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Working implementation of process waiting with threads.

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Does not require all sorts of signal handling code
that is not thread-safe and can "steal processes".

However, there is a much simpler way to add this functionality
by creating a new stream and thread for each subprocess when it is
waited on. This is perhaps _slightly_ less efficient but oh so much
simpler, since we can reuse all of our concepts from streams and there
is no need to implement a whole system around the selfpipe.
This commit is contained in:
Calvin Rose
2020-12-31 11:22:18 -06:00
parent 9e42ee153c
commit c831ecf5d2
3 changed files with 97 additions and 31 deletions
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51
src/core/ev.c
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@@ -880,7 +880,7 @@ void janet_loop(void) {
}
/*
* Signal handling code.
* Self-pipe handling code.
*/
#ifdef JANET_WINDOWS
@@ -889,43 +889,34 @@ void janet_loop(void) {
JANET_THREAD_LOCAL int janet_vm_selfpipe[2];
static void janet_ev_handle_signals(void) {
int sig = 0;
while (read(janet_vm_selfpipe[0], &sig, sizeof(sig)) > 0) {
switch (sig) {
/* Handle events from the self pipe inside the event loop */
static void janet_ev_handle_selfpipe(void) {
JanetSelfPipeEvent ev;
while (read(janet_vm_selfpipe[0], &ev, sizeof(ev)) > 0) {
switch (ev.tag) {
default:
break;
case SIGCHLD:
{
int status = 0;
pid_t pid = waitpid(-1, &status, WNOHANG | WUNTRACED);
/* invalid pid on failure will do no harm */
janet_schedule_pid(pid, status);
}
case JANET_SELFPIPE_PROC:
janet_schedule_pid(ev.as.proc.pid, ev.as.proc.status);
break;
}
}
}
static void janet_sig_handler(int sig) {
int result = write(janet_vm_selfpipe[1], &sig, sizeof(sig));
if (result) {
/* Failed to handle signal. */
;
}
signal(sig, janet_sig_handler);
}
static void janet_ev_setup_signals(void) {
static void janet_ev_setup_selfpipe(void) {
if (-1 == pipe(janet_vm_selfpipe)) goto error;
if (fcntl(janet_vm_selfpipe[0], F_SETFL, O_NONBLOCK)) goto error;
if (fcntl(janet_vm_selfpipe[1], F_SETFL, O_NONBLOCK)) goto error;
signal(SIGCHLD, janet_sig_handler);
return;
error:
JANET_EXIT("failed to initialize self pipe in event loop");
}
static void janet_ev_cleanup_selfpipe(void) {
close(janet_vm_selfpipe[0]);
close(janet_vm_selfpipe[1]);
}
#endif
#ifdef JANET_WINDOWS
@@ -1099,8 +1090,8 @@ void janet_loop1_impl(int has_timeout, JanetTimestamp timeout) {
if (&janet_vm_timerfd == p) {
/* Timer expired, ignore */;
} else if (janet_vm_selfpipe == p) {
/* Signal */
janet_ev_handle_signals();
/* Self-pipe handling */
janet_ev_handle_selfpipe();
} else {
JanetStream *stream = p;
int mask = events[i].events;
@@ -1133,7 +1124,7 @@ void janet_loop1_impl(int has_timeout, JanetTimestamp timeout) {
void janet_ev_init(void) {
janet_ev_init_common();
janet_ev_setup_signals();
janet_ev_setup_selfpipe();
janet_vm_epoll = epoll_create1(EPOLL_CLOEXEC);
janet_vm_timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC | TFD_NONBLOCK);
janet_vm_timer_enabled = 0;
@@ -1154,6 +1145,7 @@ void janet_ev_deinit(void) {
janet_ev_deinit_common();
close(janet_vm_epoll);
close(janet_vm_timerfd);
janet_ev_cleanup_selfpipe();
janet_vm_epoll = 0;
}
@@ -1226,7 +1218,7 @@ void janet_loop1_impl(int has_timeout, JanetTimestamp timeout) {
/* Check selfpipe */
if (janet_vm_fds[0].revents & POLLIN) {
janet_vm_fds[0].revents = 0;
janet_ev_handle_signals();
janet_ev_handle_selfpipe();
}
/* Step state machines */
@@ -1260,7 +1252,7 @@ void janet_loop1_impl(int has_timeout, JanetTimestamp timeout) {
void janet_ev_init(void) {
janet_ev_init_common();
janet_vm_fds = NULL;
janet_ev_setup_signals();
janet_ev_setup_selfpipe();
janet_vm_fds = malloc(sizeof(struct pollfd));
if (NULL == janet_vm_fds) {
JANET_OUT_OF_MEMORY;
@@ -1273,9 +1265,8 @@ void janet_ev_init(void) {
void janet_ev_deinit(void) {
janet_ev_deinit_common();
janet_ev_cleanup_selfpipe();
free(janet_vm_fds);
close(janet_vm_selfpipe[0]);
close(janet_vm_selfpipe[1]);
janet_vm_fds = NULL;
}