From 022001851f2f6be890f9b44c49fa45ea38fa80b2 Mon Sep 17 00:00:00 2001 From: "jar@chromium.org" Date: Mon, 1 Nov 2010 23:40:51 +0000 Subject: Try to detect internal corruption of histogram instances. Corruptions can include changes in bucket boundaries, large changes in sample counts (in a bucket), etc. We now detect problems, and don't forward the corrupt data any further. This means it won't exit the renderer and go to the browser if corrupt, and it won't exit the browser and be sent up via UMA if corrupt. IF the would-be corruption is caused by a race to snapshot the data, then a later snapshot should get the clean copy, and all data (across the precluded period) will be sent onward. BUG=61281 r=mbelshe Review URL: http://codereview.chromium.org/4174002 git-svn-id: svn://svn.chromium.org/chrome/trunk/src@64687 0039d316-1c4b-4281-b951-d872f2087c98 --- base/metrics/histogram_unittest.cc | 53 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) (limited to 'base/metrics/histogram_unittest.cc') diff --git a/base/metrics/histogram_unittest.cc b/base/metrics/histogram_unittest.cc index e7e3983..b9c51ad 100644 --- a/base/metrics/histogram_unittest.cc +++ b/base/metrics/histogram_unittest.cc @@ -308,4 +308,57 @@ TEST(HistogramTest, BucketPlacementTest) { } } // namespace + +//------------------------------------------------------------------------------ +// We can't be an an anonymous namespace while being friends, so we pop back +// out to the base namespace here. We need to be friends to corrupt the +// internals of the histogram and/or sampleset. +TEST(HistogramTest, CorruptSampleCounts) { + scoped_refptr histogram = Histogram::FactoryGet( + "Histogram", 1, 64, 8, Histogram::kNoFlags); // As per header file. + + EXPECT_EQ(0, histogram->sample_.redundant_count()); + histogram->Add(20); // Add some samples. + histogram->Add(40); + EXPECT_EQ(2, histogram->sample_.redundant_count()); + + Histogram::SampleSet snapshot; + histogram->SnapshotSample(&snapshot); + EXPECT_EQ(Histogram::NO_INCONSISTENCIES, 0); + EXPECT_EQ(0, histogram->FindCorruption(snapshot)); // No default corruption. + EXPECT_EQ(2, snapshot.redundant_count()); + + snapshot.counts_[3] += 100; // Sample count won't match redundant count. + EXPECT_EQ(Histogram::COUNT_LOW_ERROR, histogram->FindCorruption(snapshot)); + snapshot.counts_[2] -= 200; + EXPECT_EQ(Histogram::COUNT_HIGH_ERROR, histogram->FindCorruption(snapshot)); + + // But we can't spot a corruption if it is compensated for. + snapshot.counts_[1] += 100; + EXPECT_EQ(0, histogram->FindCorruption(snapshot)); +} + +TEST(HistogramTest, CorruptBucketBounds) { + scoped_refptr histogram = Histogram::FactoryGet( + "Histogram", 1, 64, 8, Histogram::kNoFlags); // As per header file. + + Histogram::SampleSet snapshot; + histogram->SnapshotSample(&snapshot); + EXPECT_EQ(Histogram::NO_INCONSISTENCIES, 0); + EXPECT_EQ(0, histogram->FindCorruption(snapshot)); // No default corruption. + + std::swap(histogram->ranges_[1], histogram->ranges_[2]); + EXPECT_EQ(Histogram::BUCKET_ORDER_ERROR, histogram->FindCorruption(snapshot)); + + std::swap(histogram->ranges_[1], histogram->ranges_[2]); + EXPECT_EQ(0, histogram->FindCorruption(snapshot)); + + ++histogram->ranges_[3]; + EXPECT_EQ(Histogram::RANGE_CHECKSUM_ERROR, + histogram->FindCorruption(snapshot)); + + // Repair histogram so that destructor won't DCHECK(). + --histogram->ranges_[3]; +} + } // namespace base -- cgit v1.1