* RING_BUFFER_WAKEUP_BY_WRITER wakeup is not lock-free.
*/
if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER
- && uatomic_read(&buf->active_readers)
+ && (uatomic_read(&buf->active_readers)
+ || uatomic_read(&buf->active_shadow_readers))
&& lib_ring_buffer_poll_deliver(config, buf, chan, handle)) {
int wakeup_fd = shm_get_wakeup_fd(handle, &buf->self._ref);
* Wake-up the other end by
* writing a null byte in the
* pipe (non-blocking).
+ * Important note: Because
+ * writing into the pipe is
+ * non-blocking (and therefore
+ * we allow dropping wakeup
+ * data, as long as there is
+ * wakeup data present in the
+ * pipe buffer to wake up the
+ * consumer), the consumer
+ * should perform the following
+ * sequence for waiting:
+ * 1) empty the pipe (reads).
+ * 2) check if there is data in
+ * the buffer.
+ * 3) wait on the pipe (poll).
*/
do {
ret = write(wakeup_fd, "", 1);