From d5ab03b4b71648bf0a06e42e3c288a68c46ba497 Mon Sep 17 00:00:00 2001
From: Jamey Sharp <jamey@minilop.net>
Date: Wed, 19 Apr 2006 20:15:15 -0700
Subject: [PATCH] Fixed poll_for_reply, added comments, and refactored
 XCBWaitForReply to call poll_for_reply.

---
 src/xcb_in.c | 56 +++++++++++++---------------------------------------
 1 file changed, 14 insertions(+), 42 deletions(-)

diff --git a/src/xcb_in.c b/src/xcb_in.c
index 4ad4654..24fb041 100644
--- a/src/xcb_in.c
+++ b/src/xcb_in.c
@@ -243,23 +243,33 @@ static int poll_for_reply(XCBConnection *c, unsigned int request, void **reply,
 {
     struct reply_list *head;
 
+    /* If an error occurred when issuing the request, fail immediately. */
     if(!request)
         head = 0;
-    else if(c->in.request_completed >= request)
+    /* We've read requests past the one we want, so if it has replies we have
+     * them all and they're in the replies map. */
+    else if(request < c->in.request_read)
     {
         head = _xcb_map_remove(c->in.replies, request);
         if(head && head->next)
             _xcb_map_put(c->in.replies, request, head->next);
     }
-    else if(c->in.request_read == request && c->in.current_reply)
+    /* We're currently processing the responses to the request we want, and we
+     * have a reply ready to return. So just return it without blocking. */
+    else if(request == c->in.request_read && c->in.current_reply)
     {
         head = c->in.current_reply;
         c->in.current_reply = head->next;
         if(!head->next)
             c->in.current_reply_tail = &c->in.current_reply;
     }
+    /* We know this request can't have any more replies, and we've already
+     * established it doesn't have a reply now. Don't bother blocking. */
+    else if(request == c->in.request_completed)
+        head = 0;
+    /* We may have more replies on the way for this request: block until we're
+     * sure. */
     else
-        /* Would block: do nothing. */
         return 0;
 
     if(error)
@@ -291,15 +301,10 @@ void *XCBWaitForReply(XCBConnection *c, unsigned int request, XCBGenericError **
     pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
     reader_list reader;
     reader_list **prev_reader;
-    struct reply_list *head;
     void *ret = 0;
     if(e)
         *e = 0;
 
-    /* If an error occurred when issuing the request, fail immediately. */
-    if(!request)
-        return 0;
-
     pthread_mutex_lock(&c->iolock);
 
     /* If this request has not been written yet, write it. */
@@ -317,43 +322,10 @@ void *XCBWaitForReply(XCBConnection *c, unsigned int request, XCBGenericError **
 
     /* If this request has not completed yet and has no reply waiting,
      * wait for one. */
-    while(c->in.request_completed < request &&
-            !(c->in.request_read == request && c->in.current_reply))
+    while(!poll_for_reply(c, request, &ret, e))
         if(!_xcb_conn_wait(c, &cond, 0, 0))
             goto done;
 
-    if(c->in.request_read != request)
-    {
-        head = _xcb_map_remove(c->in.replies, request);
-        if(head && head->next)
-            _xcb_map_put(c->in.replies, request, head->next);
-    }
-    else
-    {
-        head = c->in.current_reply;
-        if(head)
-        {
-            c->in.current_reply = head->next;
-            if(!head->next)
-                c->in.current_reply_tail = &c->in.current_reply;
-        }
-    }
-
-    if(head)
-    {
-        ret = head->reply;
-        free(head);
-
-        if(((XCBGenericRep *) ret)->response_type == XCBError)
-        {
-            if(e)
-                *e = ret;
-            else
-                free(ret);
-            ret = 0;
-        }
-    }
-
 done:
     for(prev_reader = &c->in.readers; *prev_reader && (*prev_reader)->request <= request; prev_reader = &(*prev_reader)->next)
         if(*prev_reader == &reader)
-- 
2.34.1