path: root/src/cairo-mutex-impl-private.h

/* cairo - a vector graphics library with display and print output
 *
 * Copyright © 2002 University of Southern California
 * Copyright © 2005,2007 Red Hat, Inc.
 * Copyright © 2007 Mathias Hasselmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it either under the terms of the GNU Lesser General Public
 * License version 2.1 as published by the Free Software Foundation
 * (the "LGPL") or, at your option, under the terms of the Mozilla
 * Public License Version 1.1 (the "MPL"). If you do not alter this
 * notice, a recipient may use your version of this file under either
 * the MPL or the LGPL.
 *
 * You should have received a copy of the LGPL along with this library
 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
 * You should have received a copy of the MPL along with this library
 * in the file COPYING-MPL-1.1
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
 * the specific language governing rights and limitations.
 *
 * The Original Code is the cairo graphics library.
 *
 * The Initial Developer of the Original Code is University of Southern
 * California.
 *
 * Contributor(s):
 *	Carl D. Worth <cworth@cworth.org>
 *	Mathias Hasselmann <mathias.hasselmann@gmx.de>
 *	Behdad Esfahbod <behdad@behdad.org>
 */

#ifndef CAIRO_MUTEX_IMPL_PRIVATE_H
#define CAIRO_MUTEX_IMPL_PRIVATE_H

#include "cairo.h"

#include "config.h"

#if HAVE_LOCKDEP
#include <lockdep.h>
#endif

/* A fully qualified no-operation statement */
#define CAIRO_MUTEX_IMPL_NOOP	do {/*no-op*/} while (0)
/* And one that evaluates its argument once */
#define CAIRO_MUTEX_IMPL_NOOP1(expr)        do { (void)(expr); } while (0)
/* Note: 'if (expr) {}' is an alternative to '(void)(expr);' that will 'use' the
 * result of __attribute__((warn_used_result)) functions. */

