/* Copyright (C) 1995,1996,1997,1998,2000,2001, 2002, 2004, 2006, 2008, * 2009, 2010, 2014 Free Software Foundation, Inc. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public License * as published by the Free Software Foundation; either version 3 of * the License, or (at your option) any later version. * * This library 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 * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301 USA */ #ifdef HAVE_CONFIG_H # include #endif #define SCM_BUILDING_DEPRECATED_CODE #include "libguile/_scm.h" #include "libguile/eval.h" #include "libguile/throw.h" #include "libguile/root.h" #include "libguile/smob.h" #include "libguile/dynwind.h" #include "libguile/deprecation.h" #include "libguile/validate.h" #include "libguile/async.h" #ifdef HAVE_STRING_H #include #endif #include #include /* {Asynchronous Events} * * There are two kinds of asyncs: system asyncs and user asyncs. The * two kinds have some concepts in commen but work slightly * differently and are not interchangeable. * * System asyncs are used to run arbitrary code at the next safe point * in a specified thread. You can use them to trigger execution of * Scheme code from signal handlers or to interrupt a thread, for * example. * * Each thread has a list of 'activated asyncs', which is a normal * Scheme list of procedures with zero arguments. When a thread * executes a SCM_ASYNC_TICK statement (which is included in * SCM_TICK), it will call all procedures on this list. * * Also, a thread will wake up when a procedure is added to its list * of active asyncs and call them. After that, it will go to sleep * again. (Not implemented yet.) * * * User asyncs are a little data structure that consists of a * procedure of zero arguments and a mark. There are functions for * setting the mark of a user async and for calling all procedures of * marked asyncs in a given list. Nothing you couldn't quickly * implement yourself. */ /* User asyncs. */ static scm_t_bits tc16_async; /* cmm: this has SCM_ prefix because SCM_MAKE_VALIDATE expects it. this is ugly. */ #define SCM_ASYNCP(X) SCM_TYP16_PREDICATE (tc16_async, X) #define VALIDATE_ASYNC(pos, a) SCM_MAKE_VALIDATE_MSG(pos, a, ASYNCP, "user async") #define ASYNC_GOT_IT(X) (SCM_SMOB_FLAGS (X)) #define SET_ASYNC_GOT_IT(X, V) (SCM_SET_SMOB_FLAGS ((X), ((V)))) #define ASYNC_THUNK(X) SCM_SMOB_OBJECT_1 (X) SCM_DEFINE (scm_async, "async", 1, 0, 0, (SCM thunk), "Create a new async for the procedure @var{thunk}.") #define FUNC_NAME s_scm_async { SCM_RETURN_NEWSMOB (tc16_async, SCM_UNPACK (thunk)); } #undef FUNC_NAME SCM_DEFINE (scm_async_mark, "async-mark", 1, 0, 0, (SCM a), "Mark the async @var{a} for future execution.") #define FUNC_NAME s_scm_async_mark { VALIDATE_ASYNC (1, a); SET_ASYNC_GOT_IT (a, 1); return SCM_UNSPECIFIED; } #undef FUNC_NAME SCM_DEFINE (scm_run_asyncs, "run-asyncs", 1, 0, 0, (SCM list_of_a), "Execute all thunks from the asyncs of the list @var{list_of_a}.") #define FUNC_NAME s_scm_run_asyncs { while (! SCM_NULL_OR_NIL_P (list_of_a)) { SCM a; SCM_VALIDATE_CONS (1, list_of_a); a = SCM_CAR (list_of_a); VALIDATE_ASYNC (SCM_ARG1, a); if (ASYNC_GOT_IT (a)) { SET_ASYNC_GOT_IT (a, 0); scm_call_0 (ASYNC_THUNK (a)); } list_of_a = SCM_CDR (list_of_a); } return SCM_BOOL_T; } #undef FUNC_NAME static scm_i_pthread_mutex_t async_mutex = SCM_I_PTHREAD_MUTEX_INITIALIZER; /* System asyncs. */ void scm_async_click () { scm_i_thread *t = SCM_I_CURRENT_THREAD; SCM asyncs; /* Reset pending_asyncs even when asyncs are blocked and not really executed since this will avoid future futile calls to this function. When asyncs are unblocked again, this function is invoked even when pending_asyncs is zero. */ scm_i_scm_pthread_mutex_lock (&async_mutex); t->pending_asyncs = 0; if (t->block_asyncs == 0) { asyncs = t->active_asyncs; t->active_asyncs = SCM_EOL; } else asyncs = SCM_EOL; scm_i_pthread_mutex_unlock (&async_mutex); while (scm_is_pair (asyncs)) { SCM next = SCM_CDR (asyncs); SCM_SETCDR (asyncs, SCM_BOOL_F); scm_call_0 (SCM_CAR (asyncs)); asyncs = next; } } #if (SCM_ENABLE_DEPRECATED == 1) SCM_DEFINE (scm_system_async, "system-async", 1, 0, 0, (SCM thunk), "This function is deprecated. You can use @var{thunk} directly\n" "instead of explicitly creating an async object.