Add watermark introspection

bufferevent.c

@@ -596,6 +596,27 @@ bufferevent_setwatermark(struct bufferevent *bufev, short events,
 	BEV_UNLOCK(bufev);
 }
 
+void
+bufferevent_getwatermark(struct bufferevent *bufev, short events,
+    size_t *lowmark, size_t *highmark)
+{
+	BEV_LOCK(bufev);
+	if (events & EV_WRITE) {
+		if (lowmark)
+			*lowmark = bufev->wm_write.low;
+		if (highmark)
+			*highmark = bufev->wm_write.high;
+	}
+
+	if (events & EV_READ) {
+		if (lowmark)
+			*lowmark = bufev->wm_read.low;
+		if (highmark)
+			*highmark = bufev->wm_read.high;
+	}
+	BEV_UNLOCK(bufev);
+}
+
 int
 bufferevent_flush(struct bufferevent *bufev,
     short iotype,

include/event2/bufferevent.h

@@ -507,6 +507,18 @@ int bufferevent_set_timeouts(struct bufferevent *bufev,
 void bufferevent_setwatermark(struct bufferevent *bufev, short events,
     size_t lowmark, size_t highmark);
 
+/**
+  Retrieves the watermarks for read or write events. Result is undefined if
+  events contains both EV_READ and EV_WRITE.
+
+  @param bufev the bufferevent to be examined
+  @param events EV_READ or EV_WRITE
+  @param lowmark receives the lower watermark if not NULL
+  @param highmark receives the high watermark if not NULL
+*/
+void bufferevent_getwatermark(struct bufferevent *bufev, short events,
+    size_t *lowmark, size_t *highmark);
+
 /**
    Acquire the lock on a bufferevent.  Has no effect if locking was not
    enabled with BEV_OPT_THREADSAFE.

test/regress_bufferevent.c

@@ -243,6 +243,7 @@ test_bufferevent_watermarks_impl(int use_pair)
 {
 	struct bufferevent *bev1 = NULL, *bev2 = NULL;
 	char buffer[65000];
+	size_t low, high;
 	int i;
 	test_ok = 0;
 
@@ -262,16 +263,30 @@ test_bufferevent_watermarks_impl(int use_pair)
 	bufferevent_disable(bev1, EV_READ);
 	bufferevent_enable(bev2, EV_READ);
 
+	/* By default, low watermarks are set to 0 */
+	bufferevent_getwatermark(bev1, EV_READ, &low, NULL);
+	tt_int_op(low, ==, 0);
+	bufferevent_getwatermark(bev2, EV_WRITE, &low, NULL);
+	tt_int_op(low, ==, 0);
+
 	for (i = 0; i < (int)sizeof(buffer); i++)
 		buffer[i] = (char)i;
 
 	/* limit the reading on the receiving bufferevent */
 	bufferevent_setwatermark(bev2, EV_READ, 10, 20);
 
+	bufferevent_getwatermark(bev2, EV_READ, &low, &high);
+	tt_int_op(low, ==, 10);
+	tt_int_op(high, ==, 20);
+
 	/* Tell the sending bufferevent not to notify us till it's down to
 	   100 bytes. */
 	bufferevent_setwatermark(bev1, EV_WRITE, 100, 2000);
 
+	bufferevent_getwatermark(bev1, EV_WRITE, &low, &high);
+	tt_int_op(low, ==, 100);
+	tt_int_op(high, ==, 2000);
+
 	bufferevent_write(bev1, buffer, sizeof(buffer));
 
 	event_dispatch();