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Fix linux issues with epoll on normal files.

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We use the selfpipe trick if epoll fails with EPERM when trying to
register a file descriptor.
This commit is contained in:
Calvin Rose 2021-07-25 21:47:52 -05:00
parent 030dd747e9
commit eb84200f28
4 changed files with 95 additions and 60 deletions
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36
src/core/ev.c
View File

@ -1082,6 +1082,23 @@ static int make_epoll_events(int mask) {
return events;
}
static void janet_epoll_sync_callback(JanetEVGenericMessage msg) {
JanetListenerState *state = msg.argp;
JanetAsyncStatus status1 = JANET_ASYNC_STATUS_NOT_DONE;
JanetAsyncStatus status2 = JANET_ASYNC_STATUS_NOT_DONE;
if (state->stream->_mask & JANET_ASYNC_LISTEN_WRITE)
status1 = state->machine(state, JANET_ASYNC_EVENT_WRITE);
if (state->stream->_mask & JANET_ASYNC_LISTEN_WRITE)
status2 = state->machine(state, JANET_ASYNC_EVENT_READ);
if (status1 == JANET_ASYNC_STATUS_DONE ||
status2 == JANET_ASYNC_STATUS_DONE) {
janet_unlisten(state, 0);
} else {
/* Repost event */
janet_ev_post_event(NULL, janet_epoll_sync_callback, msg);
}
}
/* Wait for the next event */
JanetListenerState *janet_listen(JanetStream *stream, JanetListener behavior, int mask, size_t size, void *user) {
int is_first = !(stream->state);
@ -1095,9 +1112,23 @@ JanetListenerState *janet_listen(JanetStream *stream, JanetListener behavior, in
status = epoll_ctl(janet_vm.epoll, op, stream->handle, &ev);
} while (status == -1 && errno == EINTR);
if (status == -1) {
if (errno == EPERM) {
/* Couldn't add to event loop, so assume that it completes
* synchronously. In that case, fire the completion
* event manually, since this should be a read or write
* event to a file. So we just post a custom event to do the read/write
* asap. */
/* Use flag to indicate state is not registered in epoll */
state->_mask |= (1 << JANET_ASYNC_EVENT_COMPLETE);
JanetEVGenericMessage msg = {0};
msg.argp = state;
janet_ev_post_event(NULL, janet_epoll_sync_callback, msg);
} else {
/* Unexpected error */
janet_unlisten_impl(state, 0);
janet_panicv(janet_ev_lasterr());
}
}
return state;
}
@ -1105,6 +1136,8 @@ JanetListenerState *janet_listen(JanetStream *stream, JanetListener behavior, in
static void janet_unlisten(JanetListenerState *state, int is_gc) {
JanetStream *stream = state->stream;
if (!(stream->flags & JANET_STREAM_CLOSED)) {
/* Use flag to indicate state is not registered in epoll */
if (!(state->_mask & (1 << JANET_ASYNC_EVENT_COMPLETE))) {
int is_last = (state->_next == NULL && stream->state == state);
int op = is_last ? EPOLL_CTL_DEL : EPOLL_CTL_MOD;
struct epoll_event ev;
@ -1118,6 +1151,7 @@ static void janet_unlisten(JanetListenerState *state, int is_gc) {
janet_panicv(janet_ev_lasterr());
}
}
}
/* Destroy state machine and free memory */
janet_unlisten_impl(state, is_gc);
}
@ -1358,7 +1392,7 @@ void janet_ev_post_event(JanetVM *vm, JanetCallback cb, JanetEVGenericMessage ms
JanetSelfPipeEvent event;
event.msg = msg;
event.cb = cb;
int fd = vm->selfpipe;
int fd = vm->selfpipe[1];
/* handle a bit of back pressure before giving up. */
int tries = 4;
while (tries > 0) {

3
src/core/util.c
View File

@ -553,7 +553,8 @@ void janet_core_cfuns(JanetTable *env, const char *regprefix, const JanetReg *cf
}
void janet_core_def_sm(JanetTable *env, const char *name, Janet x, const void *p, const void *sf, int32_t sl) {
(void) sf, sl;
(void) sf;
(void) sl;
janet_core_def(env, name, x, p);
}