ceph/src/common/Mutex.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #include "common/Mutex.h"
  16 #include "common/perf_counters.h"
  17 #include "common/config.h"
  18 #include "common/Clock.h"
  19 #include "common/valgrind.h"
  20
  21 Mutex::Mutex(const std::string &n, bool r, bool ld,
  22              bool bt,
  23              CephContext *cct) :
  24   name(n), id(-1), recursive(r), lockdep(ld), backtrace(bt), nlock(0),
  25   locked_by(0), cct(cct), logger(0)
  26 {
  27   ANNOTATE_BENIGN_RACE_SIZED(&id, sizeof(id), "Mutex lockdep id");
  28   ANNOTATE_BENIGN_RACE_SIZED(&nlock, sizeof(nlock), "Mutex nlock");
  29   ANNOTATE_BENIGN_RACE_SIZED(&locked_by, sizeof(locked_by), "Mutex locked_by");
  30   if (cct) {
  31     PerfCountersBuilder b(cct, string("mutex-") + name,
  32                           l_mutex_first, l_mutex_last);
  33     b.add_time_avg(l_mutex_wait, "wait", "Average time of mutex in locked state");
  34     logger = b.create_perf_counters();
  35     cct->get_perfcounters_collection()->add(logger);
  36     logger->set(l_mutex_wait, 0);
  37   }
  38   if (recursive) {
  39     // Mutexes of type PTHREAD_MUTEX_RECURSIVE do all the same checks as
  40     // mutexes of type PTHREAD_MUTEX_ERRORCHECK.
  41     pthread_mutexattr_t attr;
  42     pthread_mutexattr_init(&attr);
  43     pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
  44     pthread_mutex_init(&_m,&attr);
  45     pthread_mutexattr_destroy(&attr);
  46     if (lockdep && g_lockdep)
  47       _register();
  48   }
  49   else if (lockdep) {
  50     // If the mutex type is PTHREAD_MUTEX_ERRORCHECK, then error checking
  51     // shall be provided. If a thread attempts to relock a mutex that it
  52     // has already locked, an error shall be returned. If a thread
  53     // attempts to unlock a mutex that it has not locked or a mutex which
  54     // is unlocked, an error shall be returned.
  55     pthread_mutexattr_t attr;
  56     pthread_mutexattr_init(&attr);
  57     pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK);
  58     pthread_mutex_init(&_m, &attr);
  59     pthread_mutexattr_destroy(&attr);
  60     if (g_lockdep)
  61       _register();
  62   }
  63   else {
  64     // If the mutex type is PTHREAD_MUTEX_NORMAL, deadlock detection
  65     // shall not be provided. Attempting to relock the mutex causes
  66     // deadlock. If a thread attempts to unlock a mutex that  it  has not
  67     // locked or a mutex which is unlocked, undefined behavior results.
  68     pthread_mutex_init(&_m, NULL);
  69   }
  70 }
  71
  72 Mutex::~Mutex() {
  73   assert(nlock == 0);
  74
  75   // helgrind gets confused by condition wakeups leading to mutex destruction
  76   ANNOTATE_BENIGN_RACE_SIZED(&_m, sizeof(_m), "Mutex primitive");
  77   pthread_mutex_destroy(&_m);
  78
  79   if (cct && logger) {
  80     cct->get_perfcounters_collection()->remove(logger);
  81     delete logger;
  82   }
  83   if (lockdep && g_lockdep) {
  84     lockdep_unregister(id);
  85   }
  86 }
  87
  88 void Mutex::Lock(bool no_lockdep) {
  89   int r;
  90
  91   if (lockdep && g_lockdep && !no_lockdep && !recursive) _will_lock();
  92
  93   if (logger && cct && cct->_conf->mutex_perf_counter) {
  94     utime_t start;
  95     // instrumented mutex enabled
  96     start = ceph_clock_now();
  97     if (TryLock()) {
  98       goto out;
  99     }
 100
 101     r = pthread_mutex_lock(&_m);
 102
 103     logger->tinc(l_mutex_wait,
 104                  ceph_clock_now() - start);
 105   } else {
 106     r = pthread_mutex_lock(&_m);
 107   }
 108
 109   assert(r == 0);
 110   if (lockdep && g_lockdep) _locked();
 111   _post_lock();
 112
 113 out:
 114   ;
 115 }
 116
 117 void Mutex::Unlock() {
 118   _pre_unlock();
 119   if (lockdep && g_lockdep) _will_unlock();
 120   int r = pthread_mutex_unlock(&_m);
 121   assert(r == 0);
 122 }