Implement a ScopedThreadHeapUsage class to allow profiling per-thread heap usage.

base/debug/scoped_heap_usage_unittest.cc

+// Copyright 2016 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/debug/scoped_heap_usage.h"
+
+#include "base/allocator/features.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace debug {
+
+#if BUILDFLAG(USE_EXPERIMENTAL_ALLOCATOR_SHIM)
+namespace {
+
+class TestingScopedHeapUsage : public ScopedHeapUsage {
+ public:
+  using ScopedHeapUsage::TearDownForTesting;
+};
+
+class ScopedHeapUsageTest : public testing::Test {
+ public:
+  void SetUp() override { ScopedHeapUsage::Initialize(); }
+
+  void TearDown() override { TestingScopedHeapUsage::TearDownForTesting(); }
+};
+
+}  // namespace
+
+TEST_F(ScopedHeapUsageTest, SimpleUsage) {
+  ScopedHeapUsage scoped_usage;
+
+  ScopedHeapUsage::AllocatorUsage u1 = scoped_usage.usage_at_creation();
+  ScopedHeapUsage::AllocatorUsage u2 = ScopedHeapUsage::Now();
+
+  EXPECT_EQ(u1.alloc_ops, u2.alloc_ops);

[Primiano Tucci (use gerrit), 2016/08/24 14:11:46]

I'd move these expect statements below., after u3
If for any reason EXPECT_EQ does some malloc (to lazily initiailize something)
this test will break in very puzzling ways.

[Sigurður Ásgeirsson, 2016/09/01 15:18:18]

Yeah, I'm going to rewrite this test to test the intercept in two parts:
1. it's chained in from a malloc or the like.
2. invoke on the dispatch functions directly with a mocked "next" dispatch to
simulate various behaviors in the underlying get_size function.

+  EXPECT_EQ(u1.alloc_bytes, u2.alloc_bytes);
+  EXPECT_EQ(u1.alloc_overhead_bytes, u2.alloc_overhead_bytes);
+  EXPECT_EQ(u1.free_ops, u2.free_ops);
+  EXPECT_EQ(u1.free_bytes, u2.free_bytes);
+  EXPECT_EQ(0U, u2.max_allocated_bytes);
+
+  const size_t kAllocSize = 1029U;
+  void* ptr = malloc(kAllocSize);
+  free(ptr);
+
+  ScopedHeapUsage::AllocatorUsage u3 = ScopedHeapUsage::Now();
+
+  EXPECT_LT(u1.alloc_ops, u3.alloc_ops);
+  EXPECT_LE(u1.alloc_bytes + kAllocSize, u3.alloc_bytes);
+  EXPECT_LE(u1.alloc_overhead_bytes, u3.alloc_overhead_bytes);
+  EXPECT_LT(u1.free_ops, u3.free_ops);
+  EXPECT_LE(u1.free_bytes + kAllocSize, u3.free_bytes);
+  EXPECT_LE(kAllocSize, u3.max_allocated_bytes);
+}
+
+TEST_F(ScopedHeapUsageTest, NestedMaxWorks) {
+  ScopedHeapUsage outer_scoped_usage;
+
+  const size_t kOuterAllocSize = 1029U;
+  void* ptr = malloc(kOuterAllocSize);
+  free(ptr);
+
+  EXPECT_LE(kOuterAllocSize, ScopedHeapUsage::Now().max_allocated_bytes);
+
+  {
+    ScopedHeapUsage inner_scoped_usage;
+
+    const size_t kInnerAllocSize = 673U;
+    ptr = malloc(kInnerAllocSize);
+    free(ptr);
+
+    EXPECT_LE(kInnerAllocSize, ScopedHeapUsage::Now().max_allocated_bytes);
+  }
+
+  // The greater, outer allocation size should have been restored.
+  EXPECT_LE(kOuterAllocSize, ScopedHeapUsage::Now().max_allocated_bytes);
+
+  const size_t kLargerInnerAllocSize = kOuterAllocSize + 673U;
+  {
+    ScopedHeapUsage inner_scoped_usage;
+
+    ptr = malloc(kLargerInnerAllocSize);
+    free(ptr);
+
+    EXPECT_LE(kLargerInnerAllocSize,
+              ScopedHeapUsage::Now().max_allocated_bytes);
+  }
+
+  // The greater, inner allocation size should have been preserved.
+  EXPECT_LE(kLargerInnerAllocSize, ScopedHeapUsage::Now().max_allocated_bytes);
+}
+#endif  // BUILDFLAG(USE_EXPERIMENTAL_ALLOCATOR_SHIM)
+
+}  // namespace debug
+}  // namespace base