gstreamer/gst/cothreads.c
David Schleef 774edda66b Add assertion to make sure that we're in the thread containing the cothread we're trying to switch to.
Original commit message from CVS:
Add assertion to make sure that we're in the thread containing the
cothread we're trying to switch to.
2002-11-21 00:54:32 +00:00

743 lines
19 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 <glib.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 *cothreads[COTHREAD_MAXTHREADS]; /* array of cothread states */
int ncothreads;
int current;
unsigned long stack_top;
GHashTable *data;
};
/* this _cothread_ctx_key is used as a GThread key to the thread's context
* a GThread key is a "pointer" to memory space that is/can be different
* (ie. private) for each thread. The key itself is shared among threads,
* so it only needs to be initialized once.
*/
static GPrivate *_cothread_ctx_key;
/* 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;
void *sp;
/* if there already is a cotread context for this thread,
* just return it */
ctx = g_private_get (_cothread_ctx_key);
if (ctx) {
GST_INFO (GST_CAT_COTHREADS,
"returning private _cothread_ctx_key %p", ctx);
return ctx;
}
/*
* initalize the whole of the cothreads context
*/
ctx = (cothread_context *) g_malloc (sizeof (cothread_context));
/* we consider the initiating process to be cothread 0 */
ctx->ncothreads = 1;
ctx->current = 0;
ctx->data = g_hash_table_new (g_str_hash, g_str_equal);
GST_INFO (GST_CAT_COTHREADS, "initializing cothreads");
/* initialize the cothread key (for GThread space) if not done yet */
/* FIXME this should be done in cothread_init() */
if (_cothread_ctx_key == NULL) {
_cothread_ctx_key = g_private_new (NULL);
g_assert (_cothread_ctx_key);
}
/* set this thread's context pointer */
GST_INFO (GST_CAT_COTHREADS, "setting private _cothread_ctx_key to %p",
ctx);
g_private_set (_cothread_ctx_key, ctx);
/* clear the cothread data */
memset (ctx->cothreads, 0, sizeof (ctx->cothreads));
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_top is the address of the first byte past our stack segment. */
/* FIXME: an assumption is made that the stack segment is STACK_SIZE
* aligned. */
ctx->stack_top = ((gulong) sp | (STACK_SIZE - 1)) + 1;
GST_DEBUG (GST_CAT_COTHREADS, "stack top is 0x%08lx", ctx->stack_top);
/*
* initialize the 0th cothread
*/
ctx->cothreads[0] = (cothread_state *) g_malloc0 (sizeof (cothread_state));
ctx->cothreads[0]->ctx = ctx;
ctx->cothreads[0]->cothreadnum = 0;
ctx->cothreads[0]->func = NULL;
ctx->cothreads[0]->argc = 0;
ctx->cothreads[0]->argv = NULL;
ctx->cothreads[0]->priv = NULL;
ctx->cothreads[0]->flags = COTHREAD_STARTED;
ctx->cothreads[0]->sp = (void *) CURRENT_STACK_FRAME;
ctx->cothreads[0]->top_sp = ctx->cothreads[0]->sp;
ctx->cothreads[0]->pc = 0;
GST_INFO (GST_CAT_COTHREADS, "0th cothread is %p at sp:%p",
ctx->cothreads[0], ctx->cothreads[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->cothreads[i]) {
cothread_destroy (ctx->cothreads[i]);
}
}
g_hash_table_destroy (ctx->data);
/* make sure we free the private key for cothread context */
g_private_set (_cothread_ctx_key, NULL);
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 *cothread;
void *mmaped = 0;
gint slot = 0;
unsigned long page_size;
g_return_val_if_fail (ctx != NULL, NULL);
if (ctx->ncothreads == 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->ncothreads; slot++) {
if (ctx->cothreads[slot] == NULL)
break;
else if (ctx->cothreads[slot]->flags & COTHREAD_DESTROYED &&
slot != ctx->current) {
cothread_destroy (ctx->cothreads[slot]);
break;
}
}
GST_DEBUG (GST_CAT_COTHREADS, "Found free cothread slot %d", slot);
/* cothread stack space of the thread is mapped in reverse, with cothread 0
* stack space at the top */
cothread = (cothread_state *) (ctx->stack_top - (slot + 1) * COTHREAD_STACKSIZE);
GST_DEBUG (GST_CAT_COTHREADS, "cothread pointer is %p", cothread);
#if 0
/* This tests to see whether or not we can grow down the stack */
{
unsigned long ptr;
for(ptr=ctx->stack_top - 4096; ptr > (unsigned long)cothread; ptr -= 4096){
GST_DEBUG (GST_CAT_COTHREADS, "touching location 0x%08lx", ptr);
*(volatile unsigned int *)ptr = *(volatile unsigned int *)ptr;
GST_DEBUG (GST_CAT_COTHREADS, "ok (0x%08x)", *(unsigned int *)ptr);
}
}
#endif
/* The mmap is necessary on Linux/i386, and possibly others, since the
* kernel is picky about when we can expand our stack. */
GST_DEBUG (GST_CAT_COTHREADS, "mmaping %p, size 0x%08x", cothread,
COTHREAD_STACKSIZE);
mmaped = mmap ((void *) cothread, 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 != cothread) {
g_warning ("could not mmap requested memory for cothread");
return NULL;
}
#ifdef _SC_PAGESIZE
page_size = sysconf(_SC_PAGESIZE);
#else
page_size = getpagesize();
#endif
/* Unmap a guard page. This decreases our stack size by 8 kB (for
* 4 kB pages) and also wastes almost 4 kB for the cothreads
