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ruby/thread_pthread.c

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/* -*-c-*- */
/**********************************************************************
thread_pthread.c -
$Author$
Copyright (C) 2004-2007 Koichi Sasada
**********************************************************************/
#ifdef THREAD_SYSTEM_DEPENDENT_IMPLEMENTATION
#include "gc.h"
#include "mjit.h"
#ifdef HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#endif
#ifdef HAVE_THR_STKSEGMENT
#include <thread.h>
#endif
#if defined(HAVE_FCNTL_H)
#include <fcntl.h>
#elif defined(HAVE_SYS_FCNTL_H)
#include <sys/fcntl.h>
#endif
#ifdef HAVE_SYS_PRCTL_H
#include <sys/prctl.h>
#endif
#if defined(HAVE_SYS_TIME_H)
#include <sys/time.h>
#endif
#if defined(__HAIKU__)
#include <kernel/OS.h>
#endif
#ifdef __linux__
#include <sys/syscall.h> /* for SYS_gettid */
#endif
#include <time.h>
#include <signal.h>
#if defined __APPLE__
# include <AvailabilityMacros.h>
#endif
#if defined(HAVE_SYS_EVENTFD_H) && defined(HAVE_EVENTFD)
# define USE_EVENTFD (1)
# include <sys/eventfd.h>
#else
# define USE_EVENTFD (0)
#endif
#if defined(SIGVTALRM) && !defined(__CYGWIN__) && !defined(__EMSCRIPTEN__)
# define USE_UBF_LIST 1
#endif
/*
* UBF_TIMER and ubf_list both use SIGVTALRM.
*
* UBF_TIMER has NOTHING to do with thread timeslices (TIMER_INTERRUPT_MASK)
*
* UBF_TIMER is to close TOCTTOU signal race on programs where we
* cannot rely on GVL contention (vm->gvl.timer) to perform wakeups
* while a thread is doing blocking I/O on sockets or pipes. With
* rb_thread_call_without_gvl and similar functions:
*
* (1) Check interrupts.
* (2) release GVL.
* (2a) signal received
* (3) call func with data1 (blocks for a long time without ubf_timer)
* (4) acquire GVL.
* Other Ruby threads can not run in parallel any more.
* (5) Check interrupts.
*
* We need UBF_TIMER to break out of (3) if (2a) happens.
*
* ubf_list wakeups may be triggered on gvl_yield.
*
* If we have vm->gvl.timer (on GVL contention), we don't need UBF_TIMER
* as it can perform the same tasks while doing timeslices.
*/
#define UBF_TIMER_NONE 0
#define UBF_TIMER_POSIX 1
#define UBF_TIMER_PTHREAD 2
#ifndef UBF_TIMER
# if defined(HAVE_TIMER_SETTIME) && defined(HAVE_TIMER_CREATE) && \
defined(CLOCK_MONOTONIC) && defined(USE_UBF_LIST)
/* preferred */
# define UBF_TIMER UBF_TIMER_POSIX
# elif defined(USE_UBF_LIST)
/* safe, but inefficient */
# define UBF_TIMER UBF_TIMER_PTHREAD
# else
/* we'll be racy without SIGVTALRM for ubf_list */
# define UBF_TIMER UBF_TIMER_NONE
# endif
#endif
struct rb_internal_thread_event_hook {
rb_internal_thread_event_callback callback;
rb_event_flag_t event;
void *user_data;
struct rb_internal_thread_event_hook *next;
};
static rb_internal_thread_event_hook_t *rb_internal_thread_event_hooks = NULL;
static pthread_rwlock_t rb_internal_thread_event_hooks_rw_lock = PTHREAD_RWLOCK_INITIALIZER;
#define RB_INTERNAL_THREAD_HOOK(event) if (rb_internal_thread_event_hooks) { rb_thread_execute_hooks(event); }
rb_internal_thread_event_hook_t *
rb_internal_thread_add_event_hook(rb_internal_thread_event_callback callback, rb_event_flag_t internal_event, void *user_data)
{
rb_internal_thread_event_hook_t *hook = ALLOC_N(rb_internal_thread_event_hook_t, 1);
hook->callback = callback;
hook->user_data = user_data;
hook->event = internal_event;
int r;
if ((r = pthread_rwlock_wrlock(&rb_internal_thread_event_hooks_rw_lock))) {
rb_bug_errno("pthread_rwlock_wrlock", r);
}
hook->next = rb_internal_thread_event_hooks;
ATOMIC_PTR_EXCHANGE(rb_internal_thread_event_hooks, hook);
