Repo created

TMessagesProj/jni/voip/webrtc/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 <memory>
+
+#include "base/debug/alias.h"
+#include "base/metrics/histogram_flattener.h"
+#include "base/metrics/histogram_samples.h"
+#include "base/metrics/statistics_recorder.h"
+#include "base/stl_util.h"
+
+namespace base {
+
+namespace {
+
+// A simple object to set an "active" flag and clear it upon destruction. It is
+// an error if the flag is already set.
+class MakeActive {
+ public:
+  MakeActive(std::atomic<bool>* is_active) : is_active_(is_active) {
+    bool was_active = is_active_->exchange(true, std::memory_order_relaxed);
+    CHECK(!was_active);
+  }
+  ~MakeActive() { is_active_->store(false, std::memory_order_relaxed); }
+
+ private:
+  std::atomic<bool>* is_active_;
+
+  DISALLOW_COPY_AND_ASSIGN(MakeActive);
+};
+
+}  // namespace
+
+HistogramSnapshotManager::HistogramSnapshotManager(
+    HistogramFlattener* histogram_flattener)
+    : histogram_flattener_(histogram_flattener) {
+  DCHECK(histogram_flattener_);
+  is_active_.store(false, std::memory_order_relaxed);
+}
+
+HistogramSnapshotManager::~HistogramSnapshotManager() = default;
+
+void HistogramSnapshotManager::PrepareDeltas(
+    const std::vector<HistogramBase*>& histograms,
+    HistogramBase::Flags flags_to_set,
+    HistogramBase::Flags required_flags) {
+  for (HistogramBase* const histogram : histograms) {
+    histogram->SetFlags(flags_to_set);
+    if ((histogram->flags() & required_flags) == required_flags)
+      PrepareDelta(histogram);
+  }
+}
+
+void HistogramSnapshotManager::PrepareDelta(HistogramBase* histogram) {
+  histogram->ValidateHistogramContents();
+  PrepareSamples(histogram, histogram->SnapshotDelta());
+}
+
+void HistogramSnapshotManager::PrepareFinalDelta(
+    const HistogramBase* histogram) {
+  histogram->ValidateHistogramContents();
+  PrepareSamples(histogram, histogram->SnapshotFinalDelta());
+}
+
+void HistogramSnapshotManager::PrepareSamples(
+    const HistogramBase* histogram,
+    std::unique_ptr<HistogramSamples> samples) {
+  DCHECK(histogram_flattener_);
+
+  // Ensure that there is no concurrent access going on while accessing the
+  // set of known histograms. The flag will be reset when this object goes
+  // out of scope.
+  MakeActive make_active(&is_active_);
+
+  // Get information known about this histogram. If it did not previously
+  // exist, one will be created and initialized.
+  SampleInfo* sample_info = &known_histograms_[histogram->name_hash()];
+
+  // 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.
+  uint32_t corruption = histogram->FindCorruption(*samples);
+  if (HistogramBase::BUCKET_ORDER_ERROR & corruption) {
+    // Extract fields useful during debug.
+    const BucketRanges* ranges =
+        static_cast<const Histogram*>(histogram)->bucket_ranges();
+    uint32_t ranges_checksum = ranges->checksum();
+    uint32_t ranges_calc_checksum = ranges->CalculateChecksum();
+    int32_t flags = histogram->flags();
+    // The checksum should have caught this, so crash separately if it didn't.
+    CHECK_NE(0U, HistogramBase::RANGE_CHECKSUM_ERROR & corruption);
+    CHECK(false);  // Crash for the bucket order corruption.
+    // Ensure that compiler keeps around pointers to |histogram| and its
+    // internal |bucket_ranges_| for any minidumps.
+    base::debug::Alias(&ranges_checksum);
+    base::debug::Alias(&ranges_calc_checksum);
+    base::debug::Alias(&flags);
+  }
+  // Checksum corruption might not have caused order corruption.
+  CHECK_EQ(0U, 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->histogram_name()
+                << "\" has data corruption: " << corruption;
+    // Don't record corrupt data to metrics services.
+    const uint32_t old_corruption = sample_info->inconsistencies;
+    if (old_corruption == (corruption | old_corruption))
+      return;  // We've already seen this corruption for this histogram.
+    sample_info->inconsistencies |= corruption;
+    return;
+  }
+
+  if (samples->TotalCount() > 0)
+    histogram_flattener_->RecordDelta(*histogram, *samples);
+}
+
+}  // namespace base