base: Add free list implementation to browser-wide discardable memory system.

content/common/discardable_shared_memory_heap_unittest.cc

+// 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 "content/common/discardable_shared_memory_heap.h"
+
+#include "base/memory/discardable_shared_memory.h"
+#include "base/process/process_metrics.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace content {
+namespace {
+
+class DiscardableSharedMemoryHeapTest : public testing::Test {};
+
+TEST_F(DiscardableSharedMemoryHeapTest, Basic) {
+  size_t block_size = base::GetPageSize();
+  DiscardableSharedMemoryHeap heap(block_size);
+
+  // Free list is initially empty.
+  EXPECT_FALSE(heap.SearchFreeList(1));
+
+  const size_t kBlocks = 10;
+  size_t memory_size = block_size * kBlocks;
+
+  scoped_ptr<base::DiscardableSharedMemory> memory(
+      new base::DiscardableSharedMemory);
+  ASSERT_TRUE(memory->CreateAndMap(memory_size));
+
+  // Create new span for memory.
+  scoped_ptr<DiscardableSharedMemoryHeap::Span> new_span(
+      heap.Grow(memory.Pass(), memory_size));
+
+  // Free list should still be empty as |new_span| is currently in use.
+  EXPECT_FALSE(heap.SearchFreeList(1));
+
+  // Done using |new_span|. Merge it into the free list.
+  heap.MergeIntoFreeList(new_span.Pass());
+
+  // Free list should not contain a span that is larger than kBlocks.
+  EXPECT_FALSE(heap.SearchFreeList(kBlocks + 1));
+
+  // Free list should contain a span that satisfies the request for kBlocks.
+  scoped_ptr<DiscardableSharedMemoryHeap::Span> span =
+      heap.SearchFreeList(kBlocks);
+  ASSERT_TRUE(span);
+
+  // Delete span and shared memory backing.
+  heap.DeleteSpan(span.Pass());
+
+  // Free list should be empty again.
+  EXPECT_FALSE(heap.SearchFreeList(1));
+}
+
+TEST_F(DiscardableSharedMemoryHeapTest, SplitAndMerge) {
+  size_t block_size = base::GetPageSize();
+  DiscardableSharedMemoryHeap heap(block_size);
+
+  const size_t kBlocks = 6;
+  size_t memory_size = block_size * kBlocks;
+
+  scoped_ptr<base::DiscardableSharedMemory> memory(
+      new base::DiscardableSharedMemory);
+  ASSERT_TRUE(memory->CreateAndMap(memory_size));
+  scoped_ptr<DiscardableSharedMemoryHeap::Span> new_span(
+      heap.Grow(memory.Pass(), memory_size));
+
+  // Split span into two.
+  scoped_ptr<DiscardableSharedMemoryHeap::Span> leftover =
+      heap.Split(new_span.get(), 3);
+  ASSERT_TRUE(leftover);
+
+  // Merge |leftover| into free list.
+  heap.MergeIntoFreeList(leftover.Pass());
+
+  // Some of the memory is still in use.
+  EXPECT_FALSE(heap.SearchFreeList(kBlocks));
+
+  // Merge |span| into free list.
+  heap.MergeIntoFreeList(new_span.Pass());
+
+  // Remove a 2 page span from free list.
+  scoped_ptr<DiscardableSharedMemoryHeap::Span> span1 = heap.SearchFreeList(2);
+  ASSERT_TRUE(span1);
+
+  // Remove another 2 page span from free list.
+  scoped_ptr<DiscardableSharedMemoryHeap::Span> span2 = heap.SearchFreeList(2);
+  ASSERT_TRUE(span2);
+
+  // Merge |span1| back into free list.
+  heap.MergeIntoFreeList(span1.Pass());
+
+  // Some of the memory is still in use.
+  EXPECT_FALSE(heap.SearchFreeList(kBlocks));
+
+  // Merge |span2| back into free list.
+  heap.MergeIntoFreeList(span2.Pass());
+
+  // All memory has been returned to the free list.
+  scoped_ptr<DiscardableSharedMemoryHeap::Span> large_span =
+      heap.SearchFreeList(kBlocks);
+  EXPECT_TRUE(large_span);
+}
+
+TEST_F(DiscardableSharedMemoryHeapTest, Grow) {
+  size_t block_size = base::GetPageSize();
+  DiscardableSharedMemoryHeap heap(block_size);
+
+  scoped_ptr<base::DiscardableSharedMemory> memory1(
+      new base::DiscardableSharedMemory);
+  ASSERT_TRUE(memory1->CreateAndMap(block_size));
+  heap.MergeIntoFreeList(heap.Grow(memory1.Pass(), block_size).Pass());
+
+  // Remove a span from free list.
+  scoped_ptr<DiscardableSharedMemoryHeap::Span> span1 = heap.SearchFreeList(1);
+  EXPECT_TRUE(span1);
+
+  // No more memory available.
+  EXPECT_FALSE(heap.SearchFreeList(1));
+
+  // Grow free list using new memory.
+  scoped_ptr<base::DiscardableSharedMemory> memory2(
+      new base::DiscardableSharedMemory);
+  ASSERT_TRUE(memory2->CreateAndMap(block_size));
+  heap.MergeIntoFreeList(heap.Grow(memory2.Pass(), block_size).Pass());
+
+  // Memory should now be available.
+  scoped_ptr<DiscardableSharedMemoryHeap::Span> span2 = heap.SearchFreeList(1);
+  EXPECT_TRUE(span2);
+}
+
+}  // namespace
+}  // namespace content