include/llvm/Support/Timer.h

   1 //===-- llvm/Support/Timer.h - Interval Timing Support ----------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_SUPPORT_TIMER_H
  10 #define LLVM_SUPPORT_TIMER_H
  11
  12 #include "llvm/ADT/StringMap.h"
  13 #include "llvm/ADT/StringRef.h"
  14 #include "llvm/Support/DataTypes.h"
  15 #include <cassert>
  16 #include <string>
  17 #include <utility>
  18 #include <vector>
  19
  20 namespace llvm {
  21
  22 class Timer;
  23 class TimerGroup;
  24 class raw_ostream;
  25
  26 class TimeRecord {
  27   double WallTime;       ///< Wall clock time elapsed in seconds.
  28   double UserTime;       ///< User time elapsed.
  29   double SystemTime;     ///< System time elapsed.
  30   ssize_t MemUsed;       ///< Memory allocated (in bytes).
  31 public:
  32   TimeRecord() : WallTime(0), UserTime(0), SystemTime(0), MemUsed(0) {}
  33
  34   /// Get the current time and memory usage.  If Start is true we get the memory
  35   /// usage before the time, otherwise we get time before memory usage.  This
  36   /// matters if the time to get the memory usage is significant and shouldn't
  37   /// be counted as part of a duration.
  38   static TimeRecord getCurrentTime(bool Start = true);
  39
  40   double getProcessTime() const { return UserTime + SystemTime; }
  41   double getUserTime() const { return UserTime; }
  42   double getSystemTime() const { return SystemTime; }
  43   double getWallTime() const { return WallTime; }
  44   ssize_t getMemUsed() const { return MemUsed; }
  45
  46   bool operator<(const TimeRecord &T) const {
  47     // Sort by Wall Time elapsed, as it is the only thing really accurate
  48     return WallTime < T.WallTime;
  49   }
  50
  51   void operator+=(const TimeRecord &RHS) {
  52     WallTime   += RHS.WallTime;
  53     UserTime   += RHS.UserTime;
  54     SystemTime += RHS.SystemTime;
  55     MemUsed    += RHS.MemUsed;
  56   }
  57   void operator-=(const TimeRecord &RHS) {
  58     WallTime   -= RHS.WallTime;
  59     UserTime   -= RHS.UserTime;
  60     SystemTime -= RHS.SystemTime;
  61     MemUsed    -= RHS.MemUsed;
  62   }
  63
  64   /// Print the current time record to \p OS, with a breakdown showing
  65   /// contributions to the \p Total time record.
  66   void print(const TimeRecord &Total, raw_ostream &OS) const;
  67 };
  68
  69 /// This class is used to track the amount of time spent between invocations of
  70 /// its startTimer()/stopTimer() methods.  Given appropriate OS support it can
  71 /// also keep track of the RSS of the program at various points.  By default,
  72 /// the Timer will print the amount of time it has captured to standard error
  73 /// when the last timer is destroyed, otherwise it is printed when its
  74 /// TimerGroup is destroyed.  Timers do not print their information if they are
  75 /// never started.
  76 class Timer {
  77   TimeRecord Time;          ///< The total time captured.
  78   TimeRecord StartTime;     ///< The time startTimer() was last called.
  79   std::string Name;         ///< The name of this time variable.
  80   std::string Description;  ///< Description of this time variable.
  81   bool Running;             ///< Is the timer currently running?
  82   bool Triggered;           ///< Has the timer ever been triggered?
  83   TimerGroup *TG = nullptr; ///< The TimerGroup this Timer is in.
  84
  85   Timer **Prev;             ///< Pointer to \p Next of previous timer in group.
  86   Timer *Next;              ///< Next timer in the group.
  87 public:
  88   explicit Timer(StringRef Name, StringRef Description) {
  89     init(Name, Description);
  90   }
  91   Timer(StringRef Name, StringRef Description, TimerGroup &tg) {
  92     init(Name, Description, tg);
  93   }
  94   Timer(const Timer &RHS) {
  95     assert(!RHS.TG && "Can only copy uninitialized timers");
  96   }
  97   const Timer &operator=(const Timer &T) {
  98     assert(!TG && !T.TG && "Can only assign uninit timers");
  99     return *this;
 100   }
 101   ~Timer();
 102
 103   /// Create an uninitialized timer, client must use 'init'.
 104   explicit Timer() {}
 105   void init(StringRef Name, StringRef Description);
 106   void init(StringRef Name, StringRef Description, TimerGroup &tg);
 107
 108   const std::string &getName() const { return Name; }
 109   const std::string &getDescription() const { return Description; }
 110   bool isInitialized() const { return TG != nullptr; }
 111
 112   /// Check if the timer is currently running.
 113   bool isRunning() const { return Running; }
 114
 115   /// Check if startTimer() has ever been called on this timer.
 116   bool hasTriggered() const { return Triggered; }
 117
 118   /// Start the timer running.  Time between calls to startTimer/stopTimer is
 119   /// counted by the Timer class.  Note that these calls must be correctly
 120   /// paired.
