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/* 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 <stdio.h>
#include <signal.h>
#include "_scm.h"
#include "eval.h"
#include "throw.h"
#include "smob.h"
#include "validate.h"
#include "async.h"
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#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"
}
|