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/* Locking in multithreaded situations.
Copyright (C) 2005-2009 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
/* Written by Bruno Haible <bruno@clisp.org>, 2005.
Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
gthr-win32.h. */
/* This file contains locking primitives for use with a given thread library.
It does not contain primitives for creating threads or for other
synchronization primitives.
Normal (non-recursive) locks:
Type: gl_lock_t
Declaration: gl_lock_define(extern, name)
Initializer: gl_lock_define_initialized(, name)
Initialization: gl_lock_init (name);
Taking the lock: gl_lock_lock (name);
Releasing the lock: gl_lock_unlock (name);
De-initialization: gl_lock_destroy (name);
Equivalent functions with control of error handling:
Initialization: err = glthread_lock_init (&name);
Taking the lock: err = glthread_lock_lock (&name);
Releasing the lock: err = glthread_lock_unlock (&name);
De-initialization: err = glthread_lock_destroy (&name);
Read-Write (non-recursive) locks:
Type: gl_rwlock_t
Declaration: gl_rwlock_define(extern, name)
Initializer: gl_rwlock_define_initialized(, name)
Initialization: gl_rwlock_init (name);
Taking the lock: gl_rwlock_rdlock (name);
gl_rwlock_wrlock (name);
Releasing the lock: gl_rwlock_unlock (name);
De-initialization: gl_rwlock_destroy (name);
Equivalent functions with control of error handling:
Initialization: err = glthread_rwlock_init (&name);
Taking the lock: err = glthread_rwlock_rdlock (&name);
err = glthread_rwlock_wrlock (&name);
Releasing the lock: err = glthread_rwlock_unlock (&name);
De-initialization: err = glthread_rwlock_destroy (&name);
Recursive locks:
Type: gl_recursive_lock_t
Declaration: gl_recursive_lock_define(extern, name)
Initializer: gl_recursive_lock_define_initialized(, name)
Initialization: gl_recursive_lock_init (name);
Taking the lock: gl_recursive_lock_lock (name);
Releasing the lock: gl_recursive_lock_unlock (name);
De-initialization: gl_recursive_lock_destroy (name);
Equivalent functions with control of error handling:
Initialization: err = glthread_recursive_lock_init (&name);
Taking the lock: err = glthread_recursive_lock_lock (&name);
Releasing the lock: err = glthread_recursive_lock_unlock (&name);
De-initialization: err = glthread_recursive_lock_destroy (&name);
Once-only execution:
Type: gl_once_t
Initializer: gl_once_define(extern, name)
Execution: gl_once (name, initfunction);
Equivalent functions with control of error handling:
Execution: err = glthread_once (&name, initfunction);
*/
#ifndef _LOCK_H
#define _LOCK_H
#include <errno.h>
/* ========================================================================= */
#if USE_POSIX_THREADS
/* Use the POSIX threads library. */
# include <pthread.h>
# include <stdlib.h>
# ifdef __cplusplus
extern "C" {
# endif
/* -------------------------- gl_lock_t datatype -------------------------- */
typedef pthread_mutex_t gl_lock_t;
# define gl_lock_define(STORAGECLASS, NAME) \
STORAGECLASS pthread_mutex_t NAME;
# define gl_lock_define_initialized(STORAGECLASS, NAME) \
STORAGECLASS pthread_mutex_t NAME = gl_lock_initializer;
# define gl_lock_initializer \
PTHREAD_MUTEX_INITIALIZER
# define glthread_lock_init(LOCK) \
(pthread_mutex_init (LOCK, NULL))
# define glthread_lock_lock(LOCK) \
(pthread_mutex_lock (LOCK))
# define glthread_lock_unlock(LOCK) \
(pthread_mutex_unlock (LOCK))
# define glthread_lock_destroy(LOCK) \
(pthread_mutex_destroy (LOCK))
/* ------------------------- gl_rwlock_t datatype ------------------------- */
# if HAVE_PTHREAD_RWLOCK
# ifdef PTHREAD_RWLOCK_INITIALIZER
typedef pthread_rwlock_t gl_rwlock_t;
# define gl_rwlock_define(STORAGECLASS, NAME) \
STORAGECLASS pthread_rwlock_t NAME;
# define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
STORAGECLASS pthread_rwlock_t NAME = gl_rwlock_initializer;
