Add event queue splitting

This allows apps to peel off certain XGE events into separate queues
for custom handling. Designed to support the Present extension

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-By: Uli Schlachter <psychon@znc.in>

3 files changed, 107 insertions, 12 deletions

diff --git a/src/xcb.h b/src/xcb.h
index 1fd1f6c..63864dc 100644
--- a/src/xcb.h
+++ b/src/xcb.h
@@ -290,6 +290,39 @@ 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);
 
+typedef struct xcb_special_event xcb_special_event_t;
+
+/**
+ * @brief Returns the next event from a special queue
+ */
+xcb_generic_event_t *xcb_poll_for_special_event(xcb_connection_t *c,
+                                                xcb_special_event_t *se);
+ 
+/**
+ * @brief Returns the next event from a special queue, blocking until one arrives
+ */
+xcb_generic_event_t *xcb_wait_for_special_event(xcb_connection_t *c,
+                                                xcb_special_event_t *se);
+/**
+ * @typedef typedef struct xcb_extension_t xcb_extension_t
+ */
+typedef struct xcb_extension_t xcb_extension_t;  /**< Opaque structure used as key for xcb_get_extension_data_t. */
+
+ 
+/**
+ * @brief Listen for a special event
+ */
+xcb_special_event_t *xcb_register_for_special_xge(xcb_connection_t *c,
+                                                  xcb_extension_t *ext,
+                                                  uint32_t eid,
+                                                  uint32_t *stamp);
+
+/**
+ * @brief Stop listening for a special event
+ */
+void xcb_unregister_for_special_event(xcb_connection_t *c,
+                                      xcb_special_event_t *se);
+
 /**
  * @brief Return the error for a request, or NULL if none can ever arrive.
  * @param c: The connection to the X server.
@@ -328,11 +361,6 @@ void xcb_discard_reply(xcb_connection_t *c, unsigned int sequence);
 /* xcb_ext.c */
 
 /**
- * @typedef typedef struct xcb_extension_t xcb_extension_t
- */
-typedef struct xcb_extension_t xcb_extension_t;  /**< Opaque structure used as key for xcb_get_extension_data_t. */
-
-/**
  * @brief Caches reply information from QueryExtension requests.
  * @param c: The connection.
  * @param ext: The extension data.
diff --git a/src/xcb_in.c b/src/xcb_in.c
index b161e93..839f615 100644
--- a/src/xcb_in.c
+++ b/src/xcb_in.c
@@ -60,6 +60,23 @@ struct event_list {
     struct event_list *next;
 };
 
+struct xcb_special_event {
+
+    struct xcb_special_event *next;
+
+    /* Match XGE events for the specific extension and event ID (the
+     * first 32 bit word after evtype)
+     */
+    uint8_t     extension;
+    uint32_t    eid;
+    uint32_t    *stamp;
+
+    struct event_list   *events;
+    struct event_list   **events_tail;
+
+    pthread_cond_t special_event_cond;
+};
+
 struct reply_list {
     void *reply;
     struct reply_list *next;
@@ -104,6 +121,46 @@ static int read_fds(xcb_connection_t *c, int *fds, int nfd)
 }
 #endif
 
+typedef struct xcb_ge_special_event_t {
+    uint8_t  response_type; /**<  */
+    uint8_t  extension; /**<  */
+    uint16_t sequence; /**<  */
+    uint32_t length; /**<  */
+    uint16_t evtype; /**<  */
+    uint8_t  pad0[2]; /**< */
+    uint32_t eid; /**< */
+    uint8_t  pad1[16]; /**<  */
+} xcb_ge_special_event_t;
+
+static int event_special(xcb_connection_t *c,
+                         struct event_list *event)
+{
+    struct xcb_special_event *special_event;
+    struct xcb_ge_special_event_t *ges = (void *) event->event;
+
+    /* Special events are always XGE events */
+    if ((ges->response_type & 0x7f) != XCB_XGE_EVENT)
+        return 0;
+
+    for (special_event = c->in.special_events;
+         special_event;
+         special_event = special_event->next)
+    {
+        if (ges->extension == special_event->extension &&
+            ges->eid == special_event->eid)
+        {
+            *special_event->events_tail = event;
+            special_event->events_tail = &event->next;
+            if (special_event->stamp)
+                ++(*special_event->stamp);
+            pthread_cond_signal(&special_event->special_event_cond);
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
 static int read_packet(xcb_connection_t *c)
 {
     xcb_generic_reply_t genrep;
@@ -268,9 +325,12 @@ static int read_packet(xcb_connection_t *c)
     }
     event->event = buf;
     event->next = 0;
-    *c->in.events_tail = event;
-    c->in.events_tail = &event->next;
-    pthread_cond_signal(&c->in.event_cond);
+
+    if (!event_special(c, event)) {
+        *c->in.events_tail = event;
+        c->in.events_tail = &event->next;
+        pthread_cond_signal(&c->in.event_cond);
+    }
     return 1; /* I have something for you... */
 }
 
@@ -661,17 +721,21 @@ xcb_generic_event_t *xcb_wait_for_special_event(xcb_connection_t *c,
 
 xcb_special_event_t *
 xcb_register_for_special_xge(xcb_connection_t *c,
-                             uint8_t extension,
+                             xcb_extension_t *ext,
                              uint32_t eid,
                              uint32_t *stamp)
 {
     xcb_special_event_t *se;
+    const xcb_query_extension_reply_t   *ext_reply;
 
     if(c->has_error)
         return NULL;
+    ext_reply = xcb_get_extension_data(c, ext);
+    if (!ext_reply)
+        return NULL;
     pthread_mutex_lock(&c->iolock);
     for (se = c->in.special_events; se; se = se->next) {
-        if (se->extension == extension &&
+        if (se->extension == ext_reply->major_opcode &&
             se->eid == eid) {
             pthread_mutex_unlock(&c->iolock);
             return NULL;
@@ -683,7 +747,7 @@ xcb_register_for_special_xge(xcb_connection_t *c,
         return NULL;
     }
             
-    se->extension = extension;
+    se->extension = ext_reply->major_opcode;
     se->eid = eid;
 
     se->events = NULL;
@@ -694,7 +758,6 @@ xcb_register_for_special_xge(xcb_connection_t *c,
 
     se->next = c->in.special_events;
     c->in.special_events = se;
-
     pthread_mutex_unlock(&c->iolock);
     return se;
 }
@@ -706,6 +769,9 @@ xcb_unregister_for_special_event(xcb_connection_t *c,
     xcb_special_event_t *s, **prev;
     struct event_list   *events, *next;
 
+    if (!se)
+        return;
+
     if (c->has_error)
         return;
 
diff --git a/src/xcbint.h b/src/xcbint.h
index 4a01f6f..e122f2f 100644
--- a/src/xcbint.h
+++ b/src/xcbint.h
@@ -154,6 +154,7 @@ typedef struct _xcb_in {
 #if HAVE_SENDMSG
     _xcb_fd in_fd;
 #endif
+    struct xcb_special_event *special_events;
 } _xcb_in;
 
 int _xcb_in_init(_xcb_in *in);