base/memory/discardable_memory_shmem.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.h"
   6
   7 #include "base/lazy_instance.h"
   8 #include "base/memory/discardable_memory_shmem_allocator.h"
   9
  10 namespace base {
  11 namespace internal {
  12
  13 DiscardableMemoryShmem::DiscardableMemoryShmem(size_t bytes)
  14     : bytes_(bytes), is_locked_(false) {
  15 }
  16
  17 DiscardableMemoryShmem::~DiscardableMemoryShmem() {
  18   if (is_locked_)
  19     Unlock();
  20 }
  21
  22 bool DiscardableMemoryShmem::Initialize() {
  23   return Lock() != DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
  24 }
  25
  26 DiscardableMemoryLockStatus DiscardableMemoryShmem::Lock() {
  27   DCHECK(!is_locked_);
  28
  29   if (chunk_ && chunk_->Lock()) {
  30     is_locked_ = true;
  31     return DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS;
  32   }
  33
  34   chunk_ = DiscardableMemoryShmemAllocator::GetInstance()
  35                ->AllocateLockedDiscardableMemory(bytes_);
  36   if (!chunk_)
  37     return DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
  38
  39   is_locked_ = true;
  40   return DISCARDABLE_MEMORY_LOCK_STATUS_PURGED;
  41 }
  42
  43 void DiscardableMemoryShmem::Unlock() {
  44   DCHECK(is_locked_);
  45   DCHECK(chunk_);
  46   chunk_->Unlock();
  47   is_locked_ = false;
  48 }
  49
  50 void* DiscardableMemoryShmem::Memory() const {
  51   DCHECK(is_locked_);
  52   DCHECK(chunk_);
  53   return chunk_->Memory();
  54 }
  55
  56 }  // namespace internal
  57 }  // namespace base