unbound/util/locks.h

/**
 * util/locks.h - unbound locking primitives
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 * 
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef UTIL_LOCKS_H
#define UTIL_LOCKS_H

/**
 * \file
 * Locking primitives.
 * If pthreads is available, these are used.
 * If no locking exists, they do nothing.
 *
 * The idea is to have different sorts of locks for different tasks.
 * This allows the locking code to be ported more easily.
 *
 * Types of locks that are supported.
 *   o lock_rw: lock that has many readers and one writer (to a data entry).
 *   o lock_basic: simple mutex. Blocking, one person has access only.
 *     This lock is meant for non performance sensitive uses.
 *   o lock_quick: speed lock. For performance sensitive locking of critical
 *     sections. Could be implemented by a mutex or a spinlock.
 * 
 * Also thread creation and deletion functions are defined here.
 */

#include "util/log.h"

/**
 * The following macro is used to check the return value of the
 * pthread calls. They return 0 on success and an errno on error.
 * The errno is logged to the logfile with a descriptive comment.
 */
#define LOCKRET(func) do {\
	int err;		\
	if( (err=(func)) != 0)		\
		log_err("%s at %d could not " #func ": %s", \
		__FILE__, __LINE__, strerror(err));	\
 	} while(0)

#ifdef HAVE_PTHREAD
#include <pthread.h>

/******************* PTHREAD ************************/

/** we use the pthread rwlock */
typedef pthread_rwlock_t lock_rw_t;
/** small front for pthread init func, NULL is default attrs. */
#define lock_rw_init(lock) LOCKRET(pthread_rwlock_init(lock, NULL))
#define lock_rw_destroy(lock) LOCKRET(pthread_rwlock_destroy(lock))
#define lock_rw_rdlock(lock) LOCKRET(pthread_rwlock_rdlock(lock))
#define lock_rw_wrlock(lock) LOCKRET(pthread_rwlock_wrlock(lock))
#define lock_rw_unlock(lock) LOCKRET(pthread_rwlock_unlock(lock))

/** use pthread mutex for basic lock */
typedef pthread_mutex_t lock_basic_t;
/** small front for pthread init func, NULL is default attrs. */
#define lock_basic_init(lock) LOCKRET(pthread_mutex_init(lock, NULL))
#define lock_basic_destroy(lock) LOCKRET(pthread_mutex_destroy(lock))
#define lock_basic_lock(lock) LOCKRET(pthread_mutex_lock(lock))
#define lock_basic_unlock(lock) LOCKRET(pthread_mutex_unlock(lock))

#ifndef HAVE_PTHREAD_SPINLOCK_T
/** in case spinlocks are not supported, use a mutex. */
typedef pthread_mutex_t lock_quick_t;
/** small front for pthread init func, NULL is default attrs. */
#define lock_quick_init(lock) LOCKRET(pthread_mutex_init(lock, NULL))
#define lock_quick_destroy(lock) LOCKRET(pthread_mutex_destroy(lock))
#define lock_quick_lock(lock) LOCKRET(pthread_mutex_lock(lock))
#define lock_quick_unlock(lock) LOCKRET(pthread_mutex_unlock(lock))

#else /* HAVE_PTHREAD_SPINLOCK_T */
/** use pthread spinlock for the quick lock */
typedef pthread_spinlock_t lock_quick_t;
/** 
 * allocate process private since this is available whether
 * Thread Process-Shared Synchronization is supported or not.
 * This means only threads inside this process may access the lock.
 * (not threads from another process that shares memory).
 * spinlocks are not supported on all pthread platforms. 
 */
#define lock_quick_init(lock) LOCKRET(pthread_spin_init(lock, PTHREAD_PROCESS_PRIVATE))
#define lock_quick_destroy(lock) LOCKRET(pthread_spin_destroy(lock))
#define lock_quick_lock(lock) LOCKRET(pthread_spin_lock(lock))
#define lock_quick_unlock(lock) LOCKRET(pthread_spin_unlock(lock))

#endif /* HAVE SPINLOCK */

/** Thread creation */
typedef pthread_t ub_thread_t;
/** Pass where to store tread_t in thr. Use default NULL attributes. */
#define ub_thread_create(thr, func, arg) LOCKRET(pthread_create(thr, NULL, func, arg))

#else /* we do not HAVE_PTHREAD */
#ifdef HAVE_SOLARIS_THREADS

/******************* SOLARIS THREADS ************************/
typedef rwlock_t lock_rw_t;
#define lock_rw_init(lock) LOCKRET(rwlock_init(lock, USYNC_THREAD, NULL))
#define lock_rw_destroy(lock) LOCKRET(rwlock_destroy(lock))
#define lock_rw_rdlock(lock) LOCKRET(rw_rdlock(lock))
#define lock_rw_wrlock(lock) LOCKRET(rw_wrlock(lock))
#define lock_rw_unlock(lock) LOCKRET(rw_unlock(lock))

/** use basic mutex */
typedef mutex_t lock_basic_t;
#define lock_basic_init(lock) LOCKRET(mutex_init(lock, USYNC_THREAD, NULL))
#define lock_basic_destroy(lock) LOCKRET(mutex_destroy(lock))
#define lock_basic_lock(lock) LOCKRET(mutex_lock(lock))
#define lock_basic_unlock(lock) LOCKRET(mutex_unlock(lock))

/** No spinlocks in solaris threads API. Use a mutex. */
typedef mutex_t lock_quick_t;
#define lock_quick_init(lock) LOCKRET(mutex_init(lock, USYNC_THREAD, NULL))
#define lock_quick_destroy(lock) LOCKRET(mutex_destroy(lock))
#define lock_quick_lock(lock) LOCKRET(mutex_lock(lock))
#define lock_quick_unlock(lock) LOCKRET(mutex_unlock(lock))

/** Thread creation, create a default thread. */
typedef thread_t ub_thread_t;
#define ub_thread_create(thr, func, arg) LOCKRET(thr_create(NULL, NULL, func, arg, NULL, thr))

#else /* we do not HAVE_SOLARIS_THREADS and no PTHREADS */

/******************* NO THREADS ************************/
/** In case there is no thread support, define locks to do nothing */
typedef int lock_rw_t;
#define lock_rw_init(lock) /* nop */
#define lock_rw_destroy(lock) /* nop */
#define lock_rw_rdlock(lock) /* nop */
#define lock_rw_wrlock(lock) /* nop */
#define lock_rw_unlock(lock) /* nop */

/** define locks to do nothing */
typedef int lock_basic_t;
#define lock_basic_init(lock) /* nop */
#define lock_basic_destroy(lock) /* nop */
#define lock_basic_lock(lock) /* nop */
#define lock_basic_unlock(lock) /* nop */

/** define locks to do nothing */
typedef int lock_quick_t;
#define lock_quick_init(lock) /* nop */
#define lock_quick_destroy(lock) /* nop */
#define lock_quick_lock(lock) /* nop */
#define lock_quick_unlock(lock) /* nop */

/** Thread creation, threads do not exist */
typedef int ub_thread_t;
/** ub_thread_create gives an error, it should not be called. */
#define ub_thread_create(thr, func, arg) \
	fatal_exit("%s %d called thread create, but no thread support "  \
		"has been compiled in.",  __FILE__, __LINE__)

#endif /* HAVE_SOLARIS_THREADS */
#endif /* HAVE_PTHREAD */
#endif /* UTIL_LOCKS_H */