Initial support for Renderer Side Histograms

Patch contributed by Raman Tenneti

see also patch number 21038

Review URL: http://codereview.chromium.org/27034

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@10330 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 231 insertions, 40 deletions

diff --git a/base/histogram.cc b/base/histogram.cc
index 79e9497..3234eb9 100644
--- a/base/histogram.cc
+++ b/base/histogram.cc
@@ -53,17 +53,16 @@ Histogram::Histogram(const char* name, TimeDelta minimum,
 
 Histogram::~Histogram() {
   if (registered_)
-    StatisticsRecorder::UnRegister(*this);
+    StatisticsRecorder::UnRegister(this);
   // Just to make sure most derived class did this properly...
   DCHECK(ValidateBucketRanges());
 }
 
-
 // Hooks to override stats counter methods.  This ensures that we gather all
 // input the stats counter sees.
 void Histogram::Add(int value) {
   if (!registered_)
-    registered_ = StatisticsRecorder::Register(*this);
+    registered_ = StatisticsRecorder::Register(this);
   if (value >= kSampleType_MAX)
     value = kSampleType_MAX - 1;
   StatsRate::Add(value);
@@ -75,6 +74,10 @@ void Histogram::Add(int value) {
   Accumulate(value, 1, index);
 }
 
+void Histogram::AddSampleSet(const SampleSet& sample) {
+  sample_.Add(sample);
+}
+
 // The following methods provide a graphical histogram display.
 void Histogram::WriteHTMLGraph(std::string* output) const {
   // TBD(jar) Write a nice HTML bar chart, with divs an mouse-overs etc.
@@ -105,7 +108,7 @@ void Histogram::WriteAscii(bool graph_it, const std::string& newline,
   while (0 == snapshot.counts(largest_non_empty_bucket)) {
     if (0 == largest_non_empty_bucket)
       break;  // All buckets are empty.
-    largest_non_empty_bucket--;
+    --largest_non_empty_bucket;
   }
 
   // Calculate largest print width needed for any of our bucket range displays.
@@ -121,7 +124,7 @@ void Histogram::WriteAscii(bool graph_it, const std::string& newline,
   int64 remaining = sample_count;
   int64 past = 0;
   // Output the actual histogram graph.
-  for (size_t i = 0; i < bucket_count(); i++) {
+  for (size_t i = 0; i < bucket_count(); ++i) {
     Count current = snapshot.counts(i);
     if (!current && !PrintEmptyBucket(i))
       continue;
@@ -129,7 +132,7 @@ void Histogram::WriteAscii(bool graph_it, const std::string& newline,
     StringAppendF(output, "%#*s ", print_width, GetAsciiBucketRange(i).c_str());
     if (0 == current && i < bucket_count() - 1 && 0 == snapshot.counts(i + 1)) {
       while (i < bucket_count() - 1 && 0 == snapshot.counts(i + 1))
-        i++;
+        ++i;
       output->append("... ");
       output->append(newline);
       continue;  // No reason to plot emptiness.
@@ -169,7 +172,7 @@ void Histogram::Initialize() {
   ranges_[bucket_count_] = kSampleType_MAX;
   InitializeBucketRange();
   DCHECK(ValidateBucketRanges());
-  registered_ = StatisticsRecorder::Register(*this);
+  registered_ = StatisticsRecorder::Register(this);
 }
 
 // Calculate what range of values are held in each bucket.
@@ -199,7 +202,7 @@ void Histogram::InitializeBucketRange() {
     if (next > current)
       current = next;
     else
-      current++;  // Just do a narrow bucket, and keep trying.
+      ++current;  // Just do a narrow bucket, and keep trying.
     SetBucketRange(bucket_index, current);
   }
 
@@ -277,7 +280,7 @@ void Histogram::SetBucketRange(size_t i, Sample value) {
 
 double Histogram::GetPeakBucketSize(const SampleSet& snapshot) const {
   double max = 0;
-  for (size_t i = 0; i < bucket_count() ; i++) {
+  for (size_t i = 0; i < bucket_count() ; ++i) {
     double current_size = GetBucketSize(snapshot.counts(i), i);
     if (current_size > max)
       max = current_size;
@@ -349,6 +352,100 @@ void Histogram::WriteAsciiBucketGraph(double current_size, double max_size,
     output->append(" ");
 }
 
