Consolidate serialization code in base::HistogramDeltasSerializer.

base/metrics/histogram_delta_serializer.cc

Index: base/metrics/histogram_delta_serializer.cc
diff --git a/base/metrics/histogram_delta_serializer.cc b/base/metrics/histogram_delta_serializer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b2272288dc5f1c2736f7207af288f0e356119a67
--- /dev/null
+++ b/base/metrics/histogram_delta_serializer.cc
@@ -0,0 +1,110 @@
+// Copyright 2013 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_delta_serializer.h"
+
+#include "base/logging.h"
+#include "base/metrics/histogram_base.h"
+#include "base/metrics/histogram_snapshot_manager.h"
+#include "base/pickle.h"
+#include "base/values.h"
+
+namespace base {
+
+namespace {
+
+// Create or find existing histogram and add the samples from pickle.
+// Silently returns when seeing any data problem in the pickle.
+void DeserializeHistogramAndAddSamples(PickleIterator* iter) {
+  HistogramBase* histogram = DeserializeHistogramInfo(iter);
+  if (!histogram)
+    return;
+
+  if (histogram->flags() & HistogramBase::kIPCSerializationSourceFlag) {
+    DVLOG(1) << "Single process mode, histogram observed and not copied: "
+             << histogram->histogram_name();
+    return;
+  }
+  histogram->AddSamplesFromPickle(iter);
+}
+
+}
+
+HistogramDeltasSerializer::HistogramDeltasSerializer(
+    const std::string& caller_name)
+    : histogram_snapshot_manager_(this),
+      inconsistencies_histogram_(NULL),
+      inconsistencies_unique_histogram_(NULL),
+      inconsistent_stapshot_histogram_(NULL) {

[Ilya Sherman, 2013/10/17 22:41:47]

nit: No need to explicitly initialize these histograms to NULL, since you
immediately reset their values below.

[Vitaly Buka (NO REVIEWS), 2013/10/18 05:33:35]

Done.

+  inconsistencies_histogram_ =
+      LinearHistogram::FactoryGet(
+          "Histogram.Inconsistencies" + caller_name, 1,
+          HistogramBase::NEVER_EXCEEDED_VALUE,
+          HistogramBase::NEVER_EXCEEDED_VALUE + 1,
+          HistogramBase::kUmaTargetedHistogramFlag);
+
+  inconsistencies_unique_histogram_ =
+      LinearHistogram::FactoryGet(
+          "Histogram.Inconsistencies" + caller_name + "Unique", 1,
+          HistogramBase::NEVER_EXCEEDED_VALUE,
+          HistogramBase::NEVER_EXCEEDED_VALUE + 1,
+          HistogramBase::kUmaTargetedHistogramFlag);
+
+  inconsistent_stapshot_histogram_ =
+      Histogram::FactoryGet(
+          "Histogram.InconsistentSnapshot" + caller_name, 1, 1000000, 50,
+          HistogramBase::kUmaTargetedHistogramFlag);
+}
+
+HistogramDeltasSerializer::~HistogramDeltasSerializer() {
+}
+
+const std::vector<std::string>& HistogramDeltasSerializer::GetNewDeltas() {
+  serialized_deltas_.clear();
+  // Note: Before serializing, we set the kIPCSerializationSourceFlag for all
+  // the histograms, so that the receiving process can distinguish them from the
+  // local histograms.
+  histogram_snapshot_manager_.PrepareDeltas(
+      Histogram::kIPCSerializationSourceFlag, false);
+  return serialized_deltas_;
+}
+
+// static
+void HistogramDeltasSerializer::DeserializeAndAddSamples(
+    const std::vector<std::string>& deltas) {
+  for (std::vector<std::string>::const_iterator it = deltas.begin();
+       it != deltas.end(); ++it) {
+    Pickle pickle(it->data(), static_cast<int>(it->size()));

[Ilya Sherman, 2013/10/17 22:41:47]

nit: Please use checked_numeric_cast here.

[Vitaly Buka (NO REVIEWS), 2013/10/18 05:33:35]

Done.

+    PickleIterator iter(pickle);
+    DeserializeHistogramAndAddSamples(&iter);
+  }
+}
+
+void HistogramDeltasSerializer::RecordDelta(const HistogramBase& histogram,
+                                            const HistogramSamples& snapshot) {
+    DCHECK_NE(0, snapshot.TotalCount());
+
+    Pickle pickle;
+    histogram.SerializeInfo(&pickle);
+    snapshot.Serialize(&pickle);
+
+    serialized_deltas_.push_back(
+        std::string(static_cast<const char*>(pickle.data()), pickle.size()));
+  }
+
+void HistogramDeltasSerializer::InconsistencyDetected(
+    HistogramBase::Inconsistency problem) {
+  inconsistencies_histogram_->Add(problem);
+}
+
+void HistogramDeltasSerializer::UniqueInconsistencyDetected(
+    HistogramBase::Inconsistency problem) {
+  inconsistencies_unique_histogram_->Add(problem);
+}
+
+void HistogramDeltasSerializer::InconsistencyDetectedInLoggedCount(int amount) {
+  inconsistent_stapshot_histogram_->Add(std::abs(amount));
+}
+
+}  // namespace base