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PROTON-2748: Raw connection async close fix and tests. #402

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PROTON-2748: Raw connection async close fix and tests. #402

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f73813a
PROTON-2748: Raw connection async close fix and tests.
cliffjansen Aug 10, 2023
7c6fc14
PROTON-2748: pull request 402 review - replace incorrect boolean oper…
cliffjansen Aug 25, 2023
63985a9
PROTON-2748: pull request 402 review - peek->has_events
cliffjansen Sep 7, 2023
4529406
PROTON-2748: pull request 402 review - isolate !connected code, early…
cliffjansen Sep 8, 2023
546f046
PROTON-2748: pull request 402 review - internal api tests
cliffjansen Sep 21, 2023
9c83182
PROTON-2748: pull request 402 review - rename test to raw_connection_…
cliffjansen Sep 21, 2023
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105 changes: 64 additions & 41 deletions c/src/proactor/epoll_raw_connection.c
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,8 @@ struct praw_connection_t {
struct addrinfo *ai; /* Current connect address */
bool connected;
bool disconnected;
bool batch_empty;
bool hup_detected;
bool read_check;
};

static void psocket_error(praw_connection_t *rc, int err, const char* msg) {
Expand Down Expand Up @@ -304,7 +305,7 @@ void pn_raw_connection_write_close(pn_raw_connection_t *rc) {
pni_raw_write_close(rc);
}

static pn_event_t *pni_raw_batch_next(pn_event_batch_t *batch) {
static pn_event_t *pni_epoll_raw_batch_next(pn_event_batch_t *batch, bool peek_only) {
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rename this: pni_raw_batch_next_common() or pni_raw_batch_next_or_peek():
Ading epoll to the name doesn't communicate anything useful about the purpose of this function.

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pni_raw_batch_has_events() was used as suggested elsewhere.

praw_connection_t *rc = containerof(batch, praw_connection_t, batch);
pn_raw_connection_t *raw = &rc->raw_connection;

Expand All @@ -318,12 +319,18 @@ static pn_event_t *pni_raw_batch_next(pn_event_batch_t *batch) {
unlock(&rc->task.mutex);
if (waking) pni_raw_wake(raw);

pn_event_t *e = pni_raw_event_next(raw);
if (!e || pn_event_type(e) == PN_RAW_CONNECTION_DISCONNECTED)
rc->batch_empty = true;
Comment on lines -322 to -323
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Where did this logic go? It seems no longer to be anywhere. Is it no longer needed? Specifically the check against the disconnected event.

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This logic was solely there to identify edge cases where the epoll-specific code could not be sure if the state machine was up to date. In which case a non-application call to pni_raw_batch_next() would update the state machine but a resulting event would have to be put back into the collector.

The new pni_raw_batch_has_events() updates the state machine and has no side effects to the event stream, so the check for batch_empty is no longer needed.

pn_event_t *e = peek_only ? pni_raw_event_peek(raw) : pni_raw_event_next(raw);
return e;
}

static pn_event_t *pni_raw_batch_next(pn_event_batch_t *batch) {
return pni_epoll_raw_batch_next(batch, false);
}

static pn_event_t *pni_raw_batch_peek(pn_event_batch_t *batch) {
return pni_epoll_raw_batch_next(batch, true);
}
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Are you sure you want to introduce a peek operation? This is only ever used to find out whether there is an outstanding event so why not just introduce an operation bool pni_raw_batch_has_events()?

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done


task_t *pni_psocket_raw_task(psocket_t* ps) {
return &containerof(ps, praw_connection_t, psocket)->task;
}
Expand Down Expand Up @@ -393,10 +400,10 @@ pn_event_batch_t *pni_raw_connection_process(task_t *t, uint32_t io_events, bool
if (rc->disconnected) {
pni_raw_connect_failed(&rc->raw_connection);
unlock(&rc->task.mutex);
rc->batch_empty = false;
return &rc->batch;
}
if (events & (EPOLLHUP | EPOLLERR)) {
// Continuation of praw_connection_maybe_connect_lh() logic.
// A wake can be the first event. Otherwise, wait for connection to complete.
bool event_pending = task_wake || pni_raw_wake_is_pending(&rc->raw_connection) || pn_collector_peek(rc->raw_connection.collector);
t->working = event_pending;
Expand All @@ -408,32 +415,41 @@ pn_event_batch_t *pni_raw_connection_process(task_t *t, uint32_t io_events, bool
}
unlock(&rc->task.mutex);

if (events & EPOLLIN) pni_raw_read(&rc->raw_connection, fd, rcv, set_error);
if (events & EPOLLOUT) pni_raw_write(&rc->raw_connection, fd, snd, set_error);
rc->batch_empty = false;
if (rc->connected) {
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I don't think you need this condition (which is why it wasn't present previously) - if you get here without returning already you must be connected.

