gstreamer/gst/cothreads.c
Thomas Vander Stichele de6c6bcc5d doc fixes
Original commit message from CVS:
doc fixes
2002-04-19 10:26:56 +00:00

592 lines
13 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>
#include "gst_private.h"
#include "cothreads.h"
#include "gstarch.h"
#include "gstlog.h"
#define STACK_SIZE 0x200000
#define COTHREAD_MAXTHREADS 16
#define COTHREAD_STACKSIZE (STACK_SIZE/COTHREAD_MAXTHREADS)
static void cothread_destroy (cothread_state *thread);
struct _cothread_context
{
cothread_state *threads[COTHREAD_MAXTHREADS];
int nthreads;
int current;
GHashTable *data;
};
static 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_context_init:
*
* Create and initialize a new cothread context
*
* Returns: the new cothread context
*/
cothread_context *
cothread_context_init (void)
{
cothread_context *ctx = (cothread_context *) g_malloc (sizeof (cothread_context));
/* 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);
GST_INFO (GST_CAT_COTHREADS, "initializing cothreads");
if (_cothread_key == (pthread_key_t)-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 *) g_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]->priv = NULL;
ctx->threads[0]->flags = COTHREAD_STARTED;
ctx->threads[0]->sp = (void *) CURRENT_STACK_FRAME;
ctx->threads[0]->pc = 0;
/* initialize the lock */
#ifdef COTHREAD_ATOMIC
atomic_set (&ctx->threads[0]->lock, 0);
#else
ctx->threads[0]->lock = g_mutex_new ();
#endif
GST_INFO (GST_CAT_COTHREADS, "0th thread is %p at sp:%p", ctx->threads[0], ctx->threads[0]->sp);
return ctx;
}
/**
* cothread_context_free:
* @ctx: the cothread context to free
*
* Free the cothread context.
*/
void
cothread_context_free (cothread_context *ctx)
{
gint i;
g_return_if_fail (ctx != NULL);
GST_INFO (GST_CAT_COTHREADS, "free cothread context");
for (i = 0; i < COTHREAD_MAXTHREADS; i++) {
if (ctx->threads[i]) {
cothread_destroy (ctx->threads[i]);
}
}
g_hash_table_destroy (ctx->data);
g_free (ctx);
}
/**
* cothread_create:
* @ctx: the cothread context
*
* Create a new cothread state in the given context
*
* Returns: the new cothread state or NULL on error
*/
cothread_state*
cothread_create (cothread_context *ctx)
{
cothread_state *thread;
void *sp;
guchar *stack_end;
gint slot = 0;
g_return_val_if_fail (ctx != NULL, NULL);
if (ctx->nthreads == COTHREAD_MAXTHREADS) {
/* this is pretty fatal */
g_warning ("cothread_create: attempt to create > COTHREAD_MAXTHREADS\n");
return NULL;
}
/* find a free spot in the stack, note slot 0 has the main thread */
for (slot = 1; slot < ctx->nthreads; slot++) {
if (ctx->threads[slot] == NULL)
break;
else if (ctx->threads[slot]->flags & COTHREAD_DESTROYED &&
slot != ctx->current) {
cothread_destroy (ctx->threads[slot]);
break;
}
}
sp = CURRENT_STACK_FRAME;
/* FIXME this may not be 64bit clean
* could use casts to uintptr_t from inttypes.h
* if only all platforms had inttypes.h
*/
stack_end = (guchar *) ((gulong) sp & ~(STACK_SIZE - 1));
thread = (cothread_state *) (stack_end + ((slot - 1) * COTHREAD_STACKSIZE));
GST_DEBUG (0, "new stack at %p", thread);
if (mmap ((void *) thread, COTHREAD_STACKSIZE,
PROT_READ | PROT_WRITE | PROT_EXEC, MAP_FIXED | MAP_PRIVATE | MAP_ANON, -1, 0) == MAP_FAILED) {
perror ("mmap'ing cothread stack space");
return NULL;
}
thread->ctx = ctx;
thread->threadnum = slot;
thread->flags = 0;
thread->priv = NULL;
thread->sp = ((guchar *) thread + COTHREAD_STACKSIZE);
