JDK14/Java14源码在线阅读

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#ifndef SHARE_RUNTIME_TIMER_HPP
#define SHARE_RUNTIME_TIMER_HPP

#include "utilities/globalDefinitions.hpp"

// Timers for simple measurement.

class elapsedTimer {
  friend class VMStructs;
 private:
  jlong _counter;
  jlong _start_counter;
  bool  _active;
 public:
  elapsedTimer()             { _active = false; reset(); }
  elapsedTimer(jlong time, jlong timeUnitsPerSecond);
  void add(elapsedTimer t);
  void start();
  void stop();
  void reset()               { _counter = 0; }
  double seconds() const;
  jlong milliseconds() const;
  jlong ticks() const        { return _counter; }
  jlong active_ticks() const;
  bool  is_active() const { return _active; }
};

// TimeStamp is used for recording when an event took place.
class TimeStamp {
 private:
  jlong _counter;
 public:
  TimeStamp()  { _counter = 0; }
  void clear() { _counter = 0; }
  // has the timestamp been updated since being created or cleared?
  bool is_updated() const { return _counter != 0; }
  // update to current elapsed time
  void update();
  // update to given elapsed time
  void update_to(jlong ticks);
  // returns seconds since updated
  // (must not be in a cleared state:  must have been previously updated)
  double seconds() const;
  jlong milliseconds() const;
  // ticks elapsed between VM start and last update
  jlong ticks() const { return _counter; }

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