Use DiscardableMemoryManager on Android.

This allows userspace (DiscardableMemoryManager) to control eviction of
unlocked DiscardableMemory instances to prevent the process from running out of
address space in cases of heavy use of unlocked DiscardableMemory.

This also removes all the occurences of 'Android' from the ashmem allocator to
allow it to be later used on ChromeOS.

BUG=327516, 334996
R=reveman@chromium.org, willchan@chromium.org

Review URL: https://codereview.chromium.org/195863005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@267170 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 75 insertions, 0 deletions

diff --git a/base/memory/discardable_memory_ashmem.cc b/base/memory/discardable_memory_ashmem.cc
new file mode 100644
index 0000000..f830008
--- /dev/null
+++ b/base/memory/discardable_memory_ashmem.cc
@@ -0,0 +1,75 @@
+// Copyright 2014 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_ashmem.h"
+
+#include "base/memory/discardable_memory_ashmem_allocator.h"
+
+namespace base {
+namespace internal {
+
+DiscardableMemoryAshmem::DiscardableMemoryAshmem(
+    size_t bytes,
+    DiscardableMemoryAshmemAllocator* allocator,
+    DiscardableMemoryManager* manager)
+    : bytes_(bytes),
+      allocator_(allocator),
+      manager_(manager),
+      is_locked_(false) {
+  manager_->Register(this, bytes_);
+}
+
+DiscardableMemoryAshmem::~DiscardableMemoryAshmem() {
+  if (is_locked_)
+    manager_->ReleaseLock(this);
+
+  manager_->Unregister(this);
+}
+
+bool DiscardableMemoryAshmem::Initialize() {
+  return Lock() == DISCARDABLE_MEMORY_LOCK_STATUS_PURGED;
+}
+
+DiscardableMemoryLockStatus DiscardableMemoryAshmem::Lock() {
+  bool purged = false;
+  if (!manager_->AcquireLock(this, &purged))
+    return DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
+
+  return purged ? DISCARDABLE_MEMORY_LOCK_STATUS_PURGED
+                : DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS;
+}
+
+void DiscardableMemoryAshmem::Unlock() {
+  manager_->ReleaseLock(this);
+}
+
+void* DiscardableMemoryAshmem::Memory() const {
+  DCHECK(ashmem_chunk_);
+  return ashmem_chunk_->Memory();
+}
+
+bool DiscardableMemoryAshmem::AllocateAndAcquireLock() {
+  DCHECK(!is_locked_);
+  is_locked_ = true;
+
+  if (ashmem_chunk_)
+    return ashmem_chunk_->Lock();
+
+  ashmem_chunk_ = allocator_->Allocate(bytes_);
+  return false;
+}
+
+void DiscardableMemoryAshmem::ReleaseLock() {
+  DCHECK(is_locked_);
+  ashmem_chunk_->Unlock();
+  is_locked_ = false;
+}
+
+void DiscardableMemoryAshmem::Purge() {
+  DCHECK(!is_locked_);
+  ashmem_chunk_.reset();
+}
+
+}  // namespace internal
+}  // namespace base