int s_poll_wait(s_poll_set *fds, int timeout) {
CONTEXT *ctx; /* current context */
static CONTEXT *to_free=NULL; /* delayed memory deallocation */
/* remove the current context from ready queue */
ctx=ready_head;
ready_head=ready_head->next;
if(!ready_head) /* the queue is empty */
ready_tail=NULL;
if(fds) { /* something to wait for -> swap the context */
ctx->fds=fds; /* set file descriptors to wait for */
ctx->finish=timeout<0 ? -1 : time(NULL)+timeout;
/* move (append) the current context to the waiting queue */
ctx->next=NULL;
if(waiting_tail)
waiting_tail->next=ctx;
waiting_tail=ctx;
if(!waiting_head)
waiting_head=ctx;
while(!ready_head) /* no context ready */
scan_waiting_queue();
if(ctx->id!=ready_head->id) {
s_log(LOG_DEBUG, "Context swap: %ld -> %ld",
ctx->id, ready_head->id);
swapcontext(&ctx->ctx, &ready_head->ctx);
s_log(LOG_DEBUG, "Current context: %ld", ready_head->id);
if(to_free) {
s_log(LOG_DEBUG, "Releasing context %ld", to_free->id);
free(to_free);
to_free=NULL;
}
}
return ready_head->ready;
} else { /* nothing to wait for -> drop the context */
/* it's illegal to deallocate the stack of the current context */
if(to_free) {
s_log(LOG_DEBUG, "Releasing context %ld", to_free->id);
free(to_free);
}
to_free=ctx;
while(!ready_head) /* no context ready */
scan_waiting_queue();
s_log(LOG_DEBUG, "Context set: %ld (dropped) -> %ld",
ctx->id, ready_head->id);
setcontext(&ready_head->ctx);
ioerror("setcontext"); /* should not ever happen */
return 0;
}
}
int s_poll_wait(s_poll_set *fds, int sec, int msec) {
CONTEXT *context; /* current context */
static CONTEXT *to_free=NULL; /* delayed memory deallocation */
/* FIXME: msec parameter is currently ignored with UCONTEXT threads */
(void)msec; /* skip warning about unused parameter */
/* remove the current context from ready queue */
context=ready_head;
ready_head=ready_head->next;
if(!ready_head) /* the queue is empty */
ready_tail=NULL;
/* it it safe to s_log() after new ready_head is set */
/* it's illegal to deallocate the stack of the current context */
if(to_free) { /* a delayed deallocation is scheduled */
#ifdef DEBUG_UCONTEXT
s_log(LOG_DEBUG, "Releasing context %ld", to_free->id);
#endif
str_free(to_free->stack);
str_free(to_free);
to_free=NULL;
}
/* manage the current thread */
if(fds) { /* something to wait for -> swap the context */
context->fds=fds; /* set file descriptors to wait for */
context->finish=sec<0 ? -1 : time(NULL)+sec;
/* append the current context to the waiting queue */
context->next=NULL;
if(waiting_tail)
waiting_tail->next=context;
waiting_tail=context;
if(!waiting_head)
waiting_head=context;
} else { /* nothing to wait for -> drop the context */
to_free=context; /* schedule for delayed deallocation */
}
while(!ready_head) /* wait until there is a thread to switch to */
scan_waiting_queue();
/* switch threads */
if(fds) { /* swap the current context */
if(context->id!=ready_head->id) {
#ifdef DEBUG_UCONTEXT
s_log(LOG_DEBUG, "Context swap: %ld -> %ld",
context->id, ready_head->id);
#endif
swapcontext(&context->context, &ready_head->context);
#ifdef DEBUG_UCONTEXT
s_log(LOG_DEBUG, "Current context: %ld", ready_head->id);
#endif
}
return ready_head->ready;
} else { /* drop the current context */
#ifdef DEBUG_UCONTEXT
s_log(LOG_DEBUG, "Context set: %ld (dropped) -> %ld",
context->id, ready_head->id);
#endif
setcontext(&ready_head->context);
ioerror("setcontext"); /* should not ever happen */
return 0;
}
}
