return ret;
}
+static int recv_reply_ignore(struct lttcomm_relayd_sock *rsock, size_t size)
+{
+ int ret;
+ size_t cutfoff = 128;
+
+ /*
+ * To prevent ever growing size of recv_reply to ignore, if the number
+ * of bytes we want to ignore is bigger than `cutoff`, consume half of
+ * the cutoff. We might block on it but still, most of bytes to ignore
+ * should already be ready to consume at this point.
+ *
+ * This kind of scenario can easily happen on stopped session with a
+ * live_timer since no actual receive is done on the socket that would
+ * discard the `ignore` portion.
+ *
+ * TCP guarantee in-order transmission both on send and receive so this
+ * is safe to do.
+ */
+ if (rsock->bytes_to_ignore_on_recv >= cutfoff) {
+ size_t to_discard = cutfoff / 2;
+
+ ret = rsock->sock.ops->recvmsg(&rsock->sock, NULL, to_discard, MSG_TRUNC);
+ if (ret <= 0 || ret != to_discard) {
+ if (ret == 0) {
+ /* Orderly shutdown. */
+ DBG("Socket %d has performed an orderly shutdown", rsock->sock.fd);
+ } else {
+ DBG("Receiving reply to discard failed on sock %d for size %zu with ret %d",
+ rsock->sock.fd, to_discard, ret);
+ }
+ ret = -1;
+ goto error;
+ }
+
+ DBG("Force discard of %zu bytes for socket %d", to_discard, rsock->sock.fd);
+ rsock->bytes_to_ignore_on_recv -= to_discard;
+ }
+
+ DBG3("Relayd ignore reply of %zu bytes for socket %d.", size, rsock->sock.fd);
+ /* Do not wait for the current reply to be ignored */
+ rsock->bytes_to_ignore_on_recv += size;
+ ret = 0;
+
+error:
+ return ret;
+}
+
/*
* Receive reply data on socket. This MUST be call after send_command or else
* could result in unexpected behavior(s).
return -ECONNRESET;
}
+ /*
+ * We have to consume the bytes that are marked to ignore.
+ */
+ if (rsock->bytes_to_ignore_on_recv != 0) {
+ ret = rsock->sock.ops->recvmsg(&rsock->sock, NULL, rsock->bytes_to_ignore_on_recv, MSG_TRUNC);
+ if (ret <= 0 || ret != rsock->bytes_to_ignore_on_recv) {
+ if (ret == 0) {
+ /* Orderly shutdown. */
+ DBG("Socket %d has performed an orderly shutdown", rsock->sock.fd);
+ } else {
+ DBG("Receiving reply to skip failed on sock %d for size %zu with ret %d",
+ rsock->sock.fd, rsock->bytes_to_ignore_on_recv, ret);
+ }
+ ret = -1;
+ goto error;
+ }
+ DBG("Discarded %zu bytes on sock %d", rsock->bytes_to_ignore_on_recv, rsock->sock.fd);
+ rsock->bytes_to_ignore_on_recv = 0;
+ }
+
DBG3("Relayd waiting for reply of size %zu", size);
ret = rsock->sock.ops->recvmsg(&rsock->sock, data, size, 0);
goto end;
}
+ /*
+ * This ensure that we do not close the socket while the lttng-relayd
+ * expects to be able to send a response that we skipped.
+ * While we loose some time to receive everything, this keep the
+ * protocol intact from the point of view of lttng-relayd.
+ */
+ if (rsock->bytes_to_ignore_on_recv != 0) {
+ ret = rsock->sock.ops->recvmsg(&rsock->sock, NULL, rsock->bytes_to_ignore_on_recv, MSG_TRUNC);
+ if (ret <= 0 || ret != rsock->bytes_to_ignore_on_recv) {
+ if (ret == 0) {
+ /* Orderly shutdown. */
+ DBG("Socket %d has performed an orderly shutdown", rsock->sock.fd);
+ } else {
+ DBG("Receiving reply to skip failed on sock %d for size %zu with ret %d",
+ rsock->sock.fd, rsock->bytes_to_ignore_on_recv, ret);
+ }
+ }
+ DBG("Discarded %zu bytes on sock %d", rsock->bytes_to_ignore_on_recv, rsock->sock.fd);
+ rsock->bytes_to_ignore_on_recv = 0;
+ }
+
DBG3("Relayd closing socket %d", rsock->sock.fd);
if (rsock->sock.ops) {
goto error;
}
- /* Receive response */
- ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
+ /*
+ * Discard response since we do not really care for it and that TCP
+ * guarantee in-order delivery. As for error handling, there is not much
+ * to do at this point (closing).
+ **/
+ ret = recv_reply_ignore(rsock, sizeof(reply));
if (ret < 0) {
goto error;
}
- reply.ret_code = be32toh(reply.ret_code);
-
- /* Return session id or negative ret code. */
- if (reply.ret_code != LTTNG_OK) {
- ret = -1;
- ERR("Relayd close stream replied error %d", reply.ret_code);
- } else {
- /* Success */
- ret = 0;
- }
-
DBG("Relayd close stream id %" PRIu64 " successfully", stream_id);
error:
goto error;
}
- /* Receive response */
- ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
+ /*
+ * Ignore the response. TCP guarantee in-order arrival and the overall
+ * protocol do not rely on hard ordering between the control and data
+ * socket for index.
+ * Indexes are sent either at the end of the buffer consumption or
+ * during the live timer.
+ */
+ ret = recv_reply_ignore(rsock, sizeof(reply));
if (ret < 0) {
goto error;
}
- reply.ret_code = be32toh(reply.ret_code);
-
- /* Return session id or negative ret code. */
- if (reply.ret_code != LTTNG_OK) {
- ret = -1;
- ERR("Relayd send index replied error %d", reply.ret_code);
- } else {
- /* Success */
- ret = 0;
- }
-
error:
return ret;
}
projects / lttng-tools.git / blobdiff