# define gl_rwlock_initializer \
PTHREAD_RWLOCK_INITIALIZER
# define glthread_rwlock_init(LOCK) \
(pthread_rwlock_init (LOCK, NULL))
# define glthread_rwlock_rdlock(LOCK) \
(pthread_rwlock_rdlock (LOCK))
# define glthread_rwlock_wrlock(LOCK) \
(pthread_rwlock_wrlock (LOCK))
# define glthread_rwlock_unlock(LOCK) \
(pthread_rwlock_unlock (LOCK))
# define glthread_rwlock_destroy(LOCK) \
(pthread_rwlock_destroy (LOCK))
# else
typedef struct
{
int initialized;
pthread_mutex_t guard; /* protects the initialization */
pthread_rwlock_t rwlock; /* read-write lock */
}
gl_rwlock_t;
# define gl_rwlock_define(STORAGECLASS, NAME) \
STORAGECLASS gl_rwlock_t NAME;
# define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
# define gl_rwlock_initializer \
{ 0, PTHREAD_MUTEX_INITIALIZER }
extern int glthread_rwlock_init (gl_rwlock_t *lock);
extern int glthread_rwlock_rdlock (gl_rwlock_t *lock);
extern int glthread_rwlock_wrlock (gl_rwlock_t *lock);
extern int glthread_rwlock_unlock (gl_rwlock_t *lock);
extern int glthread_rwlock_destroy (gl_rwlock_t *lock);
# endif
# else
typedef struct
{
pthread_mutex_t lock; /* protects the remaining fields */
pthread_cond_t waiting_readers; /* waiting readers */
pthread_cond_t waiting_writers; /* waiting writers */
unsigned int waiting_writers_count; /* number of waiting writers */
int runcount; /* number of readers running, or -1 when a writer runs */
}
gl_rwlock_t;
# define gl_rwlock_define(STORAGECLASS, NAME) \
STORAGECLASS gl_rwlock_t NAME;
# define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
# define gl_rwlock_initializer \
{ PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, PTHREAD_COND_INITIALIZER, 0, 0 }
extern int glthread_rwlock_init (gl_rwlock_t *lock);
extern int glthread_rwlock_rdlock (gl_rwlock_t *lock);
extern int glthread_rwlock_wrlock (gl_rwlock_t *lock);
extern int glthread_rwlock_unlock (gl_rwlock_t *lock);
extern int glthread_rwlock_destroy (gl_rwlock_t *lock);
# endif
/* --------------------- gl_recursive_lock_t datatype --------------------- */
# if HAVE_PTHREAD_MUTEX_RECURSIVE
# if defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER || defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
typedef pthread_mutex_t gl_recursive_lock_t;
# define gl_recursive_lock_define(STORAGECLASS, NAME) \
STORAGECLASS pthread_mutex_t NAME;
# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
STORAGECLASS pthread_mutex_t NAME = gl_recursive_lock_initializer;
# ifdef PTHREAD_RECURSIVE_MUTEX_INITIALIZER
# define gl_recursive_lock_initializer \
PTHREAD_RECURSIVE_MUTEX_INITIALIZER
# else
# define gl_recursive_lock_initializer \
PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
# endif
# define glthread_recursive_lock_lock(LOCK) \
(pthread_mutex_lock (LOCK))
# define glthread_recursive_lock_unlock(LOCK) \
(pthread_mutex_unlock (LOCK))
# define glthread_recursive_lock_destroy(LOCK) \
(pthread_mutex_destroy (LOCK))
extern int glthread_recursive_lock_init (gl_recursive_lock_t *lock);
# else
typedef struct
{
pthread_mutex_t recmutex; /* recursive mutex */
pthread_mutex_t guard; /* protects the initialization */
int initialized;
}
gl_recursive_lock_t;
# define gl_recursive_lock_define(STORAGECLASS, NAME) \
STORAGECLASS gl_recursive_lock_t NAME;
# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
# define gl_recursive_lock_initializer \
{ PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, 0 }
extern int glthread_recursive_lock_init (gl_recursive_lock_t *lock);
extern int glthread_recursive_lock_lock (gl_recursive_lock_t *lock);
extern int glthread_recursive_lock_unlock (gl_recursive_lock_t *lock);
extern int glthread_recursive_lock_destroy (gl_recursive_lock_t *lock);
# endif
# else
/* Old versions of POSIX threads on Solaris did not have recursive locks.
