/* Copyright (C) 1995,1996,1997,1998 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 software; see the file COPYING. If not, write to * the Free Software Foundation, Inc., 59 Temple Place, Suite 330, * Boston, MA 02111-1307 USA * * As a special exception, the Free Software Foundation gives permission * for additional uses of the text contained in its release of GUILE. * * The exception is that, if you link the GUILE library with other files * to produce an executable, this does not by itself cause the * resulting executable to be covered by the GNU General Public License. * Your use of that executable is in no way restricted on account of * linking the GUILE library code into it. * * This exception does not however invalidate any other reasons why * the executable file might be covered by the GNU General Public License. * * This exception applies only to the code released by the * Free Software Foundation under the name GUILE. If you copy * code from other Free Software Foundation releases into a copy of * GUILE, as the General Public License permits, the exception does * not apply to the code that you add in this way. To avoid misleading * anyone as to the status of such modified files, you must delete * this exception notice from them. * * If you write modifications of your own for GUILE, it is your choice * whether to permit this exception to apply to your modifications. * If you do not wish that, delete this exception notice. */ /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999, gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */ #include #include #include "_scm.h" #include "eval.h" #include "throw.h" #include "smob.h" #include "scm_validate.h" #include "async.h" #ifdef HAVE_STRING_H #include #endif #ifdef HAVE_UNISTD_H #include #endif /* {Asynchronous Events} * * * Async == thunk + mark. * * Setting the mark guarantees future execution of the thunk. More * than one set may be satisfied by a single execution. * * scm_tick_clock decremented once per SCM_ALLOW_INTS. * Async execution triggered by SCM_ALLOW_INTS when scm_tick_clock drops to 0. * Async execution prevented by scm_mask_ints != 0. * * If the clock reaches 0 when scm_mask_ints != 0, then reset the clock * to 1. * * If the clock reaches 0 any other time, run marked asyncs. * * From a unix signal handler, mark a corresponding async and set the clock * to 1. Do SCM_REDEFER_INTS;/SCM_REALLOW_INTS so that if the signal handler is not * called in the dynamic scope of a critical section, it is excecuted immediately. * * Overall, closely timed signals of a particular sort may be combined. Pending signals * are delivered in a fixed priority order, regardless of arrival order. * */ /* True between SCM_DEFER_INTS and SCM_ALLOW_INTS, and * when the interpreter is not running at all. */ int scm_ints_disabled = 1; unsigned int scm_async_clock = 20; static unsigned int scm_async_rate = 20; unsigned int scm_mask_ints = 1; static unsigned int scm_tick_clock = 0; static unsigned int scm_tick_rate = 0; static unsigned int scm_desired_tick_rate = 0; static unsigned int scm_switch_clock = 0; static unsigned int scm_switch_rate = 0; static unsigned int scm_desired_switch_rate = 0; static long scm_tc16_async; int scm_asyncs_pending () { SCM pos; pos = scm_asyncs; while (pos != SCM_EOL) { SCM a; struct scm_async * it; a = SCM_CAR (pos); it = SCM_ASYNC (a); if (it->got_it) return 1; pos = SCM_CDR (pos); } return 0; } #if 0 static SCM scm_sys_tick_async_thunk (void) { scm_deliver_signal (SCM_TICK_SIGNAL); return SCM_BOOL_F; } #endif void scm_async_click () { int owe_switch; int owe_tick; if (!scm_switch_rate) { owe_switch = 0; scm_switch_clock = scm_switch_rate = scm_desired_switch_rate; scm_desired_switch_rate = 0; } else { owe_switch = (scm_async_rate >= scm_switch_clock); if (owe_switch) { if (scm_desired_switch_rate) { scm_switch_clock = scm_switch_rate = scm_desired_switch_rate; scm_desired_switch_rate = 0; } else scm_switch_clock = scm_switch_rate; } else { if (scm_desired_switch_rate) { scm_switch_clock = scm_switch_rate = scm_desired_switch_rate; scm_desired_switch_rate = 0; } else scm_switch_clock -= scm_async_rate; } } if (scm_mask_ints) { if (owe_switch) scm_switch (); scm_async_clock = 1; return;; } if (!scm_tick_rate) { unsigned int r; owe_tick = 0; r = scm_desired_tick_rate; if (r) { scm_desired_tick_rate = 0; scm_tick_rate = r; scm_tick_clock = r; } } else { owe_tick = (scm_async_rate >= scm_tick_clock); if (owe_tick) { scm_tick_clock = scm_tick_rate = scm_desired_tick_rate; scm_desired_tick_rate = 0; } else { if (scm_desired_tick_rate) { scm_tick_clock = scm_tick_rate = scm_desired_tick_rate; scm_desired_tick_rate = 0; } else scm_tick_clock -= scm_async_rate; } } /* if (owe_tick) scm_async_mark (system_signal_asyncs[SCM_SIG_ORD(SCM_TICK_SIGNAL)]); */ SCM_DEFER_INTS; if (scm_tick_rate && scm_switch_rate) { scm_async_rate = min (scm_tick_clock, scm_switch_clock); scm_async_clock = scm_async_rate; } else if (scm_tick_rate) { scm_async_clock = scm_async_rate = scm_tick_clock; } else if (scm_switch_rate) { scm_async_clock = scm_async_rate = scm_switch_clock; } else scm_async_clock = scm_async_rate = 1 << 16; SCM_ALLOW_INTS_ONLY; tail: scm_run_asyncs (scm_asyncs); SCM_DEFER_INTS; if (scm_asyncs_pending ()) { SCM_ALLOW_INTS_ONLY; goto tail; } SCM_ALLOW_INTS; if (owe_switch) scm_switch (); } void scm_switch () { #if 0 /* Thread switching code should probably reside here, but the async switching code doesn't seem to work, so it's put in the SCM_ASYNC_TICK macro instead. /mdj */ SCM_THREAD_SWITCHING_CODE; #endif } static SCM mark_async (SCM obj) { struct scm_async * it; it = SCM_ASYNC (obj); return it->thunk; } SCM_DEFINE (scm_async, "async", 1, 0, 0, (SCM thunk), "") #define FUNC_NAME s_scm_async { struct scm_async * async = (struct scm_async *) scm_must_malloc (sizeof (*async), FUNC_NAME); async->got_it = 0; async->thunk = thunk; SCM_RETURN_NEWSMOB (scm_tc16_async, async); } #undef FUNC_NAME SCM_DEFINE (scm_system_async, "system-async", 1, 0, 0, (SCM thunk), "") #define FUNC_NAME s_scm_system_async { SCM it; SCM list; it = scm_async (thunk); SCM_NEWSMOB (list, it, scm_asyncs); scm_asyncs = list; return it; } #undef FUNC_NAME SCM_DEFINE (scm_async_mark, "async-mark", 1, 0, 0, (SCM a), "") #define FUNC_NAME s_scm_async_mark { struct scm_async * it; SCM_VALIDATE_ASYNC_COPY (1,a,it); it->got_it = 1; return SCM_UNSPECIFIED; } #undef FUNC_NAME SCM_DEFINE (scm_system_async_mark, "system-async-mark", 1, 0, 0, (SCM a), "") #define FUNC_NAME s_scm_system_async_mark { struct scm_async * it; SCM_VALIDATE_ASYNC_COPY (1,a,it); SCM_REDEFER_INTS; it->got_it = 1; scm_async_rate = 1 + scm_async_rate - scm_async_clock; scm_async_clock = 1; SCM_REALLOW_INTS; return SCM_UNSPECIFIED; } #undef FUNC_NAME SCM_DEFINE (scm_run_asyncs, "run-asyncs", 1, 0, 0, (SCM list_of_a), "") #define FUNC_NAME s_scm_run_asyncs { if (scm_mask_ints) return SCM_BOOL_F; while (list_of_a != SCM_EOL) { SCM a; struct scm_async * it; SCM_VALIDATE_CONS (1,list_of_a); a = SCM_CAR (list_of_a); SCM_VALIDATE_ASYNC_COPY (SCM_ARG1,a,it); scm_mask_ints = 1; if (it->got_it) { it->got_it = 0; scm_apply (it->thunk, SCM_EOL, SCM_EOL); } scm_mask_ints = 0; list_of_a = SCM_CDR (list_of_a); } return SCM_BOOL_T; } #undef FUNC_NAME SCM_DEFINE (scm_noop, "noop", 0, 0, 1, (SCM args), "") #define FUNC_NAME s_scm_noop { return (SCM_NULLP (args) ? SCM_BOOL_F : SCM_CAR (args)); } #undef FUNC_NAME SCM_DEFINE (scm_set_tick_rate, "set-tick-rate", 1, 0, 0, (SCM n), "") #define FUNC_NAME s_scm_set_tick_rate { unsigned int old_n; SCM_VALIDATE_INUM (1,n); old_n = scm_tick_rate; scm_desired_tick_rate = SCM_INUM (n); scm_async_rate = 1 + scm_async_rate - scm_async_clock; scm_async_clock = 1; return SCM_MAKINUM (old_n); } #undef FUNC_NAME SCM_DEFINE (scm_set_switch_rate, "set-switch-rate", 1, 0, 0, (SCM n), "") #define FUNC_NAME s_scm_set_switch_rate { unsigned int old_n; SCM_VALIDATE_INUM (1,n); old_n = scm_switch_rate; scm_desired_switch_rate = SCM_INUM (n); scm_async_rate = 1 + scm_async_rate - scm_async_clock; scm_async_clock = 1; return SCM_MAKINUM (old_n); } #undef FUNC_NAME /* points to the GC system-async, so that scm_gc_end can find it. */ SCM scm_gc_async; /* the vcell for gc-thunk. */ static SCM scm_gc_vcell; /* the thunk installed in the GC system-async, which is marked at the end of garbage collection. */ static SCM scm_sys_gc_async_thunk (void) { if (SCM_NFALSEP (scm_gc_vcell)) { SCM proc = SCM_CDR (scm_gc_vcell); if (SCM_NFALSEP (proc) && !SCM_UNBNDP (proc)) scm_apply (proc, SCM_EOL, SCM_EOL); } return SCM_UNSPECIFIED; } SCM_DEFINE (scm_unmask_signals, "unmask-signals", 0, 0, 0, (), "") #define FUNC_NAME s_scm_unmask_signals { scm_mask_ints = 0; return SCM_UNSPECIFIED; } #undef FUNC_NAME SCM_DEFINE (scm_mask_signals, "mask-signals", 0, 0, 0, (), "") #define FUNC_NAME s_scm_mask_signals { scm_mask_ints = 1; return SCM_UNSPECIFIED; } #undef FUNC_NAME void scm_init_async () { SCM a_thunk; scm_tc16_async = scm_make_smob_type_mfpe ("async", sizeof (struct scm_async), mark_async, NULL, NULL, NULL); scm_gc_vcell = scm_sysintern ("gc-thunk", SCM_BOOL_F); a_thunk = scm_make_gsubr ("%gc-thunk", 0, 0, 0, scm_sys_gc_async_thunk); scm_gc_async = scm_system_async (a_thunk); #include "async.x" }