void
bufferevent_setwatermark(struct bufferevent *bufev, short events,
size_t lowmark, size_t highmark)
{
struct bufferevent_private *bufev_private =
EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
BEV_LOCK(bufev);
if (events & EV_WRITE) {
bufev->wm_write.low = lowmark;
bufev->wm_write.high = highmark;
}
if (events & EV_READ) {
bufev->wm_read.low = lowmark;
bufev->wm_read.high = highmark;
if (highmark) {
/* There is now a new high-water mark for read.
enable the callback if needed, and see if we should
suspend/bufferevent_wm_unsuspend. */
if (bufev_private->read_watermarks_cb == NULL) {
bufev_private->read_watermarks_cb =
evbuffer_add_cb(bufev->input,
bufferevent_inbuf_wm_cb,
bufev);
}
evbuffer_cb_set_flags(bufev->input,
bufev_private->read_watermarks_cb,
EVBUFFER_CB_ENABLED|EVBUFFER_CB_NODEFER);
if (evbuffer_get_length(bufev->input) > highmark)
bufferevent_wm_suspend_read(bufev);
else if (evbuffer_get_length(bufev->input) < highmark)
bufferevent_wm_unsuspend_read(bufev);
} else {
/* There is now no high-water mark for read. */
if (bufev_private->read_watermarks_cb)
evbuffer_cb_clear_flags(bufev->input,
bufev_private->read_watermarks_cb,
EVBUFFER_CB_ENABLED);
bufferevent_wm_unsuspend_read(bufev);
}
}
BEV_UNLOCK(bufev);
}
/* Callback to implement watermarks on the input buffer. Only enabled
* if the watermark is set. */
static void
bufferevent_inbuf_wm_cb(struct evbuffer *buf,
const struct evbuffer_cb_info *cbinfo,
void *arg)
{
struct bufferevent *bufev = arg;
size_t size;
size = evbuffer_get_length(buf);
if (size >= bufev->wm_read.high)
bufferevent_wm_suspend_read(bufev);
else
bufferevent_wm_unsuspend_read(bufev);
}
/* Callback to implement watermarks on the input buffer. Only enabled
* if the watermark is set. */
static void
bufferevent_inbuf_wm_cb(struct evbuffer *buf,
const struct evbuffer_cb_info *cbinfo,
void *arg)
{
struct bufferevent *bufev = arg;
size_t size;
size = evbuffer_get_length(buf);
if (cbinfo->n_added > cbinfo->n_deleted) {
/* Data got added. If it put us over the watermark, stop
* reading. */
if (size >= bufev->wm_read.high)
bufferevent_wm_suspend_read(bufev);
} else {
/* Data got removed. If it puts us under the watermark,
stop reading. */
if (size < bufev->wm_read.high)
bufferevent_wm_unsuspend_read(bufev);
}
}
