Add DiscardableMemoryAllocator to work around FD limit issue.

base/memory/discardable_memory_allocator_android_unittest.cc

+// 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.
+
+#include "base/memory/discardable_memory_allocator_android.h"
+
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "base/memory/discardable_memory.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
+#include "base/strings/stringprintf.h"
+#include "build/build_config.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace internal {
+
+const char kAllocatorName[] = "allocator-for-testing";
+
+const size_t kPageSize = 4096;
+const size_t kMinAshmemRegionSize =
+    DiscardableMemoryAllocator::kMinAshmemRegionSize;
+
+class DiscardableMemoryAllocatorTest : public testing::Test {
+ protected:
+  DiscardableMemoryAllocatorTest() : allocator_(kAllocatorName) {}
+
+  DiscardableMemoryAllocator allocator_;
+};
+
+void WriteToDiscardableMemory(DiscardableMemory* memory, size_t size) {
+  // Write to the first and the last pages only to avoid paging in up to 64
+  // MBytes.
+  static_cast<char*>(memory->Memory())[0] = 'a';
+  static_cast<char*>(memory->Memory())[size - 1] = 'a';
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, Basic) {
+  const size_t size = 128;
+  scoped_ptr<DiscardableMemory> memory(allocator_.Allocate(size));
+  ASSERT_TRUE(memory);
+  WriteToDiscardableMemory(memory.get(), size);
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, LargeAllocation) {
+  // Note that ideally large allocations should not go through the allocator in
+  // production though.

[willchan no longer on Chromium, 2013/11/28 22:51:55]

I'd explain why...that they should just use DiscardableMemoryAndroidSimple
instead.

[Philippe, 2013/11/29 12:41:05]

Yes, good point.

