gstreamer/gst/cothreads.c
Thomas Vander Stichele 76d31f5af1 readable cleanups
Original commit message from CVS:
readable cleanups
2002-08-13 14:11:33 +00:00

664 lines
16 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 <errno.h>
#include <sys/mman.h>
#include "gst_private.h"
#include "cothreads.h"
#include "gstarch.h"
#include "gstlog.h"
#include "gstutils.h"
/* older glibc's have MAP_ANON instead of MAP_ANONYMOUS */
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
#define STACK_SIZE 0x200000
#define COTHREAD_MAGIC_NUMBER 0xabcdef
#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;
/* Disabling 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_malloc0 (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;
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;
void *mmaped = 0;
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;
}
}
GST_DEBUG(GST_CAT_COTHREADS, "Found free cothread slot %d", slot);
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 (GST_CAT_COTHREADS,
"mmap cothread slot stack from %p to %p (size 0x%lx)",
thread, thread + COTHREAD_STACKSIZE,
(long) COTHREAD_STACKSIZE);
GST_DEBUG (GST_CAT_COTHREADS, "going into mmap");
/* the mmap is used to reserve part of the stack
* ie. we state explicitly that we are going to use it */
mmaped = mmap ((void *) thread, COTHREAD_STACKSIZE,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
GST_DEBUG (GST_CAT_COTHREADS, "coming out of mmap");
if (mmaped == MAP_FAILED) {
perror ("mmap'ing cothread stack space");
return NULL;
}
if (mmaped != thread) {
g_warning ("could not mmap requested memory");
return NULL;
}
thread->magic_number = COTHREAD_MAGIC_NUMBER;
GST_DEBUG (GST_CAT_COTHREADS, "create cothread %d with magic number 0x%x",
slot, thread->magic_number);
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 */
GST_INFO (GST_CAT_COTHREADS,
"created cothread #%d in slot %d: %p at sp:%p",
ctx->nthreads, slot, thread, thread->sp);
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);
if (threadnum == 0)
{
GST_INFO (GST_CAT_COTHREADS,
"trying to destroy cothread 0 with %d cothreads left",
ctx->nthreads);
if (ctx->nthreads > 1)
{
/* we're trying to destroy cothread 0 when there are still cothreads
* active, so kill those first */
int i;
for (i = 1; i < COTHREAD_MAXTHREADS; ++i)
{
if (ctx->threads[i] != NULL)
{
cothread_destroy (ctx->threads[i]);
GST_INFO (GST_CAT_COTHREADS,
"destroyed cothread %d, %d cothreads left\n",
i, ctx->nthreads);
}
}
}
g_assert (ctx->nthreads == 1);
g_free (thread);
}
else {
/* int res;
* Replaced with version below until cothreads issues solved */
int res = 0;
/* doing cleanups of the cothread create */
GST_DEBUG (GST_CAT_COTHREADS, "destroy cothread %d with magic number 0x%x",
threadnum, thread->magic_number);
g_assert (thread->magic_number == COTHREAD_MAGIC_NUMBER);
g_assert (thread->priv == NULL);
GST_DEBUG (GST_CAT_COTHREADS,
"munmap cothread slot stack from %p to %p (size 0x%lx)",
thread, thread + COTHREAD_STACKSIZE,
(long) COTHREAD_STACKSIZE);
/* res = munmap (thread, COTHREAD_STACKSIZE);
* Commented out waiting for resolution for cothread issue */
if (res != 0)
{
switch (res)
{
case EINVAL:
g_warning ("munmap doesn't like start %p or length %d\n",
thread, COTHREAD_STACKSIZE);
break;
default:
g_warning ("Thomas was too lazy to check for all errors, so I can't tell you what is wrong.\n");
break;
}
}
}
GST_DEBUG (GST_CAT_COTHREADS, "munmap done\n");
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 (GST_CAT_COTHREADS, "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;
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);
}
/**
* cothreads_stackquery:
* @stack: Will be set to point to the allocated stack location
* @stacksize: Will be set to the size of the allocated stack
*
* Returns: #TRUE on success, #FALSE otherwise.
*/
gboolean
cothread_stackquery (void **stack, glong* stacksize)
{
/* wingo says: use posix_memalign to allocate a 2M-aligned, 2M stack */
#ifdef HAVE_POSIX_MEMALIGN
int retval = posix_memalign (stack, STACK_SIZE, STACK_SIZE);
if (retval != 0)
{
g_warning ("Could not posix_memalign stack !\n");
if (retval == EINVAL)
g_warning ("The alignment parameter %d was not a power of two !\n",
STACK_SIZE);
if (retval == ENOMEM)
g_warning ("Insufficient memory to allocate the request of %d !\n",
STACK_SIZE);
*stacksize = 0;
return FALSE;
}
GST_DEBUG (GST_CAT_THREAD, "have posix_memalign at %p of size %d",
(void *) *stack, STACK_SIZE);
#else
if ((*stack = valloc (STACK_SIZE)) != 0)
{
g_warning ("Could not valloc stack !\n");
return FALSE;
}
GST_DEBUG (GST_CAT_THREAD, "have valloc at %p of size %d",
(void *) *stack, STACK_SIZE);
#endif
GST_DEBUG (GST_CAT_COTHREADS,
"Got new cothread stack from %p to %p (size %ld)",
*stack, *stack + STACK_SIZE - 1, (long) STACK_SIZE);
*stacksize = STACK_SIZE;
return TRUE;
}
/**
* 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 */
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 (GST_CAT_COTHREADS,
"enter thread #%d %d %p<->%p (%d) %p",
current->threadnum, enter, current->sp, current->top_sp,
(char*) current->top_sp - (char*) current->sp, current->jmp);
return;
}
GST_DEBUG (GST_CAT_COTHREADS, "exit thread #%d %d %p<->%p (%d) %p",
current->threadnum, enter, current->sp, current->top_sp,
(char*) current->top_sp - (char*) current->sp, current->jmp);
enter = 1;
if (current->flags & COTHREAD_DESTROYED) {
cothread_destroy (current);
}
GST_DEBUG (GST_CAT_COTHREADS, "set stack to %p", thread->sp);
/* restore stack pointer and other stuff of new cothread */
if (thread->flags & COTHREAD_STARTED) {
GST_DEBUG (GST_CAT_COTHREADS, "in thread %p", thread->jmp);
/* 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 (GST_CAT_COTHREADS, "exit thread ");
ctx->current = 0;
}
return;
#ifdef COTHREAD_PARANOID
nothread:
g_warning ("cothread: can't switch to NULL cothread!\n");
return;
nocontext:
g_warning ("cothread: there's no context, help!\n");
exit (2);
nocurrent:
g_warning ("cothread: there's no current thread, help!\n");
exit (2);
#endif /* COTHREAD_PARANOID */
selfswitch:
g_warning ("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)
{
}
/**
* 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)
{
return TRUE;
}
/**
* cothread_unlock:
* @thread: cothread state to unlock
*
* Unlock the cothread state.
*/
void
cothread_unlock (cothread_state * thread)
{
}