base/memory/discardable_memory_ashmem.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_ashmem.h"
   6
   7 #include "base/memory/discardable_memory_ashmem_allocator.h"
   8
   9 namespace base {
  10 namespace internal {
  11
  12 DiscardableMemoryAshmem::DiscardableMemoryAshmem(
  13     size_t bytes,
  14     DiscardableMemoryAshmemAllocator* allocator,
  15     DiscardableMemoryManager* manager)
  16     : bytes_(bytes),
  17       allocator_(allocator),
  18       manager_(manager),
  19       is_locked_(false) {
  20   manager_->Register(this, bytes_);
  21 }
  22
  23 DiscardableMemoryAshmem::~DiscardableMemoryAshmem() {
  24   if (is_locked_)
  25     Unlock();
  26
  27   manager_->Unregister(this);
  28 }
  29
  30 bool DiscardableMemoryAshmem::Initialize() {
  31   return Lock() != DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
  32 }
  33
  34 DiscardableMemoryLockStatus DiscardableMemoryAshmem::Lock() {
  35   DCHECK(!is_locked_);
  36
  37   bool purged = false;
  38   if (!manager_->AcquireLock(this, &purged))
  39     return DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
  40
  41   is_locked_ = true;
  42   return purged ? DISCARDABLE_MEMORY_LOCK_STATUS_PURGED
  43                 : DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS;
  44 }
  45
  46 void DiscardableMemoryAshmem::Unlock() {
  47   DCHECK(is_locked_);
  48   manager_->ReleaseLock(this);
  49   is_locked_ = false;
  50 }
  51
  52 void* DiscardableMemoryAshmem::Memory() const {
  53   DCHECK(is_locked_);
  54   DCHECK(ashmem_chunk_);
  55   return ashmem_chunk_->Memory();
  56 }
  57
  58 bool DiscardableMemoryAshmem::AllocateAndAcquireLock() {
  59   if (ashmem_chunk_)
  60     return ashmem_chunk_->Lock();
  61
  62   ashmem_chunk_ = allocator_->Allocate(bytes_);
  63   return false;
  64 }
  65
  66 void DiscardableMemoryAshmem::ReleaseLock() {
  67   ashmem_chunk_->Unlock();
  68 }
  69
  70 void DiscardableMemoryAshmem::Purge() {
  71   ashmem_chunk_.reset();
  72 }
  73
  74 }  // namespace internal
  75 }  // namespace base