New semantics for evbuffer_cb_set_flags().

Previously, set_flags() would replace all previous user-visible flags.
Now it just sets the flags, and there is a clear_flags() function to
clear other flags.

svn:r1293

ChangeLog

@@ -26,6 +26,8 @@ Changes in 2.0.2-alpha:
  o Make bufferevent_setfd() return an error code if the operation is not successful.
  o Shave 22 bytes off struct event on 32-bit platforms by shrinking and re-ordering fields.  The savings on 64-bit platforms is likely higher.
  o Cap the maximum number of priorities at 256.
+ o Change the semantics of evbuffer_cb_set_flags() to be set-flag only; add a new evbuffer_cb_clear_flags() to remove set flags.
+
 
 Changes in 2.0.1-alpha:
  o free minheap on event_base_free(); from Christopher Layne

buffer.c

@@ -2253,8 +2253,22 @@ int
 evbuffer_cb_set_flags(struct evbuffer *buffer,
 		      struct evbuffer_cb_entry *cb, ev_uint32_t flags)
 {
+	/* the user isn't allowed to mess with these. */
+	flags &= ~EVBUFFER_CB_INTERNAL_FLAGS;
         EVBUFFER_LOCK(buffer, EVTHREAD_WRITE);
-	cb->flags = (cb->flags & EVBUFFER_CB_INTERNAL_FLAGS) | flags;
+	cb->flags |= flags;
+        EVBUFFER_UNLOCK(buffer, EVTHREAD_WRITE);
+	return 0;
+}
+
+int
+evbuffer_cb_clear_flags(struct evbuffer *buffer,
+		      struct evbuffer_cb_entry *cb, ev_uint32_t flags)
+{
+	/* the user isn't allowed to mess with these. */
+	flags &= ~EVBUFFER_CB_INTERNAL_FLAGS;
+        EVBUFFER_LOCK(buffer, EVTHREAD_WRITE);
+	cb->flags &= ~flags;
         EVBUFFER_UNLOCK(buffer, EVTHREAD_WRITE);
 	return 0;
 }

bufferevent.c

@@ -438,9 +438,9 @@ bufferevent_setwatermark(struct bufferevent *bufev, short events,
 		} else {
 			/* There is now no high-water mark for read. */
 			if (bufev_private->read_watermarks_cb)
-				evbuffer_cb_set_flags(bufev->input,
+				evbuffer_cb_clear_flags(bufev->input,
 				    bufev_private->read_watermarks_cb,
-				    EVBUFFER_CB_DISABLED);
+				    EVBUFFER_CB_ENABLED);
 			bufferevent_wm_unsuspend_read(bufev);
 		}
 	}

include/event2/buffer.h

@@ -494,23 +494,30 @@ int evbuffer_remove_cb_entry(struct evbuffer *buffer,
  */
 int evbuffer_remove_cb(struct evbuffer *buffer, evbuffer_cb_func cb, void *cbarg);
 
-#define EVBUFFER_CB_DISABLED 0
+/** If this flag is not set, then a callback is temporarily disabled, and
+ * should not be invoked. */
 #define EVBUFFER_CB_ENABLED 1
 
-/** Change whether a given callback is enabled on a buffer or not.  A
+/** Change the flags that are set for a callback on a buffer by adding more.
-    disabled callback is not invoked even when the buffer size changes.
 
     @param buffer the evbuffer that the callback is watching.
     @param cb the callback whose status we want to change.
-    @param flags EVBUFFER_CB_ENABLED to enable the callback, or
+    @param flags EVBUFFER_CB_ENABLED to re-enable the callback.
-        EVBUFFER_CB_DISABLED to disable it.
     @return 0 on success, -1 on failure.
  */
-/* XXXX It would be better to have a set_flags() and a clear_flags()
- * interface, and make them separate. -nickm FIXME */
 int evbuffer_cb_set_flags(struct evbuffer *buffer,
 			  struct evbuffer_cb_entry *cb, ev_uint32_t flags);
 
+/** Change the flags that are set for a callback on a buffer by removing some
+
+    @param buffer the evbuffer that the callback is watching.
+    @param cb the callback whose status we want to change.
+    @param flags EVBUFFER_CB_ENABLED to disable the callback.
+    @return 0 on success, -1 on failure.
+ */
+int evbuffer_cb_clear_flags(struct evbuffer *buffer,
+			  struct evbuffer_cb_entry *cb, ev_uint32_t flags);
+
 #if 0
 /** Postpone calling a given callback until unsuspend is called later.
 

test/regress_buffer.c

@@ -659,7 +659,7 @@ test_evbuffer_callbacks(void *ptr)
 	 * adds a summary of length changes to buf_out1/buf_out2 when called. */
 	/* size: 0-> 36. */
 	evbuffer_add_printf(buf, "The %d magic words are spotty pudding", 2);
-	evbuffer_cb_set_flags(buf, cb2, 0);
+	evbuffer_cb_clear_flags(buf, cb2, EVBUFFER_CB_ENABLED);
 	evbuffer_drain(buf, 10); /*36->26*/
 	evbuffer_prepend(buf, "Hello", 5);/*26->31*/
 	evbuffer_cb_set_flags(buf, cb2, EVBUFFER_CB_ENABLED);