Serialize/Deserialize support in HistogramBase

base/metrics/histogram.cc

Index: base/metrics/histogram.cc
diff --git a/base/metrics/histogram.cc b/base/metrics/histogram.cc
index 795ea3a832387c4bbaa1ddb8d101c94b5166f806..d5da3711409dc61002e4bc9e8efd5ee0f0fc24af 100644
--- a/base/metrics/histogram.cc
+++ b/base/metrics/histogram.cc
@@ -30,6 +30,54 @@ using std::vector;
 
 namespace base {
 
+namespace {
+
+bool ReadHistogramArguments(PickleIterator* iter,
+                            string* histogram_name,
+                            int* flags,
+                            int* declared_min,
+                            int* declared_max,
+                            uint64* bucket_count,
+                            uint32* range_checksum) {
+  if (!iter->ReadString(histogram_name) ||
+      !iter->ReadInt(flags) ||
+      !iter->ReadInt(declared_min) ||
+      !iter->ReadInt(declared_max) ||
+      !iter->ReadUInt64(bucket_count) ||
+      !iter->ReadUInt32(range_checksum)) {
+    DLOG(ERROR) << "Pickle error decoding Histogram: " << *histogram_name;
+    return false;
+  }
+
+  // Since these fields may have come from an untrusted renderer, do additional
+  // checks above and beyond those in Histogram::Initialize()
+  if (*declared_max <= 0 ||
+      *declared_min <= 0 ||
+      *declared_max < *declared_min ||
+      INT_MAX / sizeof(HistogramBase::Count) <= *bucket_count ||
+      *bucket_count < 2) {
+    DLOG(ERROR) << "Values error decoding Histogram: " << histogram_name;
+    return false;
+  }
+
+  // We use the arguments to find or create the local version of the histogram
+  // in this process, so we need to clear the IPC flag.
+  DCHECK(*flags & HistogramBase::kIPCSerializationSourceFlag);
+  *flags &= ~HistogramBase::kIPCSerializationSourceFlag;
+
+  return true;
+}
+
+bool ValidateRangeChecksum(const HistogramBase& histogram,
+                           uint32 range_checksum) {
+  const Histogram& casted_histogram =
+      static_cast<const Histogram&>(histogram);
+
+  return casted_histogram.bucket_ranges()->checksum() == range_checksum;
+}
+
+}  // namespace
+
 typedef HistogramBase::Count Count;
 typedef HistogramBase::Sample Sample;
 
@@ -153,117 +201,6 @@ void Histogram::AddBoolean(bool value) {
   DCHECK(false);
 }
 
