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/assert.h"
  19 #include "lockdep.h"
  20 #include "common/ceph_context.h"
  21
  22 #include <pthread.h>
  23
  24 using namespace ceph;
  25
  26 class PerfCounters;
  27
  28 enum {
  29   l_mutex_first = 999082,
  30   l_mutex_wait,
  31   l_mutex_last
  32 };
  33
  34 class Mutex {
  35 private:
  36   std::string name;
  37   int id;
  38   bool recursive;
  39   bool lockdep;
  40   bool backtrace;  // gather backtrace on lock acquisition
  41
  42   pthread_mutex_t _m;
  43   int nlock;
  44   pthread_t locked_by;
  45   CephContext *cct;
  46   PerfCounters *logger;
  47
  48   // don't allow copying.
  49   void operator=(const Mutex &M);
  50   Mutex(const Mutex &M);
  51
  52   void _register() {
  53     id = lockdep_register(name.c_str());
  54   }
  55   void _will_lock() { // about to lock
  56     id = lockdep_will_lock(name.c_str(), id, backtrace);
  57   }
  58   void _locked() {    // just locked
  59     id = lockdep_locked(name.c_str(), id, backtrace);
  60   }
  61   void _will_unlock() {  // about to unlock
  62     id = lockdep_will_unlock(name.c_str(), id);
  63   }
  64
  65 public:
  66   Mutex(const std::string &n, bool r = false, bool ld=true, bool bt=false,
  67         CephContext *cct = 0);
  68   ~Mutex();
  69   bool is_locked() const {
  70     return (nlock > 0);
  71   }
  72   bool is_locked_by_me() const {
  73     return nlock > 0 && locked_by == pthread_self();
  74   }
  75
  76   bool TryLock() {
  77     int r = pthread_mutex_trylock(&_m);
  78     if (r == 0) {
  79       if (lockdep && g_lockdep) _locked();
  80       _post_lock();
  81     }
  82     return r == 0;
  83   }
  84
  85   void Lock(bool no_lockdep=false);
  86
  87   void _post_lock() {
  88     if (!recursive) {
  89       assert(nlock == 0);
  90       locked_by = pthread_self();
  91     };
  92     nlock++;
  93   }
  94
  95   void _pre_unlock() {
  96     assert(nlock > 0);
  97     --nlock;
  98     if (!recursive) {
  99       assert(locked_by == pthread_self());
 100       locked_by = 0;
 101       assert(nlock == 0);
 102     }
 103   }
 104   void Unlock();
 105
 106   friend class Cond;
 107
 108
 109 public:
 110   class Locker {
 111     Mutex &mutex;
 112
 113   public:
 114     explicit Locker(Mutex& m) : mutex(m) {
 115       mutex.Lock();
 116     }
 117     ~Locker() {
 118       mutex.Unlock();
 119     }
 120   };
 121 };
 122
 123
 124 #endif