Histograms - Support histograms for Plugins, GPU

base/metrics/histogram_flattener.h

 // 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.
 
-#ifndef CHROME_COMMON_METRICS_HISTOGRAM_SENDER_H_
-#define CHROME_COMMON_METRICS_HISTOGRAM_SENDER_H_
-#pragma once
+#ifndef BASE_METRICS_HISTOGRAM_FLATTENER_H_
+#define BASE_METRICS_HISTOGRAM_FLATTENER_H_
 
 #include <map>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
 
-// HistogramSender handles the logistics of gathering up available histograms
-// for transmission (such as from renderer to browser, or from browser to UMA
-// upload).  It has several pure virtual functions that are replaced in
-// derived classes to allow the exact lower level transmission mechanism,
-// or error report mechanism, to be replaced.  Since histograms can sit in
-// memory for an extended period of time, and are vulnerable to memory
-// corruption, this class also validates as much rendundancy as it can before
-// calling for the marginal change (a.k.a., delta) in a histogram to be sent
-// onward.
-class HistogramSender {
- protected:
-  HistogramSender();
-  virtual ~HistogramSender();
+namespace base {
 
-  // Snapshot all histograms, and transmit the delta.
-  // The arguments allow a derived class to select only a subset for
-  // transmission, or to set a flag in each transmitted histogram.
-  void TransmitAllHistograms(base::Histogram::Flags flags_to_set,
-                             bool send_only_uma);
+// HistogramFlattener is an interface for the logistics of gathering up
+// available histograms for recording. The implementors handle the exact lower
+// level recording mechanism, or error report mechanism.
+class BASE_EXPORT HistogramFlattener {
+ public:
+  virtual void RecordDelta(const base::Histogram& histogram,
+                           const base::Histogram::SampleSet& snapshot) = 0;
 
-  // Send the histograms onward, as defined in a derived class.
-  // This is only called with a delta, listing samples that have not previously
-  // been transmitted.
-  virtual void TransmitHistogramDelta(
-      const base::Histogram& histogram,
-      const base::Histogram::SampleSet& snapshot) = 0;
-
-  // Record various errors found during attempts to send histograms.
+  // Record various errors found during attempts to record histograms.
   virtual void InconsistencyDetected(int problem) = 0;
   virtual void UniqueInconsistencyDetected(int problem) = 0;
   virtual void SnapshotProblemResolved(int amount) = 0;
 
+ protected:
+  HistogramFlattener() {}
+  virtual ~HistogramFlattener() {}
+
  private:
-  // Maintain a map of histogram names to the sample stats we've sent.
-  typedef std::map<std::string, base::Histogram::SampleSet> LoggedSampleMap;
-  // List of histograms names, and their encontered corruptions.
-  typedef std::map<std::string, int> ProblemMap;
-
-  // Snapshot this histogram, and transmit the delta.
-  void TransmitHistogram(const base::Histogram& histogram);
-
-  // For histograms, record what we've already transmitted (as a sample for each
-  // histogram) so that we can send only the delta with the next log.
-  LoggedSampleMap logged_samples_;
-
-  // List of histograms found corrupt to be corrupt, and their problems.
-  scoped_ptr<ProblemMap> inconsistencies_;
-
-  DISALLOW_COPY_AND_ASSIGN(HistogramSender);
+  DISALLOW_COPY_AND_ASSIGN(HistogramFlattener);
 };
 
-#endif  // CHROME_COMMON_METRICS_HISTOGRAM_SENDER_H_
+}  // namespace base
+
+#endif  // BASE_METRICS_HISTOGRAM_FLATTENER_H_