Initial import.

1 files changed, 117 insertions, 0 deletions

diff --git a/chromium/base/metrics/histogram_snapshot_manager.cc b/chromium/base/metrics/histogram_snapshot_manager.cc
new file mode 100644
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+++ b/chromium/base/metrics/histogram_snapshot_manager.cc
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+// Copyright (c) 2012 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/histogram_snapshot_manager.h"
+
+#include "base/memory/scoped_ptr.h"
+#include "base/metrics/histogram_flattener.h"
+#include "base/metrics/histogram_samples.h"
+#include "base/metrics/statistics_recorder.h"
+#include "base/stl_util.h"
+
+using std::map;
+using std::string;
+
+namespace base {
+
+HistogramSnapshotManager::HistogramSnapshotManager(
+    HistogramFlattener* histogram_flattener)
+    : histogram_flattener_(histogram_flattener) {
+  DCHECK(histogram_flattener_);
+}
+
+HistogramSnapshotManager::~HistogramSnapshotManager() {
+  STLDeleteValues(&logged_samples_);
+}
+
+void HistogramSnapshotManager::PrepareDeltas(HistogramBase::Flags flag_to_set,
+                                             bool record_only_uma) {
+  StatisticsRecorder::Histograms histograms;
+  StatisticsRecorder::GetHistograms(&histograms);
+  for (StatisticsRecorder::Histograms::const_iterator it = histograms.begin();
+       histograms.end() != it;
+       ++it) {
+    (*it)->SetFlags(flag_to_set);
+    if (record_only_uma &&
+        0 == ((*it)->flags() & Histogram::kUmaTargetedHistogramFlag))
+      continue;
+    PrepareDelta(**it);
+  }
+}
+
+void HistogramSnapshotManager::PrepareDelta(const HistogramBase& histogram) {
+  DCHECK(histogram_flattener_);
+
+  // Get up-to-date snapshot of sample stats.
+  scoped_ptr<HistogramSamples> snapshot(histogram.SnapshotSamples());
+  const std::string& histogram_name = histogram.histogram_name();
+
+  int corruption = histogram.FindCorruption(*snapshot);
+
+  // Crash if we detect that our histograms have been overwritten.  This may be
+  // a fair distance from the memory smasher, but we hope to correlate these
+  // crashes with other events, such as plugins, or usage patterns, etc.
+  if (HistogramBase::BUCKET_ORDER_ERROR & corruption) {
+    // The checksum should have caught this, so crash separately if it didn't.
+    CHECK_NE(0, HistogramBase::RANGE_CHECKSUM_ERROR & corruption);
+    CHECK(false);  // Crash for the bucket order corruption.
+  }
+  // Checksum corruption might not have caused order corruption.
+  CHECK_EQ(0, HistogramBase::RANGE_CHECKSUM_ERROR & corruption);
+
+  // Note, at this point corruption can only be COUNT_HIGH_ERROR or
+  // COUNT_LOW_ERROR and they never arise together, so we don't need to extract
+  // bits from corruption.
+  if (corruption) {
+    DLOG(ERROR) << "Histogram: " << histogram_name
+                << " has data corruption: " << corruption;
+    histogram_flattener_->InconsistencyDetected(
+        static_cast<HistogramBase::Inconsistency>(corruption));
+    // Don't record corrupt data to metrics services.
+    int old_corruption = inconsistencies_[histogram_name];
+    if (old_corruption == (corruption | old_corruption))
+      return;  // We've already seen this corruption for this histogram.
+    inconsistencies_[histogram_name] |= corruption;
+    histogram_flattener_->UniqueInconsistencyDetected(
+        static_cast<HistogramBase::Inconsistency>(corruption));
+    return;
+  }
+
+  HistogramSamples* to_log;
+  map<string, HistogramSamples*>::iterator it =
+      logged_samples_.find(histogram_name);
+  if (it == logged_samples_.end()) {
+    to_log = snapshot.release();
+
+    // This histogram has not been logged before, add a new entry.
+    logged_samples_[histogram_name] = to_log;
+  } else {
+    HistogramSamples* already_logged = it->second;
+    InspectLoggedSamplesInconsistency(*snapshot, already_logged);
+    snapshot->Subtract(*already_logged);
+    already_logged->Add(*snapshot);
+    to_log = snapshot.get();
+  }
+
+  if (to_log->redundant_count() > 0)
+    histogram_flattener_->RecordDelta(histogram, *to_log);
+}
+
+void HistogramSnapshotManager::InspectLoggedSamplesInconsistency(
+      const HistogramSamples& new_snapshot,
+      HistogramSamples* logged_samples) {
+  HistogramBase::Count discrepancy =
+      logged_samples->TotalCount() - logged_samples->redundant_count();
+  if (!discrepancy)
+    return;
+
+  histogram_flattener_->InconsistencyDetectedInLoggedCount(discrepancy);
+  if (discrepancy > Histogram::kCommonRaceBasedCountMismatch) {
+    // Fix logged_samples.
+    logged_samples->Subtract(*logged_samples);
+    logged_samples->Add(new_snapshot);
+  }
+}
+
+}  // namespace base