+// static
+std::string Histogram::SerializeHistogramInfo(const Histogram& histogram,
+                                              const SampleSet& snapshot) {
+  Pickle pickle;
+
+  pickle.WriteString(histogram.histogram_name());
+  pickle.WriteInt(histogram.declared_min());
+  pickle.WriteInt(histogram.declared_max());
+  pickle.WriteSize(histogram.bucket_count());
+  pickle.WriteInt(histogram.histogram_type());
+  pickle.WriteInt(histogram.flags());
+
+  snapshot.Serialize(&pickle);
+  return std::string(static_cast<const char*>(pickle.data()), pickle.size());
+}
+
+// static
+void Histogram::DeserializeHistogramList(
+    const std::vector<std::string>& histograms) {
+  for (std::vector<std::string>::const_iterator it = histograms.begin();
+       it < histograms.end();
+       ++it) {
+    DeserializeHistogramInfo(*it);
+  }
+}
+
+// static
+bool Histogram::DeserializeHistogramInfo(const std::string& histogram_info) {
+  if (histogram_info.empty()) {
+      return false;
+  }
+
+  Pickle pickle(histogram_info.data(),
+                static_cast<int>(histogram_info.size()));
+  void* iter = NULL;
+  size_t bucket_count;
+  int declared_min;
+  int declared_max;
+  int histogram_type;
+  int flags;
+  std::string histogram_name;
+  SampleSet sample;
+
+  if (!pickle.ReadString(&iter, &histogram_name) ||
+      !pickle.ReadInt(&iter, &declared_min) ||
+      !pickle.ReadInt(&iter, &declared_max) ||
+      !pickle.ReadSize(&iter, &bucket_count) ||
+      !pickle.ReadInt(&iter, &histogram_type) ||
+      !pickle.ReadInt(&iter, &flags) ||
+      !sample.Histogram::SampleSet::Deserialize(&iter, pickle)) {
+    LOG(ERROR) << "Picke error decoding Histogram: " << histogram_name;
+    return false;
+  }
+
+  Histogram* render_histogram =
+      StatisticsRecorder::GetHistogram(histogram_name);
+
+  if (render_histogram == NULL) {
+    if (histogram_type ==  EXPONENTIAL) {
+      render_histogram = new Histogram(histogram_name.c_str(),
+                                       declared_min,
+                                       declared_max,
+                                       bucket_count);
+    } else if (histogram_type == LINEAR) {
+      render_histogram = reinterpret_cast<Histogram*>
+        (new LinearHistogram(histogram_name.c_str(),
+                             declared_min,
+                             declared_max,
+                             bucket_count));
+    } else {
+      LOG(ERROR) << "Error Deserializing Histogram Unknown histogram_type: " <<
+          histogram_type;
+      return false;
+    }
+    DCHECK(!(flags & kRendererHistogramFlag));
+    render_histogram->SetFlags(flags | kRendererHistogramFlag);
+  }
+
+  DCHECK(declared_min == render_histogram->declared_min());
+  DCHECK(declared_max == render_histogram->declared_max());
+  DCHECK(bucket_count == render_histogram->bucket_count());
+  DCHECK(histogram_type == render_histogram->histogram_type());
+
+  if (render_histogram->flags() & kRendererHistogramFlag) {
+    render_histogram->AddSampleSet(sample);
+  } else {
+    DLOG(INFO) << "Single thread mode, histogram observed and not copied: " <<
+        histogram_name;
+  }
+
+  return true;
+}
+
+
 //------------------------------------------------------------------------------
 // Methods for the Histogram::SampleSet class
 //------------------------------------------------------------------------------
@@ -383,7 +480,7 @@ Count Histogram::SampleSet::TotalCount() const {
   Count total = 0;
   for (Counts::const_iterator it = counts_.begin();
        it != counts_.end();
-       it++) {
+       ++it) {
     total += *it;
   }
   return total;
@@ -393,7 +490,7 @@ void Histogram::SampleSet::Add(const SampleSet& other) {
   DCHECK(counts_.size() == other.counts_.size());
   sum_ += other.sum_;
   square_sum_ += other.square_sum_;
-  for (size_t index = 0; index < counts_.size(); index++)
+  for (size_t index = 0; index < counts_.size(); ++index)
     counts_[index] += other.counts_[index];
 }
 
@@ -404,19 +501,57 @@ void Histogram::SampleSet::Subtract(const SampleSet& other) {
   // calculated).  As a result, we don't currently CHCEK() for positive values.
   sum_ -= other.sum_;
   square_sum_ -= other.square_sum_;
-  for (size_t index = 0; index < counts_.size(); index++) {
+  for (size_t index = 0; index < counts_.size(); ++index) {
     counts_[index] -= other.counts_[index];
     DCHECK(counts_[index] >= 0);
   }
 }
 
