Revert "Introduce xcb_wait_for_event_until, for consuming responses in wire-order."

This function was intended to allow libX11 to fix a multi-threaded hang,
but the corresponding libX11 patch caused single-threaded apps to spin
sometimes. Since I've retracted that patch, this patch has no users and
shouldn't go into a release unless/until that changes.

This reverts commit 2415c11dec.

Conflicts:

	src/xcb.h
	src/xcb_in.c

Signed-off-by: Jamey Sharp <jamey@minilop.net>

src/xcb.h

@@ -287,41 +287,6 @@ xcb_generic_event_t *xcb_poll_for_event(xcb_connection_t *c);
  */
 xcb_generic_event_t *xcb_poll_for_queued_event(xcb_connection_t *c);
 
-/**
- * @brief Returns the next event or error that precedes the given request.
- * @param c: The connection to the X server.
- * @param request: The limiting sequence number.
- * @return The next event from the server.
- *
- * Returns the next event or error with a sequence number less than or
- * equal to the given sequence number, or returns NULL if no such event can
- * ever arrive. Blocks until either a suitable event or error arrive, or a
- * response arrives that proves no such event is coming, or an I/O error
- * occurs.
- *
- * After processing a request, the X server sends responses in a specific
- * order. First come any events that the request generated, then any
- * replies for the request, then the error response if there is one. After
- * that, the server may spontaneously send more events with the same
- * sequence number, which are not related to that request.
- *
- * This function will always return events from the pre-reply phase of the
- * specified request. It may also return events from the unrelated
- * post-reply stream, as long as they have the same sequence number.
- *
- * This function is useful for callers that need to process responses in
- * wire-order.
- *
- * Implementation note: You cannot currently use this function to ensure
- * that you process responses in exactly wire-order, because depending on
- * the sequence of calls you make and the timing of server responses,
- * post-reply events with the same sequence number may be returned as part
- * of the pre-reply event stream, even though they were separated by a
- * reply or error. In practice this kind of error is unlikely to matter,
- * but it may be fixed in the future.
- */
-xcb_generic_event_t *xcb_wait_for_event_until(xcb_connection_t *c, unsigned int request);
-
 /**
  * @brief Return the error for a request, or NULL if none can ever arrive.
  * @param c: The connection to the X server.

src/xcb_in.c

@@ -57,7 +57,6 @@
 #endif
 
 struct event_list {
-    uint64_t sequence;
     xcb_generic_event_t *event;
     struct event_list *next;
 };
@@ -126,7 +125,7 @@ static int read_packet(xcb_connection_t *c)
                 c->in.current_reply = 0;
                 c->in.current_reply_tail = &c->in.current_reply;
             }
-            c->in.request_completed = c->in.event_responses_completed = c->in.request_read - 1;
+            c->in.request_completed = c->in.request_read - 1;
         }
 
         while(c->in.pending_replies && 
@@ -141,12 +140,9 @@ static int read_packet(xcb_connection_t *c)
         }
 
         if(genrep.response_type == XCB_ERROR)
-            c->in.request_completed = c->in.event_responses_completed = c->in.request_read;
-        else if(genrep.response_type == XCB_REPLY)
-            c->in.event_responses_completed = c->in.request_read;
+            c->in.request_completed = c->in.request_read;
 
         remove_finished_readers(&c->in.readers, c->in.request_completed);
-        remove_finished_readers(&c->in.event_readers, c->in.event_responses_completed);
     }
 
     if(genrep.response_type == XCB_ERROR || genrep.response_type == XCB_REPLY)
@@ -235,15 +231,11 @@ static int read_packet(xcb_connection_t *c)
         free(buf);
         return 0;
     }
-    event->sequence = c->in.request_read;
     event->event = buf;
     event->next = 0;
     *c->in.events_tail = event;
     c->in.events_tail = &event->next;
-    if(c->in.event_readers)
-        pthread_cond_signal(c->in.event_readers->data);
-    else
-        pthread_cond_signal(&c->in.event_cond);
+    pthread_cond_signal(&c->in.event_cond);
     return 1; /* I have something for you... */
 }
 
@@ -560,35 +552,6 @@ xcb_generic_event_t *xcb_poll_for_queued_event(xcb_connection_t *c)
     return poll_for_next_event(c, 1);
 }
 
-static xcb_generic_event_t *get_event_until(xcb_connection_t *c, uint64_t request)
-{
-    if(c->in.events && XCB_SEQUENCE_COMPARE(c->in.events->sequence, <=, request))
-        return get_event(c);
-    return 0;
-}
-
-xcb_generic_event_t *xcb_wait_for_event_until(xcb_connection_t *c, unsigned int request)
-{
-    pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
-    reader_list reader;
-    xcb_generic_event_t *ret;
-    if(c->has_error)
-        return 0;
-    pthread_mutex_lock(&c->iolock);
-
-    insert_reader(&c->in.event_readers, &reader, widen(c, request), &cond);
-
-    while(!(ret = get_event_until(c, reader.request)) && XCB_SEQUENCE_COMPARE(c->in.event_responses_completed, <, reader.request))
-        if(!_xcb_conn_wait(c, &cond, 0, 0))
-            break;
-
-    remove_reader(&c->in.event_readers, &reader);
-    pthread_cond_destroy(&cond);
-    _xcb_in_wake_up_next_reader(c);
-    pthread_mutex_unlock(&c->iolock);
-    return ret;
-}
-
 xcb_generic_error_t *xcb_request_check(xcb_connection_t *c, xcb_void_cookie_t cookie)
 {
     uint64_t request;
@@ -659,8 +622,6 @@ void _xcb_in_wake_up_next_reader(xcb_connection_t *c)
     int pthreadret;
     if(c->in.readers)
         pthreadret = pthread_cond_signal(c->in.readers->data);
-    else if(c->in.event_readers)
-        pthreadret = pthread_cond_signal(c->in.event_readers->data);
     else
         pthreadret = pthread_cond_signal(&c->in.event_cond);
     assert(pthreadret == 0);

src/xcbint.h

@@ -121,7 +121,6 @@ typedef struct _xcb_in {
 
     uint64_t request_expected;
     uint64_t request_read;
-    uint64_t event_responses_completed;
     uint64_t request_completed;
     struct reply_list *current_reply;
     struct reply_list **current_reply_tail;
@@ -130,7 +129,6 @@ typedef struct _xcb_in {
     struct event_list *events;
     struct event_list **events_tail;
     struct reader_list *readers;
-    struct reader_list *event_readers;
 
     struct pending_reply *pending_replies;
     struct pending_reply **pending_replies_tail;