Le mardi 22 juillet 2008 à 01:44 +0200, Bruno Haible a écrit :
> > > > - Implement support for condition variable.
> > >
> > > You are welcome to contribute a module for this.
> >
> > I started working on condition variable support. To me, it make sense to
> > do that directly within the lock module (the code is very much similar
> > to what currently exist for mutex primitive). Any objection?
>
> Yes, I continue to think that it belongs into a different module, because
>
> 1) For 95% of all multithread programming, all one needs is
> - locks,
> - thread-local storage,
> - starting and joining threads.
> Wait queues and condition variables are less needed and harder to
> use correctly (without introducing bugs or deadlocks).
>
> 2) The 'lock' module is compiled into libintl, and therefore I prefer to
> avoid increasing its .o file size for things that libintl does not need.
Attached is an initial implementation of the glcond module, based on
your lock module.
Regards,
--
Yoann Vandoorselaere <[EMAIL PROTECTED]>
diff --git a/lib/glcond.h b/lib/glcond.h
new file mode 100644
index 0000000..012f316
--- /dev/null
+++ b/lib/glcond.h
@@ -0,0 +1,301 @@
+/* Locking in multithreaded situations.
+ Copyright (C) 2005-2008 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 <[EMAIL PROTECTED]>, 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.
+
+ Condition variable:
+ Type: gl_cond_t
+ Declaration: gl_cond_define(extern, name)
+ Initializer: gl_cond_define_initialized(, name)
+ Waiting: gl_cond_wait(name)
+ Timed wait: gl_cond_timedwait(name, tv)
+ Signaling: gl_cond_signal(name)
+ Broadcasting: gl_cond_broadcast(name)
+*/
+
+
+#ifndef _GLCOND_H
+#define _GLCOND_H
+
+#include <errno.h>
+
+/* ========================================================================= */
+
+#if USE_POSIX_THREADS
+
+/* Use the POSIX threads library. */
+
+# include <pthread.h>
+# include <stdlib.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if PTHREAD_IN_USE_DETECTION_HARD
+
+/* The pthread_in_use() detection needs to be done at runtime. */
+# define pthread_in_use() \
+ glthread_in_use ()
+extern int glthread_in_use (void);
+
+# endif
+
+# if USE_POSIX_THREADS_WEAK
+
+/* Use weak references to the POSIX threads library. */
+
+/* Weak references avoid dragging in external libraries if the other parts
+ of the program don't use them. Here we use them, because we don't want
+ every program that uses libintl to depend on libpthread. This assumes
+ that libpthread would not be loaded after libintl; i.e. if libintl is
+ loaded first, by an executable that does not depend on libpthread, and
+ then a module is dynamically loaded that depends on libpthread, libintl
+ will not be multithread-safe. */
+
+/* The way to test at runtime whether libpthread is present is to test
+ whether a function pointer's value, such as &pthread_mutex_init, is
+ non-NULL. However, some versions of GCC have a bug through which, in
+ PIC mode, &foo != NULL always evaluates to true if there is a direct
+ call to foo(...) in the same function. To avoid this, we test the
+ address of a function in libpthread that we don't use. */
+
+# pragma weak pthread_cond_init
+# pragma weak pthread_cond_wait
+# pragma weak pthread_cond_timedwait
+# pragma weak pthread_cond_signal
+# pragma weak pthread_cond_broadcast
+# pragma weak pthread_cond_destroy
+
+# if !PTHREAD_IN_USE_DETECTION_HARD
+# pragma weak pthread_cancel
+# define pthread_in_use() (pthread_cancel != NULL)
+# endif
+
+# else
+
+# if !PTHREAD_IN_USE_DETECTION_HARD
+# define pthread_in_use() 1
+# endif
+
+# endif
+
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+typedef pthread_cond_t gl_cond_t;
+# define gl_cond_define(STORAGECLASS, NAME) \
+ STORAGECLASS pthread_cond_t NAME;
+# define gl_cond_define_initialized(STORAGECLASS, NAME) \
+ STORAGECLASS pthread_cond_t NAME = gl_cond_initializer;
+# define gl_cond_initializer \
+ PTHREAD_COND_INITIALIZER
+# define glthread_cond_init(COND) \
+ (pthread_in_use () ? pthread_cond_init (COND, NULL) : 0)
+# define glthread_cond_wait(COND, LOCK) \
+ (pthread_in_use () ? pthread_cond_wait (COND, LOCK) : 0)
+# define glthread_cond_timedwait(COND, LOCK, TS) \
+ (pthread_in_use () ? pthread_cond_timedwait (COND, LOCK, TS) : 0)
+# define glthread_cond_signal(COND) \
+ (pthread_in_use () ? pthread_cond_signal (COND) : 0)
+# define glthread_cond_broadcast(COND) \
+ (pthread_in_use () ? pthread_cond_broadcast (COND) : 0)
+# define glthread_cond_destroy(COND) \
+ (pthread_in_use () ? pthread_cond_destroy (COND) : 0)
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_PTH_THREADS
+
+/* Use the GNU Pth threads library. */
+
+# include <pth.h>
+# include <stdlib.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if USE_PTH_THREADS_WEAK
+
+/* Use weak references to the GNU Pth threads library. */