if ((r = pthread_rwlock_unlock(&rb_internal_thread_event_hooks_rw_lock))) {
rb_bug_errno("pthread_rwlock_unlock", r);
}
return hook;
}
bool
rb_internal_thread_remove_event_hook(rb_internal_thread_event_hook_t * hook)
{
int r;
if ((r = pthread_rwlock_wrlock(&rb_internal_thread_event_hooks_rw_lock))) {
rb_bug_errno("pthread_rwlock_wrlock", r);
}
bool success = FALSE;
if (rb_internal_thread_event_hooks == hook) {
ATOMIC_PTR_EXCHANGE(rb_internal_thread_event_hooks, hook->next);
success = TRUE;
} else {
rb_internal_thread_event_hook_t *h = rb_internal_thread_event_hooks;
do {
if (h->next == hook) {
h->next = hook->next;
success = TRUE;
break;
}
} while ((h = h->next));
}
if ((r = pthread_rwlock_unlock(&rb_internal_thread_event_hooks_rw_lock))) {
rb_bug_errno("pthread_rwlock_unlock", r);
}
if (success) {
ruby_xfree(hook);
}
return success;
}
static void
rb_thread_execute_hooks(rb_event_flag_t event)
{
int r;
if ((r = pthread_rwlock_rdlock(&rb_internal_thread_event_hooks_rw_lock))) {
rb_bug_errno("pthread_rwlock_rdlock", r);
}
if (rb_internal_thread_event_hooks) {
rb_internal_thread_event_hook_t *h = rb_internal_thread_event_hooks;
do {
if (h->event & event) {
(*h->callback)(event, NULL, h->user_data);
}
} while((h = h->next));
}
if ((r = pthread_rwlock_unlock(&rb_internal_thread_event_hooks_rw_lock))) {
rb_bug_errno("pthread_rwlock_unlock", r);
}
}
enum rtimer_state {
/* alive, after timer_create: */
RTIMER_DISARM,
RTIMER_ARMING,
RTIMER_ARMED,
RTIMER_DEAD
};
#if UBF_TIMER == UBF_TIMER_POSIX
static const struct itimerspec zero;
static struct {
rb_atomic_t state_; /* rtimer_state */
rb_pid_t owner;
timer_t timerid;
} timer_posix = {
/* .state = */ RTIMER_DEAD,
};
#define TIMER_STATE_DEBUG 0
static const char *
rtimer_state_name(enum rtimer_state state)
{
switch (state) {
case RTIMER_DISARM: return "disarm";
case RTIMER_ARMING: return "arming";
case RTIMER_ARMED: return "armed";
case RTIMER_DEAD: return "dead";
default: rb_bug("unreachable");
}
}
static enum rtimer_state
timer_state_exchange(enum rtimer_state state)
{
enum rtimer_state prev = ATOMIC_EXCHANGE(timer_posix.state_, state);
if (TIMER_STATE_DEBUG) fprintf(stderr, "state (exc): %s->%s\n", rtimer_state_name(prev), rtimer_state_name(state));
return prev;
}
static enum rtimer_state
timer_state_cas(enum rtimer_state expected_prev, enum rtimer_state state)
{
enum rtimer_state prev = ATOMIC_CAS(timer_posix.state_, expected_prev, state);
if (TIMER_STATE_DEBUG) {
if (prev == expected_prev) {
fprintf(stderr, "state (cas): %s->%s\n", rtimer_state_name(prev), rtimer_state_name(state));
}
else {
fprintf(stderr, "state (cas): %s (expected:%s)\n", rtimer_state_name(prev), rtimer_state_name(expected_prev));
}
}
return prev;
}
#elif UBF_TIMER == UBF_TIMER_PTHREAD
static void *timer_pthread_fn(void *);
static struct {
int low[2];
rb_atomic_t armed; /* boolean */
rb_pid_t owner;
pthread_t thid;
} timer_pthread = {
{ -1, -1 },
};
#endif
static const rb_hrtime_t *sigwait_timeout(rb_thread_t *, int sigwait_fd,
const rb_hrtime_t *,
int *drained_p);
static void ubf_timer_disarm(void);
static void threadptr_trap_interrupt(rb_thread_t *);
static void ubf_wakeup_all_threads(void);
static int ubf_threads_empty(void);
#define TIMER_THREAD_CREATED_P() (signal_self_pipe.owner_process == getpid())
/* for testing, and in case we come across a platform w/o pipes: */
#define BUSY_WAIT_SIGNALS (0)
/*
* sigwait_th is the thread which owns sigwait_fd and sleeps on it
* (using ppoll). MJIT worker can be sigwait_th==0, so we initialize
* it to THREAD_INVALID at startup and fork time. It is the ONLY thread
* allowed to read from sigwait_fd, otherwise starvation can occur.
