProgramCacheLruHelper::PopKey() {
+  if (queue.empty()) {
+    return;
+  }
+  const std::string& last = queue.back();
+  location_map.erase(last);
+  queue.pop_back();
+}
+
+}  // namespace gpu
+}  // namespace gles2