+
+# pragma weak pth_cond_init
+# pragma weak pth_cond_await
+# pragma weak pth_cond_notify
+# pragma weak pth_event
+# pragma weak pth_timeout
+# pragma weak pth_cancel
+# define pth_in_use() (pth_cancel != NULL)
+
+# else
+
+# define pth_in_use() 1
+
+# endif
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+typedef pth_cond_t gl_cond_t;
+# define gl_cond_define(STORAGECLASS, NAME) \
+ STORAGECLASS pth_cond_t NAME;
+# define gl_cond_define_initialized(STORAGECLASS, NAME) \
+ STORAGECLASS pth_cond_t NAME = gl_cond_initializer;
+# define gl_cond_initializer \
+ PTH_COND_INIT
+# define glthread_cond_init(COND) \
+ (pth_in_use () ? pth_cond_init (COND) : 0)
+# define glthread_cond_wait(COND, LOCK) \
+ (pth_in_use () ? pth_cond_await (COND, LOCK, NULL) : 0)
+# define glthread_cond_timedwait(COND, LOCK, TS) \
+ (pth_in_use () ? pth_cond_await (COND, LOCK, pth_event(PTH_EVENT_TIME, pth_timeout((TS)->tv_sec, (TS)->tv_nsec / 1000))) : 0)
+# define glthread_cond_signal(COND) \
+ (pth_in_use () ? pth_cond_notify (COND, FALSE) : 0)
+# define glthread_cond_broadcast(COND) \
+ (pth_in_use () ? pth_cond_notify (COND, TRUE) : 0)
+# define glhread_cond_destroy(COND) \
+ (void)
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_SOLARIS_THREADS
+
+/* Use the old Solaris threads library. */
+
+# include <thread.h>
+# include <synch.h>
+# include <stdlib.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if USE_SOLARIS_THREADS_WEAK
+
+/* Use weak references to the old Solaris threads library. */
+
+# pragma weak cond_init
+# pragma weak cond_wait
+# pragma weak cond_timedwait
+# pragma weak cond_signal
+# pragma weak cond_broadcast
+# pragma weak cond_destroy
+# pragma weak thr_suspend
+# define thread_in_use() (thr_suspend != NULL)
+
+# else
+
+# define thread_in_use() 1
+
+# endif
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+#define ETIMEDOUT ETIME
+
+typedef pthread_cond_t gl_cond_t;
+# define gl_cond_define(STORAGECLASS, NAME) \
+ STORAGECLASS cond_t NAME;
+# define gl_cond_define_initialized(STORAGECLASS, NAME) \
+ STORAGECLASS cond_t NAME = gl_cond_initializer;
+# define gl_cond_initializer \
+ DEFAULTCV
+# define glthread_cond_init(COND) \
+ (pthread_in_use () ? cond_init (COND, USYNC_THREAD, NULL) : 0)
+# define glthread_cond_wait(COND, LOCK) \
+ (pthread_in_use () ? cond_wait (COND, LOCK) : 0)
+# define glthread_cond_timedwait(COND, LOCK, TS) \
+ (pthread_in_use () ? cond_timedwait (COND, LOCK, TS) : 0)
+# define glthread_cond_signal(COND) \
+ (pthread_in_use () ? cond_signal (COND) : 0)
+# define glthread_cond_broadcast(COND) \
+ (pthread_in_use () ? cond_broadcast (COND) : 0)
+# define glthread_cond_destroy(COND) \
+ (pthread_in_use () ? cond_destroy (COND) : 0)
+
+#endif
+
+/* ========================================================================= */
+
+#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WIN32_THREADS)
+
+/* Provide dummy implementation if threads are not supported. */
+
+typedef int gl_cond_t;
+# define gl_cond_define(STORAGECLASS, NAME)
+# define gl_cond_define_initialized(STORAGECLASS, NAME)
+# define glthread_cond_init(COND) 0
+# define glthread_cond_signal(COND) 0
+# define glthread_cond_broadcast(COND) 0
+# define glthread_cond_wait(COND, LOCK) 0
+# define glthread_cond_timedwait(COND, LOCK, TS) 0
+# define glthread_cond_destroy(COND) 0
+
+#endif
+
+
+/* ========================================================================= */
+
+/* Macros with built-in error handling. */
+
+#define gl_cond_init(COND) \
+ do \
+ { \
+ if (glthread_cond_init (&COND)) \
+ abort (); \
+ } \
+ while (0)
+#define gl_cond_wait(COND, LOCK) \
+ do \
+ { \
+ if (glthread_cond_wait (&COND, &LOCK)) \
+ abort (); \
+ } \
+ while (0)
+#define gl_cond_signal(COND) \
+ do \
+ { \
+ if (glthread_cond_signal (&COND)) \
+ abort (); \
+ } \
+ while (0)
+#define gl_cond_broadcast(COND) \
+ do \
+ { \
+ if (glthread_cond_broadcast (&COND)) \
+ abort (); \
+ } \
+ while (0)
+#define gl_cond_destroy(COND) \
+ do \
+ { \
+ if (glthread_cond_destroy (&COND)) \
+ abort (); \
+ } \
+ while (0)
+
+#endif /* _GLCOND_H */
diff --git a/m4/glcond.m4 b/m4/glcond.m4
new file mode 100644
index 0000000..b31d6ae
--- /dev/null
+++ b/m4/glcond.m4
@@ -0,0 +1,10 @@
+# glcond.m4 serial 1 (gettext-0.15)
+dnl Copyright (C) 2005 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_COND],
+[
+ AC_REQUIRE([gl_LOCK])
+])
diff --git a/modules/glcond b/modules/glcond
new file mode 100644
index 0000000..1ea412f
--- /dev/null
+++ b/modules/glcond
@@ -0,0 +1,22 @@
+Description:
+Condition in multithreaded situations.
+
+Files:
+lib/glcond.h
+m4/glcond.m4
+
+configure.ac:
+gl_COND
+
+Makefile.am:
+lib_SOURCES += glcond.h
+
+Include:
+"glcond.h"
+
+License:
+LGPLv2+
+
+Maintainer:
+Yoann Vandoorselaere
+
