libxl: devstate: Use libxl__xswait*

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---
v3: Initialise ds->w.ao

tools/libxl/libxl_device.c

@@ -758,7 +758,7 @@ void libxl__wait_device_connection(libxl__egc *egc, libxl__ao_device *aodev)
         return;
     }
 
-    rc = libxl__ev_devstate_wait(gc, &aodev->backend_ds,
+    rc = libxl__ev_devstate_wait(ao, &aodev->backend_ds,
                                  device_backend_callback,
                                  state_path, XenbusStateInitWait,
                                  LIBXL_INIT_TIMEOUT * 1000);
@@ -859,7 +859,7 @@ void libxl__initiate_device_remove(libxl__egc *egc,
         if (rc < 0) goto out;
     }
 
-    rc = libxl__ev_devstate_wait(gc, &aodev->backend_ds,
+    rc = libxl__ev_devstate_wait(ao, &aodev->backend_ds,
                                  device_backend_callback,
                                  state_path, XenbusStateClosed,
                                  LIBXL_DESTROY_TIMEOUT * 1000);

tools/libxl/libxl_event.c

@@ -816,68 +816,59 @@ void libxl__ev_evtchn_cancel(libxl__gc *gc, libxl__ev_evtchn *evev)
  * waiting for device state
  */
 
-static void devstate_watch_callback(libxl__egc *egc, libxl__ev_xswatch *watch,
-                                const char *watch_path, const char *event_path)
+static void devstate_callback(libxl__egc *egc, libxl__xswait_state *xsw,
+                              int rc, const char *sstate)
 {
     EGC_GC;
-    libxl__ev_devstate *ds = CONTAINER_OF(watch, *ds, watch);
-    int rc;
+    libxl__ev_devstate *ds = CONTAINER_OF(xsw, *ds, w);
 
-    char *sstate = libxl__xs_read(gc, XBT_NULL, watch_path);
-    if (!sstate) {
-        if (errno == ENOENT) {
-            LIBXL__LOG(CTX, LIBXL__LOG_DEBUG, "backend %s wanted state %d"
-                       " but it was removed", watch_path, ds->wanted);
-            rc = ERROR_INVAL;
-        } else {
-            LIBXL__LOG_ERRNO(CTX, LIBXL__LOG_ERROR, "backend %s wanted state"
-                             " %d but read failed", watch_path, ds->wanted);
-            rc = ERROR_FAIL;
-        }
-    } else {
-        int got = atoi(sstate);
-        if (got == ds->wanted) {
-            LIBXL__LOG(CTX, LIBXL__LOG_DEBUG, "backend %s wanted state %d ok",
-                       watch_path, ds->wanted);
-            rc = 0;
-        } else {
-            LIBXL__LOG(CTX, LIBXL__LOG_DEBUG, "backend %s wanted state %d"
-                       " still waiting state %d", watch_path, ds->wanted, got);
-            return;
-        }
+    if (rc) {
+        if (rc == ERROR_TIMEDOUT)
+            LIBXL__LOG(CTX, LIBXL__LOG_DEBUG, "backend %s wanted state %d "
+                       " timed out", ds->w.path, ds->wanted);
+        goto out;
     }
+    if (!sstate) {
+        LIBXL__LOG(CTX, LIBXL__LOG_DEBUG, "backend %s wanted state %d"
+                   " but it was removed", ds->w.path, ds->wanted);
+        rc = ERROR_INVAL;
+        goto out;
+    }
+
+    int got = atoi(sstate);
+    if (got == ds->wanted) {
+        LIBXL__LOG(CTX, LIBXL__LOG_DEBUG, "backend %s wanted state %d ok",
+                   ds->w.path, ds->wanted);
+        rc = 0;
+    } else {
+        LIBXL__LOG(CTX, LIBXL__LOG_DEBUG, "backend %s wanted state %d"
+                   " still waiting state %d", ds->w.path, ds->wanted, got);
+        return;
+    }
+
+ out:
     libxl__ev_devstate_cancel(gc, ds);
     ds->callback(egc, ds, rc);
 }
 
-static void devstate_timeout(libxl__egc *egc, libxl__ev_time *ev,
-                             const struct timeval *requested_abs)
-{
-    EGC_GC;
-    libxl__ev_devstate *ds = CONTAINER_OF(ev, *ds, timeout);
-    LIBXL__LOG(CTX, LIBXL__LOG_DEBUG, "backend %s wanted state %d "
-               " timed out", ds->watch.path, ds->wanted);
-    libxl__ev_devstate_cancel(gc, ds);
-    ds->callback(egc, ds, ERROR_TIMEDOUT);
-}
-
-int libxl__ev_devstate_wait(libxl__gc *gc, libxl__ev_devstate *ds,
+int libxl__ev_devstate_wait(libxl__ao *ao, libxl__ev_devstate *ds,
                             libxl__ev_devstate_callback cb,
                             const char *state_path, int state, int milliseconds)
 {
+    AO_GC;
     int rc;
 
-    libxl__ev_time_init(&ds->timeout);
-    libxl__ev_xswatch_init(&ds->watch);
+    libxl__xswait_init(&ds->w);
     ds->wanted = state;
     ds->callback = cb;
 
-    rc = libxl__ev_time_register_rel(gc, &ds->timeout, devstate_timeout,
-                                     milliseconds);
-    if (rc) goto out;
-
-    rc = libxl__ev_xswatch_register(gc, &ds->watch, devstate_watch_callback,
-                                    state_path);
+    ds->w.ao = ao;
+    ds->w.what = GCSPRINTF("backend %s (hoping for state change to %d)",
+                           state_path, state);
+    ds->w.path = state_path;
+    ds->w.timeout_ms = milliseconds;
+    ds->w.callback = devstate_callback;
+    rc = libxl__xswait_start(gc, &ds->w);
     if (rc) goto out;
 
     return 0;

tools/libxl/libxl_internal.h

@@ -1189,24 +1189,21 @@ struct libxl__ev_devstate {
     libxl__ev_devstate_callback *callback;
     /* as for the remainder, read-only public parts may also be
      * read by the caller (notably, watch.path), but only when waiting: */
-    libxl__ev_xswatch watch;
-    libxl__ev_time timeout;
+    libxl__xswait_state w;
 };
 
 static inline void libxl__ev_devstate_init(libxl__ev_devstate *ds)
 {
-    libxl__ev_time_init(&ds->timeout);
-    libxl__ev_xswatch_init(&ds->watch);
+    libxl__xswait_init(&ds->w);
 }
 
 static inline void libxl__ev_devstate_cancel(libxl__gc *gc,
                                              libxl__ev_devstate *ds)
 {
-    libxl__ev_time_deregister(gc,&ds->timeout);
-    libxl__ev_xswatch_deregister(gc,&ds->watch);
+    libxl__xswait_stop(gc,&ds->w);
 }
 
-_hidden int libxl__ev_devstate_wait(libxl__gc *gc, libxl__ev_devstate *ds,
+_hidden int libxl__ev_devstate_wait(libxl__ao *ao, libxl__ev_devstate *ds,
                                     libxl__ev_devstate_callback cb,
                                     const char *state_path,
                                     int state, int milliseconds);