mirrors/janet
1
0
Fork 0
mirror of https://github.com/janet-lang/janet synced 2024-11-24 17:27:18 +00:00
Code Issues 1 Releases Wiki Activity

Address #1125 - fix ev/select to only take and release locks once.

Browse Source 
By take and releasing locks twice per channel in the case where nothing
is reading, there was an opportunity for ev/select to hang in the
multithreaded case. Also silence valgrind/helgrind errors.
This commit is contained in:
Calvin Rose 2023-05-07 11:52:11 -05:00
parent cabbaded68
commit 2360164e4f
1 changed files with 56 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

85
src/core/ev.c
View File

@ -672,19 +672,6 @@ static void janet_chan_init(JanetChannel *chan, int32_t limit, int threaded) {
janet_os_mutex_init((JanetOSMutex *) &chan->lock);
}
static void janet_chan_deinit(JanetChannel *chan) {
janet_q_deinit(&chan->read_pending);
janet_q_deinit(&chan->write_pending);
if (janet_chan_is_threaded(chan)) {
Janet item;
while (!janet_q_pop(&chan->items, &item, sizeof(item))) {
janet_chan_unpack(chan, &item, 1);
}
}
janet_q_deinit(&chan->items);
janet_os_mutex_deinit((JanetOSMutex *) &chan->lock);
}
static void janet_chan_lock(JanetChannel *chan) {
if (!janet_chan_is_threaded(chan)) return;
janet_os_mutex_lock((JanetOSMutex *) &chan->lock);
@ -695,6 +682,25 @@ static void janet_chan_unlock(JanetChannel *chan) {
janet_os_mutex_unlock((JanetOSMutex *) &chan->lock);
}
static void janet_chan_deinit(JanetChannel *chan) {
if (janet_chan_is_threaded(chan)) {
Janet item;
janet_chan_lock(chan);
janet_q_deinit(&chan->read_pending);
janet_q_deinit(&chan->write_pending);
while (!janet_q_pop(&chan->items, &item, sizeof(item))) {
janet_chan_unpack(chan, &item, 1);
}
janet_q_deinit(&chan->items);
janet_chan_unlock(chan);
} else {
janet_q_deinit(&chan->read_pending);
janet_q_deinit(&chan->write_pending);
janet_q_deinit(&chan->items);
}
janet_os_mutex_deinit((JanetOSMutex *) &chan->lock);
}
/*
* Janet Channel abstract type
*/
@ -771,6 +777,7 @@ static void janet_thread_chan_cb(JanetEVGenericMessage msg) {
int mode = msg.tag;
JanetChannel *channel = (JanetChannel *) msg.argp;
Janet x = msg.argj;
janet_chan_lock(channel);
if (fiber->sched_id == sched_id) {
if (mode == JANET_CP_MODE_CHOICE_READ) {
janet_assert(!janet_chan_unpack(channel, &x, 0), "packing error");
@ -791,7 +798,6 @@ static void janet_thread_chan_cb(JanetEVGenericMessage msg) {
int is_read = (mode == JANET_CP_MODE_CHOICE_READ) || (mode == JANET_CP_MODE_READ);
if (is_read) {
JanetChannelPending reader;
janet_chan_lock(channel);
if (!janet_q_pop(&channel->read_pending, &reader, sizeof(reader))) {
JanetVM *vm = reader.thread;
JanetEVGenericMessage msg;
@ -802,10 +808,8 @@ static void janet_thread_chan_cb(JanetEVGenericMessage msg) {
msg.argj = x;
janet_ev_post_event(vm, janet_thread_chan_cb, msg);
}
janet_chan_unlock(channel);
} else {
JanetChannelPending writer;
janet_chan_lock(channel);
if (!janet_q_pop(&channel->write_pending, &writer, sizeof(writer))) {
JanetVM *vm = writer.thread;
JanetEVGenericMessage msg;
@ -816,21 +820,21 @@ static void janet_thread_chan_cb(JanetEVGenericMessage msg) {
msg.argj = janet_wrap_nil();
janet_ev_post_event(vm, janet_thread_chan_cb, msg);
}
janet_chan_unlock(channel);
}
}
janet_chan_unlock(channel);
}
/* Push a value to a channel, and return 1 if channel should block, zero otherwise.
* If the push would block, will add to the write_pending queue in the channel.
* Handles both threaded and unthreaded channels. */
