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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
#ifndef __SPINLOCK_H
#define __SPINLOCK_H
#include <pthread.h>
#include "assert.h"
namespace ceph {
//#define SPINLOCK_LOCKDEP
#ifdef SPINLOCK_LOCKDEP
# include "lockdep.h"
#endif
class Spinlock {
private:
pthread_spinlock_t _s;
int nlock;
// don't allow copying.
void operator=(Spinlock &M) {}
Spinlock( const Spinlock &M ) {}
#ifdef SPINLOCK_LOCKDEP
const char *name;
int id;
bool lockdep;
bool backtrace; // gather backtrace on lock acquisition
void _register() {
if (lockdep && g_lockdep)
id = lockdep_register(name);
}
void _will_lock() { // about to lock
if (lockdep && g_lockdep)
id = lockdep_will_lock(name, id);
}
void _locked() { // just locked
if (lockdep && g_lockdep)
id = lockdep_locked(name, id, backtrace);
}
void _will_unlock() { // about to unlock
if (lockdep && g_lockdep)
id = lockdep_will_unlock(name, id);
}
#else
void _register() {}
void _will_lock() {} // about to lock
void _locked() {} // just locked
void _will_unlock() {} // about to unlock
#endif
public:
Spinlock(const char *n, bool ld=true, bool bt=false) :
nlock(0)
#ifdef SPINLOCK_LOCKDEP
, name(n), id(-1), lockdep(ld), backtrace(bt)
#endif
{
pthread_spin_init(&_s, 0);
_register();
}
~Spinlock() {
assert(nlock == 0);
pthread_spin_destroy(&_s);
}
bool is_locked() {
return (nlock > 0);
}
bool try_lock() {
int r = pthread_spin_trylock(&_s);
if (r == 0) {
_locked();
nlock++;
}
return r == 0;
}
void lock() {
_will_lock();
int r = pthread_spin_lock(&_s);
_locked();
assert(r == 0);
nlock++;
}
void unlock() {
assert(nlock > 0);
--nlock;
_will_unlock();
int r = pthread_spin_unlock(&_s);
assert(r == 0);
}
public:
class Locker {
Spinlock &spinlock;
public:
Locker(Spinlock& m) : spinlock(m) {
spinlock.lock();
}
~Locker() {
spinlock.unlock();
}
};
};
}
#endif
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