We have to implement them ourselves. */
typedef struct
{
pthread_mutex_t mutex;
pthread_t owner;
unsigned long depth;
}
gl_recursive_lock_t;
# define gl_recursive_lock_define(STORAGECLASS, NAME) \
STORAGECLASS gl_recursive_lock_t NAME;
# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
# define gl_recursive_lock_initializer \
{ PTHREAD_MUTEX_INITIALIZER, (pthread_t) 0, 0 }
extern int glthread_recursive_lock_init (gl_recursive_lock_t *lock);
extern int glthread_recursive_lock_lock (gl_recursive_lock_t *lock);
extern int glthread_recursive_lock_unlock (gl_recursive_lock_t *lock);
extern int glthread_recursive_lock_destroy (gl_recursive_lock_t *lock);
# endif
/* -------------------------- gl_once_t datatype -------------------------- */
typedef pthread_once_t gl_once_t;
# define gl_once_define(STORAGECLASS, NAME) \
STORAGECLASS pthread_once_t NAME = PTHREAD_ONCE_INIT;
# define glthread_once(ONCE_CONTROL, INITFUNCTION) \
(pthread_once (ONCE_CONTROL, INITFUNCTION))
# ifdef __cplusplus
}
# endif
#endif
/* ========================================================================= */
#if USE_WIN32_THREADS
# include <windows.h>
# ifdef __cplusplus
extern "C" {
# endif
/* We can use CRITICAL_SECTION directly, rather than the Win32 Event, Mutex,
Semaphore types, because
- we need only to synchronize inside a single process (address space),
not inter-process locking,
- we don't need to support trylock operations. (TryEnterCriticalSection
does not work on Windows 95/98/ME. Packages that need trylock usually
define their own mutex type.) */
/* There is no way to statically initialize a CRITICAL_SECTION. It needs
to be done lazily, once only. For this we need spinlocks. */
typedef struct { volatile int done; volatile long started; } gl_spinlock_t;
/* -------------------------- gl_lock_t datatype -------------------------- */
typedef struct
{
gl_spinlock_t guard; /* protects the initialization */
CRITICAL_SECTION lock;
}
gl_lock_t;
# define gl_lock_define(STORAGECLASS, NAME) \
STORAGECLASS gl_lock_t NAME;
# define gl_lock_define_initialized(STORAGECLASS, NAME) \
STORAGECLASS gl_lock_t NAME = gl_lock_initializer;
# define gl_lock_initializer \
{ { 0, -1 } }
# define glthread_lock_init(LOCK) \
(glthread_lock_init_func (LOCK), 0)
extern void glthread_lock_init_func (gl_lock_t *lock);
extern int glthread_lock_lock (gl_lock_t *lock);
extern int glthread_lock_unlock (gl_lock_t *lock);
extern int glthread_lock_destroy (gl_lock_t *lock);
/* ------------------------- gl_rwlock_t datatype ------------------------- */
/* It is impossible to implement read-write locks using plain locks, without
introducing an extra thread dedicated to managing read-write locks.