\n") #define FUNC_NAME s_scm_system_async { scm_c_issue_deprecation_warning ("'system-async' is deprecated. " "Use the procedure directly with 'system-async-mark'."); return thunk; } #undef FUNC_NAME #endif /* SCM_ENABLE_DEPRECATED == 1 */ void scm_i_queue_async_cell (SCM c, scm_i_thread *t) { SCM sleep_object; scm_i_pthread_mutex_t *sleep_mutex; int sleep_fd; SCM p; scm_i_scm_pthread_mutex_lock (&async_mutex); p = t->active_asyncs; SCM_SETCDR (c, SCM_EOL); if (!scm_is_pair (p)) t->active_asyncs = c; else { SCM pp; while (scm_is_pair (pp = SCM_CDR (p))) { if (scm_is_eq (SCM_CAR (p), SCM_CAR (c))) { scm_i_pthread_mutex_unlock (&async_mutex); return; } p = pp; } SCM_SETCDR (p, c); } t->pending_asyncs = 1; sleep_object = t->sleep_object; sleep_mutex = t->sleep_mutex; sleep_fd = t->sleep_fd; scm_i_pthread_mutex_unlock (&async_mutex); if (sleep_mutex) { /* By now, the thread T might be out of its sleep already, or might even be in the next, unrelated sleep. Interrupting it anyway does no harm, however. The important thing to prevent here is to signal sleep_cond before T waits on it. This can not happen since T has sleep_mutex locked while setting t->sleep_mutex and will only unlock it again while waiting on sleep_cond. */ scm_i_scm_pthread_mutex_lock (sleep_mutex); scm_i_pthread_cond_signal (&t->sleep_cond); scm_i_pthread_mutex_unlock (sleep_mutex); } if (sleep_fd >= 0) { char dummy = 0; /* Likewise, T might already been done with sleeping here, but interrupting it once too often does no harm. T might also not yet have started sleeping, but this is no problem either since the data written to a pipe will not be lost, unlike a condition variable signal. */ full_write (sleep_fd, &dummy, 1); } /* This is needed to protect sleep_mutex. */ scm_remember_upto_here_1 (sleep_object); } int scm_i_setup_sleep (scm_i_thread *t, SCM sleep_object, scm_i_pthread_mutex_t *sleep_mutex, int sleep_fd) { int pending; scm_i_scm_pthread_mutex_lock (&async_mutex); pending = t->pending_asyncs; if (!pending) { t->sleep_object = sleep_object; t->sleep_mutex = sleep_mutex; t->sleep_fd = sleep_fd; } scm_i_pthread_mutex_unlock (&async_mutex); return pending; } void scm_i_reset_sleep (scm_i_thread *t) { scm_i_scm_pthread_mutex_lock (&async_mutex); t->sleep_object = SCM_BOOL_F; t->sleep_mutex = NULL; t->sleep_fd = -1; scm_i_pthread_mutex_unlock (&async_mutex); } SCM_DEFINE (scm_system_async_mark_for_thread, "system-async-mark", 1, 1, 0, (SCM proc, SCM thread), "Mark @var{proc} (a procedure with zero arguments) for future execution\n" "in @var{thread}. If @var{proc} has already been marked for\n" "@var{thread} but has not been executed yet, this call has no effect.\n" "If @var{thread} is omitted, the thread that called\n" "@code{system-async-mark} is used.\n\n" "This procedure is not safe to be called from C signal handlers. Use\n" "@code{scm_sigaction} or @code{scm_sigaction_for_thread} to install\n" "signal handlers.") #define FUNC_NAME s_scm_system_async_mark_for_thread { /* The current thread might not have a handle yet. This can happen when the GC runs immediately before allocating the handle. At the end of that GC, a system async might be marked. Thus, we can not use scm_current_thread here. */ scm_i_thread *t; if (SCM_UNBNDP (thread)) t = SCM_I_CURRENT_THREAD; else { SCM_VALIDATE_THREAD (2, thread); if (scm_c_thread_exited_p (thread)) SCM_MISC_ERROR ("thread has already exited", SCM_EOL); t = SCM_I_THREAD_DATA (thread); } scm_i_queue_async_cell (scm_cons (proc, SCM_BOOL_F), t); return SCM_UNSPECIFIED; } #undef FUNC_NAME SCM scm_system_async_mark (SCM proc) #define FUNC_NAME s_scm_system_async_mark_for_thread { return scm_system_async_mark_for_thread (proc, SCM_UNDEFINED); } #undef FUNC_NAME SCM_DEFINE (scm_noop, "noop", 0, 0, 1, (SCM args), "Do nothing. When called without arguments, return @code{#f},\n" "otherwise return the first argument.") #define FUNC_NAME s_scm_noop { SCM_VALIDATE_REST_ARGUMENT (args); return (SCM_NULL_OR_NIL_P (args) ? SCM_BOOL_F : SCM_CAR (args)); } #undef FUNC_NAME #if (SCM_ENABLE_DEPRECATED == 1) SCM_DEFINE (scm_unmask_signals, "unmask-signals", 0, 0, 0, (), "Unmask signals. The returned value is not specified.") #define FUNC_NAME s_scm_unmask_signals { scm_i_thread *t = SCM_I_CURRENT_THREAD; scm_c_issue_deprecation_warning ("'unmask-signals' is deprecated. " "Use 'call-with-blocked-asyncs' instead."); if (t->block_asyncs == 0) SCM_MISC_ERROR ("signals already unmasked", SCM_EOL); t->block_asyncs = 0; scm_async_click (); return SCM_UNSPECIFIED; } #undef FUNC_NAME SCM_DEFINE (scm_mask_signals, "mask-signals", 0, 0, 0, (), "Mask signals. The returned value is not specified.") #define FUNC_NAME s_scm_mask_signals { scm_i_thread *t = SCM_I_CURRENT_THREAD; scm_c_issue_deprecation_warning ("'mask-signals' is deprecated. Use 'call-with-blocked-asyncs' instead."); if (t->block_asyncs > 0) SCM_MISC_ERROR ("signals already masked", SCM_EOL); t->block_asyncs = 1; return SCM_UNSPECIFIED; } #undef FUNC_NAME #endif /* SCM_ENABLE_DEPRECATED == 1 */ static void increase_block (void *data) { scm_i_thread *t = data; t->block_asyncs++; } static void decrease_block (void *data) { scm_i_thread *t = data; if (--t->block_asyncs == 0) scm_async_click (); } void scm_dynwind_block_asyncs (void) { scm_i_thread *t = SCM_I_CURRENT_THREAD; scm_dynwind_rewind_handler (increase_block, t, SCM_F_WIND_EXPLICITLY); scm_dynwind_unwind_handler (decrease_block, t, SCM_F_WIND_EXPLICITLY); } void scm_dynwind_unblock_asyncs (void) { scm_i_thread *t = SCM_I_CURRENT_THREAD; if (t->block_asyncs == 0) scm_misc_error ("scm_with_unblocked_asyncs", "asyncs already unblocked", SCM_EOL); scm_dynwind_rewind_handler (decrease_block, t, SCM_F_WIND_EXPLICITLY); scm_dynwind_unwind_handler (increase_block, t, SCM_F_WIND_EXPLICITLY); } SCM_DEFINE (scm_call_with_blocked_asyncs, "call-with-blocked-asyncs", 1, 0, 0, (SCM proc), "Call @var{proc} with no arguments and block the execution\n" "of system asyncs by one level for the current thread while\n" "it is running. Return the value returned by @var{proc}.\n") #define FUNC_NAME s_scm_call_with_blocked_asyncs { SCM ans; scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE); scm_dynwind_block_asyncs (); ans = scm_call_0 (proc); scm_dynwind_end (); return ans; } #undef FUNC_NAME void * scm_c_call_with_blocked_asyncs (void *(*proc) (void *data), void *data) { void* ans; scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE); scm_dynwind_block_asyncs (); ans = proc (data); scm_dynwind_end (); return ans; } SCM_DEFINE (scm_call_with_unblocked_asyncs, "call-with-unblocked-asyncs", 1, 0, 0, (SCM proc), "Call @var{proc} with no arguments and unblock the execution\n" "of system asyncs by one level for the current thread while\n" "it is running. Return the value returned by @var{proc}.\n") #define FUNC_NAME s_scm_call_with_unblocked_asyncs { SCM ans; if (SCM_I_CURRENT_THREAD->block_asyncs == 0) SCM_MISC_ERROR ("asyncs already unblocked", SCM_EOL); scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE); scm_dynwind_unblock_asyncs (); ans = scm_call_0 (proc); scm_dynwind_end (); return ans; } #undef FUNC_NAME void * scm_c_call_with_unblocked_asyncs (void *(*proc) (void *data), void *data) { void* ans; if (SCM_I_CURRENT_THREAD->block_asyncs == 0) scm_misc_error ("scm_c_call_with_unblocked_asyncs", "asyncs already unblocked", SCM_EOL); scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE); scm_dynwind_unblock_asyncs (); ans = proc (data); scm_dynwind_end (); return ans; } /* These are function variants of the same-named macros (uppercase) for use outside of libguile. This is so that `SCM_I_CURRENT_THREAD', which may reside in TLS, is not accessed from outside of libguile. It thus allows libguile to be built with the "local-dynamic" TLS model. */ void scm_critical_section_start (void) { SCM_CRITICAL_SECTION_START; } void scm_critical_section_end (void) { SCM_CRITICAL_SECTION_END; } void scm_async_tick (void) { SCM_ASYNC_TICK; } void scm_init_async () { tc16_async = scm_make_smob_type ("async", 0); #include "libguile/async.x" } /* Local Variables: c-file-style: "gnu" End: */