base/memory/discardable_memory_shmem_allocator.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/memory/discardable_memory_shmem_allocator.h"
   6
   7 #include "base/lazy_instance.h"
   8 #include "base/logging.h"
   9 #include "base/memory/discardable_shared_memory.h"
  10
  11 namespace base {
  12 namespace {
  13
  14 // Default allocator implementation that allocates in-process
  15 // DiscardableSharedMemory instances.
  16 class DiscardableMemoryShmemAllocatorImpl
  17     : public DiscardableMemoryShmemAllocator {
  18  public:
  19   // Overridden from DiscardableMemoryShmemAllocator:
  20   virtual scoped_ptr<DiscardableSharedMemory>
  21   AllocateLockedDiscardableSharedMemory(size_t size) override {
  22     scoped_ptr<DiscardableSharedMemory> memory(new DiscardableSharedMemory);
  23     if (!memory->CreateAndMap(size))
  24       return scoped_ptr<DiscardableSharedMemory>();
  25
  26     return memory.Pass();
  27   }
  28 };
  29
  30 LazyInstance<DiscardableMemoryShmemAllocatorImpl>::Leaky g_default_allocator =
  31     LAZY_INSTANCE_INITIALIZER;
  32
  33 DiscardableMemoryShmemAllocator* g_allocator = nullptr;
  34
  35 }  // namespace
  36
  37 // static
  38 void DiscardableMemoryShmemAllocator::SetInstance(
  39     DiscardableMemoryShmemAllocator* allocator) {
  40   DCHECK(allocator);
  41
  42   // Make sure this function is only called once before the first call
  43   // to GetInstance().
  44   DCHECK(!g_allocator);
  45
  46   g_allocator = allocator;
  47 }
  48
  49 // static
  50 DiscardableMemoryShmemAllocator*
  51 DiscardableMemoryShmemAllocator::GetInstance() {
  52   if (!g_allocator)
  53     g_allocator = g_default_allocator.Pointer();
  54
  55   return g_allocator;
  56 }
  57
  58 }  // namespace base