Therefore here we need to use the low-level Event type. */
typedef struct
{
HANDLE *array; /* array of waiting threads, each represented by an event */
unsigned int count; /* number of waiting threads */
unsigned int alloc; /* length of allocated array */
unsigned int offset; /* index of first waiting thread in array */
}
gl_waitqueue_t;
typedef struct
{
gl_spinlock_t guard; /* protects the initialization */
CRITICAL_SECTION lock; /* protects the remaining fields */
gl_waitqueue_t waiting_readers; /* waiting readers */
gl_waitqueue_t waiting_writers; /* waiting writers */
int runcount; /* number of readers running, or -1 when a writer runs */
}
gl_rwlock_t;
# define gl_rwlock_define(STORAGECLASS, NAME) \
STORAGECLASS gl_rwlock_t NAME;
# define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
# define gl_rwlock_initializer \
{ { 0, -1 } }
# define glthread_rwlock_init(LOCK) \
(glthread_rwlock_init_func (LOCK), 0)
extern void glthread_rwlock_init_func (gl_rwlock_t *lock);
extern int glthread_rwlock_rdlock (gl_rwlock_t *lock);
extern int glthread_rwlock_wrlock (gl_rwlock_t *lock);
extern int glthread_rwlock_unlock (gl_rwlock_t *lock);
extern int glthread_rwlock_destroy (gl_rwlock_t *lock);
/* --------------------- gl_recursive_lock_t datatype --------------------- */
/* The Win32 documentation says that CRITICAL_SECTION already implements a
recursive lock. But we need not rely on it: It's easy to implement a
recursive lock without this assumption. */
typedef struct
{
gl_spinlock_t guard; /* protects the initialization */
DWORD owner;
unsigned long depth;
CRITICAL_SECTION lock;
}
gl_recursive_lock_t;
# define gl_recursive_lock_define(STORAGECLASS, NAME) \
STORAGECLASS gl_recursive_lock_t NAME;
# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
# define gl_recursive_lock_initializer \
{ { 0, -1 }, 0, 0 }
# define glthread_recursive_lock_init(LOCK) \
(glthread_recursive_lock_init_func (LOCK), 0)
extern void glthread_recursive_lock_init_func (gl_recursive_lock_t *lock);
extern int glthread_recursive_lock_lock (gl_recursive_lock_t *lock);
extern int glthread_recursive_lock_unlock (gl_recursive_lock_t *lock);
extern int glthread_recursive_lock_destroy (gl_recursive_lock_t *lock);
/* -------------------------- gl_once_t datatype -------------------------- */
typedef struct
{
volatile int inited;
volatile long started;
CRITICAL_SECTION lock;
}
gl_once_t;
# define gl_once_define(STORAGECLASS, NAME) \
STORAGECLASS gl_once_t NAME = { -1, -1 };
# define glthread_once(ONCE_CONTROL, INITFUNCTION) \
(glthread_once_func (ONCE_CONTROL, INITFUNCTION), 0)
extern void glthread_once_func (gl_once_t *once_control, void (*initfunction) (void));
# ifdef __cplusplus
}
# endif
#endif
/* ========================================================================= */
#if !(USE_POSIX_THREADS || USE_WIN32_THREADS)
/* Provide dummy implementation if threads are not supported. */
/* -------------------------- gl_lock_t datatype -------------------------- */
typedef int gl_lock_t;
# define gl_lock_define(STORAGECLASS, NAME)
# define gl_lock_define_initialized(STORAGECLASS, NAME)
# define glthread_lock_init(NAME) 0
# define glthread_lock_lock(NAME) 0
# define glthread_lock_unlock(NAME) 0
# define glthread_lock_destroy(NAME) 0
/* ------------------------- gl_rwlock_t datatype ------------------------- */
