ceph/src/common/Mutex.h

   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 #ifndef CEPH_MUTEX_H
  16 #define CEPH_MUTEX_H
  17
  18 #include "include/ceph_assert.h"
  19 #include "lockdep.h"
  20
  21 #include <string>
  22 #include <pthread.h>
  23 #include <mutex>
  24
  25 using namespace ceph;
  26
  27 class Mutex {
  28 private:
  29   std::string name;
  30   int id;
  31   bool recursive;
  32   bool lockdep;
  33   bool backtrace;  // gather backtrace on lock acquisition
  34
  35   pthread_mutex_t _m;
  36   int nlock;
  37   pthread_t locked_by;
  38
  39   // don't allow copying.
  40   void operator=(const Mutex &M);
  41   Mutex(const Mutex &M);
  42
  43   void _register() {
  44     id = lockdep_register(name.c_str());
  45   }
  46   void _will_lock() { // about to lock
  47     id = lockdep_will_lock(name.c_str(), id, backtrace, recursive);
  48   }
  49   void _locked() {    // just locked
  50     id = lockdep_locked(name.c_str(), id, backtrace);
  51   }
  52   void _will_unlock() {  // about to unlock
  53     id = lockdep_will_unlock(name.c_str(), id);
  54   }
  55
  56 public:
  57   Mutex(const std::string &n, bool r = false, bool ld=true, bool bt=false);
  58   ~Mutex();
  59   bool is_locked() const {
  60     return (nlock > 0);
  61   }
  62   bool is_locked_by_me() const {
  63     return nlock > 0 && locked_by == pthread_self();
  64   }
  65
  66   bool TryLock() {
  67     return try_lock();
  68   }
  69   bool try_lock() {
  70     int r = pthread_mutex_trylock(&_m);
  71     if (r == 0) {
  72       if (lockdep && g_lockdep) _locked();
  73       _post_lock();
  74     }
  75     return r == 0;
  76   }
  77
  78   void Lock(bool no_lockdep=false) {
  79     lock(no_lockdep);
  80   }
  81   void lock(bool no_lockdep=false);
  82
  83   void _post_lock() {
  84     if (!recursive) {
  85       ceph_assert(nlock == 0);
  86       locked_by = pthread_self();
  87     };
  88     nlock++;
  89   }
  90
  91   void _pre_unlock() {
  92     ceph_assert(nlock > 0);
  93     --nlock;
  94     if (!recursive) {
  95       ceph_assert(locked_by == pthread_self());
  96       locked_by = 0;
  97       ceph_assert(nlock == 0);
  98     }
  99   }
 100   void Unlock() {
 101     unlock();
 102   }
 103   void unlock();
 104
 105   friend class Cond;
 106
 107
 108 public:
 109   typedef std::lock_guard<Mutex> Locker;
 110 };
 111
 112
 113 #endif