/* Notify the listener that the client has finished sending a message, and
* transfer all details for handling the response to it. Blocking. */
static bool enqueue_EXPECT_message_to_listener(bus *b, boxed_msg *box) {
/* Notify listener that it should expect a response to a
* successfully sent message. */
BUS_LOG_SNPRINTF(b, 3, LOG_SENDER, b->udata, 128,
"telling listener to EXPECT sent response, with box %p, seq_id %lld",
(void *)box, (long long)box->out_seq_id);
if (box->result.status == BUS_SEND_UNDEFINED) {
box->result.status = BUS_SEND_REQUEST_COMPLETE;
}
struct listener *l = Bus_GetListenerForSocket(b, box->fd);
for (int retries = 0; retries < SEND_NOTIFY_LISTENER_RETRIES; retries++) {
#ifndef TEST
uint16_t backpressure = 0;
#endif
/* If this succeeds, then this thread cannot touch the box anymore. */
if (Listener_ExpectResponse(l, box, &backpressure)) {
Bus_BackpressureDelay(b, backpressure,
LISTENER_EXPECT_BACKPRESSURE_SHIFT);
return true;
} else {
BUS_LOG_SNPRINTF(b, 5, LOG_SENDER, b->udata, 64,
"enqueue_request_sent: failed delivery %d", retries);
syscall_poll(NULL, 0, SEND_NOTIFY_LISTENER_RETRY_DELAY);
}
}
/* Timeout, will be treated as a TX error */
return false;
}
bool BusPoll_OnCompletion(struct bus *b, int fd) {
/* POLL in a pipe */
#ifndef TEST
struct pollfd fds[1];
#endif
fds[0].fd = fd;
fds[0].events = POLLIN;
for (;;) {
BUS_LOG(b, 5, LOG_SENDING_REQUEST, "Polling on completion...tick...", b->udata);
#ifdef TEST
errno = poll_errno;
#endif
BUS_LOG_SNPRINTF(b, 5, LOG_SENDING_REQUEST, b->udata, 64,
"poll_on_completion, polling %d", fd);
int res = syscall_poll(fds, 1, -1);
BUS_LOG_SNPRINTF(b, 5, LOG_SENDING_REQUEST, b->udata, 64,
"poll_on_completion for %d, res %d (errno %d)", fd, res, errno);
if (res == -1) {
if (Util_IsResumableIOError(errno)) {
BUS_LOG_SNPRINTF(b, 5, LOG_SENDING_REQUEST, b->udata, 64,
"poll_on_completion, resumable IO error %d", errno);
errno = 0;
continue;
} else {
BUS_LOG_SNPRINTF(b, 1, LOG_SENDING_REQUEST, b->udata, 64,
"poll_on_completion, non-resumable IO error %d", errno);
return false;
}
} else if (res == 1) {
uint16_t msec = 0;
#ifndef TEST
uint8_t read_buf[sizeof(uint8_t) + sizeof(uint16_t)];
#endif
if (fds[0].revents & (POLLERR | POLLHUP | POLLNVAL)) {
BUS_LOG(b, 1, LOG_SENDING_REQUEST, "failed (broken alert pipe)", b->udata);
return false;
}
BUS_LOG(b, 3, LOG_SENDING_REQUEST, "Reading alert pipe...", b->udata);
#ifdef TEST
errno = read_errno;
#endif
ssize_t sz = syscall_read(fd, read_buf, sizeof(read_buf));
if (sz == sizeof(read_buf)) {
/* Payload: little-endian uint16_t, msec of backpressure. */
assert(read_buf[0] == LISTENER_MSG_TAG);
msec = (read_buf[1] << 0) + (read_buf[2] << 8);
Bus_BackpressureDelay(b, msec, LISTENER_BACKPRESSURE_SHIFT);
BUS_LOG(b, 4, LOG_SENDING_REQUEST, "sent!", b->udata);
return true;
} else if (sz == -1) {
if (Util_IsResumableIOError(errno)) {
BUS_LOG_SNPRINTF(b, 5, LOG_SENDING_REQUEST, b->udata, 64,
"poll_on_completion read, resumable IO error %d", errno);
errno = 0;
continue;
} else {
BUS_LOG_SNPRINTF(b, 2, LOG_SENDING_REQUEST, b->udata, 64,
"poll_on_completion read, non-resumable IO error %d", errno);
errno = 0;
return false;
}
} else {
BUS_LOG_SNPRINTF(b, 1, LOG_SENDING_REQUEST, b->udata, 64,
"poll_on_completion bad read size %zd", sz);
return false;
}
} else {
/* This should never happen, but I have seen it occur on OSX.
* If we log it, reset errno, and continue, it does not appear
* to fall into busywaiting by always returning 0. */
BUS_LOG_SNPRINTF(b, 1, LOG_SENDING_REQUEST, b->udata, 64,
"poll_on_completion, blocking forever returned %d, errno %d", res, errno);
errno = 0;
}
}
}
