base: Discardable memory types.

base/memory/discardable_memory.cc

Index: base/memory/discardable_memory.cc
diff --git a/base/memory/discardable_memory.cc b/base/memory/discardable_memory.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5caae53a637a60aa0eee802b4e94ca669c2f7293
--- /dev/null
+++ b/base/memory/discardable_memory.cc
@@ -0,0 +1,85 @@
+// Copyright 2013 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 "base/memory/discardable_memory.h"
+
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+
+namespace base {
+namespace {
+
+const struct TypeNamePair {
+  DiscardableMemoryType type;
+  const char* name;
+} kTypeNamePairs[] = {
+  { DISCARDABLE_MEMORY_TYPE_ANDROID, "android" },
+  { DISCARDABLE_MEMORY_TYPE_MAC, "mac" },
+  { DISCARDABLE_MEMORY_TYPE_EMULATED, "emulated" }
+};
+
+DiscardableMemoryType g_preferred_type = DISCARDABLE_MEMORY_TYPE_NONE;
+
+struct DefaultPreferredType {
+  DefaultPreferredType() : value(DISCARDABLE_MEMORY_TYPE_NONE) {
+    std::vector<DiscardableMemoryType> supported_types;
+    DiscardableMemory::GetSupportedTypes(&supported_types);
+    DCHECK(!supported_types.empty());
+    value = supported_types[0];
+  }
+  DiscardableMemoryType value;
+};
+LazyInstance<DefaultPreferredType>::Leaky g_default_preferred_type =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+// static
+DiscardableMemoryType DiscardableMemory::GetNamedType(
+    const std::string& name) {
+  for (size_t i = 0; i < arraysize(kTypeNamePairs); ++i) {
+    if (name == kTypeNamePairs[i].name)
+      return kTypeNamePairs[i].type;
+  }
+
+  return DISCARDABLE_MEMORY_TYPE_NONE;
+}
+
+// static
+const char* DiscardableMemory::GetTypeName(DiscardableMemoryType type) {
+  for (size_t i = 0; i < arraysize(kTypeNamePairs); ++i) {
+    if (type == kTypeNamePairs[i].type)
+      return kTypeNamePairs[i].name;
+  }
+
+  return "unknown";
+}
+
+// static
+void DiscardableMemory::SetPreferredType(DiscardableMemoryType type) {
+  // NONE is a reserved value and not a valid default type.
+  DCHECK_NE(DISCARDABLE_MEMORY_TYPE_NONE, type);
+
+  // Make sure this function is only called once before the first call
+  // to GetPreferredType().
+  DCHECK_EQ(DISCARDABLE_MEMORY_TYPE_NONE, g_preferred_type);
+
+  g_preferred_type = type;
+}
+
+// static
+DiscardableMemoryType DiscardableMemory::GetPreferredType() {
+  if (g_preferred_type == DISCARDABLE_MEMORY_TYPE_NONE)
+    g_preferred_type = g_default_preferred_type.Get().value;
+
+  return g_preferred_type;
+}
+
+// static
+scoped_ptr<DiscardableMemory> DiscardableMemory::CreateLockedMemory(
+    size_t size) {
+  return CreateLockedMemoryWithType(GetPreferredType(), size);
+}
+
+}  // namespace base