-void Histogram::AddSamples(const HistogramSamples& samples) {
-  samples_->Add(samples);
-}
-
-bool Histogram::AddSamplesFromPickle(PickleIterator* iter) {
-  return samples_->AddFromPickle(iter);
-}
-
-// static
-string Histogram::SerializeHistogramInfo(const Histogram& histogram,
-                                         const HistogramSamples& snapshot) {
-  DCHECK(histogram.bucket_ranges()->HasValidChecksum());
-
-  Pickle pickle;
-  pickle.WriteString(histogram.histogram_name());
-  pickle.WriteInt(histogram.declared_min());
-  pickle.WriteInt(histogram.declared_max());
-  pickle.WriteUInt64(histogram.bucket_count());
-  pickle.WriteUInt32(histogram.bucket_ranges()->checksum());
-  pickle.WriteInt(histogram.GetHistogramType());
-  pickle.WriteInt(histogram.flags());
-
-  histogram.SerializeRanges(&pickle);
-
-  snapshot.Serialize(&pickle);
-
-  return string(static_cast<const char*>(pickle.data()), pickle.size());
-}
-
-// static
-bool Histogram::DeserializeHistogramInfo(const string& histogram_info) {
-  if (histogram_info.empty()) {
-    return false;
-  }
-
-  Pickle pickle(histogram_info.data(),
-                static_cast<int>(histogram_info.size()));
-  string histogram_name;
-  int declared_min;
-  int declared_max;
-  uint64 bucket_count;
-  uint32 range_checksum;
-  int histogram_type;
-  int pickle_flags;
-
-  PickleIterator iter(pickle);
-  if (!iter.ReadString(&histogram_name) ||
-      !iter.ReadInt(&declared_min) ||
-      !iter.ReadInt(&declared_max) ||
-      !iter.ReadUInt64(&bucket_count) ||
-      !iter.ReadUInt32(&range_checksum) ||
-      !iter.ReadInt(&histogram_type) ||
-      !iter.ReadInt(&pickle_flags)) {
-    DLOG(ERROR) << "Pickle error decoding Histogram: " << histogram_name;
-    return false;
-  }
-
-  DCHECK(pickle_flags & kIPCSerializationSourceFlag);
-  // Since these fields may have come from an untrusted renderer, do additional
-  // checks above and beyond those in Histogram::Initialize()
-  if (declared_max <= 0 || declared_min <= 0 || declared_max < declared_min ||
-      INT_MAX / sizeof(Count) <= bucket_count || bucket_count < 2) {
-    DLOG(ERROR) << "Values error decoding Histogram: " << histogram_name;
-    return false;
-  }
-
-  Flags flags = static_cast<Flags>(pickle_flags & ~kIPCSerializationSourceFlag);
-
-  Histogram* render_histogram(NULL);
-
-  if (histogram_type == HISTOGRAM) {
-    render_histogram = Histogram::FactoryGet(
-        histogram_name, declared_min, declared_max, bucket_count, flags);
-  } else if (histogram_type == LINEAR_HISTOGRAM) {
-    render_histogram = LinearHistogram::FactoryGet(
-        histogram_name, declared_min, declared_max, bucket_count, flags);
-  } else if (histogram_type == BOOLEAN_HISTOGRAM) {
-    render_histogram = BooleanHistogram::FactoryGet(histogram_name, flags);
-  } else if (histogram_type == CUSTOM_HISTOGRAM) {
-    vector<Sample> sample_ranges(bucket_count);
-    if (!CustomHistogram::DeserializeRanges(&iter, &sample_ranges)) {
-      DLOG(ERROR) << "Pickle error decoding ranges: " << histogram_name;
-      return false;
-    }
-    render_histogram =
-        CustomHistogram::FactoryGet(histogram_name, sample_ranges, flags);
-  } else {
-    DLOG(ERROR) << "Error Deserializing Histogram Unknown histogram_type: "
-                << histogram_type;
-    return false;
-  }
-
-  DCHECK_EQ(render_histogram->declared_min(), declared_min);
-  DCHECK_EQ(render_histogram->declared_max(), declared_max);
-  DCHECK_EQ(render_histogram->bucket_count(), bucket_count);
-  DCHECK_EQ(render_histogram->GetHistogramType(), histogram_type);
-
-  if (render_histogram->bucket_ranges()->checksum() != range_checksum) {
-    return false;
-  }
-
-  if (render_histogram->flags() & kIPCSerializationSourceFlag) {
-    DVLOG(1) << "Single process mode, histogram observed and not copied: "
-             << histogram_name;
-    return true;
-  }
-
-  DCHECK_EQ(flags & render_histogram->flags(), flags);
-  return render_histogram->AddSamplesFromPickle(&iter);
-}
-
 // static
 const int Histogram::kCommonRaceBasedCountMismatch = 5;
 
@@ -363,6 +300,14 @@ scoped_ptr<HistogramSamples> Histogram::SnapshotSamples() const {
   return SnapshotSampleVector().PassAs<HistogramSamples>();
 }
 
+void Histogram::AddSamples(const HistogramSamples& samples) {
+  samples_->Add(samples);
+}
+
+bool Histogram::AddSamplesFromPickle(PickleIterator* iter) {
+  return samples_->AddFromPickle(iter);
+}
+
 // The following methods provide a graphical histogram display.
 void Histogram::WriteHTMLGraph(string* output) const {
   // TBD(jar) Write a nice HTML bar chart, with divs an mouse-overs etc.
@@ -375,6 +320,16 @@ void Histogram::WriteAscii(string* output) const {
   WriteAsciiImpl(true, "\n", output);
 }
 
+bool Histogram::SerializeInfoImpl(Pickle* pickle) const {
+  DCHECK(bucket_ranges()->HasValidChecksum());
+  return pickle->WriteString(histogram_name()) &&
+      pickle->WriteInt(flags()) &&
+      pickle->WriteInt(declared_min()) &&
+      pickle->WriteInt(declared_max()) &&
+      pickle->WriteUInt64(bucket_count()) &&
+      pickle->WriteUInt32(bucket_ranges()->checksum());
+}
+
 Histogram::Histogram(const string& name,
                      Sample minimum,
                      Sample maximum,
@@ -397,10 +352,6 @@ Histogram::~Histogram() {
   }
 }
 
-bool Histogram::SerializeRanges(Pickle* pickle) const {
-  return true;
-}
-
 bool Histogram::PrintEmptyBucket(size_t index) const {
   return true;
 }
@@ -431,6 +382,31 @@ const string Histogram::GetAsciiBucketRange(size_t i) const {
 //------------------------------------------------------------------------------
 // Private methods
 
