Add DiscardableMemoryAllocator to work around FD limit issue.

base/memory/discardable_memory_allocator_unittest.cc

Index: base/memory/discardable_memory_allocator_unittest.cc
diff --git a/base/memory/discardable_memory_allocator_unittest.cc b/base/memory/discardable_memory_allocator_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5c4344037d6f33305c9d122b0c773148c8153695
--- /dev/null
+++ b/base/memory/discardable_memory_allocator_unittest.cc
@@ -0,0 +1,239 @@
+// 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.h"
+
+#include "base/logging.h"
+#include "base/memory/discardable_memory.h"
+#include "base/memory/scoped_ptr.h"
+#include "build/build_config.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+#if defined(OS_ANDROID)
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
+#include "base/strings/stringprintf.h"
+#endif
+
+namespace base {
+
+scoped_ptr<DiscardableMemoryAllocator>
+CreateDiscardableMemoryAllocatorForTesting(const std::string& name);
+
+namespace {
+
+const char kAllocatorName[] = "allocator-for-testing";
+const size_t kPageSize = 4096;
+
+scoped_ptr<DiscardableMemoryAllocator> CreateAllocator() {
+  return CreateDiscardableMemoryAllocatorForTesting(kAllocatorName);
+}
+
+void WriteToDiscardableMemory(DiscardableMemory* memory) {
+  DCHECK_EQ(0U, memory->Size() % sizeof(int));
+  // Write to the first and the last pages only to avoid paging in up to 64
+  // MBytes.
+  static_cast<int*>(memory->Memory())[0] = 1;
+  static_cast<int*>(memory->Memory())[memory->Size() / sizeof(int) - 1] = 1;
+}
+
+TEST(DiscardableMemoryAllocatorTest, Basic) {
+  const scoped_ptr<DiscardableMemoryAllocator> allocator(CreateAllocator());
+  ASSERT_TRUE(allocator);
+  scoped_ptr<DiscardableMemory> memory(allocator->Allocate(128 * sizeof(int)));
+  ASSERT_TRUE(memory);
+  WriteToDiscardableMemory(memory.get());
+}
+
+TEST(DiscardableMemoryAllocatorTest, LargeAllocation) {
+  const scoped_ptr<DiscardableMemoryAllocator> allocator(CreateAllocator());
+  ASSERT_TRUE(allocator);
+  scoped_ptr<DiscardableMemory> memory(allocator->Allocate(64 * 1024 * 1024));
+  ASSERT_TRUE(memory);
+  WriteToDiscardableMemory(memory.get());
+}
+
+TEST(DiscardableMemoryAllocatorTest, ChunksArePageAligned) {
+  const scoped_ptr<DiscardableMemoryAllocator> allocator(CreateAllocator());
+  ASSERT_TRUE(allocator);
+  scoped_ptr<DiscardableMemory> memory(allocator->Allocate(kPageSize));
+  ASSERT_TRUE(memory);
+  EXPECT_EQ(0U, reinterpret_cast<uint64_t>(memory->Memory()) % kPageSize);
+  WriteToDiscardableMemory(memory.get());
+}
+
+#if defined(OS_ANDROID)
+
+const size_t kAshmemRegionSize = 32 * 1024 * 1024;
+
+TEST(DiscardableMemoryAllocatorTest, AllocateFreeAllocate) {
+  const scoped_ptr<DiscardableMemoryAllocator> allocator(CreateAllocator());
+  ASSERT_TRUE(allocator);
+  scoped_ptr<DiscardableMemory> memory(allocator->Allocate(kPageSize));
+  ASSERT_TRUE(memory);
+  void* const address = memory->Memory();
+  memory->Unlock();  // Tests that the recycled 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());
+}
+
+TEST(DiscardableMemoryAllocatorTest, FreeingWholeAshmemRegionClosesAshmem) {
+  const scoped_ptr<DiscardableMemoryAllocator> allocator(CreateAllocator());
+  ASSERT_TRUE(allocator);
+  scoped_ptr<DiscardableMemory> memory(allocator->Allocate(kAshmemRegionSize));
+  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
+  // recycled.
+  memory = allocator->Allocate(kPageSize);
+  ASSERT_TRUE(memory);
+  EXPECT_NE(kMagic, *static_cast<const int*>(memory->Memory()));
+}
+
+TEST(DiscardableMemoryAllocatorTest, AllocateUsesBestFitAlgorithm) {
+  const scoped_ptr<DiscardableMemoryAllocator> allocator(CreateAllocator());
+  ASSERT_TRUE(allocator);
+  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 recycled.