+  const size_t size = 64 * 1024 * 1024;
+  scoped_ptr<DiscardableMemory> memory(allocator_.Allocate(size));
+  ASSERT_TRUE(memory);
+  WriteToDiscardableMemory(memory.get(), size);
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, ChunksArePageAligned) {
+  scoped_ptr<DiscardableMemory> memory(allocator_.Allocate(kPageSize));
+  ASSERT_TRUE(memory);
+  EXPECT_EQ(0U, reinterpret_cast<uint64_t>(memory->Memory()) % kPageSize);
+  WriteToDiscardableMemory(memory.get(), kPageSize);
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, AllocateFreeAllocate) {
+  scoped_ptr<DiscardableMemory> memory(allocator_.Allocate(kPageSize));
+  // Extra allocation that prevents the region from being deleted when |memory|
+  // gets deleted.
+  scoped_ptr<DiscardableMemory> memory_lock(allocator_.Allocate(kPageSize));
+  ASSERT_TRUE(memory);
+  void* const address = memory->Memory();
+  memory->Unlock();  // Tests that the reused chunk is being locked correctly.
+  memory.reset();
+  memory = allocator_.Allocate(kPageSize);
+  ASSERT_TRUE(memory);
+  // The previously freed chunk should be reused.
+  EXPECT_EQ(address, memory->Memory());
+  WriteToDiscardableMemory(memory.get(), kPageSize);
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, FreeingWholeAshmemRegionClosesAshmem) {
+  scoped_ptr<DiscardableMemory> memory(allocator_.Allocate(kPageSize));
+  ASSERT_TRUE(memory);
+  const int kMagic = 0xdeadbeef;
+  *static_cast<int*>(memory->Memory()) = kMagic;
+  memory.reset();
+  // The previous ashmem region should have been closed thus it should not be
+  // reused.
+  memory = allocator_.Allocate(kPageSize);
+  ASSERT_TRUE(memory);
+  EXPECT_NE(kMagic, *static_cast<const int*>(memory->Memory()));
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, AllocateUsesBestFitAlgorithm) {
+  scoped_ptr<DiscardableMemory> memory1(allocator_.Allocate(3 * kPageSize));
+  ASSERT_TRUE(memory1);
+  scoped_ptr<DiscardableMemory> memory2(allocator_.Allocate(2 * kPageSize));
+  ASSERT_TRUE(memory2);
+  scoped_ptr<DiscardableMemory> memory3(allocator_.Allocate(1 * kPageSize));
+  ASSERT_TRUE(memory3);
+  void* const address_3 = memory3->Memory();
+  memory1.reset();
+  // Don't free |memory2| to avoid merging the 3 blocks together.
+  memory3.reset();
+  memory1 = allocator_.Allocate(1 * kPageSize);
+  ASSERT_TRUE(memory1);
+  // The chunk whose size is closest to the requested size should be reused.
+  EXPECT_EQ(address_3, memory1->Memory());
+  WriteToDiscardableMemory(memory1.get(), kPageSize);
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, MergeFreeChunks) {
+  scoped_ptr<DiscardableMemory> memory1(allocator_.Allocate(kPageSize));
+  ASSERT_TRUE(memory1);
+  scoped_ptr<DiscardableMemory> memory2(allocator_.Allocate(kPageSize));
+  ASSERT_TRUE(memory2);
+  scoped_ptr<DiscardableMemory> memory3(allocator_.Allocate(kPageSize));
+  ASSERT_TRUE(memory3);
+  scoped_ptr<DiscardableMemory> memory4(allocator_.Allocate(kPageSize));
+  ASSERT_TRUE(memory4);
+  void* const memory1_address = memory1->Memory();
+  memory1.reset();
+  memory3.reset();
+  // Freeing |memory2| (located between memory1 and memory3) should merge the
+  // three free blocks together.
+  memory2.reset();
+  memory1 = allocator_.Allocate(3 * kPageSize);
+  EXPECT_EQ(memory1_address, memory1->Memory());
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, MergeFreeChunksAdvanced) {
+  scoped_ptr<DiscardableMemory> memory1(allocator_.Allocate(4 * kPageSize));
+  ASSERT_TRUE(memory1);
+  scoped_ptr<DiscardableMemory> memory2(allocator_.Allocate(4 * kPageSize));
+  ASSERT_TRUE(memory2);
+  void* const memory1_address = memory1->Memory();
+  memory1.reset();
+  memory1 = allocator_.Allocate(2 * kPageSize);
+  memory2.reset();
+  // At this point, the region should be in this state:
+  // 8 KBytes (used), 24 KBytes (free).
+  memory2 = allocator_.Allocate(6 * kPageSize);
+  EXPECT_EQ(
+      static_cast<const char*>(memory2->Memory()),
+      static_cast<const char*>(memory1_address) + 2 * kPageSize);
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, MergeFreeChunksAdvanced2) {
+  scoped_ptr<DiscardableMemory> memory1(allocator_.Allocate(4 * kPageSize));
+  ASSERT_TRUE(memory1);
+  scoped_ptr<DiscardableMemory> memory2(allocator_.Allocate(4 * kPageSize));
+  ASSERT_TRUE(memory2);
+  void* const memory1_address = memory1->Memory();
+  memory1.reset();
+  memory1 = allocator_.Allocate(2 * kPageSize);
+  scoped_ptr<DiscardableMemory> memory3(allocator_.Allocate(2 * kPageSize));
+  // At this point, the region should be in this state:
+  // 8 KBytes (used), 8 KBytes (used), 16 KBytes (used).
+  memory3.reset();
+  memory2.reset();
+  // At this point, the region should be in this state:
+  // 8 KBytes (used), 24 KBytes (free).
+  memory2 = allocator_.Allocate(6 * kPageSize);
+  EXPECT_EQ(
+      static_cast<const char*>(memory2->Memory()),
+      static_cast<const char*>(memory1_address) + 2 * kPageSize);
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, MergeFreeChunksAdvanced3) {

[willchan no longer on Chromium, 2013/11/28 22:51:55]

I try to avoid numbers if possible, although sometimes it's unavoidable. In this
case, maybe name MergeFreeChunksAndDeleteAshmemRegion?

