base/perftimer.h

   1 // Copyright (c) 2006-2008 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 #ifndef BASE_PERFTIMER_H_
   6 #define BASE_PERFTIMER_H_
   7 #pragma once
   8
   9 #include <string>
  10
  11 #include "base/basictypes.h"
  12 #include "base/time.h"
  13
  14 class FilePath;
  15
  16 // ----------------------------------------------------------------------
  17 // Initializes and finalizes the perf log. These functions should be
  18 // called at the beginning and end (respectively) of running all the
  19 // performance tests. The init function returns true on success.
  20 // ----------------------------------------------------------------------
  21 bool InitPerfLog(const FilePath& log_path);
  22 void FinalizePerfLog();
  23
  24 // ----------------------------------------------------------------------
  25 // LogPerfResult
  26 //   Writes to the perf result log the given 'value' resulting from the
  27 //   named 'test'. The units are to aid in reading the log by people.
  28 // ----------------------------------------------------------------------
  29 void LogPerfResult(const char* test_name, double value, const char* units);
  30
  31 // ----------------------------------------------------------------------
  32 // PerfTimer
  33 //   A simple wrapper around Now()
  34 // ----------------------------------------------------------------------
  35 class PerfTimer {
  36  public:
  37   PerfTimer() {
  38     begin_ = base::TimeTicks::Now();
  39   }
  40
  41   // Returns the time elapsed since object construction
  42   base::TimeDelta Elapsed() const {
  43     return base::TimeTicks::Now() - begin_;
  44   }
  45
  46  private:
  47   base::TimeTicks begin_;
  48 };
  49
  50 // ----------------------------------------------------------------------
  51 // PerfTimeLogger
  52 //   Automates calling LogPerfResult for the common case where you want
  53 //   to measure the time that something took. Call Done() when the test
  54 //   is complete if you do extra work after the test or there are stack
  55 //   objects with potentially expensive constructors. Otherwise, this
  56 //   class with automatically log on destruction.
  57 // ----------------------------------------------------------------------
  58 class PerfTimeLogger {
  59  public:
  60   explicit PerfTimeLogger(const char* test_name)
  61       : logged_(false),
  62         test_name_(test_name) {
  63   }
  64
  65   ~PerfTimeLogger() {
  66     if (!logged_)
  67       Done();
  68   }
  69
  70   void Done() {
  71     // we use a floating-point millisecond value because it is more
  72     // intuitive than microseconds and we want more precision than
  73     // integer milliseconds
  74     LogPerfResult(test_name_.c_str(), timer_.Elapsed().InMillisecondsF(), "ms");
  75     logged_ = true;
  76   }
  77
  78  private:
  79   bool logged_;
  80   std::string test_name_;
  81   PerfTimer timer_;
  82 };
  83
  84 #endif  // BASE_PERFTIMER_H_