*/
#define THREAD_INVALID ((const rb_thread_t *)-1)
static const rb_thread_t *sigwait_th;
#ifdef HAVE_SCHED_YIELD
#define native_thread_yield() (void)sched_yield()
#else
#define native_thread_yield() ((void)0)
#endif
#if defined(HAVE_PTHREAD_CONDATTR_SETCLOCK) && \
defined(CLOCK_REALTIME) && defined(CLOCK_MONOTONIC) && \
defined(HAVE_CLOCK_GETTIME)
static pthread_condattr_t condattr_mono;
static pthread_condattr_t *condattr_monotonic = &condattr_mono;
#else
static const void *const condattr_monotonic = NULL;
#endif
/* 100ms. 10ms is too small for user level thread scheduling
* on recent Linux (tested on 2.6.35)
*/
#define TIME_QUANTUM_MSEC (100)
#define TIME_QUANTUM_USEC (TIME_QUANTUM_MSEC * 1000)
#define TIME_QUANTUM_NSEC (TIME_QUANTUM_USEC * 1000)
static rb_hrtime_t native_cond_timeout(rb_nativethread_cond_t *, rb_hrtime_t);
static int native_cond_timedwait(rb_nativethread_cond_t *cond, pthread_mutex_t *mutex, const rb_hrtime_t *abs);
/*
* Designate the next sched.timer thread, favor the last thread in
* the readyq since it will be in readyq longest
*/
static int
designate_timer_thread(struct rb_thread_sched *sched)
{
rb_thread_t *last;
last = ccan_list_tail(&sched->readyq, rb_thread_t, sched.node.readyq);
if (last) {
rb_native_cond_signal(&last->nt->cond.readyq);
return TRUE;
}
else {
return FALSE;
}
}
/*
* We become designated timer thread to kick vm->gvl.owner
* periodically. Continue on old timeout if it expired.
*/
static void
do_gvl_timer(struct rb_thread_sched *sched, rb_thread_t *th)
{
rb_vm_t *vm = GET_VM();
static rb_hrtime_t abs;
sched->timer = th;
/* take over wakeups from UBF_TIMER */
ubf_timer_disarm();
if (sched->timer_err == ETIMEDOUT) {
abs = native_cond_timeout(&th->nt->cond.readyq, TIME_QUANTUM_NSEC);
}
sched->timer_err = native_cond_timedwait(&th->nt->cond.readyq, &sched->lock, &abs);
ubf_wakeup_all_threads();
ruby_sigchld_handler(vm);
if (UNLIKELY(rb_signal_buff_size())) {
if (th == vm->ractor.main_thread) {
RUBY_VM_SET_TRAP_INTERRUPT(th->ec);
}
else {
threadptr_trap_interrupt(vm->ractor.main_thread);
}
}
/*
* Timeslice. Warning: the process may fork while this
* thread is contending for GVL:
*/
const rb_thread_t *running;
if ((running = sched->running) != 0) {
// strictly speaking, accessing "running" is not thread-safe
RUBY_VM_SET_TIMER_INTERRUPT(running->ec);
}
sched->timer = 0;
}
static void
thread_sched_to_ready_common(struct rb_thread_sched *sched, rb_thread_t *th)
{
ccan_list_add_tail(&sched->readyq, &th->sched.node.readyq);
}
static void
thread_sched_to_running_common(struct rb_thread_sched *sched, rb_thread_t *th)
{
RB_INTERNAL_THREAD_HOOK(RUBY_INTERNAL_THREAD_EVENT_READY);
if (sched->running) {
VM_ASSERT(th->unblock.func == 0 &&
"we must not be in ubf_list and GVL readyq at the same time");
// waiting -> ready
thread_sched_to_ready_common(sched, th);
// wait for running chance
do {
if (!sched->timer) {
do_gvl_timer(sched, th);
}
else {
rb_native_cond_wait(&th->nt->cond.readyq, &sched->lock);
}
} while (sched->running);
ccan_list_del_init(&th->sched.node.readyq);
if (sched->need_yield) {
sched->need_yield = 0;
rb_native_cond_signal(&sched->switch_cond);