typedef int gl_rwlock_t;
# define gl_rwlock_define(STORAGECLASS, NAME)
# define gl_rwlock_define_initialized(STORAGECLASS, NAME)
# define glthread_rwlock_init(NAME) 0
# define glthread_rwlock_rdlock(NAME) 0
# define glthread_rwlock_wrlock(NAME) 0
# define glthread_rwlock_unlock(NAME) 0
# define glthread_rwlock_destroy(NAME) 0
/* --------------------- gl_recursive_lock_t datatype --------------------- */
typedef int gl_recursive_lock_t;
# define gl_recursive_lock_define(STORAGECLASS, NAME)
# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME)
# define glthread_recursive_lock_init(NAME) 0
# define glthread_recursive_lock_lock(NAME) 0
# define glthread_recursive_lock_unlock(NAME) 0
# define glthread_recursive_lock_destroy(NAME) 0
/* -------------------------- gl_once_t datatype -------------------------- */
typedef int gl_once_t;
# define gl_once_define(STORAGECLASS, NAME) \
STORAGECLASS gl_once_t NAME = 0;
# define glthread_once(ONCE_CONTROL, INITFUNCTION) \
(*(ONCE_CONTROL) == 0 ? (*(ONCE_CONTROL) = ~ 0, INITFUNCTION (), 0) : 0)
#endif
/* ========================================================================= */
/* Macros with built-in error handling. */
/* -------------------------- gl_lock_t datatype -------------------------- */
#define gl_lock_init(NAME) \
do \
{ \
if (glthread_lock_init (&NAME)) \
abort (); \
} \
while (0)
#define gl_lock_lock(NAME) \
do \
{ \
if (glthread_lock_lock (&NAME)) \
abort (); \
} \
while (0)
#define gl_lock_unlock(NAME) \
do \
{ \
if (glthread_lock_unlock (&NAME)) \
abort (); \
} \
while (0)
#define gl_lock_destroy(NAME) \
do \
{ \
if (glthread_lock_destroy (&NAME)) \
abort (); \
} \
while (0)
/* ------------------------- gl_rwlock_t datatype ------------------------- */
#define gl_rwlock_init(NAME) \
do \
{ \
if (glthread_rwlock_init (&NAME)) \
abort (); \
} \
while (0)
#define gl_rwlock_rdlock(NAME) \
do \
{ \
if (glthread_rwlock_rdlock (&NAME)) \
abort (); \
} \
while (0)
#define gl_rwlock_wrlock(NAME) \
do \
{ \
if (glthread_rwlock_wrlock (&NAME)) \
abort (); \
} \
while (0)
#define gl_rwlock_unlock(NAME) \
do \
{ \
if (glthread_rwlock_unlock (&NAME)) \
abort (); \
} \
while (0)
#define gl_rwlock_destroy(NAME) \
do \
{ \
if (glthread_rwlock_destroy (&NAME)) \
abort (); \
} \
while (0)
/* --------------------- gl_recursive_lock_t datatype --------------------- */
#define gl_recursive_lock_init(NAME) \
do \
{ \
if (glthread_recursive_lock_init (&NAME)) \
abort (); \
} \
while (0)
#define gl_recursive_lock_lock(NAME) \
do \
{ \
if (glthread_recursive_lock_lock (&NAME)) \
abort (); \
} \
while (0)
#define gl_recursive_lock_unlock(NAME) \
do \
{ \
if (glthread_recursive_lock_unlock (&NAME)) \
abort (); \
} \
while (0)
#define gl_recursive_lock_destroy(NAME) \
do \
{ \
if (glthread_recursive_lock_destroy (&NAME)) \
abort (); \
} \
while (0)
/* -------------------------- gl_once_t datatype -------------------------- */
#define gl_once(NAME, INITFUNCTION) \
do \
{ \
if (glthread_once (&NAME, INITFUNCTION)) \
abort (); \
} \
while (0)
/* ========================================================================= */
#endif /* _LOCK_H */