Move StatisticsRecorder out of histogram.cc/h for further refactoring.

base/metrics/statistics_recorder.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.
+
+// StatisticsRecorder handles all histograms in the system. It provides a
+// general place for histograms to register, and supports a global API for
+// accessing (i.e., dumping, or graphing) the data in all the histograms.
+
+#ifndef BASE_METRICS_STATISTICS_RECORDER_H_
+#define BASE_METRICS_STATISTICS_RECORDER_H_
+
+#include <list>
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+
+namespace base {
+
+class CachedRanges;
+class Histogram;
+class Lock;
+
+class BASE_EXPORT StatisticsRecorder {
+ public:
+  typedef std::vector<Histogram*> Histograms;
+
+  StatisticsRecorder();
+
+  ~StatisticsRecorder();
+
+  // Find out if histograms can now be registered into our list.
+  static bool IsActive();
+
+  // Register, or add a new histogram to the collection of statistics. If an
+  // identically named histogram is already registered, then the argument
+  // |histogram| will deleted.  The returned value is always the registered
+  // histogram (either the argument, or the pre-existing registered histogram).
+  static Histogram* RegisterOrDeleteDuplicate(Histogram* histogram);
+
+  // Register, or add a new cached_ranges_ of |histogram|. If an identical
+  // cached_ranges_ is already registered, then the cached_ranges_ of
+  // |histogram| is deleted and the |histogram|'s cached_ranges_ is reset to the
+  // registered cached_ranges_.  The cached_ranges_ of |histogram| is always the
+  // registered CachedRanges (either the argument's cached_ranges_, or the
+  // pre-existing registered cached_ranges_).
+  static void RegisterOrDeleteDuplicateRanges(Histogram* histogram);
+
+  // Method for collecting stats about histograms created in browser and
+  // renderer processes. |suffix| is appended to histogram names. |suffix| could
+  // be either browser or renderer.
+  static void CollectHistogramStats(const std::string& suffix);
+
+  // Methods for printing histograms.  Only histograms which have query as
+  // a substring are written to output (an empty string will process all
+  // registered histograms).
+  static void WriteHTMLGraph(const std::string& query, std::string* output);
+  static void WriteGraph(const std::string& query, std::string* output);
+
+  // Method for extracting histograms which were marked for use by UMA.
+  static void GetHistograms(Histograms* output);
+
+  // Find a histogram by name. It matches the exact name. This method is thread
+  // safe.  If a matching histogram is not found, then the |histogram| is
+  // not changed.
+  static bool FindHistogram(const std::string& query, Histogram** histogram);
+
+  static bool dump_on_exit() { return dump_on_exit_; }
+
+  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
+  // query are returned. The query must be a substring of histogram name for its
+  // 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;
+
+  // We keep all |cached_ranges_| in a map, from checksum to a list of
+  // |cached_ranges_|.  Checksum is calculated from the |ranges_| in
+  // |cached_ranges_|.
+  typedef std::map<uint32, std::list<CachedRanges*>*> RangesMap;
+
+  static HistogramMap* histograms_;
+
+  static RangesMap* ranges_;
+
+  // lock protects access to the above map.
+  static base::Lock* lock_;
+
+  // Dump all known histograms to log.
+  static bool dump_on_exit_;
+
+  DISALLOW_COPY_AND_ASSIGN(StatisticsRecorder);
+};
+
+}  // namespace base
+
+#endif  // BASE_METRICS_STATISTICS_RECORDER_H_