}
}
else { /* reset timer if uncontended */
sched->timer_err = ETIMEDOUT;
}
// ready -> running
sched->running = th;
RB_INTERNAL_THREAD_HOOK(RUBY_INTERNAL_THREAD_EVENT_RESUMED);
if (!sched->timer) {
if (!designate_timer_thread(sched) && !ubf_threads_empty()) {
rb_thread_wakeup_timer_thread(-1);
}
}
}
static void
thread_sched_to_running(struct rb_thread_sched *sched, rb_thread_t *th)
{
rb_native_mutex_lock(&sched->lock);
thread_sched_to_running_common(sched, th);
rb_native_mutex_unlock(&sched->lock);
}
static rb_thread_t *
thread_sched_to_waiting_common(struct rb_thread_sched *sched)
{
rb_thread_t *next;
sched->running = NULL;
next = ccan_list_top(&sched->readyq, rb_thread_t, sched.node.readyq);
if (next) rb_native_cond_signal(&next->nt->cond.readyq);
return next;
}
static void
thread_sched_to_waiting(struct rb_thread_sched *sched)
{
RB_INTERNAL_THREAD_HOOK(RUBY_INTERNAL_THREAD_EVENT_SUSPENDED);
rb_native_mutex_lock(&sched->lock);
thread_sched_to_waiting_common(sched);
rb_native_mutex_unlock(&sched->lock);
}
static void
thread_sched_to_dead(struct rb_thread_sched *sched)
{
thread_sched_to_waiting(sched);
RB_INTERNAL_THREAD_HOOK(RUBY_INTERNAL_THREAD_EVENT_EXITED);
}
static void
thread_sched_yield(struct rb_thread_sched *sched, rb_thread_t *th)
{
rb_thread_t *next;
/*
* Perhaps other threads are stuck in blocking region w/o GVL, too,
* (perhaps looping in io_close_fptr) so we kick them:
*/
ubf_wakeup_all_threads();
rb_native_mutex_lock(&sched->lock);
next = thread_sched_to_waiting_common(sched);
/* An another thread is processing GVL yield. */
if (UNLIKELY(sched->wait_yield)) {
while (sched->wait_yield)
rb_native_cond_wait(&sched->switch_wait_cond, &sched->lock);
}
else if (next) {
/* Wait until another thread task takes GVL. */
sched->need_yield = 1;
sched->wait_yield = 1;
while (sched->need_yield)
rb_native_cond_wait(&sched->switch_cond, &sched->lock);
sched->wait_yield = 0;
rb_native_cond_broadcast(&sched->switch_wait_cond);
}
else {
rb_native_mutex_unlock(&sched->lock);
native_thread_yield();
rb_native_mutex_lock(&sched->lock);
rb_native_cond_broadcast(&sched->switch_wait_cond);
}
thread_sched_to_running_common(sched, th);
rb_native_mutex_unlock(&sched->lock);
}
void
rb_thread_sched_init(struct rb_thread_sched *sched)
{
rb_native_mutex_initialize(&sched->lock);
rb_native_cond_initialize(&sched->switch_cond);
rb_native_cond_initialize(&sched->switch_wait_cond);
ccan_list_head_init(&sched->readyq);
sched->running = NULL;
sched->timer = 0;
sched->timer_err = ETIMEDOUT;
sched->need_yield = 0;
sched->wait_yield = 0;
}
#if 0
// TODO
static void clear_thread_cache_altstack(void);
static void
rb_thread_sched_destroy(struct rb_thread_sched *sched)
{
/*
* only called once at VM shutdown (not atfork), another thread
* may still grab vm->gvl.lock when calling gvl_release at
* the end of thread_start_func_2
*/
if (0) {
rb_native_cond_destroy(&sched->switch_wait_cond);
rb_native_cond_destroy(&sched->switch_cond);
rb_native_mutex_destroy(&sched->lock);
}
clear_thread_cache_altstack();
}
#endif
#if defined(HAVE_WORKING_FORK)
static void thread_cache_reset(void);
static void