+bool Histogram::SampleSet::Serialize(Pickle* pickle) const {
+  pickle->WriteInt64(sum_);
+  pickle->WriteInt64(square_sum_);
+  pickle->WriteSize(counts_.size());
+
+  for (size_t index = 0; index < counts_.size(); ++index) {
+    pickle->WriteInt(counts_[index]);
+  }
+
+  return true;
+}
+
+bool Histogram::SampleSet::Deserialize(void** iter, const Pickle& pickle) {
+  DCHECK(counts_.size() == 0);
+  DCHECK(sum_ == 0);
+  DCHECK(square_sum_ == 0);
+
+  size_t counts_size;
+
+  if (!pickle.ReadInt64(iter, &sum_) ||
+      !pickle.ReadInt64(iter, &square_sum_) ||
+      !pickle.ReadSize(iter, &counts_size)) {
+    return false;
+  }
+
+  if (counts_size <= 0)
+    return false;
+
+  counts_.resize(counts_size, 0);
+  for (size_t index = 0; index < counts_size; ++index) {
+    if (!pickle.ReadInt(iter, &counts_[index])) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
 //------------------------------------------------------------------------------
 // LinearHistogram: This histogram uses a traditional set of evenly spaced
 // buckets.
 //------------------------------------------------------------------------------
 
-LinearHistogram::LinearHistogram(const char* name,
-    Sample minimum, Sample maximum, size_t bucket_count)
+LinearHistogram::LinearHistogram(const char* name, Sample minimum,
+    Sample maximum, size_t bucket_count)
     : Histogram(name, minimum >= 1 ? minimum : 1, maximum, bucket_count) {
   InitializeBucketRange();
   DCHECK(ValidateBucketRanges());
@@ -457,7 +592,7 @@ void LinearHistogram::InitializeBucketRange() {
   double min = declared_min();
   double max = declared_max();
   size_t i;
-  for (i = 1; i < bucket_count(); i++) {
+  for (i = 1; i < bucket_count(); ++i) {
     double linear_range = (min * (bucket_count() -1 - i) + max * (i - 1)) /
                           (bucket_count() - 2);
     SetBucketRange(i, static_cast<int> (linear_range + 0.5));
@@ -548,30 +683,30 @@ bool StatisticsRecorder::WasStarted() {
 }
 
 // static
-bool StatisticsRecorder::Register(const Histogram& histogram) {
+bool StatisticsRecorder::Register(Histogram* histogram) {
   if (!histograms_)
     return false;
-  const std::string name = histogram.histogram_name();
+  const std::string name = histogram->histogram_name();
   AutoLock auto_lock(*lock_);
 
   DCHECK(histograms_->end() == histograms_->find(name)) << name << " is already"
       "registered as a histogram.  Check for duplicate use of the name, or a "
       "race where a static initializer could be run by several threads.";
-  (*histograms_)[name] = &histogram;
+  (*histograms_)[name] = histogram;
   return true;
 }
 
 // static
-void StatisticsRecorder::UnRegister(const Histogram& histogram) {
+void StatisticsRecorder::UnRegister(Histogram* histogram) {
   if (!histograms_)
     return;
-  const std::string name = histogram.histogram_name();
+  const std::string name = histogram->histogram_name();
   AutoLock auto_lock(*lock_);
   DCHECK(histograms_->end() != histograms_->find(name));
   histograms_->erase(name);
   if (dump_on_exit_) {
     std::string output;
-    histogram.WriteAscii(true, "\n", &output);
+    histogram->WriteAscii(true, "\n", &output);
     LOG(INFO) << output;
   }
 }
@@ -593,7 +728,7 @@ void StatisticsRecorder::WriteHTMLGraph(const std::string& query,
   GetSnapshot(query, &snapshot);
   for (Histograms::iterator it = snapshot.begin();
        it != snapshot.end();
-       it++) {
+       ++it) {
     (*it)->WriteHTMLGraph(output);
     output->append("<br><hr><br>");
   }
@@ -602,7 +737,7 @@ void StatisticsRecorder::WriteHTMLGraph(const std::string& query,
 
 // static
 void StatisticsRecorder::WriteGraph(const std::string& query,
-                                        std::string* output) {
+                                    std::string* output) {
   if (!histograms_)
     return;
   if (query.length())
@@ -614,7 +749,7 @@ void StatisticsRecorder::WriteGraph(const std::string& query,
   GetSnapshot(query, &snapshot);
   for (Histograms::iterator it = snapshot.begin();
        it != snapshot.end();
-       it++) {
+       ++it) {
     (*it)->WriteAscii(true, "\n", output);
     output->append("\n");
   }
@@ -627,18 +762,31 @@ void StatisticsRecorder::GetHistograms(Histograms* output) {
   AutoLock auto_lock(*lock_);
   for (HistogramMap::iterator it = histograms_->begin();
        histograms_->end() != it;
-       it++) {
+       ++it) {
     output->push_back(it->second);
   }
 }
 
