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Don't crash when new threads can't be created

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Přemysl Eric Janouch 2016-01-16 06:00:41 +01:00
parent a90aeaf0d9
commit 38d105dede
1 changed files with 59 additions and 5 deletions
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64
liberty.c
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@ -1073,6 +1073,7 @@ struct async
// "cancelled" may not be accesed or modified by the worker thread
pthread_t worker; ///< Worker thread ID
bool started; ///< Worker thread ID is valid
bool cancelled; ///< Task has been cancelled
async_fn execute; ///< Worker main function
@ -1087,6 +1088,8 @@ async_init (struct async *self, struct async_manager *manager)
self->manager = manager;
}
static bool async_run (struct async *self);
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
struct async_manager
@ -1095,6 +1098,12 @@ struct async_manager
struct async *running; ///< Queue of running jobs
struct async *finished; ///< Queue of completed/cancelled jobs
// It's upon the user to call async_manager_dispatch() to retry the delayed.
// It's somewhat questionable if this feature is of any use. Possibly if we
// provide a means of actively limiting the amount of running async jobs.
struct async *delayed; ///< Resource exhaustion queue
// We need the pipe in order to abort polling (instead of using EINTR)
pthread_cond_t finished_cond; ///< Signals that a task has finished
@ -1114,6 +1123,18 @@ async_manager_init (struct async_manager *self)
set_cloexec (self->finished_pipe[1]);
}
static bool
async_manager_retry (struct async_manager *self, struct async *async)
{
if (async->cancelled)
{
if (async->destroy)
async->destroy (async);
return true;
}
return async_run (async);
}
static struct async *
async_manager_dispatch_fetch (struct async_manager *self)
{
@ -1145,6 +1166,13 @@ async_manager_dispatch (struct async_manager *self)
if (iter->destroy)
iter->destroy (iter);
}
LIST_FOR_EACH (struct async, iter, self->delayed)
{
LIST_UNLINK (self->delayed, iter);
if (!async_manager_retry (self, iter))
break;
}
}
static void
@ -1164,6 +1192,8 @@ async_manager_cancel_all (struct async_manager *self)
// Mark everything cancelled so that it's not actually dispatched
LIST_FOR_EACH (struct async, iter, self->finished)
iter->cancelled = true;
LIST_FOR_EACH (struct async, iter, self->delayed)
iter->cancelled = true;
hard_assert (!pthread_mutex_unlock (&self->lock));
async_manager_dispatch (self);
@ -1187,7 +1217,8 @@ async_manager_free (struct async_manager *self)
static void
async_cancel (struct async *self)
{
soft_assert (!pthread_cancel (self->worker));
if (self->started)
soft_assert (!pthread_cancel (self->worker));
self->cancelled = true;
}
@ -1219,7 +1250,7 @@ async_routine (void *user_data)
return NULL;
}
static void
static bool
async_run (struct async *self)
{
hard_assert (!pthread_mutex_lock (&self->manager->lock));
@ -1231,11 +1262,24 @@ async_run (struct async *self)
hard_assert (!sigfillset (&all_blocked));
hard_assert (!pthread_sigmask (SIG_SETMASK, &all_blocked, &old_blocked));
hard_assert (!pthread_create (&self->worker, NULL,
async_routine, self));
int error = pthread_create (&self->worker, NULL, async_routine, self);
// Now that we've created the thread, resume signal processing as usual
hard_assert (!pthread_sigmask (SIG_SETMASK, &old_blocked, NULL));
if (error)
{
hard_assert (error == EAGAIN);
hard_assert (!pthread_mutex_lock (&self->manager->lock));
LIST_UNLINK (self->manager->running, self);
hard_assert (!pthread_mutex_unlock (&self->manager->lock));
// FIXME: we probably want to have some kind of a limit on the queue
LIST_PREPEND (self->manager->delayed, self);
return false;
}
return (self->started = true);
}
#endif // LIBERTY_WANT_ASYNC
@ -2138,7 +2182,17 @@ poller_common_free (struct poller_common *self)
static int
poller_common_get_timeout (struct poller_common *self)
{
return self->idle ? 0 : poller_timers_get_poll_timeout (&self->timers);
if (self->idle)
return 0;
int timeout = poller_timers_get_poll_timeout (&self->timers);
#ifdef LIBERTY_WANT_ASYNC
// This is completely arbitrary, in general we have no idea when to retry,
// however one second doesn't sound like a particularly bad number
if (self->async.delayed)
timeout = MIN (timeout, 1000);
#endif // LIBERTY_WANT_ASYNC
return timeout;
}
static void