thread_sched_atfork(struct rb_thread_sched *sched)
{
thread_cache_reset();
rb_thread_sched_init(sched);
thread_sched_to_running(sched, GET_THREAD());
}
#endif
#define NATIVE_MUTEX_LOCK_DEBUG 0
static void
mutex_debug(const char *msg, void *lock)
{
if (NATIVE_MUTEX_LOCK_DEBUG) {
int r;
static pthread_mutex_t dbglock = PTHREAD_MUTEX_INITIALIZER;
if ((r = pthread_mutex_lock(&dbglock)) != 0) {exit(EXIT_FAILURE);}
fprintf(stdout, "%s: %p\n", msg, lock);
if ((r = pthread_mutex_unlock(&dbglock)) != 0) {exit(EXIT_FAILURE);}
}
}
void
rb_native_mutex_lock(pthread_mutex_t *lock)
{
int r;
mutex_debug("lock", lock);
if ((r = pthread_mutex_lock(lock)) != 0) {
rb_bug_errno("pthread_mutex_lock", r);
}
}
void
rb_native_mutex_unlock(pthread_mutex_t *lock)
{
int r;
mutex_debug("unlock", lock);
if ((r = pthread_mutex_unlock(lock)) != 0) {
rb_bug_errno("pthread_mutex_unlock", r);
}
}
int
rb_native_mutex_trylock(pthread_mutex_t *lock)
{
int r;
mutex_debug("trylock", lock);
if ((r = pthread_mutex_trylock(lock)) != 0) {
if (r == EBUSY) {
return EBUSY;
}
else {
rb_bug_errno("pthread_mutex_trylock", r);
}
}
return 0;
}
void
rb_native_mutex_initialize(pthread_mutex_t *lock)
{
int r = pthread_mutex_init(lock, 0);
mutex_debug("init", lock);
if (r != 0) {
rb_bug_errno("pthread_mutex_init", r);
}
}
void
rb_native_mutex_destroy(pthread_mutex_t *lock)
{
int r = pthread_mutex_destroy(lock);
mutex_debug("destroy", lock);
if (r != 0) {
rb_bug_errno("pthread_mutex_destroy", r);
}
}
void
rb_native_cond_initialize(rb_nativethread_cond_t *cond)
{
int r = pthread_cond_init(cond, condattr_monotonic);
if (r != 0) {
rb_bug_errno("pthread_cond_init", r);
}
}
void
rb_native_cond_destroy(rb_nativethread_cond_t *cond)
{
int r = pthread_cond_destroy(cond);
if (r != 0) {
rb_bug_errno("pthread_cond_destroy", r);
}
}
/*
* In OS X 10.7 (Lion), pthread_cond_signal and pthread_cond_broadcast return
* EAGAIN after retrying 8192 times. You can see them in the following page:
*
* http://www.opensource.apple.com/source/Libc/Libc-763.11/pthreads/pthread_cond.c
*
* The following rb_native_cond_signal and rb_native_cond_broadcast functions
* need to retrying until pthread functions don't return EAGAIN.
*/
void
rb_native_cond_signal(rb_nativethread_cond_t *cond)
{
int r;
do {
r = pthread_cond_signal(cond);
} while (r == EAGAIN);
if (r != 0) {
rb_bug_errno("pthread_cond_signal", r);
}
}
void
rb_native_cond_broadcast(rb_nativethread_cond_t *cond)
{
int r;
do {
r = pthread_cond_broadcast(cond);
} while (r == EAGAIN);
if (r != 0) {
rb_bug_errno("rb_native_cond_broadcast", r);
}
}
void
rb_native_cond_wait(rb_nativethread_cond_t *cond, pthread_mutex_t *mutex)
{
int r = pthread_cond_wait(cond, mutex);
if (r != 0) {
rb_bug_errno("pthread_cond_wait", r);
}
}
static int
native_cond_timedwait(rb_nativethread_cond_t *cond, pthread_mutex_t *mutex, const rb_hrtime_t *abs)
{
int r;
struct timespec ts;
/*
* An old Linux may return EINTR. Even though POSIX says
* "These functions shall not return an error code of [EINTR]".
* http://pubs.opengroup.org/onlinepubs/009695399/functions/pthread_cond_timedwait.html
* Let's hide it from arch generic code.
