gstreamer/gst/cothreads.c
Erik Walthinsen f12fae5c3d fixed missing comment noticed by David Lehn
Original commit message from CVS:
fixed missing comment noticed by David Lehn
2001-01-05 00:28:09 +00:00

308 lines
7.8 KiB
C

/* GStreamer
* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
* 2000 Wim Taymans <wtay@chello.be>
*
* cothreads.c: Cothreading routines
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <setjmp.h>
#include <unistd.h>
#include <sys/mman.h>
/* we make too much noise for normal debugging... */
#define GST_DEBUG_FORCE_DISABLE
#include "gst_private.h"
#include "cothreads.h"
#include "gstarch.h"
pthread_key_t _cothread_key = -1;
/* Disablig this define allows you to shut off a few checks in
* cothread_switch. This likely will speed things up fractionally */
#define COTHREAD_PARANOID
/**
* cothread_init:
*
* Create and initialize a new cothread context
*
* Returns: the new cothread context
*/
cothread_context*
cothread_init (void)
{
cothread_context *ctx = (cothread_context *)malloc(sizeof(cothread_context));
GST_INFO (GST_CAT_COTHREADS,"initializing cothreads");
if (_cothread_key == -1) {
if (pthread_key_create (&_cothread_key,NULL) != 0) {
perror ("pthread_key_create");
return NULL;
}
}
pthread_setspecific (_cothread_key,ctx);
memset (ctx->threads,0,sizeof(ctx->threads));
ctx->threads[0] = (cothread_state *)malloc(sizeof(cothread_state));
ctx->threads[0]->ctx = ctx;
ctx->threads[0]->threadnum = 0;
ctx->threads[0]->func = NULL;
ctx->threads[0]->argc = 0;
ctx->threads[0]->argv = NULL;
ctx->threads[0]->flags = COTHREAD_STARTED;
ctx->threads[0]->sp = (int *)CURRENT_STACK_FRAME;
ctx->threads[0]->pc = 0;
GST_INFO (GST_CAT_COTHREADS,"0th thread is %p at sp:%p",ctx->threads[0], ctx->threads[0]->sp);
// we consider the initiating process to be cothread 0
ctx->nthreads = 1;
ctx->current = 0;
ctx->data = g_hash_table_new(g_str_hash, g_str_equal);
return ctx;
}
/**
* cothread_create:
* @ctx: the cothread context
*
* Create a new cothread state in the given context
*
* Returns: the new cothread state
*/
cothread_state*
cothread_create (cothread_context *ctx)
{
cothread_state *s;
GST_DEBUG (0,"pthread_self() %ld\n",pthread_self());
//if (0) {
if (pthread_self() == 0) {
s = (cothread_state *)malloc(sizeof(int) * COTHREAD_STACKSIZE);
GST_DEBUG (0,"new stack (case 1) at %p\n",s);
} else {
char *sp = CURRENT_STACK_FRAME;
unsigned long *stack_end = (unsigned long *)((unsigned long)sp &
~(STACK_SIZE - 1));
s = (cothread_state *)(stack_end + ((ctx->nthreads - 1) *
COTHREAD_STACKSIZE));
GST_DEBUG (0,"new stack (case 2) at %p\n",s);
if (mmap((char *)s,COTHREAD_STACKSIZE*(sizeof(int)),
PROT_READ|PROT_WRITE|PROT_EXEC,MAP_FIXED|MAP_PRIVATE|MAP_ANONYMOUS,
-1,0) < 0) {
perror("mmap'ing cothread stack space");
return NULL;
}
}
s->ctx = ctx;
s->threadnum = ctx->nthreads;
s->flags = 0;
s->sp = ((int *)s + COTHREAD_STACKSIZE);
s->top_sp = s->sp;
GST_INFO (GST_CAT_COTHREADS,"created cothread #%d: %p at sp:%p", ctx->nthreads, s, s->sp);
ctx->threads[ctx->nthreads++] = s;
return s;
}
/**
* cothread_setfunc:
* @thread: the cothread state
* @func: the function to call
* @argc: argument count for the cothread function
* @argv: arguments for the cothread function
*
* Set the cothread function
*/
void
cothread_setfunc (cothread_state *thread,
cothread_func func,
int argc,
char **argv)
{
thread->func = func;
thread->argc = argc;
thread->argv = argv;
thread->pc = (int *)func;
}
/**