+Histogram* StatisticsRecorder::GetHistogram(const std::string& query) {
+  if (!histograms_)
+    return NULL;
+  AutoLock auto_lock(*lock_);
+  for (HistogramMap::iterator it = histograms_->begin();
+       histograms_->end() != it;
+       ++it) {
+    if (it->first.find(query) != std::string::npos)
+      return it->second;
+  }
+  return NULL;
+}
+
 // private static
 void StatisticsRecorder::GetSnapshot(const std::string& query,
                                      Histograms* snapshot) {
   AutoLock auto_lock(*lock_);
   for (HistogramMap::iterator it = histograms_->begin();
        histograms_->end() != it;
-       it++) {
+       ++it) {
     if (it->first.find(query) != std::string::npos)
       snapshot->push_back(it->second);
   }
diff --git a/base/histogram.h b/base/histogram.h
index cf80c09..5bf0fc1 100644
--- a/base/histogram.h
+++ b/base/histogram.h
@@ -36,6 +36,7 @@
 #include <vector>
 
 #include "base/lock.h"
+#include "base/pickle.h"
 #include "base/scoped_ptr.h"
 #include "base/stats_counters.h"
 
@@ -118,6 +119,11 @@
 
 static const int kUmaTargetedHistogramFlag = 0x1;
 
+// This indicates the histogram is shadow copy of renderer histrogram
+// constructed by unpick method and updated regularly from renderer upload
+// of histograms.
+static const int kRendererHistogramFlag = 1 << 4;
+
 #define UMA_HISTOGRAM_TIMES(name, sample) do { \
     static Histogram counter((name), base::TimeDelta::FromMilliseconds(1), \
                              base::TimeDelta::FromSeconds(10), 50); \
@@ -183,6 +189,11 @@ class Histogram : public StatsRate {
 
   static const int kHexRangePrintingFlag;
 
+  enum BucketLayout {
+    EXPONENTIAL,
+    LINEAR
+  };
+
   //----------------------------------------------------------------------------
   // Statistic values, developed over the life of the histogram.
 
@@ -206,6 +217,9 @@ class Histogram : public StatsRate {
     void Add(const SampleSet& other);
     void Subtract(const SampleSet& other);
 
+    bool Serialize(Pickle* pickle) const;
+    bool Deserialize(void** iter, const Pickle& pickle);
+
    protected:
     // Actual histogram data is stored in buckets, showing the count of values
     // that fit into each bucket.
@@ -228,6 +242,8 @@ class Histogram : public StatsRate {
   // input the stats counter sees.
   virtual void Add(int value);
 
+  void AddSampleSet(const SampleSet& sample);
+
   // The following methods provide graphical histogram displays.
   void WriteHTMLGraph(std::string* output) const;
   void WriteAscii(bool graph_it, const std::string& newline,
@@ -240,6 +256,26 @@ class Histogram : public StatsRate {
   void ClearFlags(int flags) { flags_ &= ~flags; }
   int flags() const { return flags_; }
 
+  virtual BucketLayout histogram_type() const { return EXPONENTIAL; }
+
+  // Convenience methods for serializing/deserializing the histograms.
+  // Histograms from Renderer process are serialized and sent to the browser.
+  // Browser process reconstructs the histogram from the pickled version
+  // accumulates the browser-side shadow copy of histograms (that mirror
+  // histograms created in the renderer).
+
+  // Serialize the given snapshot of a Histogram into a String. Uses
+  // Pickle class to flatten the object.
+  static std::string SerializeHistogramInfo(const Histogram& histogram,
+                                            const SampleSet& snapshot);
+  // The following method accepts a list of pickled histograms and
+  // builds a histogram and updates shadow copy of histogram data in the
+  // browser process.
+  static void DeserializeHistogramList(
+      const std::vector<std::string>& histograms);
+  static bool DeserializeHistogramInfo(const std::string& state);
+
+
   //----------------------------------------------------------------------------
   // Accessors for serialization and testing.
   //----------------------------------------------------------------------------
@@ -344,7 +380,7 @@ class Histogram : public StatsRate {
   // Indicate if successfully registered.
   bool registered_;
 