*/
do {
rb_hrtime2timespec(&ts, abs);
r = pthread_cond_timedwait(cond, mutex, &ts);
} while (r == EINTR);
if (r != 0 && r != ETIMEDOUT) {
rb_bug_errno("pthread_cond_timedwait", r);
}
return r;
}
void
rb_native_cond_timedwait(rb_nativethread_cond_t *cond, pthread_mutex_t *mutex, unsigned long msec)
{
rb_hrtime_t hrmsec = native_cond_timeout(cond, RB_HRTIME_PER_MSEC * msec);
native_cond_timedwait(cond, mutex, &hrmsec);
}
static rb_hrtime_t
native_cond_timeout(rb_nativethread_cond_t *cond, const rb_hrtime_t rel)
{
if (condattr_monotonic) {
return rb_hrtime_add(rb_hrtime_now(), rel);
}
else {
struct timespec ts;
rb_timespec_now(&ts);
return rb_hrtime_add(rb_timespec2hrtime(&ts), rel);
}
}
#define native_cleanup_push pthread_cleanup_push
#define native_cleanup_pop pthread_cleanup_pop
#ifdef RB_THREAD_LOCAL_SPECIFIER
static RB_THREAD_LOCAL_SPECIFIER rb_thread_t *ruby_native_thread;
#else
static pthread_key_t ruby_native_thread_key;
#endif
static void
null_func(int i)
{
/* null */
}
rb_thread_t *
ruby_thread_from_native(void)
{
#ifdef RB_THREAD_LOCAL_SPECIFIER
return ruby_native_thread;
#else
return pthread_getspecific(ruby_native_thread_key);
#endif
}
int
ruby_thread_set_native(rb_thread_t *th)
{
if (th) {
#ifdef USE_UBF_LIST
ccan_list_node_init(&th->sched.node.ubf);
#endif
}
// setup TLS
if (th && th->ec) {
rb_ractor_set_current_ec(th->ractor, th->ec);
}
#ifdef RB_THREAD_LOCAL_SPECIFIER
ruby_native_thread = th;
return 1;
#else
return pthread_setspecific(ruby_native_thread_key, th) == 0;
#endif
}
#ifdef RB_THREAD_T_HAS_NATIVE_ID
static int
get_native_thread_id(void)
{
#ifdef __linux__
return (int)syscall(SYS_gettid);
#elif defined(__FreeBSD__)
return pthread_getthreadid_np();
#endif
}
#endif
static void
native_thread_init(struct rb_native_thread *nt)
{
#ifdef RB_THREAD_T_HAS_NATIVE_ID
nt->tid = get_native_thread_id();
#endif
rb_native_cond_initialize(&nt->cond.readyq);
if (&nt->cond.readyq != &nt->cond.intr)
rb_native_cond_initialize(&nt->cond.intr);
}
void
Init_native_thread(rb_thread_t *main_th)
{
#if defined(HAVE_PTHREAD_CONDATTR_SETCLOCK)
if (condattr_monotonic) {
int r = pthread_condattr_init(condattr_monotonic);
if (r == 0) {
r = pthread_condattr_setclock(condattr_monotonic, CLOCK_MONOTONIC);
}
if (r) condattr_monotonic = NULL;
}
#endif
#ifndef RB_THREAD_LOCAL_SPECIFIER
if (pthread_key_create(&ruby_native_thread_key, 0) == EAGAIN) {
rb_bug("pthread_key_create failed (ruby_native_thread_key)");
}
if (pthread_key_create(&ruby_current_ec_key, 0) == EAGAIN) {
rb_bug("pthread_key_create failed (ruby_current_ec_key)");
}
#endif
posix_signal(SIGVTALRM, null_func);
// setup main thread
main_th->nt->thread_id = pthread_self();
ruby_thread_set_native(main_th);
native_thread_init(main_th->nt);
}
#ifndef USE_THREAD_CACHE
#define USE_THREAD_CACHE 1
#endif
static void
native_thread_destroy(rb_thread_t *th)
{
struct rb_native_thread *nt = th->nt;
rb_native_cond_destroy(&nt->cond.readyq);
if (&nt->cond.readyq != &nt->cond.intr)
rb_native_cond_destroy(&nt->cond.intr);
/*
* prevent false positive from ruby_thread_has_gvl_p if that
* gets called from an interposing function wrapper
*/
if (USE_THREAD_CACHE)
ruby_thread_set_native(0);
}
#if USE_THREAD_CACHE
static rb_thread_t *register_cached_thread_and_wait(void *);
#endif
#if defined HAVE_PTHREAD_GETATTR_NP || defined HAVE_PTHREAD_ATTR_GET_NP
#define STACKADDR_AVAILABLE 1
#elif defined HAVE_PTHREAD_GET_STACKADDR_NP && defined HAVE_PTHREAD_GET_STACKSIZE_NP