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done

if (events & EPOLLERR) {
// Read and write sides closed via RST. Tear down immediately.
int soerr;
socklen_t soerrlen = sizeof(soerr);
int ec = getsockopt(fd, SOL_SOCKET, SO_ERROR, &soerr, &soerrlen);
if (ec == 0 && soerr) {
psocket_error(rc, soerr, "async disconnect");
}
pni_raw_async_disconnect(&rc->raw_connection);
} else if (events & EPOLLHUP) {
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The style of this function is early return. So please change this to have a return with no 'else if' if that is possible - I don't understand enough of this logic to see if you could get EPOLLERR as well as EPOLLIN, EPOLLOUT or EPOLLRDHUP at the same time with a useful action of reading or writing, but it seems unlikely to me.
And if this change is possible it lowers the cognitive load (and indentation) of the function.

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done

rc->hup_detected = true;
}

if (events & (EPOLLIN | EPOLLRDHUP) || rc->read_check) {
pni_raw_read(&rc->raw_connection, fd, rcv, set_error);
rc->read_check = false;
}
if (events & EPOLLOUT) pni_raw_write(&rc->raw_connection, fd, snd, set_error);
}
return &rc->batch;
}

void pni_raw_connection_done(praw_connection_t *rc) {
bool notify = false;
bool ready = false;
bool have_event = false;

// If !batch_empty, can't be sure state machine up to date, so reschedule task if necessary.
if (!rc->batch_empty) {
if (pn_collector_peek(rc->raw_connection.collector))
have_event = true;
else {
pn_event_t *e = pni_raw_batch_next(&rc->batch);
// State machine up to date.
if (e) {
have_event = true;
// Sole event. Can put back without order issues.
// Edge case, performance not important.
pn_collector_put(rc->raw_connection.collector, pn_event_class(e), pn_event_context(e), pn_event_type(e));
}
}
}
pn_raw_connection_t *raw = &rc->raw_connection;
int fd = rc->psocket.epoll_io.fd;

// Try write
if (pni_raw_can_write(raw)) pni_raw_write(raw, fd, snd, set_error);
pni_raw_process_shutdown(raw, fd, shutr, shutw);

// Update state machine and check for possible pending event.
bool have_event = pni_raw_batch_peek(&rc->batch);

lock(&rc->task.mutex);
pn_proactor_t *p = rc->task.proactor;
Expand All @@ -442,24 +458,31 @@ void pni_raw_connection_done(praw_connection_t *rc) {
// The task may be in the ready state even if we've got no raw connection
// wakes outstanding because we dealt with it already in pni_raw_batch_next()
notify = (pni_task_wake_pending(&rc->task) || have_event) && schedule(&rc->task);
ready = rc->task.ready;
ready = rc->task.ready; // No need to poll. Already scheduled.
unlock(&rc->task.mutex);

pn_raw_connection_t *raw = &rc->raw_connection;
int fd = rc->psocket.epoll_io.fd;
pni_raw_process_shutdown(raw, fd, shutr, shutw);
int wanted =
(pni_raw_can_read(raw) ? EPOLLIN : 0) |
(pni_raw_can_write(raw) ? EPOLLOUT : 0);
if (wanted) {
rc->psocket.epoll_io.wanted = wanted;
rearm_polling(&rc->psocket.epoll_io, p->epollfd); // TODO: check for error
bool finished_disconnect = raw->state==conn_fini && !ready && !raw->disconnectpending;
if (finished_disconnect) {
// If we're closed and we've sent the disconnect then close
pni_raw_finalize(raw);
praw_connection_cleanup(rc);
} else if (ready) {
// Already scheduled to run. Skip poll. Remember if we want a read.
rc->read_check = pni_raw_can_read(raw);
} else if (!rc->connected) {
// Connect logic has already armed the socket.
} else {
bool finished_disconnect = raw->state==conn_fini && !ready && !raw->disconnectpending;
if (finished_disconnect) {
// If we're closed and we've sent the disconnect then close
pni_raw_finalize(raw);
praw_connection_cleanup(rc);
// Must poll for iO.
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typo

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fixed

int wanted =
(pni_raw_can_read(raw) ? (EPOLLIN | EPOLLRDHUP) : 0) |
(pni_raw_can_write(raw) ? EPOLLOUT : 0);