/* Cairo mutex implementation:
 *
 * Any new mutex implementation needs to do the following:
 *
 * - Condition on the right header or feature.  Headers are
 *   preferred as eg. you still can use win32 mutex implementation
 *   on a win32 system even if you do not compile the win32
 *   surface/backend.
 *
 * - typedef #cairo_mutex_impl_t to the proper mutex type on your target
 *   system.  Note that you may or may not need to use a pointer,
 *   depending on what kinds of initialization your mutex
 *   implementation supports.  No trailing semicolon needed.
 *   You should be able to compile the following snippet (don't try
 *   running it):
 *
 *   <programlisting>
 *	cairo_mutex_impl_t _cairo_some_mutex;
 *   </programlisting>
 *
 * - #define %CAIRO_MUTEX_IMPL_<NAME> 1 with suitable name for your platform.  You
 *   can later use this symbol in cairo-system.c.
 *
 * - #define CAIRO_MUTEX_IMPL_LOCK(mutex) and CAIRO_MUTEX_IMPL_UNLOCK(mutex) to
 *   proper statement to lock/unlock the mutex object passed in.
 *   You can (and should) assume that the mutex is already
 *   initialized, and is-not-already-locked/is-locked,
 *   respectively.  Use the "do { ... } while (0)" idiom if necessary.
 *   No trailing semicolons are needed (in any macro you define here).
 *   You should be able to compile the following snippet:
 *
 * - #define CAIRO_MUTEX_IMPL_TRY_LOCK(mutex) to try locking the mutex object,
 *   returning TRUE if the lock is acquired, FALSE if the mutex could not be locked.
 *
 *   <programlisting>
 *	cairo_mutex_impl_t _cairo_some_mutex;
 *
 *      if (1)
 *          CAIRO_MUTEX_IMPL_LOCK (_cairo_some_mutex);
 *      else
 *          CAIRO_MUTEX_IMPL_UNLOCK (_cairo_some_mutex);
 *   </programlisting>
 *
 * - #define %CAIRO_MUTEX_IMPL_NIL_INITIALIZER to something that can
 *   initialize the #cairo_mutex_impl_t type you defined.  Most of the
 *   time one of 0, %NULL, or {} works.  At this point
 *   you should be able to compile the following snippet:
 *
 *   <programlisting>
 *	cairo_mutex_impl_t _cairo_some_mutex = CAIRO_MUTEX_IMPL_NIL_INITIALIZER;
 *
 *      if (1)
 *          CAIRO_MUTEX_IMPL_LOCK (_cairo_some_mutex);
 *      else
 *          CAIRO_MUTEX_IMPL_UNLOCK (_cairo_some_mutex);
 *   </programlisting>
 *
 * - If the above code is not enough to initialize a mutex on
 *   your platform, #define CAIRO_MUTEX_IMPL_INIT(mutex) to statement
 *   to initialize the mutex (allocate resources, etc).  Such that
 *   you should be able to compile AND RUN the following snippet:
 *
 *   <programlisting>
 *	cairo_mutex_impl_t _cairo_some_mutex = CAIRO_MUTEX_IMPL_NIL_INITIALIZER;
 *
 *      CAIRO_MUTEX_IMPL_INIT (_cairo_some_mutex);
 *
 *      if (1)
 *          CAIRO_MUTEX_IMPL_LOCK (_cairo_some_mutex);
 *      else
 *          CAIRO_MUTEX_IMPL_UNLOCK (_cairo_some_mutex);
 *   </programlisting>
 *
 * - If you define CAIRO_MUTEX_IMPL_INIT(mutex), cairo will use it to
 *   initialize all static mutex'es.  If for any reason that should
 *   not happen (eg. %CAIRO_MUTEX_IMPL_INIT is just a faster way than
 *   what cairo does using %CAIRO_MUTEX_IMPL_NIL_INITIALIZER), then
 *   <programlisting>
 *      #define CAIRO_MUTEX_IMPL_INITIALIZE() CAIRO_MUTEX_IMPL_NOOP
 *   </programlisting>
 *
 * - If your system supports freeing a mutex object (deallocating
 *   resources, etc), then #define CAIRO_MUTEX_IMPL_FINI(mutex) to do
 *   that.
 *
 * - If you define CAIRO_MUTEX_IMPL_FINI(mutex), cairo will use it to
 *   define a finalizer function to finalize all static mutex'es.
 *   However, it's up to you to call CAIRO_MUTEX_IMPL_FINALIZE() at
 *   proper places, eg. when the system is unloading the cairo library.
 *   So, if for any reason finalizing static mutex'es is not needed
 *   (eg. you never call CAIRO_MUTEX_IMPL_FINALIZE()), then
 *   <programlisting>
 *      #define CAIRO_MUTEX_IMPL_FINALIZE() CAIRO_MUTEX_IMPL_NOOP
 *   </programlisting>
 *
 * - That is all.  If for any reason you think the above API is
 *   not enough to implement #cairo_mutex_impl_t on your system, please
 *   stop and write to the cairo mailing list about it.  DO NOT
 *   poke around cairo-mutex-private.h for possible solutions.
 */

#if CAIRO_NO_MUTEX

/* No mutexes */

  typedef int cairo_mutex_impl_t;

# define CAIRO_MUTEX_IMPL_NO 1
# define CAIRO_MUTEX_IMPL_INITIALIZE() CAIRO_MUTEX_IMPL_NOOP
# define CAIRO_MUTEX_IMPL_LOCK(mutex) CAIRO_MUTEX_IMPL_NOOP1(mutex)
# define CAIRO_MUTEX_IMPL_TRY_LOCK(mutex) ((mutex), TRUE)
# define CAIRO_MUTEX_IMPL_UNLOCK(mutex) CAIRO_MUTEX_IMPL_NOOP1(mutex)
# define CAIRO_MUTEX_IMPL_NIL_INITIALIZER 0

# define CAIRO_MUTEX_HAS_RECURSIVE_IMPL 1

  typedef int cairo_recursive_mutex_impl_t;

