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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. */
/* $Id: coop.c,v 1.15 1998-11-19 08:15:22 mdj Exp $ */
/* Cooperative thread library, based on QuickThreads */
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <qt.h>
#include "eval.h"
/* #define COOP_STKSIZE (0x10000) */
#define COOP_STKSIZE (scm_eval_stack)
/* `alignment' must be a power of 2. */
#define COOP_STKALIGN(sp, alignment) \
((void *)((((qt_word_t)(sp)) + (alignment) - 1) & ~((alignment)-1)))
/* Queue access functions. */
#ifdef __STDC__
static void
coop_qinit (coop_q_t *q)
#else
static void
coop_qinit (q)
coop_q_t *q;
#endif
{
q->t.next = q->tail = &q->t;
q->t.all_prev = NULL;
q->t.all_next = NULL;
#ifdef GUILE_ISELECT
q->t.nfds = 0;
q->t.readfds = NULL;
q->t.writefds = NULL;
q->t.exceptfds = NULL;
q->t.timeoutp = 0;
#endif
}
#ifdef __STDC__
coop_t *
coop_qget (coop_q_t *q)
#else
coop_t *
coop_qget (q)
coop_q_t *q;
#endif
{
coop_t *t;
t = q->t.next;
q->t.next = t->next;
if (t->next == &q->t) {
if (t == &q->t) { /* If it was already empty .. */
return (NULL); /* .. say so. */
}
q->tail = &q->t; /* Else now it is empty. */
}
return (t);
}
#ifdef __STDC__
void
coop_qput (coop_q_t *q, coop_t *t)
#else
void
coop_qput (q, t)
coop_q_t *q;
coop_t *t;
#endif
{
q->tail->next = t;
t->next = &q->t;
q->tail = t;
}
#ifdef __STDC__
static void
coop_all_qput (coop_q_t *q, coop_t *t)
#else
static void
coop_all_qput (q, t)
coop_q_t *q;
coop_t *t;
#endif
{
if (q->t.all_next)
q->t.all_next->all_prev = t;
t->all_prev = NULL;
t->all_next = q->t.all_next;
q->t.all_next = t;
}
#ifdef __STDC__
static void
coop_all_qremove (coop_q_t *q, coop_t *t)
#else
static void
coop_all_qremove (q, t)
coop_q_t *q;
coop_t *t;
#endif
{
if (t->all_prev)
t->all_prev->all_next = t->all_next;
else
q->t.all_next = t->all_next;
if (t->all_next)
t->all_next->all_prev = t->all_prev;
}
/* Thread routines. */
coop_q_t coop_global_runq; /* A queue of runable threads. */
coop_q_t coop_global_sleepq; /* A queue of sleeping threads. */
coop_q_t coop_tmp_queue; /* A temp working queue */
coop_q_t coop_global_allq; /* A queue of all threads. */
static coop_t coop_global_main; /* Thread for the process. */
coop_t *coop_global_curr; /* Currently-executing thread. */
static void *coop_starthelp (qt_t *old, void *ignore0, void *ignore1);
static void coop_only (void *pu, void *pt, qt_userf_t *f);
static void *coop_aborthelp (qt_t *sp, void *old, void *null);
static void *coop_yieldhelp (qt_t *sp, void *old, void *blockq);
#ifdef __STDC__
void
coop_init()
#else
void
coop_init()
#endif
{
coop_qinit (&coop_global_runq);
coop_qinit (&coop_global_sleepq);
coop_qinit (&coop_tmp_queue);
coop_qinit (&coop_global_allq);
coop_global_curr = &coop_global_main;
}
/* Return the next runnable thread. If no threads are currently runnable,
and there are sleeping threads - wait until one wakes up. Otherwise,
return NULL. */
#ifndef GUILE_ISELECT
#ifdef __STDC__
coop_t *
coop_next_runnable_thread()
#else
coop_t *
coop_next_runnable_thread()
#endif
{
int sleepers;
coop_t *t;
time_t now;
do {
sleepers = 0;
now = time(NULL);
/* Check the sleeping queue */
while ((t = coop_qget(&coop_global_sleepq)) != NULL)
{
sleepers++;
if (t->wakeup_time <= now)
coop_qput(&coop_global_runq, t);
else
coop_qput(&coop_tmp_queue, t);
}
while ((t = coop_qget(&coop_tmp_queue)) != NULL)
coop_qput(&coop_global_sleepq, t);
t = coop_qget (&coop_global_runq);
} while ((t == NULL) && (sleepers > 0));
return t;
}
#endif
#ifdef __STDC__
void
coop_start()
#else
void
coop_start()
#endif
{
coop_t *next;
while ((next = coop_qget (&coop_global_runq)) != NULL) {
coop_global_curr = next;
QT_BLOCK (coop_starthelp, 0, 0, next->sp);
}
}
#ifdef __STDC__
static void *
coop_starthelp (qt_t *old, void *ignore0, void *ignore1)
#else
static void *
coop_starthelp (old, ignore0, ignore1)
qt_t *old;
void *ignore0;
void *ignore1;
#endif
{
coop_global_main.sp = old;
coop_global_main.joining = NULL;
coop_qput (&coop_global_runq, &coop_global_main);
return NULL; /* not used, but keeps compiler happy */
}
#ifdef __STDC__
int
coop_mutex_init (coop_m *m)
#else
int
coop_mutex_init (m)
coop_m *m;
#endif
{
m->owner = NULL;
coop_qinit(&(m->waiting));
return 0;
}
#ifdef __STDC__