* cothread_main:
* @ctx: cothread context to find main thread of
*
* Returns: the #cothread_state of the main (0th) thread
*/
static cothread_state*
cothread_main(cothread_context *ctx)
{
GST_DEBUG (0,"returning %p, the 0th cothread\n",ctx->threads[0]);
return ctx->threads[0];
}
static void
cothread_stub (void)
{
cothread_context *ctx = pthread_getspecific(_cothread_key);
register cothread_state *thread = ctx->threads[ctx->current];
GST_DEBUG_ENTER("");
thread->flags |= COTHREAD_STARTED;
if (thread->func)
thread->func(thread->argc,thread->argv);
thread->flags &= ~COTHREAD_STARTED;
thread->pc = 0;
thread->sp = thread->top_sp;
GST_DEBUG_LEAVE("");
// printf("uh, yeah, we shouldn't be here, but we should deal anyway\n");
}
/**
* cothread_getcurrent:
*
* Returns: the current cothread id
*/
int cothread_getcurrent(void) {
cothread_context *ctx = pthread_getspecific(_cothread_key);
if (!ctx) return -1;
return ctx->current;
}
/**
* cothread_set_data:
* @thread: the cothread state
* @key: a key for the data
* @data: the data
*
* adds data to a cothread
*/
void
cothread_set_data (cothread_state *thread,
gchar *key,
gpointer data)
{
cothread_context *ctx = pthread_getspecific(_cothread_key);
g_hash_table_insert(ctx->data, key, data);
}
/**
* cothread_get_data:
* @thread: the cothread state
* @key: a key for the data
*
* get data from the cothread
*
* Returns: the data assiciated with the key
*/
gpointer
cothread_get_data (cothread_state *thread,
gchar *key)
{
cothread_context *ctx = pthread_getspecific(_cothread_key);
return g_hash_table_lookup(ctx->data, key);
}
/**
* cothread_switch:
* @thread: cothread state to switch to
*
* Switches to the given cothread state
*/
void
cothread_switch (cothread_state *thread)
{
cothread_context *ctx;
cothread_state *current;
int enter;
#ifdef COTHREAD_PARANOID
if (thread == NULL) goto nothread;
#endif
ctx = thread->ctx;
#ifdef COTHREAD_PARANOID
if (ctx == NULL) goto nocontext;
#endif
current = ctx->threads[ctx->current];
#ifdef COTHREAD_PARANOID
if (current == NULL) goto nocurrent;
#endif
if (current == thread) goto selfswitch;
// find the number of the thread to switch to
ctx->current = thread->threadnum;
GST_INFO (GST_CAT_COTHREAD_SWITCH,"switching to thread #%d",ctx->current);
/* save the current stack pointer, frame pointer, and pc */
GET_SP(current->sp);
enter = setjmp(current->jmp);
if (enter != 0) {
GST_DEBUG (0,"enter thread #%d %d %p<->%p (%d)\n",current->threadnum, enter,
current->sp, current->top_sp, current->top_sp-current->sp);
return;
}
GST_DEBUG (0,"exit thread #%d %d %p<->%p (%d)\n",current->threadnum, enter,
current->sp, current->top_sp, current->top_sp-current->sp);
enter = 1;
GST_DEBUG (0,"set stack to %p\n", thread->sp);
/* restore stack pointer and other stuff of new cothread */
if (thread->flags & COTHREAD_STARTED) {
GST_DEBUG (0,"in thread \n");
SET_SP(thread->sp);
// switch to it
longjmp(thread->jmp,1);
} else {
SETUP_STACK(thread->sp);
SET_SP(thread->sp);
// start it
cothread_stub();
GST_DEBUG (0,"exit thread \n");
ctx->current = 0;
}
return;
#ifdef COTHREAD_PARANOID
nothread:
g_print("cothread: there's no thread, strange...\n");
return;
nocontext:
g_print("cothread: there's no context, help!\n");
exit(2);
nocurrent:
g_print("cothread: there's no current thread, help!\n");
exit(2);
#endif /* COTHREAD_PARANOID */
selfswitch:
g_print("cothread: trying to switch to same thread, legal but not necessary\n");
return;
}