# define CAIRO_RECURSIVE_MUTEX_IMPL_INIT(mutex)
# define CAIRO_RECURSIVE_MUTEX_IMPL_NIL_INITIALIZER 0

#elif defined(_WIN32) /******************************************************/

# include <windows.h>

  typedef CRITICAL_SECTION cairo_mutex_impl_t;

# define CAIRO_MUTEX_IMPL_WIN32 1
# define CAIRO_MUTEX_IMPL_LOCK(mutex) EnterCriticalSection (&(mutex))
# define CAIRO_MUTEX_IMPL_TRY_LOCK(mutex) TryEnterCriticalSection (&(mutex))
# define CAIRO_MUTEX_IMPL_UNLOCK(mutex) LeaveCriticalSection (&(mutex))
# define CAIRO_MUTEX_IMPL_INIT(mutex) InitializeCriticalSection (&(mutex))
# define CAIRO_MUTEX_IMPL_FINI(mutex) DeleteCriticalSection (&(mutex))
# define CAIRO_MUTEX_IMPL_NIL_INITIALIZER { NULL, 0, 0, NULL, NULL, 0 }

#elif CAIRO_HAS_PTHREAD /* and finally if there are no native mutexes ********/

# include <pthread.h>

  typedef pthread_mutex_t cairo_mutex_impl_t;
  typedef pthread_mutex_t cairo_recursive_mutex_impl_t;

# define CAIRO_MUTEX_IMPL_PTHREAD 1
#if HAVE_LOCKDEP
/* expose all mutexes to the validator */
# define CAIRO_MUTEX_IMPL_INIT(mutex) pthread_mutex_init (&(mutex), NULL)
#endif
# define CAIRO_MUTEX_IMPL_LOCK(mutex) pthread_mutex_lock (&(mutex))
# define CAIRO_MUTEX_IMPL_TRY_LOCK(mutex) (pthread_mutex_trylock (&(mutex)) == 0)
# define CAIRO_MUTEX_IMPL_UNLOCK(mutex) pthread_mutex_unlock (&(mutex))
#if HAVE_LOCKDEP
# define CAIRO_MUTEX_IS_LOCKED(mutex) LOCKDEP_IS_LOCKED (&(mutex))
# define CAIRO_MUTEX_IS_UNLOCKED(mutex) LOCKDEP_IS_UNLOCKED (&(mutex))
#endif
# define CAIRO_MUTEX_IMPL_FINI(mutex) pthread_mutex_destroy (&(mutex))
#if ! HAVE_LOCKDEP
# define CAIRO_MUTEX_IMPL_FINALIZE() CAIRO_MUTEX_IMPL_NOOP
#endif
# define CAIRO_MUTEX_IMPL_NIL_INITIALIZER PTHREAD_MUTEX_INITIALIZER

# define CAIRO_MUTEX_HAS_RECURSIVE_IMPL 1
# define CAIRO_RECURSIVE_MUTEX_IMPL_INIT(mutex) do { \
    pthread_mutexattr_t attr; \
    pthread_mutexattr_init (&attr); \
    pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE); \
    pthread_mutex_init (&(mutex), &attr); \
    pthread_mutexattr_destroy (&attr); \
} while (0)
# define CAIRO_RECURSIVE_MUTEX_IMPL_NIL_INITIALIZER PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP

#else /**********************************************************************/

# error "XXX: No mutex implementation found.  Cairo will not work with multiple threads.  Define CAIRO_NO_MUTEX to 1 to acknowledge and accept this limitation and compile cairo without thread-safety support."

#endif

/* By default mutex implementations are assumed to be recursive */
#if ! CAIRO_MUTEX_HAS_RECURSIVE_IMPL

# define CAIRO_MUTEX_HAS_RECURSIVE_IMPL 1

  typedef cairo_mutex_impl_t cairo_recursive_mutex_impl_t;

# define CAIRO_RECURSIVE_MUTEX_IMPL_INIT(mutex) CAIRO_MUTEX_IMPL_INIT(mutex)
# define CAIRO_RECURSIVE_MUTEX_IMPL_NIL_INITIALIZER CAIRO_MUTEX_IMPL_NIL_INITIALIZER

#endif

#endif