int
coop_mutex_lock (coop_m *m)
#else
int
coop_mutex_lock ()
coop_m *m;
#endif
{
if (m->owner == NULL)
{
m->owner = coop_global_curr;
}
else
{
coop_t *old, *newthread;
/* Record the current top-of-stack before going to sleep */
coop_global_curr->top = &old;
#ifdef GUILE_ISELECT
newthread = coop_wait_for_runnable_thread();
if (newthread == coop_global_curr)
coop_abort ();
#else
newthread = coop_next_runnable_thread();
#endif
old = coop_global_curr;
coop_global_curr = newthread;
QT_BLOCK (coop_yieldhelp, old, &(m->waiting), newthread->sp);
}
return 0;
}
#ifdef __STDC__
int
coop_mutex_unlock (coop_m *m)
#else
int
coop_mutex_unlock (m)
coop_m *m;
#endif
{
coop_t *old, *newthread;
newthread = coop_qget (&(m->waiting));
if (newthread != NULL)
{
/* Record the current top-of-stack before going to sleep */
coop_global_curr->top = &old;
old = coop_global_curr;
coop_global_curr = newthread;
/* The new thread came into m->waiting through a lock operation.
It now owns this mutex. */
m->owner = coop_global_curr;
QT_BLOCK (coop_yieldhelp, old, &coop_global_runq, newthread->sp);
}
else
{
m->owner = NULL;
}
return 0;
}
#ifdef __STDC__
int
coop_mutex_destroy (coop_m *m)
#else
int
coop_mutex_destroy (m)
coop_m *m;
#endif
{
return 0;
}
#ifdef __STDC__
int
coop_condition_variable_init (coop_c *c)
#else
int
coop_condition_variable_init (c)
coop_c *c;
#endif
{
coop_qinit(&(c->waiting));
return 0;
}
#ifdef __STDC__
int
coop_condition_variable_wait_mutex (coop_c *c, coop_m *m)
#else
int
coop_condition_variable_wait_mutex (c, m)
coop_c *c;
coop_m *m;
#endif
{
coop_t *old, *newthread;
/* coop_mutex_unlock (m); */
newthread = coop_qget (&(m->waiting));
if (newthread != NULL)
{
m->owner = newthread;
}
else
{
m->owner = NULL;
#ifdef GUILE_ISELECT
newthread = coop_wait_for_runnable_thread();
if (newthread == coop_global_curr)
coop_abort ();
#else
newthread = coop_next_runnable_thread();
#endif
}
coop_global_curr->top = &old;
old = coop_global_curr;
coop_global_curr = newthread;
QT_BLOCK (coop_yieldhelp, old, &(c->waiting), newthread->sp);
coop_mutex_lock (m);
return 0;
}
#ifdef __STDC__
int
coop_condition_variable_signal (coop_c *c)
#else
int
coop_condition_variable_signal (c)
coop_c *c;
#endif
{
coop_t *newthread;
while ((newthread = coop_qget (&(c->waiting))) != NULL)
{
coop_qput (&coop_global_runq, newthread);
}
return 0;
}
#ifdef __STDC__
int
coop_condition_variable_destroy (coop_c *c)
#else
int
coop_condition_variable_destroy (c)
coop_c *c;
#endif
{
return 0;
}
#ifdef __STDC__
coop_t *
coop_create (coop_userf_t *f, void *pu)
#else
coop_t *
coop_create (f, pu)
coop_userf_t *f;
void *pu;
#endif
{
coop_t *t;
void *sto;
t = malloc (sizeof(coop_t));
t->data = NULL;
t->sto = malloc (COOP_STKSIZE);
sto = COOP_STKALIGN (t->sto, QT_STKALIGN);
t->sp = QT_SP (sto, COOP_STKSIZE - QT_STKALIGN);
t->base = t->sp;
t->sp = QT_ARGS (t->sp, pu, t, (qt_userf_t *)f, coop_only);
t->joining = NULL;
coop_qput (&coop_global_runq, t);
coop_all_qput (&coop_global_allq, t);
return t;
}
#ifdef __STDC__
static void
coop_only (void *pu, void *pt, qt_userf_t *f)
#else
static void
coop_only (pu. pt, f)
void *pu,
void *pt,
qt_userf_t *f;
#endif
{
coop_global_curr = (coop_t *)pt;
(*(coop_userf_t *)f)(pu);
coop_abort();
/* NOTREACHED */
}
#ifdef __STDC__
void
coop_abort ()
#else
void
coop_abort ()
#endif
{
coop_t *old, *newthread;
/* Wake up any threads that are waiting to join this one */
if (coop_global_curr->joining)
{
while ((newthread = coop_qget ((coop_q_t *)(coop_global_curr->joining)))
!= NULL)
{
coop_qput (&coop_global_runq, newthread);
}
free(coop_global_curr->joining);
}
#ifdef GUILE_ISELECT
scm_I_am_dead = 1;
do {
newthread = coop_wait_for_runnable_thread();
} while (newthread == coop_global_curr);
scm_I_am_dead = 0;
#else
newthread = coop_next_runnable_thread();
#endif
coop_all_qremove(&coop_global_allq, coop_global_curr);
old = coop_global_curr;
coop_global_curr = newthread;
QT_ABORT (coop_aborthelp, old, (void *)NULL, newthread->sp);
}
#ifdef __STDC__
static void *
coop_aborthelp (qt_t *sp, void *old, void *null)
#else
static void *
coop_aborthelp (sp, old, null)
qt_t *sp;
void *old;
void *null;
#endif
{
coop_t *oldthread = (coop_t *) old;
free (oldthread->sto);
/* "old" is freed in scm_threads_thread_die().
