components/metrics/metrics_log_base.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This file defines a set of user experience metrics data recorded by
   6 // the MetricsService.  This is the unit of data that is sent to the server.
   7
   8 #ifndef COMPONENTS_METRICS_METRICS_LOG_BASE_H_
   9 #define COMPONENTS_METRICS_METRICS_LOG_BASE_H_
  10
  11 #include <string>
  12
  13 #include "base/basictypes.h"
  14 #include "base/metrics/histogram.h"
  15 #include "base/time/time.h"
  16 #include "components/metrics/proto/chrome_user_metrics_extension.pb.h"
  17
  18 namespace base {
  19 class HistogramSamples;
  20 }  // namespace base
  21
  22 namespace metrics {
  23
  24 // This class provides base functionality for logging metrics data.
  25 class MetricsLogBase {
  26  public:
  27   // TODO(asvitkine): Remove the NO_LOG value.
  28   enum LogType {
  29     INITIAL_STABILITY_LOG,  // The initial log containing stability stats.
  30     ONGOING_LOG,            // Subsequent logs in a session.
  31     NO_LOG,                 // Placeholder value for when there is no log.
  32   };
  33
  34   // Creates a new metrics log of the specified type.
  35   // client_id is the identifier for this profile on this installation
  36   // session_id is an integer that's incremented on each application launch
  37   MetricsLogBase(const std::string& client_id,
  38                  int session_id,
  39                  LogType log_type,
  40                  const std::string& version_string);
  41   virtual ~MetricsLogBase();
  42
  43   // Computes the MD5 hash of the given string, and returns the first 8 bytes of
  44   // the hash.
  45   static uint64 Hash(const std::string& value);
  46
  47   // Get the GMT buildtime for the current binary, expressed in seconds since
  48   // January 1, 1970 GMT.
  49   // The value is used to identify when a new build is run, so that previous
  50   // reliability stats, from other builds, can be abandoned.
  51   static int64 GetBuildTime();
  52
  53   // Convenience function to return the current time at a resolution in seconds.
  54   // This wraps base::TimeTicks, and hence provides an abstract time that is
  55   // always incrementing for use in measuring time durations.
  56   static int64 GetCurrentTime();
  57
  58   // Records a user-initiated action.
  59   void RecordUserAction(const std::string& key);
  60
  61   // Record any changes in a given histogram for transmission.
  62   void RecordHistogramDelta(const std::string& histogram_name,
  63                             const base::HistogramSamples& snapshot);
  64
  65   // Stop writing to this record and generate the encoded representation.
  66   // None of the Record* methods can be called after this is called.
  67   void CloseLog();
  68
  69   // Fills |encoded_log| with the serialized protobuf representation of the
  70   // record.  Must only be called after CloseLog() has been called.
  71   void GetEncodedLog(std::string* encoded_log);
  72
  73   int num_events() { return num_events_; }
  74
  75   void set_hardware_class(const std::string& hardware_class) {
  76     uma_proto_.mutable_system_profile()->mutable_hardware()->set_hardware_class(
  77         hardware_class);
  78   }
  79
  80   LogType log_type() const { return log_type_; }
  81
  82  protected:
  83   bool locked() const { return locked_; }
  84
  85   metrics::ChromeUserMetricsExtension* uma_proto() { return &uma_proto_; }
  86   const metrics::ChromeUserMetricsExtension* uma_proto() const {
  87     return &uma_proto_;
  88   }
  89
  90   // TODO(isherman): Remove this once the XML pipeline is outta here.
  91   int num_events_;  // the number of events recorded in this log
  92
  93  private:
  94   // locked_ is true when record has been packed up for sending, and should
  95   // no longer be written to.  It is only used for sanity checking and is
  96   // not a real lock.
  97   bool locked_;
  98
  99   // The type of the log, i.e. initial or ongoing.
 100   const LogType log_type_;
 101
 102   // Stores the protocol buffer representation for this log.
 103   metrics::ChromeUserMetricsExtension uma_proto_;
 104
 105   DISALLOW_COPY_AND_ASSIGN(MetricsLogBase);
 106 };
 107
 108 }  // namespace metrics
 109
 110 #endif  // COMPONENTS_METRICS_METRICS_LOG_BASE_H_