+// static
+HistogramBase* Histogram::DeserializeInfoImpl(PickleIterator* iter) {
+  string histogram_name;
+  int flags;
+  int declared_min;
+  int declared_max;
+  uint64 bucket_count;
+  uint32 range_checksum;
+
+  if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
+                              &declared_max, &bucket_count, &range_checksum)) {
+    return NULL;
+  }
+
+  // Find or create the local version of the histogram in this process.
+  HistogramBase* histogram = Histogram::FactoryGet(
+      histogram_name, declared_min, declared_max, bucket_count, flags);
+
+  if (!ValidateRangeChecksum(*histogram, range_checksum)) {
+    // The serialized histogram might be corrupted.
+    return NULL;
+  }
+  return histogram;
+}
+
 scoped_ptr<SampleVector> Histogram::SnapshotSampleVector() const {
   scoped_ptr<SampleVector> samples(new SampleVector(bucket_ranges()));
   samples->Add(*samples_);
@@ -710,6 +686,29 @@ void LinearHistogram::InitializeBucketRanges(Sample minimum,
   ranges->ResetChecksum();
 }
 
+// static
+HistogramBase* LinearHistogram::DeserializeInfoImpl(PickleIterator* iter) {
+  string histogram_name;
+  int flags;
+  int declared_min;
+  int declared_max;
+  uint64 bucket_count;
+  uint32 range_checksum;
+
+  if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
+                              &declared_max, &bucket_count, &range_checksum)) {
+    return NULL;
+  }
+
+  HistogramBase* histogram = LinearHistogram::FactoryGet(
+      histogram_name, declared_min, declared_max, bucket_count, flags);
+  if (!ValidateRangeChecksum(*histogram, range_checksum)) {
+    // The serialized histogram might be corrupted.
+    return NULL;
+  }
+  return histogram;
+}
+
 //------------------------------------------------------------------------------
 // This section provides implementation for BooleanHistogram.
 //------------------------------------------------------------------------------
@@ -750,6 +749,28 @@ BooleanHistogram::BooleanHistogram(const string& name,
                                    const BucketRanges* ranges)
     : LinearHistogram(name, 1, 2, 3, ranges) {}
 
+HistogramBase* BooleanHistogram::DeserializeInfoImpl(PickleIterator* iter) {
+  string histogram_name;
+  int flags;
+  int declared_min;
+  int declared_max;
+  uint64 bucket_count;
+  uint32 range_checksum;
+
+  if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
+                              &declared_max, &bucket_count, &range_checksum)) {
+    return NULL;
+  }
+
+  HistogramBase* histogram = BooleanHistogram::FactoryGet(
+      histogram_name, flags);
+  if (!ValidateRangeChecksum(*histogram, range_checksum)) {
+    // The serialized histogram might be corrupted.
+    return NULL;
+  }
+  return histogram;
+}
+
 //------------------------------------------------------------------------------
 // CustomHistogram:
 //------------------------------------------------------------------------------
@@ -809,26 +830,52 @@ CustomHistogram::CustomHistogram(const string& name,
                 ranges->size() - 1,
                 ranges) {}
 
-bool CustomHistogram::SerializeRanges(Pickle* pickle) const {
-  for (size_t i = 0; i < bucket_ranges()->size(); ++i) {
+bool CustomHistogram::SerializeInfoImpl(Pickle* pickle) const {
+  if (!Histogram::SerializeInfoImpl(pickle))
+    return false;
+
+  // Serialize ranges. First and last ranges are alwasy 0 and INT_MAX, so don't
+  // write them.
+  for (size_t i = 1; i < bucket_ranges()->size() - 1; ++i) {
     if (!pickle->WriteInt(bucket_ranges()->range(i)))
       return false;
   }
   return true;
 }
 
+double CustomHistogram::GetBucketSize(Count current, size_t i) const {
+  return 1;
+}
+
 // static
-bool CustomHistogram::DeserializeRanges(
-    PickleIterator* iter, vector<Sample>* ranges) {
-  for (size_t i = 0; i < ranges->size(); ++i) {
-    if (!iter->ReadInt(&(*ranges)[i]))
-      return false;
+HistogramBase* CustomHistogram::DeserializeInfoImpl(PickleIterator* iter) {
+  string histogram_name;
+  int flags;
+  int declared_min;
+  int declared_max;
+  uint64 bucket_count;
+  uint32 range_checksum;
+
+  if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
+                              &declared_max, &bucket_count, &range_checksum)) {
+    return NULL;
   }
-  return true;
-}
 
-double CustomHistogram::GetBucketSize(Count current, size_t i) const {
-  return 1;
+  // First and last ranges are not serialized.
+  vector<Sample> sample_ranges(bucket_count - 1);
+
+  for (size_t i = 0; i < sample_ranges.size(); ++i) {
+    if (!iter->ReadInt(&sample_ranges[i]))
+      return NULL;
+  }
+
+  HistogramBase* histogram = CustomHistogram::FactoryGet(
+      histogram_name, sample_ranges, flags);
+  if (!ValidateRangeChecksum(*histogram, range_checksum)) {
+    // The serialized histogram might be corrupted.
+    return NULL;
+  }
+  return histogram;
 }
 
 // static