Marking old->base NULL indicates that this thread is dead */
oldthread->base = NULL;
return NULL;
}
#ifdef __STDC__
void
coop_join(coop_t *t)
#else
void
coop_join()
coop_t *t;
#endif
{
coop_t *old, *newthread;
/* Check if t is already finished */
if (t->base == NULL)
return;
/* Create a join list if necessary */
if (t->joining == NULL)
{
t->joining = malloc(sizeof(coop_q_t));
coop_qinit((coop_q_t *) t->joining);
}
#ifdef GUILE_ISELECT
newthread = coop_wait_for_runnable_thread();
if (newthread == coop_global_curr)
return;
#else
newthread = coop_next_runnable_thread();
#endif
old = coop_global_curr;
coop_global_curr = newthread;
QT_BLOCK (coop_yieldhelp, old, (coop_q_t *) t->joining, newthread->sp);
}
#ifdef __STDC__
void
coop_yield()
#else
void
coop_yield()
#endif
{
coop_t *old = NULL;
coop_t *newthread;
newthread = coop_next_runnable_thread();
/* There may be no other runnable threads. Return if this is the
case. */
#if GUILE_ISELECT
if (newthread == coop_global_curr)
return;
#else
if (newthread == NULL)
return;
#endif
old = coop_global_curr;
coop_global_curr = newthread;
QT_BLOCK (coop_yieldhelp, old, &coop_global_runq, newthread->sp);
}
#ifdef __STDC__
static void *
coop_yieldhelp (qt_t *sp, void *old, void *blockq)
#else
static void *
coop_yieldhelp (sp, old, blockq)
qt_t *sp;
void *old;
void *blockq;
#endif
{
((coop_t *)old)->sp = sp;
coop_qput ((coop_q_t *)blockq, (coop_t *)old);
return NULL;
}
/* Replacement for the system's sleep() function. Does the right thing
for the process - but not for the system (it busy-waits) */
void *
coop_sleephelp (qt_t *sp, void *old, void *blockq)
{
((coop_t *)old)->sp = sp;
/* old is already on the sleep queue - so there's no need to
do anything extra here */
return NULL;
}
#ifdef GUILE_ISELECT
unsigned long
scm_thread_usleep (unsigned long usec)
{
struct timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = usec;
scm_internal_select (0, NULL, NULL, NULL, &timeout);
return 0; /* Maybe we should calculate actual time slept,
but this is faster... :) */
}
unsigned long
scm_thread_sleep (unsigned long sec)
{
time_t now = time (NULL);
struct timeval timeout;
unsigned long slept;
timeout.tv_sec = sec;
timeout.tv_usec = 0;
scm_internal_select (0, NULL, NULL, NULL, &timeout);
slept = time (NULL) - now;
return slept > sec ? 0 : sec - slept;
}
#else /* GUILE_ISELECT */
unsigned long
scm_thread_sleep (unsigned long s)
{
coop_t *newthread, *old;
time_t now = time (NULL);
coop_global_curr->wakeup_time = now + s;
/* Put the current thread on the sleep queue */
coop_qput (&coop_global_sleepq, coop_global_curr);
newthread = coop_next_runnable_thread();
/* If newthread is the same as the sleeping thread, do nothing */
if (newthread == coop_global_curr)
return s;
old = coop_global_curr;
coop_global_curr = newthread;
QT_BLOCK (coop_sleephelp, old, NULL, newthread->sp);
return s;
}
unsigned long
scm_thread_usleep (unsigned long usec)
{
/* We're so cheap. */
scm_thread_sleep (usec / 1000000);
struct timeval timeout;
return 0; /* Maybe we should calculate actual time slept,
but this is faster... :) */
}
#endif /* GUILE_ISELECT */
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