//===-- 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/Support/DataTypes.h"
#include <string>
#include <vector>
#include <iosfwd>
#include <cassert>

namespace llvm {

class TimerGroup;

/// Timer - This class is used to track the amount of time spent between
/// invocations of it's 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 {
  double Elapsed;        // Wall clock time elapsed in seconds
  double UserTime;       // User time elapsed
  double SystemTime;     // System time elapsed
  ssize_t MemUsed;       // Memory allocated (in bytes)
  size_t PeakMem;        // Peak memory used
  size_t PeakMemBase;    // Temporary for peak calculation...
  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.
public:
  explicit Timer(const std::string &N);
  Timer(const std::string &N, TimerGroup &tg);
  Timer(const Timer &T);
  ~Timer();

  double getProcessTime() const { return UserTime+SystemTime; }
  double getWallTime() const { return Elapsed; }
  ssize_t getMemUsed() const { return MemUsed; }
  size_t getPeakMem() const { return PeakMem; }
  std::string getName() const { return Name; }

  const Timer &operator=(const Timer &T) {
    Elapsed = T.Elapsed;
    UserTime = T.UserTime;
    SystemTime = T.SystemTime;
    MemUsed = T.MemUsed;
    PeakMem = T.PeakMem;
    PeakMemBase = T.PeakMemBase;
    Name = T.Name;
    Started = T.Started;
    assert(TG == T.TG && "Can only assign timers in the same TimerGroup!");
    return *this;
  }

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

  /// 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();

  /// addPeakMemoryMeasurement - This method should be called whenever memory
  /// usage needs to be checked.  It adds a peak memory measurement to the
  /// currently active timers, which will be printed when the timer group prints
  ///
  static void addPeakMemoryMeasurement();

  /// print - Print the current timer to standard error, and reset the "Started"
  /// flag.
  void print(const Timer &Total, std::ostream &OS);

private:
  friend class TimerGroup;

  // Copy ctor, initialize with no TG member.
  Timer(bool, const Timer &T);

  /// sum - Add the time accumulated in the specified timer into this timer.
  ///
  void sum(const Timer &T);
};


/// 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;
  unsigned NumTimers;
  std::vector<Timer> TimersToPrint;
public:
  explicit TimerGroup(const std::string &name) : Name(name), NumTimers(0) {}
  ~TimerGroup() {
    assert(NumTimers == 0 &&
           "TimerGroup destroyed before all contained timers!");
  }

private:
  friend class Timer;
  void addTimer() { ++NumTimers; }
  void removeTimer();
  void addTimerToPrint(const Timer &T) {
    TimersToPrint.push_back(Timer(true, T));
  }
};

} // End llvm namespace

#endif
