Add support for persistent sparse histograms.

base/metrics/persistent_sample_map_unittest.cc

Index: base/metrics/persistent_sample_map_unittest.cc
diff --git a/base/metrics/persistent_sample_map_unittest.cc b/base/metrics/persistent_sample_map_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c735f8fd278458011c06c1ca1fc81a951a7efc7d
--- /dev/null
+++ b/base/metrics/persistent_sample_map_unittest.cc
@@ -0,0 +1,243 @@
+// Copyright (c) 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/metrics/persistent_sample_map.h"
+
+#include "base/memory/scoped_ptr.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace {
+
+TEST(PersistentSampleMapTest, AccumulateTest) {
+  LocalPersistentMemoryAllocator allocator(64 << 10, 0, "");  // 64 KiB
+
+  HistogramSamples::Metadata* meta =
+      allocator.GetAsObject<HistogramSamples::Metadata>(
+          allocator.Allocate(sizeof(HistogramSamples::Metadata), 0), 0);
+  PersistentSampleMap samples(1, &allocator, meta);
+
+  samples.Accumulate(1, 100);
+  samples.Accumulate(2, 200);
+  samples.Accumulate(1, -200);
+  EXPECT_EQ(-100, samples.GetCount(1));
+  EXPECT_EQ(200, samples.GetCount(2));
+
+  EXPECT_EQ(300, samples.sum());
+  EXPECT_EQ(100, samples.TotalCount());
+  EXPECT_EQ(samples.redundant_count(), samples.TotalCount());
+}
+
+TEST(PersistentSampleMapTest, Accumulate_LargeValuesDontOverflow) {
+  LocalPersistentMemoryAllocator allocator(64 << 10, 0, "");  // 64 KiB
+
+  HistogramSamples::Metadata* meta =
+      allocator.GetAsObject<HistogramSamples::Metadata>(
+          allocator.Allocate(sizeof(HistogramSamples::Metadata), 0), 0);
+  PersistentSampleMap samples(1, &allocator, meta);
+
+  samples.Accumulate(250000000, 100);
+  samples.Accumulate(500000000, 200);
+  samples.Accumulate(250000000, -200);
+  EXPECT_EQ(-100, samples.GetCount(250000000));
+  EXPECT_EQ(200, samples.GetCount(500000000));
+
+  EXPECT_EQ(75000000000LL, samples.sum());
+  EXPECT_EQ(100, samples.TotalCount());
+  EXPECT_EQ(samples.redundant_count(), samples.TotalCount());
+}
+
+TEST(PersistentSampleMapTest, AddSubtractTest) {
+  LocalPersistentMemoryAllocator allocator(64 << 10, 0, "");  // 64 KiB
+
+  HistogramSamples::Metadata* meta1 =
+      allocator.GetAsObject<HistogramSamples::Metadata>(
+          allocator.Allocate(sizeof(HistogramSamples::Metadata), 0), 0);
+  HistogramSamples::Metadata* meta2 =
+      allocator.GetAsObject<HistogramSamples::Metadata>(
+          allocator.Allocate(sizeof(HistogramSamples::Metadata), 0), 0);
+  PersistentSampleMap samples1(1, &allocator, meta1);
+  PersistentSampleMap samples2(2, &allocator, meta2);
+
+  samples1.Accumulate(1, 100);
+  samples1.Accumulate(2, 100);
+  samples1.Accumulate(3, 100);
+
+  samples2.Accumulate(1, 200);
+  samples2.Accumulate(2, 200);
+  samples2.Accumulate(4, 200);
+
+  samples1.Add(samples2);
+  EXPECT_EQ(300, samples1.GetCount(1));
+  EXPECT_EQ(300, samples1.GetCount(2));
+  EXPECT_EQ(100, samples1.GetCount(3));
+  EXPECT_EQ(200, samples1.GetCount(4));
+  EXPECT_EQ(2000, samples1.sum());
+  EXPECT_EQ(900, samples1.TotalCount());
+  EXPECT_EQ(samples1.redundant_count(), samples1.TotalCount());
+
+  samples1.Subtract(samples2);
+  EXPECT_EQ(100, samples1.GetCount(1));
+  EXPECT_EQ(100, samples1.GetCount(2));
+  EXPECT_EQ(100, samples1.GetCount(3));
+  EXPECT_EQ(0, samples1.GetCount(4));
+  EXPECT_EQ(600, samples1.sum());
+  EXPECT_EQ(300, samples1.TotalCount());
+  EXPECT_EQ(samples1.redundant_count(), samples1.TotalCount());
+}
+
+TEST(PersistentSampleMapTest, PersistenceTest) {
+  LocalPersistentMemoryAllocator allocator(64 << 10, 0, "");  // 64 KiB
+
+  HistogramSamples::Metadata* meta12 =
+      allocator.GetAsObject<HistogramSamples::Metadata>(
+          allocator.Allocate(sizeof(HistogramSamples::Metadata), 0), 0);
+  PersistentSampleMap samples1(12, &allocator, meta12);
+  samples1.Accumulate(1, 100);
+  samples1.Accumulate(2, 200);
+  samples1.Accumulate(1, -200);
+  EXPECT_EQ(-100, samples1.GetCount(1));
+  EXPECT_EQ(200, samples1.GetCount(2));
+  EXPECT_EQ(300, samples1.sum());
+  EXPECT_EQ(100, samples1.TotalCount());
+  EXPECT_EQ(samples1.redundant_count(), samples1.TotalCount());
+
+  PersistentSampleMap samples2(12, &allocator, meta12);
