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Unified Diff: base/memory/discardable_memory_allocator_android.h

Issue 25293002: Add DiscardableMemoryAllocator to work around FD limit issue. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: Fix Clang build Created 7 years ago
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Index: base/memory/discardable_memory_allocator_android.h
diff --git a/base/memory/discardable_memory_allocator_android.h b/base/memory/discardable_memory_allocator_android.h
new file mode 100644
index 0000000000000000000000000000000000000000..7991656cff600d418871f23992e85b1dcdfbf585
--- /dev/null
+++ b/base/memory/discardable_memory_allocator_android.h
@@ -0,0 +1,65 @@
+// 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.
+
+#ifndef BASE_MEMORY_DISCARDABLE_MEMORY_ALLOCATOR_H_
+#define BASE_MEMORY_DISCARDABLE_MEMORY_ALLOCATOR_H_
+
+#include <string>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/thread_checker.h"
+
+namespace base {
+
+class DiscardableMemory;
+
+namespace internal {
+
+// On Android ashmem is used to implement discardable memory. It is backed by a
+// file (descriptor) thus is a limited resource. This allocator minimizes the
+// problem by allocating large ashmem regions internally and returning smaller
+// chunks to the client.
+// Allocated chunks are systematically aligned on a page boundary therefore this
+// allocator should not be used for small allocations.
+//
+// Threading: The allocator must be deleted on the thread it was constructed on
+// although its Allocate() method can be invoked on any thread. See
+// discardable_memory.h for DiscardableMemory's threading guarantees.
+class BASE_EXPORT_PRIVATE DiscardableMemoryAllocator {
+ public:
+ // Exposed for testing.
+ enum {
+ kMinAshmemRegionSize = 32 * 1024 * 1024,
+ };
+
+ // Note that |name| is only used for debugging/measurement purposes.
+ explicit DiscardableMemoryAllocator(const std::string& name);
+ ~DiscardableMemoryAllocator();
+
+ // Note that the allocator must outlive the returned DiscardableMemory
+ // instance.
+ scoped_ptr<DiscardableMemory> Allocate(size_t size);
+
+ private:
+ class AshmemRegion;
+ class DiscardableAshmemChunk;
+
+ void DeleteAshmemRegion_Locked(AshmemRegion* region);
+
+ base::ThreadChecker thread_checker_;
+ const std::string name_;
+ base::Lock lock_;
+ ScopedVector<AshmemRegion> ashmem_regions_;
+
+ DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryAllocator);
+};
+
+} // namespace internal
+} // namespace base
+
+#endif // BASE_MEMORY_DISCARDABLE_MEMORY_ALLOCATOR_H_

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