thread->top_sp = thread->sp; /* for debugging purposes to detect stack overruns */
/* initialize the lock */
#ifdef COTHREAD_ATOMIC
atomic_set (thread->lock, 0);
#else
thread->lock = g_mutex_new ();
#endif
GST_INFO (GST_CAT_COTHREADS, "created cothread #%d in slot %d: %p at sp:%p lock:%p",
ctx->nthreads, slot, thread, thread->sp, thread->lock);
ctx->threads[slot] = thread;
ctx->nthreads++;
return thread;
}
/**
* cothread_free:
* @thread: the cothread state
*
* Free the given cothread state
*/
void
cothread_free (cothread_state *thread)
{
g_return_if_fail (thread != NULL);
GST_INFO (GST_CAT_COTHREADS, "flag cothread %d for destruction", thread->threadnum);
/* we simply flag the cothread for destruction here */
thread->flags |= COTHREAD_DESTROYED;
}
static void
cothread_destroy (cothread_state *thread)
{
cothread_context *ctx;
gint threadnum;
g_return_if_fail (thread != NULL);
threadnum = thread->threadnum;
ctx = thread->ctx;
GST_INFO (GST_CAT_COTHREADS, "destroy cothread %d %p %d", threadnum, thread, ctx->current);
/* we have to unlock here because we might be switched out with the lock held */
cothread_unlock (thread);
#ifndef COTHREAD_ATOMIC
g_mutex_free (thread->lock);
#endif
if (threadnum == 0) {
g_free (thread);
}
else {
/* this doesn't seem to work very well */
/* munmap ((void *) thread, COTHREAD_STACKSIZE); */
}
ctx->threads[threadnum] = NULL;
ctx->nthreads--;
}
/**
* 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 = (void *) func;
}
/**
* cothread_stop:
* @thread: the cothread to stop
*
* Stop the cothread and reset the stack and program counter.
*/
void
cothread_stop (cothread_state * thread)
{
thread->flags &= ~COTHREAD_STARTED;
thread->pc = 0;
thread->sp = thread->top_sp;
}
/**
* cothread_main:
* @ctx: cothread context to find main thread of
*
* Get the main thread.
*
* Returns: the #cothread_state of the main (0th) thread
*/
cothread_state *
cothread_main (cothread_context * ctx)
{
GST_DEBUG (0, "returning %p, the 0th cothread", ctx->threads[0]);
return ctx->threads[0];
}
/**
* cothread_current_main:
*
* Get the main thread in the current pthread.
*
* Returns: the #cothread_state of the main (0th) thread in the current pthread
*/
cothread_state *
cothread_current_main (void)
{
cothread_context *ctx = pthread_getspecific (_cothread_key);
return ctx->threads[0];
}
/**
* cothread_current:
*
* Get the currenttly executing cothread
*
* Returns: the #cothread_state of the current cothread
*/
cothread_state *
cothread_current (void)
{
cothread_context *ctx = pthread_getspecific (_cothread_key);
return ctx->threads[ctx->current];
}
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;
/*
* ifdef COTHREAD_ATOMIC
* do something here to lock
* else
* g_mutex_lock(thread->lock);
* endif
*/
while (TRUE) {
thread->func (thread->argc, thread->argv);
/* we do this to avoid ever returning, we just switch to 0th thread */
cothread_switch (cothread_main (ctx));
}
GST_DEBUG_LEAVE ("");
}
/**
* cothread_getcurrent:
*
* Get the current cothread id
*
* Returns: the current cothread id
*/
int cothread_getcurrent (void) __attribute__ ((no_instrument_function));
int
cothread_getcurrent (void)
{
cothread_context *ctx = pthread_getspecific (_cothread_key);
if (!ctx)
return -1;
return ctx->current;
}
/**
* cothread_set_private:
* @thread: the cothread state
* @data: the data
*
* set private data for the cothread.