[Philippe, 2013/11/29 12:41:05]

Done.

+  scoped_ptr<DiscardableMemory> memory1(allocator_.Allocate(4 * kPageSize));
+  ASSERT_TRUE(memory1);
+  scoped_ptr<DiscardableMemory> memory2(allocator_.Allocate(4 * kPageSize));
+  ASSERT_TRUE(memory2);
+  memory1.reset();
+  memory1 = allocator_.Allocate(2 * kPageSize);
+  scoped_ptr<DiscardableMemory> memory3(allocator_.Allocate(2 * kPageSize));
+  // At this point, the region should be in this state:
+  // 8 KBytes (used), 8 KBytes (used), 16 KBytes (used).
+  memory1.reset();
+  memory3.reset();
+  // At this point, the region should be in this state:
+  // 8 KBytes (free), 8 KBytes (used), 8 KBytes (free).
+  const int kMagic = 0xdeadbeef;
+  *static_cast<int*>(memory2->Memory()) = kMagic;
+  memory2.reset();
+  // The whole region should have been deleted.
+  memory2 = allocator_.Allocate(2 * kPageSize);
+  EXPECT_NE(kMagic, *static_cast<int*>(memory2->Memory()));
+}
+
+TEST_F(DiscardableMemoryAllocatorTest,
+     TooLargeFreeChunksDontCauseTooMuchFragmentationWhenRecycled) {
+  // Keep |memory_1| below allocated so that the ashmem region doesn't get
+  // closed when |memory_2| is deleted.
+  scoped_ptr<DiscardableMemory> memory_1(allocator_.Allocate(64 * 1024));
+  ASSERT_TRUE(memory_1);
+  scoped_ptr<DiscardableMemory> memory_2(allocator_.Allocate(32 * 1024));
+  ASSERT_TRUE(memory_2);
+  void* const address = memory_2->Memory();
+  memory_2.reset();
+  const size_t size = 16 * 1024;
+  memory_2 = allocator_.Allocate(size);
+  ASSERT_TRUE(memory_2);
+  EXPECT_EQ(address, memory_2->Memory());
+  WriteToDiscardableMemory(memory_2.get(), size);
+  scoped_ptr<DiscardableMemory> memory_3(allocator_.Allocate(size));
+  // The unused tail (16 KBytes large) of the previously freed chunk should be
+  // reused.
+  EXPECT_EQ(static_cast<char*>(address) + size, memory_3->Memory());
+  WriteToDiscardableMemory(memory_3.get(), size);
+}
+
+TEST_F(DiscardableMemoryAllocatorTest, UseMultipleAshmemRegions) {
+  // Leave one page untouched at the end of the ashmem region.
+  const size_t size = kMinAshmemRegionSize - kPageSize;
+  scoped_ptr<DiscardableMemory> memory1(allocator_.Allocate(size));
+  ASSERT_TRUE(memory1);
+  WriteToDiscardableMemory(memory1.get(), size);
+
+  scoped_ptr<DiscardableMemory> memory2(
+      allocator_.Allocate(kMinAshmemRegionSize));
+  ASSERT_TRUE(memory2);
+  WriteToDiscardableMemory(memory2.get(), kMinAshmemRegionSize);
+  // The last page of the first ashmem region should be used for this
+  // allocation.
+  scoped_ptr<DiscardableMemory> memory3(allocator_.Allocate(kPageSize));
+  ASSERT_TRUE(memory3);
+  WriteToDiscardableMemory(memory3.get(), kPageSize);
+  EXPECT_EQ(memory3->Memory(), static_cast<char*>(memory1->Memory()) + size);
+}
+
+}  // namespace internal
+}  // namespace base