 121   void startTimer();
 122
 123   /// Stop the timer.
 124   void stopTimer();
 125
 126   /// Clear the timer state.
 127   void clear();
 128
 129   /// Return the duration for which this timer has been running.
 130   TimeRecord getTotalTime() const { return Time; }
 131
 132 private:
 133   friend class TimerGroup;
 134 };
 135
 136 /// The TimeRegion class is used as a helper class to call the startTimer() and
 137 /// stopTimer() methods of the Timer class.  When the object is constructed, it
 138 /// starts the timer specified as its argument.  When it is destroyed, it stops
 139 /// the relevant timer.  This makes it easy to time a region of code.
 140 class TimeRegion {
 141   Timer *T;
 142   TimeRegion(const TimeRegion &) = delete;
 143
 144 public:
 145   explicit TimeRegion(Timer &t) : T(&t) {
 146     T->startTimer();
 147   }
 148   explicit TimeRegion(Timer *t) : T(t) {
 149     if (T) T->startTimer();
 150   }
 151   ~TimeRegion() {
 152     if (T) T->stopTimer();
 153   }
 154 };
 155
 156 /// This class is basically a combination of TimeRegion and Timer.  It allows
 157 /// you to declare a new timer, AND specify the region to time, all in one
 158 /// statement.  All timers with the same name are merged.  This is primarily
 159 /// used for debugging and for hunting performance problems.
 160 struct NamedRegionTimer : public TimeRegion {
 161   explicit NamedRegionTimer(StringRef Name, StringRef Description,
 162                             StringRef GroupName,
 163                             StringRef GroupDescription, bool Enabled = true);
 164 };
 165
 166 /// The TimerGroup class is used to group together related timers into a single
 167 /// report that is printed when the TimerGroup is destroyed.  It is illegal to
 168 /// destroy a TimerGroup object before all of the Timers in it are gone.  A
 169 /// TimerGroup can be specified for a newly created timer in its constructor.
 170 class TimerGroup {
 171   struct PrintRecord {
 172     TimeRecord Time;
 173     std::string Name;
 174     std::string Description;
 175
 176     PrintRecord(const PrintRecord &Other) = default;
 177     PrintRecord(const TimeRecord &Time, const std::string &Name,
 178                 const std::string &Description)
 179       : Time(Time), Name(Name), Description(Description) {}
 180
 181     bool operator <(const PrintRecord &Other) const {
 182       return Time < Other.Time;
 183     }
 184   };
 185   std::string Name;
 186   std::string Description;
 187   Timer *FirstTimer = nullptr; ///< First timer in the group.
 188   std::vector<PrintRecord> TimersToPrint;
 189
 190   TimerGroup **Prev; ///< Pointer to Next field of previous timergroup in list.
 191   TimerGroup *Next;  ///< Pointer to next timergroup in list.
 192   TimerGroup(const TimerGroup &TG) = delete;
 193   void operator=(const TimerGroup &TG) = delete;
 194
 195 public:
 196   explicit TimerGroup(StringRef Name, StringRef Description);
 197
 198   explicit TimerGroup(StringRef Name, StringRef Description,
 199                       const StringMap<TimeRecord> &Records);
 200
 201   ~TimerGroup();
 202
 203   void setName(StringRef NewName, StringRef NewDescription) {
 204     Name.assign(NewName.begin(), NewName.end());
 205     Description.assign(NewDescription.begin(), NewDescription.end());
 206   }
 207
 208   /// Print any started timers in this group, optionally resetting timers after
 209   /// printing them.
 210   void print(raw_ostream &OS, bool ResetAfterPrint = false);
 211
 212   /// Clear all timers in this group.
 213   void clear();
 214
 215   /// This static method prints all timers.
 216   static void printAll(raw_ostream &OS);
 217
 218   /// Clear out all timers. This is mostly used to disable automatic
 219   /// printing on shutdown, when timers have already been printed explicitly
 220   /// using \c printAll or \c printJSONValues.
 221   static void clearAll();
 222
 223   const char *printJSONValues(raw_ostream &OS, const char *delim);
 224
 225   /// Prints all timers as JSON key/value pairs.
 226   static const char *printAllJSONValues(raw_ostream &OS, const char *delim);
 227
 228   /// Ensure global timer group lists are initialized. This function is mostly
 229   /// used by the Statistic code to influence the construction and destruction
 230   /// order of the global timer lists.
 231   static void ConstructTimerLists();
 232 private:
 233   friend class Timer;
 234   friend void PrintStatisticsJSON(raw_ostream &OS);
 235   void addTimer(Timer &T);
 236   void removeTimer(Timer &T);
 237   void prepareToPrintList(bool reset_time = false);
 238   void PrintQueuedTimers(raw_ostream &OS);
 239   void printJSONValue(raw_ostream &OS, const PrintRecord &R,
 240                       const char *suffix, double Value);
 241 };
 242
 243 } // end namespace llvm
 244
 245 #endif