+  EXPECT_EQ(samples1.id(), samples2.id());
+  EXPECT_EQ(samples1.sum(), samples2.sum());
+  EXPECT_EQ(samples1.redundant_count(), samples2.redundant_count());
+  EXPECT_EQ(samples1.TotalCount(), samples2.TotalCount());
+  EXPECT_EQ(-100, samples2.GetCount(1));
+  EXPECT_EQ(200, samples2.GetCount(2));
+  EXPECT_EQ(300, samples2.sum());
+  EXPECT_EQ(100, samples2.TotalCount());
+  EXPECT_EQ(samples2.redundant_count(), samples2.TotalCount());
+
+  EXPECT_EQ(0, samples2.GetCount(3));
+  EXPECT_EQ(0, samples1.GetCount(3));
+  samples2.Accumulate(3, 300);
+  EXPECT_EQ(300, samples2.GetCount(3));
+  EXPECT_EQ(300, samples1.GetCount(3));
+  EXPECT_EQ(samples1.sum(), samples2.sum());
+  EXPECT_EQ(samples1.redundant_count(), samples2.redundant_count());
+  EXPECT_EQ(samples1.TotalCount(), samples2.TotalCount());
+}
+
+TEST(PersistentSampleMapIteratorTest, IterateTest) {
+  LocalPersistentMemoryAllocator allocator(64 << 10, 0, "");  // 64 KiB
+
+  HistogramSamples::Metadata* meta =
+      allocator.GetAsObject<HistogramSamples::Metadata>(
+          allocator.Allocate(sizeof(HistogramSamples::Metadata), 0), 0);
+  PersistentSampleMap samples(1, &allocator, meta);
+  samples.Accumulate(1, 100);
+  samples.Accumulate(2, 200);
+  samples.Accumulate(4, -300);
+  samples.Accumulate(5, 0);
+
+  scoped_ptr<SampleCountIterator> it = samples.Iterator();
+
+  HistogramBase::Sample min;
+  HistogramBase::Sample max;
+  HistogramBase::Count count;
+
+  it->Get(&min, &max, &count);
+  EXPECT_EQ(1, min);
+  EXPECT_EQ(2, max);
+  EXPECT_EQ(100, count);
+  EXPECT_FALSE(it->GetBucketIndex(NULL));
+
+  it->Next();
+  it->Get(&min, &max, &count);
+  EXPECT_EQ(2, min);
+  EXPECT_EQ(3, max);
+  EXPECT_EQ(200, count);
+
+  it->Next();
+  it->Get(&min, &max, &count);
+  EXPECT_EQ(4, min);
+  EXPECT_EQ(5, max);
+  EXPECT_EQ(-300, count);
+
+  it->Next();
+  EXPECT_TRUE(it->Done());
+}
+
+TEST(PersistentSampleMapIteratorTest, SkipEmptyRanges) {
+  LocalPersistentMemoryAllocator allocator(64 << 10, 0, "");  // 64 KiB
+
+  HistogramSamples::Metadata* meta =
+      allocator.GetAsObject<HistogramSamples::Metadata>(
+          allocator.Allocate(sizeof(HistogramSamples::Metadata), 0), 0);
+  PersistentSampleMap samples(1, &allocator, meta);
+  samples.Accumulate(5, 1);
+  samples.Accumulate(10, 2);
+  samples.Accumulate(15, 3);
+  samples.Accumulate(20, 4);
+  samples.Accumulate(25, 5);
+
+  HistogramSamples::Metadata* meta2 =
+      allocator.GetAsObject<HistogramSamples::Metadata>(
+          allocator.Allocate(sizeof(HistogramSamples::Metadata), 0), 0);
+  PersistentSampleMap samples2(2, &allocator, meta2);
+  samples2.Accumulate(5, 1);
+  samples2.Accumulate(20, 4);
+  samples2.Accumulate(25, 5);
+
+  samples.Subtract(samples2);
+
+  scoped_ptr<SampleCountIterator> it = samples.Iterator();
+  EXPECT_FALSE(it->Done());
+
+  HistogramBase::Sample min;
+  HistogramBase::Sample max;
+  HistogramBase::Count count;
+
+  it->Get(&min, &max, &count);
+  EXPECT_EQ(10, min);
+  EXPECT_EQ(11, max);
+  EXPECT_EQ(2, count);
+
+  it->Next();
+  EXPECT_FALSE(it->Done());
+
+  it->Get(&min, &max, &count);
+  EXPECT_EQ(15, min);
+  EXPECT_EQ(16, max);
+  EXPECT_EQ(3, count);
+
+  it->Next();
+  EXPECT_TRUE(it->Done());
+}
+
+// Only run this test on builds that support catching a DCHECK crash.
+#if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)) && GTEST_HAS_DEATH_TEST
+TEST(PersistentSampleMapIteratorDeathTest, IterateDoneTest) {
+  LocalPersistentMemoryAllocator allocator(64 << 10, 0, "");  // 64 KiB
+
+  HistogramSamples::Metadata* meta =
+      allocator.GetAsObject<HistogramSamples::Metadata>(
+          allocator.Allocate(sizeof(HistogramSamples::Metadata), 0), 0);
+  PersistentSampleMap samples(1, &allocator, meta);
+
+  scoped_ptr<SampleCountIterator> it = samples.Iterator();
+
+  EXPECT_TRUE(it->Done());
+
+  HistogramBase::Sample min;
+  HistogramBase::Sample max;
+  HistogramBase::Count count;
+  EXPECT_DEATH(it->Get(&min, &max, &count), "");
+
+  EXPECT_DEATH(it->Next(), "");
+
+  samples.Accumulate(1, 100);
+  it = samples.Iterator();
+  EXPECT_FALSE(it->Done());
+}
+#endif
+// (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)) && GTEST_HAS_DEATH_TEST
+
+}  // namespace
+}  // namespace base