* structure */
munmap((void *)cothread + page_size, page_size);
cothread->magic_number = COTHREAD_MAGIC_NUMBER;
GST_DEBUG (GST_CAT_COTHREADS, "create cothread %d with magic number 0x%x",
slot, cothread->magic_number);
cothread->ctx = ctx;
cothread->cothreadnum = slot;
cothread->flags = 0;
cothread->priv = NULL;
cothread->sp = ((guchar *) cothread + COTHREAD_STACKSIZE);
cothread->sp -= 16; /* necessary for PowerPC */
cothread->top_sp = cothread->sp; /* for debugging purposes
to detect stack overruns */
GST_INFO (GST_CAT_COTHREADS,
"created cothread #%d in slot %d: %p at sp:%p",
ctx->ncothreads, slot, cothread, cothread->sp);
ctx->cothreads[slot] = cothread;
ctx->ncothreads++;
return cothread;
}
/**
* cothread_free:
* @cothread: the cothread state
*
* Free the given cothread state
*/
void
cothread_free (cothread_state *cothread)
{
g_return_if_fail (cothread != NULL);
GST_INFO (GST_CAT_COTHREADS, "flag cothread %d for destruction",
cothread->cothreadnum);
/* we simply flag the cothread for destruction here */
cothread->flags |= COTHREAD_DESTROYED;
}
static void
cothread_destroy (cothread_state *cothread)
{
cothread_context *ctx;
gint cothreadnum;
g_return_if_fail (cothread != NULL);
cothreadnum = cothread->cothreadnum;
ctx = cothread->ctx;
GST_INFO (GST_CAT_COTHREADS, "destroy cothread %d %p %d",
cothreadnum, cothread, ctx->current);
/* we have to unlock here because we might be switched out
* with the lock held */
cothread_unlock (cothread);
if (cothreadnum == 0)
{
GST_INFO (GST_CAT_COTHREADS,
"trying to destroy cothread 0 with %d cothreads left",
ctx->ncothreads);
if (ctx->ncothreads > 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->cothreads[i] != NULL)
{
cothread_destroy (ctx->cothreads[i]);
GST_INFO (GST_CAT_COTHREADS,
"destroyed cothread %d, %d cothreads left",
i, ctx->ncothreads);
}
}
}
g_assert (ctx->ncothreads == 1);
GST_INFO (GST_CAT_COTHREADS, "freeing 0th cothread");
g_free (cothread);
}
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",
cothreadnum, cothread->magic_number);
g_assert (cothread->magic_number == COTHREAD_MAGIC_NUMBER);
g_assert (cothread->priv == NULL);
GST_DEBUG (GST_CAT_COTHREADS,
"munmap cothread slot stack from %p to %p (size 0x%lx)",
cothread, cothread + 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",
cothread, 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");
ctx->cothreads[cothreadnum] = NULL;
ctx->ncothreads--;
}
/**
* 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 cothread of.
*
* Gets the main thread.
*
* Returns: the #cothread_state of the main (0th) cothread.
*/
cothread_state *
cothread_main (cothread_context * ctx)
{
GST_DEBUG (GST_CAT_COTHREADS, "returning %p, the 0th cothread",
ctx->cothreads[0]);
return ctx->cothreads[0];
}
/**
* cothread_current_main:
*
* Get the main thread in the current GThread.
*
* Returns: the #cothread_state of the main (0th) thread in the current GThread
*/
cothread_state *
cothread_current_main (void)
{
cothread_context *ctx = g_private_get (_cothread_ctx_key);
return ctx->cothreads[0];
}
/**
* cothread_current:
*
* Get the currenttly executing cothread
*
* Returns: the #cothread_state of the current cothread
*/
cothread_state *
cothread_current (void)
{
cothread_context *ctx = g_private_get (_cothread_ctx_key);
return ctx->cothreads[ctx->current];
}
static void
cothread_stub (void)
{
cothread_context *ctx = g_private_get (_cothread_ctx_key);
register cothread_state *thread = ctx->cothreads[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 = g_private_get (_cothread_ctx_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 = g_private_get (_cothread_ctx_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 = g_private_get (_cothread_ctx_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)
{
/* use either
* - posix_memalign to allocate a 2M-aligned, 2M stack
* or
* - valloc
*
* memory allocated by either of these two can be freed using free ()
* FIXME: define how the stack grows */
#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_context *current_ctx;
cothread_state *current;
int enter;
#ifdef COTHREAD_PARANOID
if (thread == NULL)
goto nothread;
#endif
ctx = thread->ctx;
/* paranoia check to make sure we're in the right thread */
current_ctx = g_private_get(_cothread_ctx_key);
g_assert (ctx == current_ctx);
#ifdef COTHREAD_PARANOID
if (ctx == NULL)
goto nocontext;
#endif
current = ctx->cothreads[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->cothreadnum);
ctx->current = thread->cothreadnum;
/* 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 cothread #%d %d %p<->%p (%d) %p",
current->cothreadnum, enter, current->sp, current->top_sp,
(char*) current->top_sp - (char*) current->sp, current->jmp);
return;
}
GST_DEBUG (GST_CAT_COTHREADS, "exit cothread #%d %d %p<->%p (%d) %p",
current->cothreadnum, 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)
{
}