// wanted == 0 implies we block until either application wake() or EPOLLHUP | EPOLLERR.
// If wanted == 0 and hup_detected, blocking not possible, so skip arming until
// application provides read buffers.
if (wanted || !rc->hup_detected) {
rc->psocket.epoll_io.wanted = wanted;
rearm_polling(&rc->psocket.epoll_io, p->epollfd); // TODO: check for error
}
}

Expand Down
2 changes: 2 additions & 0 deletions c/src/proactor/raw_connection-internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -134,9 +134,11 @@ void pni_raw_write_close(pn_raw_connection_t *conn);
void pni_raw_read(pn_raw_connection_t *conn, int sock, long (*recv)(int, void*, size_t), void (*set_error)(pn_raw_connection_t *, const char *, int));
void pni_raw_write(pn_raw_connection_t *conn, int sock, long (*send)(int, const void*, size_t), void (*set_error)(pn_raw_connection_t *, const char *, int));
void pni_raw_process_shutdown(pn_raw_connection_t *conn, int sock, int (*shutdown_rd)(int), int (*shutdown_wr)(int));
void pni_raw_async_disconnect(pn_raw_connection_t *conn);
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As this is a new event going to the raw connection state machine maybe there should be a new test for this event in raw_connection_test.

bool pni_raw_can_read(pn_raw_connection_t *conn);
bool pni_raw_can_write(pn_raw_connection_t *conn);
pn_event_t *pni_raw_event_next(pn_raw_connection_t *conn);
pn_event_t *pni_raw_event_peek(pn_raw_connection_t *conn);
void pni_raw_initialize(pn_raw_connection_t *conn);
void pni_raw_finalize(pn_raw_connection_t *conn);

Expand Down
32 changes: 29 additions & 3 deletions c/src/proactor/raw_connection.c
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Original file line number Diff line number Diff line change
Expand Up @@ -669,12 +669,14 @@ bool pni_raw_can_write(pn_raw_connection_t *conn) {
return !pni_raw_wdrained(conn) && conn->wbuffer_first_towrite;
}

pn_event_t *pni_raw_event_next(pn_raw_connection_t *conn) {
static pn_event_t *pni_get_next_raw_event(pn_raw_connection_t *conn, bool peek_only) {
// Return event if available or advance state machine event stream.
// Note that pn_collector_next increments event refcount but peek does not.
assert(conn);
do {
pn_event_t *event = pn_collector_next(conn->collector);
pn_event_t *event = peek_only ? pn_collector_peek(conn->collector) : pn_collector_next(conn->collector);
if (event) {
return pni_log_event(conn, event);
return peek_only ? event : pni_log_event(conn, event);
} else if (conn->connectpending) {
pni_raw_put_event(conn, PN_RAW_CONNECTION_CONNECTED);
conn->connectpending = false;
Expand Down Expand Up @@ -721,6 +723,14 @@ pn_event_t *pni_raw_event_next(pn_raw_connection_t *conn) {
} while (true);
}

pn_event_t *pni_raw_event_next(pn_raw_connection_t *conn) {
return pni_get_next_raw_event(conn, false);
}

pn_event_t *pni_raw_event_peek(pn_raw_connection_t *conn) {
return pni_get_next_raw_event(conn, true);
}

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I think I would refactor pni_raw_event_next differently:

  • Refactor the event generating if chain into a separate function that is called by ...next() and ...peek() (or if you follow my earlier suggestion ...has_events()
  • Then wrap that with pn_collector_next/peek logic.

Just in case it's not clear the do ... while (true) is a bit of a red herring and somewhat bad coding on my part in that there is never more than one effective pass through the loop. There can be 2 but that if only if there was no initial event. So it make more sense really to separate out the event generating logic.

Hope that is clear enough.

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done with has_events().

void pni_raw_read_close(pn_raw_connection_t *conn) {
// If already fully closed nothing to do
if (pni_raw_rwclosed(conn)) {
Expand Down Expand Up @@ -781,6 +791,22 @@ void pni_raw_close(pn_raw_connection_t *conn) {
}
}

void pni_raw_async_disconnect(pn_raw_connection_t *conn) {
if (pni_raw_rwclosed(conn))
return;

if (!pni_raw_rclosed(conn)) {
conn->state = pni_raw_new_state(conn, conn_read_closed);
conn->rclosedpending = true;
}
if (!pni_raw_wclosed(conn)) {
pni_raw_release_buffers(conn);
conn->state = pni_raw_new_state(conn, conn_write_closed);
conn->wclosedpending = true;
}
pni_raw_disconnect(conn);
}

bool pn_raw_connection_is_read_closed(pn_raw_connection_t *conn) {
assert(conn);
return pni_raw_rclosed(conn);
Expand Down
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