mirror of
https://git.savannah.gnu.org/git/guile.git
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fcc6a7ba20
* NEWS: Deprecate critical sections. * doc/ref/api-scheduling.texi (Critical Sections): Remove. * libguile/async.c: * libguile/async.h: * libguile/deprecated.c: * libguile/deprecated.h: * libguile/threads.c: * libguile/threads.h: Deprecate critical section API.
313 lines
8.3 KiB
C
313 lines
8.3 KiB
C
/* Copyright (C) 1995,1996,1997,1998,2000,2001, 2002, 2004, 2006, 2008,
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* 2009, 2010, 2011, 2014 Free Software Foundation, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public License
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* as published by the Free Software Foundation; either version 3 of
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* the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301 USA
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*/
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "libguile/_scm.h"
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#include "libguile/atomics-internal.h"
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#include "libguile/eval.h"
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#include "libguile/throw.h"
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#include "libguile/root.h"
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#include "libguile/smob.h"
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#include "libguile/dynwind.h"
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#include "libguile/deprecation.h"
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#include "libguile/validate.h"
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#include "libguile/async.h"
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#ifdef HAVE_STRING_H
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#include <string.h>
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#endif
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#include <unistd.h>
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#include <full-write.h>
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/* {Asynchronous Events}
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*
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* Asyncs are used to run arbitrary code at the next safe point in a
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* specified thread. You can use them to trigger execution of Scheme
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* code from signal handlers or to interrupt a thread, for example.
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*
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* Each thread has a list of 'activated asyncs', which is a normal
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* Scheme list of procedures with zero arguments. When a thread
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* executes an scm_async_tick (), it will call all procedures on this
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* list.
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*/
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void
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scm_async_tick (void)
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{
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scm_i_thread *t = SCM_I_CURRENT_THREAD;
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SCM asyncs;
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if (t->block_asyncs)
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return;
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asyncs = scm_atomic_swap_scm (&t->pending_asyncs, SCM_EOL);
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while (!scm_is_null (asyncs))
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{
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SCM next = scm_cdr (asyncs);
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scm_call_0 (scm_car (asyncs));
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scm_set_cdr_x (asyncs, SCM_BOOL_F);
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asyncs = next;
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}
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}
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int
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scm_i_setup_sleep (scm_i_thread *t,
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SCM sleep_object, scm_i_pthread_mutex_t *sleep_mutex,
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int sleep_fd)
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{
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struct scm_thread_wake_data *wake;
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wake = scm_gc_typed_calloc (struct scm_thread_wake_data);
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wake->object = sleep_object;
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wake->mutex = sleep_mutex;
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wake->fd = sleep_fd;
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scm_atomic_set_pointer ((void **)&t->wake, wake);
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return !scm_is_null (scm_atomic_ref_scm (&t->pending_asyncs));
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}
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void
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scm_i_reset_sleep (scm_i_thread *t)
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{
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scm_atomic_set_pointer ((void **)&t->wake, NULL);
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}
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SCM_DEFINE (scm_system_async_mark_for_thread, "system-async-mark", 1, 1, 0,
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(SCM proc, SCM thread),
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"Mark @var{proc} (a procedure with zero arguments) for future execution\n"
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"in @var{thread}. If @var{proc} has already been marked for\n"
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"@var{thread} but has not been executed yet, this call has no effect.\n"
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"If @var{thread} is omitted, the thread that called\n"
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"@code{system-async-mark} is used.\n\n"
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"This procedure is not safe to be called from C signal handlers. Use\n"
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"@code{scm_sigaction} or @code{scm_sigaction_for_thread} to install\n"
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"signal handlers.")
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#define FUNC_NAME s_scm_system_async_mark_for_thread
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{
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scm_i_thread *t;
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SCM asyncs;
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struct scm_thread_wake_data *wake;
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if (SCM_UNBNDP (thread))
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t = SCM_I_CURRENT_THREAD;
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else
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{
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SCM_VALIDATE_THREAD (2, thread);
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if (scm_c_thread_exited_p (thread))
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SCM_MISC_ERROR ("thread has already exited", SCM_EOL);
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t = SCM_I_THREAD_DATA (thread);
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}
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asyncs = scm_atomic_ref_scm (&t->pending_asyncs);
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do
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if (scm_is_true (scm_c_memq (proc, asyncs)))
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return SCM_UNSPECIFIED;
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while (!scm_atomic_compare_and_swap_scm (&t->pending_asyncs, &asyncs,
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scm_cons (proc, asyncs)));
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/* At this point the async is enqueued. However if the thread is
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sleeping, we have to wake it up. */
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if ((wake = scm_atomic_ref_pointer ((void **) &t->wake)))
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{
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/* By now, the thread T might be out of its sleep already, or
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might even be in the next, unrelated sleep. Interrupting it
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anyway does no harm, however.
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The important thing to prevent here is to signal sleep_cond
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before T waits on it. This can not happen since T has
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sleep_mutex locked while setting t->sleep_mutex and will only
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unlock it again while waiting on sleep_cond.