+  EXPECT_EQ(address_3, memory1->Memory());
+  WriteToDiscardableMemory(memory1.get());
+}
+
+TEST(DiscardableMemoryAllocatorTest, MergeFreeChunks) {
+  const scoped_ptr<DiscardableMemoryAllocator> allocator(CreateAllocator());
+  ASSERT_TRUE(allocator);
+  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);
+  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.reset(allocator->Allocate(3 * kPageSize).release());
+  EXPECT_EQ(memory1_address, memory1->Memory());
+}
+
+TEST(DiscardableMemoryAllocatorTest,
+     TooLargeFreeChunksDontCauseTooMuchFragmentationWhenRecycled) {
+  const scoped_ptr<DiscardableMemoryAllocator> allocator(CreateAllocator());
+  ASSERT_TRUE(allocator);
+  // 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();
+  memory_2 = allocator->Allocate(16 * 1024);
+  ASSERT_TRUE(memory_2);
+  EXPECT_EQ(address, memory_2->Memory());
+  WriteToDiscardableMemory(memory_2.get());
+  scoped_ptr<DiscardableMemory> memory_3(allocator->Allocate(16 * 1024));
+  // The unused tail (16 KBytes large) of the previously freed chunk should be
+  // recycled.
+  EXPECT_EQ(static_cast<char*>(address) + memory_2->Size(), memory_3->Memory());
+  WriteToDiscardableMemory(memory_3.get());
+}
+
+TEST(DiscardableMemoryAllocatorTest, UseMultipleAshmemRegions) {
+  const scoped_ptr<DiscardableMemoryAllocator> allocator(CreateAllocator());
+  ASSERT_TRUE(allocator);
+  const size_t kAshmemRegionSize = 32 * 1024 * 1024;
+  // Leave one page untouched at the end of the ashmem region.
+  scoped_ptr<DiscardableMemory> memory1(
+      allocator->Allocate(kAshmemRegionSize - kPageSize));
+  ASSERT_TRUE(memory1);
+  WriteToDiscardableMemory(memory1.get());
+
+  scoped_ptr<DiscardableMemory> memory2(
+      allocator->Allocate(kAshmemRegionSize));
+  ASSERT_TRUE(memory2);
+  WriteToDiscardableMemory(memory2.get());
+  // 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());
+  EXPECT_EQ(memory3->Memory(),
+            static_cast<char*>(memory1->Memory()) + memory1->Size());
+}
+
+// Returns -1 if an error happened during parsing.
+int GetAllocatorDirtyMemoryInKBytes() {
+  const std::string smaps_path = StringPrintf("/proc/%d/smaps", getpid());
+  std::ifstream stream(smaps_path.c_str());
+  if (!stream.good())
+    return -1;
+  std::vector<std::string> lines;
+  for (std::string line; std::getline(stream, line); lines.push_back(line));
+  int dirty_kbytes = 0;
+  for (std::vector<std::string>::const_iterator it = lines.begin();
+       it != lines.end(); ++it) {
+    if (it->find(kAllocatorName) == std::string::npos)
+      continue;
+    const std::string& private_dirty_line = it[7];
+    if (private_dirty_line.find("Private_Dirty") == std::string::npos)
+      return -1;
+    std::vector<std::string> tokens;
+    SplitString(private_dirty_line, ' ', &tokens);
+    if (tokens.size() < 3U)
+      return -1;
+    int size;
+    if (!base::StringToInt(tokens[tokens.size() - 2], &size))
+      return -1;
+    dirty_kbytes += size;
+    it += 6;
+  }
+  return dirty_kbytes;
+}
+
+TEST(DiscardableMemoryAllocatorTest, PagesAreCommittedLazily) {
+  const scoped_ptr<DiscardableMemoryAllocator> allocator(CreateAllocator());
+  ASSERT_TRUE(allocator);
+  scoped_ptr<DiscardableMemory> memory(allocator->Allocate(2 * 4096));
+  ASSERT_TRUE(memory);
+  EXPECT_EQ(0, GetAllocatorDirtyMemoryInKBytes());
+  static_cast<char*>(memory->Memory())[0] = 'a';
+  EXPECT_EQ(4, GetAllocatorDirtyMemoryInKBytes());
+  // Write to the second page.
+  static_cast<char*>(memory->Memory())[kPageSize] = 'b';
+  EXPECT_EQ(8, GetAllocatorDirtyMemoryInKBytes());
+}
+
+#endif  // OS_ANDROID
+
+}  // namespace
+}  // namespace base