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 #include <string>
  15
  16 #include "common/Mutex.h"
  17 #include "common/perf_counters.h"
  18 #include "common/ceph_context.h"
  19 #include "common/config.h"
  20 #include "include/stringify.h"
  21 #include "include/utime.h"
  22 #include "common/Clock.h"
  23 #include "common/valgrind.h"
  24
  25 Mutex::Mutex(const std::string &n, bool r, bool ld,
  26              bool bt,
  27              CephContext *cct) :
  28   name(n), id(-1), recursive(r), lockdep(ld), backtrace(bt), nlock(0),
  29   locked_by(0), cct(cct), logger(0)
  30 {
  31   ANNOTATE_BENIGN_RACE_SIZED(&id, sizeof(id), "Mutex lockdep id");
  32   ANNOTATE_BENIGN_RACE_SIZED(&nlock, sizeof(nlock), "Mutex nlock");
  33   ANNOTATE_BENIGN_RACE_SIZED(&locked_by, sizeof(locked_by), "Mutex locked_by");
  34   if (cct) {
  35     PerfCountersBuilder b(cct, string("mutex-") + name,
  36                           l_mutex_first, l_mutex_last);
  37     b.add_time_avg(l_mutex_wait, "wait", "Average time of mutex in locked state");
  38     logger = b.create_perf_counters();
  39     cct->get_perfcounters_collection()->add(logger);
  40     logger->set(l_mutex_wait, 0);
  41   }
  42   if (recursive) {
  43     // Mutexes of type PTHREAD_MUTEX_RECURSIVE do all the same checks as
  44     // mutexes of type PTHREAD_MUTEX_ERRORCHECK.
  45     pthread_mutexattr_t attr;
  46     pthread_mutexattr_init(&attr);
  47     pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
  48     pthread_mutex_init(&_m,&attr);
  49     pthread_mutexattr_destroy(&attr);
  50     if (lockdep && g_lockdep)
  51       _register();
  52   }
  53   else if (lockdep) {
  54     // If the mutex type is PTHREAD_MUTEX_ERRORCHECK, then error checking
  55     // shall be provided. If a thread attempts to relock a mutex that it
  56     // has already locked, an error shall be returned. If a thread
  57     // attempts to unlock a mutex that it has not locked or a mutex which
  58     // is unlocked, an error shall be returned.
  59     pthread_mutexattr_t attr;
  60     pthread_mutexattr_init(&attr);
  61     pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK);
  62     pthread_mutex_init(&_m, &attr);
  63     pthread_mutexattr_destroy(&attr);
  64     if (g_lockdep)
  65       _register();
  66   }
  67   else {
  68     // If the mutex type is PTHREAD_MUTEX_NORMAL, deadlock detection
  69     // shall not be provided. Attempting to relock the mutex causes
  70     // deadlock. If a thread attempts to unlock a mutex that  it  has not
  71     // locked or a mutex which is unlocked, undefined behavior results.
  72     pthread_mutex_init(&_m, NULL);
  73   }
  74 }
  75
  76 Mutex::~Mutex() {
  77   assert(nlock == 0);
  78
  79   // helgrind gets confused by condition wakeups leading to mutex destruction
  80   ANNOTATE_BENIGN_RACE_SIZED(&_m, sizeof(_m), "Mutex primitive");
  81   pthread_mutex_destroy(&_m);
  82
  83   if (cct && logger) {
  84     cct->get_perfcounters_collection()->remove(logger);
  85     delete logger;
  86   }
  87   if (lockdep && g_lockdep) {
  88     lockdep_unregister(id);
  89   }
  90 }
  91
  92 void Mutex::Lock(bool no_lockdep) {
  93   int r;
  94
  95   if (lockdep && g_lockdep && !no_lockdep && !recursive) _will_lock();
  96
  97   if (logger && cct && cct->_conf->mutex_perf_counter) {
  98     utime_t start;
  99     // instrumented mutex enabled
 100     start = ceph_clock_now();
 101     if (TryLock()) {
 102       goto out;
 103     }
 104
 105     r = pthread_mutex_lock(&_m);
 106
 107     logger->tinc(l_mutex_wait,
 108                  ceph_clock_now() - start);
 109   } else {
 110     r = pthread_mutex_lock(&_m);
 111   }
 112
 113   assert(r == 0);
 114   if (lockdep && g_lockdep) _locked();
 115   _post_lock();
 116
 117 out:
 118   ;
 119 }
 120
 121 void Mutex::Unlock() {
 122   _pre_unlock();
 123   if (lockdep && g_lockdep) _will_unlock();
 124   int r = pthread_mutex_unlock(&_m);
 125   assert(r == 0);
 126 }