#define STACKADDR_AVAILABLE 1
#undef MAINSTACKADDR_AVAILABLE
#define MAINSTACKADDR_AVAILABLE 1
void *pthread_get_stackaddr_np(pthread_t);
size_t pthread_get_stacksize_np(pthread_t);
#elif defined HAVE_THR_STKSEGMENT || defined HAVE_PTHREAD_STACKSEG_NP
#define STACKADDR_AVAILABLE 1
#elif defined HAVE_PTHREAD_GETTHRDS_NP
#define STACKADDR_AVAILABLE 1
#elif defined __HAIKU__
#define STACKADDR_AVAILABLE 1
#endif
#ifndef MAINSTACKADDR_AVAILABLE
# ifdef STACKADDR_AVAILABLE
# define MAINSTACKADDR_AVAILABLE 1
# else
# define MAINSTACKADDR_AVAILABLE 0
# endif
#endif
#if MAINSTACKADDR_AVAILABLE && !defined(get_main_stack)
# define get_main_stack(addr, size) get_stack(addr, size)
#endif
#ifdef STACKADDR_AVAILABLE
/*
* Get the initial address and size of current thread's stack
*/
static int
get_stack(void **addr, size_t *size)
{
#define CHECK_ERR(expr) \
{int err = (expr); if (err) return err;}
#ifdef HAVE_PTHREAD_GETATTR_NP /* Linux */
pthread_attr_t attr;
size_t guard = 0;
STACK_GROW_DIR_DETECTION;
CHECK_ERR(pthread_getattr_np(pthread_self(), &attr));
# ifdef HAVE_PTHREAD_ATTR_GETSTACK
CHECK_ERR(pthread_attr_getstack(&attr, addr, size));
STACK_DIR_UPPER((void)0, (void)(*addr = (char *)*addr + *size));
# else
CHECK_ERR(pthread_attr_getstackaddr(&attr, addr));
CHECK_ERR(pthread_attr_getstacksize(&attr, size));
# endif
# ifdef HAVE_PTHREAD_ATTR_GETGUARDSIZE
CHECK_ERR(pthread_attr_getguardsize(&attr, &guard));
# else
guard = getpagesize();
# endif
*size -= guard;
pthread_attr_destroy(&attr);
#elif defined HAVE_PTHREAD_ATTR_GET_NP /* FreeBSD, DragonFly BSD, NetBSD */
pthread_attr_t attr;
CHECK_ERR(pthread_attr_init(&attr));
CHECK_ERR(pthread_attr_get_np(pthread_self(), &attr));
# ifdef HAVE_PTHREAD_ATTR_GETSTACK
CHECK_ERR(pthread_attr_getstack(&attr, addr, size));
# else
CHECK_ERR(pthread_attr_getstackaddr(&attr, addr));
CHECK_ERR(pthread_attr_getstacksize(&attr, size));
# endif
STACK_DIR_UPPER((void)0, (void)(*addr = (char *)*addr + *size));
pthread_attr_destroy(&attr);
#elif (defined HAVE_PTHREAD_GET_STACKADDR_NP && defined HAVE_PTHREAD_GET_STACKSIZE_NP) /* MacOS X */
pthread_t th = pthread_self();
*addr = pthread_get_stackaddr_np(th);
*size = pthread_get_stacksize_np(th);
#elif defined HAVE_THR_STKSEGMENT || defined HAVE_PTHREAD_STACKSEG_NP
stack_t stk;
# if defined HAVE_THR_STKSEGMENT /* Solaris */
CHECK_ERR(thr_stksegment(&stk));
# else /* OpenBSD */
CHECK_ERR(pthread_stackseg_np(pthread_self(), &stk));
# endif
*addr = stk.ss_sp;
*size = stk.ss_size;
#elif defined HAVE_PTHREAD_GETTHRDS_NP /* AIX */
pthread_t th = pthread_self();
struct __pthrdsinfo thinfo;
char reg[256];
int regsiz=sizeof(reg);
CHECK_ERR(pthread_getthrds_np(&th, PTHRDSINFO_QUERY_ALL,
&thinfo, sizeof(thinfo),
&reg, &regsiz));
*addr = thinfo.__pi_stackaddr;
/* Must not use thinfo.__pi_stacksize for size.
It is around 3KB smaller than the correct size
calculated by thinfo.__pi_stackend - thinfo.__pi_stackaddr. */
*size = thinfo.__pi_stackend - thinfo.__pi_stackaddr;
STACK_DIR_UPPER((void)0, (void)(*addr = (char *)*addr + *size));
#elif defined __HAIKU__
thread_info info;
STACK_GROW_DIR_DETECTION;
CHECK_ERR(get_thread_info(find_thread(NULL), &info));
*addr = info.stack_base;
*size = (uintptr_t)info.stack_end - (uintptr_t)info.stack_base;
STACK_DIR_UPPER((void)0, (void)(*addr = (char *)*addr + *size));
#else
#error STACKADDR_AVAILABLE is defined but not implemented.