static int janet_channel_push(JanetChannel *channel, Janet x, int mode) {
static int janet_channel_push_with_lock(JanetChannel *channel, Janet x, int mode) {
JanetChannelPending reader;
int is_empty;
if (janet_chan_pack(channel, &x)) {
janet_chan_unlock(channel);
janet_panicf("failed to pack value for channel: %v", x);
}
janet_chan_lock(channel);
if (channel->closed) {
janet_chan_unlock(channel);
janet_panic("cannot write to closed channel");
@ -891,12 +895,16 @@ static int janet_channel_push(JanetChannel *channel, Janet x, int mode) {
return 0;
}
static int janet_channel_push(JanetChannel *channel, Janet x, int mode) {
janet_chan_lock(channel);
return janet_channel_push_with_lock(channel, x, mode);
}
/* Pop from a channel - returns 1 if item was obtained, 0 otherwise. The item
* is returned by reference. If the pop would block, will add to the read_pending
* queue in the channel. */
static int janet_channel_pop(JanetChannel *channel, Janet *item, int is_choice) {
static int janet_channel_pop_with_lock(JanetChannel *channel, Janet *item, int is_choice) {
JanetChannelPending writer;
janet_chan_lock(channel);
if (channel->closed) {
janet_chan_unlock(channel);
*item = janet_wrap_nil();
@ -941,6 +949,11 @@ static int janet_channel_pop(JanetChannel *channel, Janet *item, int is_choice)
return 1;
}
static int janet_channel_pop(JanetChannel *channel, Janet *item, int is_choice) {
janet_chan_lock(channel);
return janet_channel_pop_with_lock(channel, item, is_choice);
}
JanetChannel *janet_channel_unwrap(void *abstract) {
return abstract;
}
@ -983,6 +996,20 @@ JANET_CORE_FN(cfun_channel_pop,
janet_await();
}
static void chan_unlock_args(const Janet *argv, int32_t n) {
for (int32_t i = 0; i < n; i++) {
int32_t len;
const Janet *data;
JanetChannel *chan;
if (janet_indexed_view(argv[i], &data, &len) && len == 2) {
chan = janet_getchannel(data, 0);
} else {
chan = janet_getchannel(argv, i);
}
janet_chan_unlock(chan);
}
}
JANET_CORE_FN(cfun_channel_choice,
"(ev/select & clauses)",
"Block until the first of several channel operations occur. Returns a tuple of the form [:give chan], [:take chan x], or [:close chan], where "
@ -1002,29 +1029,29 @@ JANET_CORE_FN(cfun_channel_choice,
janet_chan_lock(chan);
if (chan->closed) {
janet_chan_unlock(chan);
chan_unlock_args(argv, i);
return make_close_result(chan);
}
if (janet_q_count(&chan->items) < chan->limit) {
janet_chan_unlock(chan);
janet_channel_push(chan, data[1], 1);
janet_channel_push_with_lock(chan, data[1], 1);
chan_unlock_args(argv, i);
return make_write_result(chan);
}
janet_chan_unlock(chan);
} else {
/* Read */
JanetChannel *chan = janet_getchannel(argv, i);
janet_chan_lock(chan);
if (chan->closed) {
janet_chan_unlock(chan);
chan_unlock_args(argv, i);
return make_close_result(chan);
}
if (chan->items.head != chan->items.tail) {
Janet item;
janet_chan_unlock(chan);
janet_channel_pop(chan, &item, 1);
janet_channel_pop_with_lock(chan, &item, 1);
chan_unlock_args(argv, i);
return make_read_result(chan, item);
}
janet_chan_unlock(chan);
}
}
@ -1033,12 +1060,12 @@ JANET_CORE_FN(cfun_channel_choice,
if (janet_indexed_view(argv[i], &data, &len) && len == 2) {
/* Write */
JanetChannel *chan = janet_getchannel(data, 0);
janet_channel_push(chan, data[1], 1);
janet_channel_push_with_lock(chan, data[1], 1);
} else {
/* Read */
Janet item;
JanetChannel *chan = janet_getchannel(argv, i);
janet_channel_pop(chan, &item, 1);
janet_channel_pop_with_lock(chan, &item, 1);
}
}