*/
void
cothread_set_private (cothread_state *thread, gpointer data)
{
thread->priv = data;
}
/**
* cothread_context_set_data:
* @thread: the cothread state
* @key: a key for the data
* @data: the data
*
* adds data to a cothread
*/
void
cothread_context_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_private:
* @thread: the cothread state
*
* get the private data from the cothread
*
* Returns: the private data of the cothread
*/
gpointer
cothread_get_private (cothread_state *thread)
{
return thread->priv;
}
/**
* cothread_context_get_data:
* @thread: the cothread state
* @key: a key for the data
*
* get data from the cothread
*
* Returns: the data associated with the key
*/
gpointer
cothread_context_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;
/* unlock the current thread, we're out of that context now */
#ifdef COTHREAD_ATOMIC
/* do something to unlock the cothread */
#else
g_mutex_unlock (current->lock);
#endif
/* lock the next cothread before we even switch to it */
#ifdef COTHREAD_ATOMIC
/* do something to lock the cothread */
#else
g_mutex_lock (thread->lock);
#endif
/* find the number of the thread to switch to */
GST_INFO (GST_CAT_COTHREAD_SWITCH, "switching from cothread #%d to cothread #%d",
ctx->current, thread->threadnum);
ctx->current = thread->threadnum;
/* save the current stack pointer, frame pointer, and pc */
#ifdef GST_ARCH_PRESETJMP
GST_ARCH_PRESETJMP ();
#endif
enter = setjmp (current->jmp);
if (enter != 0) {
GST_DEBUG (0, "enter thread #%d %d %p<->%p (%d)", current->threadnum, enter,
current->sp, current->top_sp, (char*)current->top_sp - (char*)current->sp);
return;
}
GST_DEBUG (0, "exit thread #%d %d %p<->%p (%d)", current->threadnum, enter,
current->sp, current->top_sp, (char*)current->top_sp - (char*)current->sp);
enter = 1;
if (current->flags & COTHREAD_DESTROYED)
cothread_destroy (current);
GST_DEBUG (0, "set stack to %p", thread->sp);
/* restore stack pointer and other stuff of new cothread */
if (thread->flags & COTHREAD_STARTED) {
GST_DEBUG (0, "in thread ");
/* switch to it */
longjmp (thread->jmp, 1);
}
else {
GST_ARCH_SETUP_STACK ((char*)thread->sp);
GST_ARCH_SET_SP (thread->sp);
/* start it */
GST_ARCH_CALL (cothread_stub);
GST_DEBUG (0, "exit thread ");
ctx->current = 0;
}
return;
#ifdef COTHREAD_PARANOID
nothread:
g_print ("cothread: can't switch to NULL cothread!\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;
}
/**
* cothread_lock:
* @thread: cothread state to lock
*
* Locks the cothread state.
*/
void
cothread_lock (cothread_state * thread)
{
#ifdef COTHREAD_ATOMIC
/* do something to lock the cothread */
#else
if (thread->lock)
g_mutex_lock (thread->lock);
#endif
}
/**
* cothread_trylock:
* @thread: cothread state to try to lock
*
* Try to lock the cothread state
*
* Returns: TRUE if the cothread could be locked.
*/
gboolean
cothread_trylock (cothread_state * thread)
{
#ifdef COTHREAD_ATOMIC
/* do something to try to lock the cothread */
#else
if (thread->lock)
return g_mutex_trylock (thread->lock);
else
return FALSE;
#endif
}
/**
* cothread_unlock:
* @thread: cothread state to unlock
*
* Unlock the cothread state.
*/
void
cothread_unlock (cothread_state * thread)
{
#ifdef COTHREAD_ATOMIC
/* do something to unlock the cothread */
#else
if (thread->lock)
g_mutex_unlock (thread->lock);
#endif
}