llvm/Support/Timer.h

//===-- llvm/Support/Timer.h - Interval Timing Support ----------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines three classes: Timer, TimeRegion, and TimerGroup,
// documented below.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_TIMER_H
#define LLVM_SUPPORT_TIMER_H

#include "llvm/System/DataTypes.h"
#include <cassert>
#include <string>
#include <vector>
#include <utility>

namespace llvm {

class Timer;
class TimerGroup;
class raw_ostream;

class TimeRecord {
  double WallTime;       // Wall clock time elapsed in seconds
  double UserTime;       // User time elapsed
  double SystemTime;     // System time elapsed
  ssize_t MemUsed;       // Memory allocated (in bytes)
public:
  TimeRecord() : WallTime(0), UserTime(0), SystemTime(0), MemUsed(0) {}

  /// getCurrentTime - Get the current time and memory usage.  If Start is true
  /// we get the memory usage before the time, otherwise we get time before
  /// memory usage.  This matters if the time to get the memory usage is
  /// significant and shouldn't be counted as part of a duration.
  static TimeRecord getCurrentTime(bool Start = true);

  double getProcessTime() const { return UserTime+SystemTime; }
  double getUserTime() const { return UserTime; }
  double getSystemTime() const { return SystemTime; }
  double getWallTime() const { return WallTime; }
  ssize_t getMemUsed() const { return MemUsed; }


  // operator< - Allow sorting.
  bool operator<(const TimeRecord &T) const {
    // Sort by Wall Time elapsed, as it is the only thing really accurate
    return WallTime < T.WallTime;
  }

  void operator+=(const TimeRecord &RHS) {
    WallTime   += RHS.WallTime;
    UserTime   += RHS.UserTime;
    SystemTime += RHS.SystemTime;
    MemUsed    += RHS.MemUsed;
  }
  void operator-=(const TimeRecord &RHS) {
    WallTime   -= RHS.WallTime;
    UserTime   -= RHS.UserTime;
    SystemTime -= RHS.SystemTime;
    MemUsed    -= RHS.MemUsed;
  }

  /// print - Print the current timer to standard error, and reset the "Started"
  /// flag.
  void print(const TimeRecord &Total, raw_ostream &OS) const;
};

/// Timer - This class is used to track the amount of time spent between
/// invocations of its startTimer()/stopTimer() methods.  Given appropriate OS
/// support it can also keep track of the RSS of the program at various points.
/// By default, the Timer will print the amount of time it has captured to
/// standard error when the laster timer is destroyed, otherwise it is printed
/// when its TimerGroup is destroyed.  Timers do not print their information
/// if they are never started.
///
class Timer {
  TimeRecord Time;
  std::string Name;      // The name of this time variable.
  bool Started;          // Has this time variable ever been started?
  TimerGroup *TG;        // The TimerGroup this Timer is in.

  Timer **Prev, *Next;   // Doubly linked list of timers in the group.
public:
  explicit Timer(const std::string &N) : TG(0) { init(N); }
  Timer(const std::string &N, TimerGroup &tg) : TG(0) { init(N, tg); }
  Timer(const Timer &RHS) : TG(0) {
    assert(RHS.TG == 0 && "Can only copy uninitialized timers");
  }
  const Timer &operator=(const Timer &T) {
    assert(TG == 0 && T.TG == 0 && "Can only assign uninit timers");
    return *this;
  }
  ~Timer();

  // Create an uninitialized timer, client must use 'init'.
  explicit Timer() : TG(0) {}
  void init(const std::string &N);
  void init(const std::string &N, TimerGroup &tg);

  const std::string &getName() const { return Name; }
  bool isInitialized() const { return TG != 0; }

  /// startTimer - Start the timer running.  Time between calls to
  /// startTimer/stopTimer is counted by the Timer class.  Note that these calls
  /// must be correctly paired.
  ///
  void startTimer();

  /// stopTimer - Stop the timer.
  ///
  void stopTimer();

private:
  friend class TimerGroup;
};


/// The TimeRegion class is used as a helper class to call the startTimer() and
/// stopTimer() methods of the Timer class.  When the object is constructed, it
/// starts the timer specified as it's argument.  When it is destroyed, it stops
/// the relevant timer.  This makes it easy to time a region of code.
///
class TimeRegion {
  Timer *T;
  TimeRegion(const TimeRegion &); // DO NOT IMPLEMENT
public:
  explicit TimeRegion(Timer &t) : T(&t) {
    T->startTimer();
  }
  explicit TimeRegion(Timer *t) : T(t) {
    if (T) T->startTimer();
  }
  ~TimeRegion() {
    if (T) T->stopTimer();
  }
};


/// NamedRegionTimer - This class is basically a combination of TimeRegion and
/// Timer.  It allows you to declare a new timer, AND specify the region to
/// time, all in one statement.  All timers with the same name are merged.  This
/// is primarily used for debugging and for hunting performance problems.
///
struct NamedRegionTimer : public TimeRegion {
  explicit NamedRegionTimer(const std::string &Name);
  explicit NamedRegionTimer(const std::string &Name,
                            const std::string &GroupName);
};


/// The TimerGroup class is used to group together related timers into a single
/// report that is printed when the TimerGroup is destroyed.  It is illegal to
/// destroy a TimerGroup object before all of the Timers in it are gone.  A
/// TimerGroup can be specified for a newly created timer in its constructor.
///
class TimerGroup {
  std::string Name;
  Timer *FirstTimer;   // First timer in the group.
  std::vector<std::pair<TimeRecord, std::string> > TimersToPrint;
public:
  explicit TimerGroup(const std::string &name) : Name(name), FirstTimer(0) {}
  explicit TimerGroup() : FirstTimer(0) {}

  explicit TimerGroup(const TimerGroup &TG) : FirstTimer(0) {
    operator=(TG);
  }

  void operator=(const TimerGroup &TG) {
    assert(TG.FirstTimer == 0 && FirstTimer == 0 &&
           "Cannot assign group with timers");
    Name = TG.Name;
  }


  void setName(const std::string &name) { Name = name; }

  ~TimerGroup() {
    assert(FirstTimer == 0 &&
           "TimerGroup destroyed before all contained timers!");
  }

  void PrintQueuedTimers(raw_ostream &OS);

private:
  friend class Timer;
  void addTimer(Timer &T);
  void removeTimer(Timer &T);
};

} // End llvm namespace

#endif