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