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