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*/
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scm_i_scm_pthread_mutex_lock (wake->mutex);
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scm_i_pthread_cond_signal (&t->sleep_cond);
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scm_i_pthread_mutex_unlock (wake->mutex);
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/* This is needed to protect wake->mutex.
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*/
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scm_remember_upto_here_1 (wake->object);
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if (wake->fd >= 0)
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{
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char dummy = 0;
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/* Likewise, T might already been done with sleeping here, but
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interrupting it once too often does no harm. T might also
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not yet have started sleeping, but this is no problem
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either since the data written to a pipe will not be lost,
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unlike a condition variable signal. */
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full_write (wake->fd, &dummy, 1);
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}
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}
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return SCM_UNSPECIFIED;
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}
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#undef FUNC_NAME
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SCM
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scm_system_async_mark (SCM proc)
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#define FUNC_NAME s_scm_system_async_mark_for_thread
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{
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return scm_system_async_mark_for_thread (proc, SCM_UNDEFINED);
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}
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#undef FUNC_NAME
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SCM_DEFINE (scm_noop, "noop", 0, 0, 1,
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(SCM args),
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"Do nothing. When called without arguments, return @code{#f},\n"
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"otherwise return the first argument.")
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#define FUNC_NAME s_scm_noop
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{
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SCM_VALIDATE_REST_ARGUMENT (args);
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return (SCM_NULL_OR_NIL_P (args) ? SCM_BOOL_F : SCM_CAR (args));
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}
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#undef FUNC_NAME
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static void
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increase_block (void *data)
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{
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scm_i_thread *t = data;
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t->block_asyncs++;
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}
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static void
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decrease_block (void *data)
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{
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scm_i_thread *t = data;
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if (--t->block_asyncs == 0)
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scm_async_tick ();
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}
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void
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scm_dynwind_block_asyncs (void)
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{
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scm_i_thread *t = SCM_I_CURRENT_THREAD;
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scm_dynwind_rewind_handler (increase_block, t, SCM_F_WIND_EXPLICITLY);
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scm_dynwind_unwind_handler (decrease_block, t, SCM_F_WIND_EXPLICITLY);
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}
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void
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scm_dynwind_unblock_asyncs (void)
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{
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scm_i_thread *t = SCM_I_CURRENT_THREAD;
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if (t->block_asyncs == 0)
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scm_misc_error ("scm_with_unblocked_asyncs",
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"asyncs already unblocked", SCM_EOL);
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scm_dynwind_rewind_handler (decrease_block, t, SCM_F_WIND_EXPLICITLY);
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scm_dynwind_unwind_handler (increase_block, t, SCM_F_WIND_EXPLICITLY);
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}
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SCM_DEFINE (scm_call_with_blocked_asyncs, "call-with-blocked-asyncs", 1, 0, 0,
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(SCM proc),
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"Call @var{proc} with no arguments and block the execution\n"
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"of system asyncs by one level for the current thread while\n"
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"it is running. Return the value returned by @var{proc}.\n")
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#define FUNC_NAME s_scm_call_with_blocked_asyncs
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{
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SCM ans;
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scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE);
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scm_dynwind_block_asyncs ();
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ans = scm_call_0 (proc);
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scm_dynwind_end ();
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return ans;
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}
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#undef FUNC_NAME
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void *
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scm_c_call_with_blocked_asyncs (void *(*proc) (void *data), void *data)
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{
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void* ans;
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scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE);
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scm_dynwind_block_asyncs ();
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ans = proc (data);
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scm_dynwind_end ();
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return ans;
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}
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SCM_DEFINE (scm_call_with_unblocked_asyncs, "call-with-unblocked-asyncs", 1, 0, 0,
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(SCM proc),
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"Call @var{proc} with no arguments and unblock the execution\n"
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"of system asyncs by one level for the current thread while\n"
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"it is running. Return the value returned by @var{proc}.\n")
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#define FUNC_NAME s_scm_call_with_unblocked_asyncs
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{
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SCM ans;
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if (SCM_I_CURRENT_THREAD->block_asyncs == 0)
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SCM_MISC_ERROR ("asyncs already unblocked", SCM_EOL);
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scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE);
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scm_dynwind_unblock_asyncs ();
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ans = scm_call_0 (proc);
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scm_dynwind_end ();
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return ans;
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}
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#undef FUNC_NAME
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void *
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scm_c_call_with_unblocked_asyncs (void *(*proc) (void *data), void *data)
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{
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void* ans;
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if (SCM_I_CURRENT_THREAD->block_asyncs == 0)
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scm_misc_error ("scm_c_call_with_unblocked_asyncs",
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"asyncs already unblocked", SCM_EOL);
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scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE);
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scm_dynwind_unblock_asyncs ();
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ans = proc (data);
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scm_dynwind_end ();
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return ans;
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}
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void
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scm_init_async ()
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{
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#include "libguile/async.x"
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}
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/*
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Local Variables:
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c-file-style: "gnu"
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End:
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*/
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