st/xlib: Support unlimited number of display connections

There is a limit of 10 display connections, which was a
problem for apps/tests that were continuously opening/closing display
connections.

This fix uses XAddExtension() and XESetCloseDisplay() to keep track
of the status of the display connections from the X server, freeing
mesa-related data as X displays get destroyed by the X server.

Poster child is the VTK "TimingTests"

Tested-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>

src/gallium/state_trackers/glx/xlib/xm_api.c

@@ -110,14 +110,6 @@ void xmesa_set_driver( const struct xm_driver *templ )
 }
 
 
-/*
- * XXX replace this with a linked list, or better yet, try to attach the
- * gallium/mesa extra bits to the X Display object with XAddExtension().
- */
-#define MAX_DISPLAYS 10
-static struct xmesa_display Displays[MAX_DISPLAYS];
-static int NumDisplays = 0;
-
 static int
 xmesa_get_param(struct st_manager *smapi,
                 enum st_manager_param param)
@@ -130,34 +122,125 @@ xmesa_get_param(struct st_manager *smapi,
    }
 }
 
+/* linked list of XMesaDisplay hooks per display */
+typedef struct _XMesaExtDisplayInfo {
+   struct _XMesaExtDisplayInfo *next;
+   Display *display;
+   XExtCodes *codes;
+   struct xmesa_display mesaDisplay;
+} XMesaExtDisplayInfo;
+
+typedef struct _XMesaExtInfo {
+   XMesaExtDisplayInfo *head;
+   int ndisplays;
+} XMesaExtInfo;
+
+static XMesaExtInfo MesaExtInfo;
+
+/* hook to delete XMesaDisplay on XDestroyDisplay */
+static int
+xmesa_close_display(Display *display, XExtCodes *codes)
+{
+   XMesaExtDisplayInfo *info, *prev;
+
+   assert(MesaExtInfo.ndisplays > 0);
+   assert(MesaExtInfo.head);
+
+   _XLockMutex(_Xglobal_lock);
+   /* first find display */
+   prev = NULL;
+   for (info = MesaExtInfo.head; info; info = info->next) {
+      if (info->display == display) {
+         prev = info;
+         break;
+      }
+   }
+
+   if (info == NULL) {
+      /* no display found */
+      _XUnlockMutex(_Xglobal_lock);
+      return 0;
+   }
+
+   /* remove display entry from list */
+   if (prev != MesaExtInfo.head) {
+      prev->next = info->next;
+   } else {
+      MesaExtInfo.head = info->next;
+   }
+   MesaExtInfo.ndisplays--;
+
+   _XUnlockMutex(_Xglobal_lock);
+
+   /* don't forget to clean up mesaDisplay */
+   XMesaDisplay xmdpy = &info->mesaDisplay;
+
+   if (xmdpy->screen) {
+      xmdpy->screen->destroy(xmdpy->screen);
+   }
+   free(xmdpy->smapi);
+
+   XFree((char *) info);
+   return 1;
+}
+
 static XMesaDisplay
 xmesa_init_display( Display *display )
 {
    pipe_static_mutex(init_mutex);
    XMesaDisplay xmdpy;
-   int i;
+   XMesaExtDisplayInfo *info;
+
+   if (display == NULL) {
+      return NULL;
+   }
 
    pipe_mutex_lock(init_mutex);
 
-   /* Look for XMesaDisplay which corresponds to 'display' */
-   for (i = 0; i < NumDisplays; i++) {
-      if (Displays[i].display == display) {
+   /* Look for XMesaDisplay which corresponds to this display */
+   info = MesaExtInfo.head;
+   while(info) {
+      if (info->display == display) {
          /* Found it */
          pipe_mutex_unlock(init_mutex);
-         return &Displays[i];
+         return  &info->mesaDisplay;
       }
+      info = info->next;
    }
 
-   /* Create new XMesaDisplay */
+   /* Not found.  Create new XMesaDisplay */
+   /* first allocate X-related resources and hook destroy callback */
 
-   assert(NumDisplays < MAX_DISPLAYS);
-   xmdpy = &Displays[NumDisplays];
-   NumDisplays++;
+   /* allocate mesa display info */
+   info = (XMesaExtDisplayInfo *) Xmalloc(sizeof(XMesaExtDisplayInfo));
+   if (info == NULL) {
+      pipe_mutex_unlock(init_mutex);
+      return NULL;
+   }
+   info->display = display;
+   info->codes = XAddExtension(display);
+   if (info->codes == NULL) {
+      /* could not allocate extension.  Fail */
+      Xfree(info);
+      pipe_mutex_unlock(init_mutex);
+      return NULL;
+   }
+   XESetCloseDisplay(display, info->codes->extension, xmesa_close_display);
+   xmdpy = &info->mesaDisplay; /* to be filled out below */
 
-   if (!xmdpy->display && display) {
+   /* chain to the list of displays */
+   _XLockMutex(_Xglobal_lock);
+   info->next = MesaExtInfo.head;
+   MesaExtInfo.head = info;
+   MesaExtInfo.ndisplays++;
+   _XUnlockMutex(_Xglobal_lock);
+
+   /* now create the new XMesaDisplay info */
+   if (display) {
       xmdpy->display = display;
       xmdpy->screen = driver.create_pipe_screen(display);
       xmdpy->smapi = CALLOC_STRUCT(st_manager);
+      xmdpy->pipe = NULL;
       if (xmdpy->smapi) {
          xmdpy->smapi->screen = xmdpy->screen;
          xmdpy->smapi->get_param = xmesa_get_param;
@@ -185,6 +268,7 @@ xmesa_init_display( Display *display )
    return xmdpy;
 }
 
+
 /**********************************************************************/
 /*****                     X Utility Functions                    *****/
 /**********************************************************************/