-  DISALLOW_EVIL_CONSTRUCTORS(Histogram);
+  DISALLOW_COPY_AND_ASSIGN(Histogram);
 };
 
 //------------------------------------------------------------------------------
@@ -358,15 +394,18 @@ class LinearHistogram : public Histogram {
     const char* description;  // Null means end of a list of pairs.
   };
   LinearHistogram(const char* name, Sample minimum,
-            Sample maximum, size_t bucket_count);
+                  Sample maximum, size_t bucket_count);
+
   LinearHistogram(const char* name, base::TimeDelta minimum,
-            base::TimeDelta maximum, size_t bucket_count);
+                  base::TimeDelta maximum, size_t bucket_count);
   ~LinearHistogram() {}
 
   // Store a list of number/text values for use in rendering the histogram.
   // The last element in the array has a null in its "description" slot.
   void SetRangeDescriptions(const DescriptionPair descriptions[]);
 
+  virtual BucketLayout histogram_type() const { return LINEAR; }
+
  protected:
   // Initialize ranges_ mapping.
   virtual void InitializeBucketRange();
@@ -389,7 +428,7 @@ class LinearHistogram : public Histogram {
   typedef std::map<Sample, std::string> BucketDescriptionMap;
   BucketDescriptionMap bucket_description_;
 
-  DISALLOW_EVIL_CONSTRUCTORS(LinearHistogram);
+  DISALLOW_COPY_AND_ASSIGN(LinearHistogram);
 };
 
 //------------------------------------------------------------------------------
@@ -404,7 +443,7 @@ class BooleanHistogram : public LinearHistogram {
   virtual void AddBoolean(bool value) { Add(value ? 1 : 0); }
 
  private:
-  DISALLOW_EVIL_CONSTRUCTORS(BooleanHistogram);
+  DISALLOW_COPY_AND_ASSIGN(BooleanHistogram);
 };
 
 //------------------------------------------------------------------------------
@@ -428,7 +467,7 @@ class ThreadSafeHistogram : public Histogram {
  private:
   Lock lock_;
 
-  DISALLOW_EVIL_CONSTRUCTORS(ThreadSafeHistogram);
+  DISALLOW_COPY_AND_ASSIGN(ThreadSafeHistogram);
 };
 
 //------------------------------------------------------------------------------
@@ -438,7 +477,7 @@ class ThreadSafeHistogram : public Histogram {
 
 class StatisticsRecorder {
  public:
-  typedef std::vector<const Histogram*> Histograms;
+  typedef std::vector<Histogram*> Histograms;
 
   StatisticsRecorder();
 
@@ -449,9 +488,9 @@ class StatisticsRecorder {
 
   // Register, or add a new histogram to the collection of statistics.
   // Return true if registered.
-  static bool Register(const Histogram& histogram);
+  static bool Register(Histogram* histogram);
   // Unregister, or remove, a histogram from the collection of statistics.
-  static void UnRegister(const Histogram& histogram);
+  static void UnRegister(Histogram* histogram);
 
   // Methods for printing histograms.  Only histograms which have query as
   // a substring are written to output (an empty string will process all
@@ -462,11 +501,9 @@ class StatisticsRecorder {
   // Method for extracting histograms which were marked for use by UMA.
   static void GetHistograms(Histograms* output);
 
-  static void set_dump_on_exit(bool enable) { dump_on_exit_ = enable; }
+  static Histogram* GetHistogram(const std::string& query);
 
- private:
-  typedef std::map<std::string, const Histogram*> HistogramMap;
-  // We keep all registered histograms in a map, from name to histogram.
+  static void set_dump_on_exit(bool enable) { dump_on_exit_ = enable; }
 
   // GetSnapshot copies some of the pointers to registered histograms into the
   // caller supplied vector (Histograms).  Only histograms with names matching
@@ -474,14 +511,20 @@ class StatisticsRecorder {
   // pointer to be copied.
   static void GetSnapshot(const std::string& query, Histograms* snapshot);
 
+
+ private:
+  // We keep all registered histograms in a map, from name to histogram.
+  typedef std::map<std::string, Histogram*> HistogramMap;
+
   static HistogramMap* histograms_;
+
   // lock protects access to the above map.
   static Lock* lock_;
 
   // Dump all known histograms to log.
   static bool dump_on_exit_;
 
-  DISALLOW_EVIL_CONSTRUCTORS(StatisticsRecorder);
+  DISALLOW_COPY_AND_ASSIGN(StatisticsRecorder);
 };
 
 #endif  // BASE_HISTOGRAM_H__