#endif
return 0;
#undef CHECK_ERR
}
#endif
static struct {
rb_nativethread_id_t id;
size_t stack_maxsize;
VALUE *stack_start;
} native_main_thread;
#ifdef STACK_END_ADDRESS
extern void *STACK_END_ADDRESS;
#endif
enum {
RUBY_STACK_SPACE_LIMIT = 1024 * 1024, /* 1024KB */
RUBY_STACK_SPACE_RATIO = 5
};
static size_t
space_size(size_t stack_size)
{
size_t space_size = stack_size / RUBY_STACK_SPACE_RATIO;
if (space_size > RUBY_STACK_SPACE_LIMIT) {
return RUBY_STACK_SPACE_LIMIT;
}
else {
return space_size;
}
}
#ifdef __linux__
static __attribute__((noinline)) void
reserve_stack(volatile char *limit, size_t size)
{
# ifdef C_ALLOCA
# error needs alloca()
# endif
struct rlimit rl;
volatile char buf[0x100];
enum {stack_check_margin = 0x1000}; /* for -fstack-check */
STACK_GROW_DIR_DETECTION;
if (!getrlimit(RLIMIT_STACK, &rl) && rl.rlim_cur == RLIM_INFINITY)
return;
if (size < stack_check_margin) return;
size -= stack_check_margin;
size -= sizeof(buf); /* margin */
if (IS_STACK_DIR_UPPER()) {
const volatile char *end = buf + sizeof(buf);
limit += size;
if (limit > end) {
/* |<-bottom (=limit(a)) top->|
* | .. |<-buf 256B |<-end | stack check |
* | 256B | =size= | margin (4KB)|
* | =size= limit(b)->| 256B | |
* | | alloca(sz) | | |
* | .. |<-buf |<-limit(c) [sz-1]->0> | |
*/
size_t sz = limit - end;
limit = alloca(sz);
limit[sz-1] = 0;
}
}
else {
limit -= size;
if (buf > limit) {
/* |<-top (=limit(a)) bottom->|
* | .. | 256B buf->| | stack check |
* | 256B | =size= | margin (4KB)|
* | =size= limit(b)->| 256B | |
* | | alloca(sz) | | |
* | .. | buf->| limit(c)-><0> | |
*/
size_t sz = buf - limit;
limit = alloca(sz);
limit[0] = 0;
}
}
}
#else
# define reserve_stack(limit, size) ((void)(limit), (void)(size))
#endif
#undef ruby_init_stack
void
ruby_init_stack(volatile VALUE *addr)
{
native_main_thread.id = pthread_self();
#if MAINSTACKADDR_AVAILABLE
if (native_main_thread.stack_maxsize) return;
{
void* stackaddr;
size_t size;
if (get_main_stack(&stackaddr, &size) == 0) {
native_main_thread.stack_maxsize = size;
native_main_thread.stack_start = stackaddr;
reserve_stack(stackaddr, size);
goto bound_check;
}
}
#endif
#ifdef STACK_END_ADDRESS
native_main_thread.stack_start = STACK_END_ADDRESS;
#else
if (!native_main_thread.stack_start ||
STACK_UPPER((VALUE *)(void *)&addr,
native_main_thread.stack_start > addr,
native_main_thread.stack_start < addr)) {
native_main_thread.stack_start = (VALUE *)addr;
}
#endif
{
#if defined(HAVE_GETRLIMIT)
#if defined(PTHREAD_STACK_DEFAULT)
# if PTHREAD_STACK_DEFAULT < RUBY_STACK_SPACE*5
# error "PTHREAD_STACK_DEFAULT is too small"
# endif
size_t size = PTHREAD_STACK_DEFAULT;
#else
size_t size = RUBY_VM_THREAD_VM_STACK_SIZE;
#endif
size_t space;
int pagesize = getpagesize();
struct rlimit rlim;
STACK_GROW_DIR_DETECTION;
if (getrlimit(RLIMIT_STACK, &rlim) == 0) {
size = (size_t)rlim.rlim_cur;
}
addr = native_main_thread.stack_start;
if (IS_STACK_DIR_UPPER()) {
space = ((size_t)((char *)addr + size) / pagesize) * pagesize - (size_t)addr;
}
else {
space = (size_t)addr - ((size_t)((char *)addr - size) / pagesize + 1) * pagesize;
}
native_main_thread.stack_maxsize = space;
#endif
}
#if MAINSTACKADDR_AVAILABLE
bound_check:
#endif
/* If addr is out of range of main-thread stack range estimation, */
/* it should be on co-routine (alternative stack). [Feature #2294] */
{
void *start, *end;
STACK_GROW_DIR_DETECTION;
if (IS_STACK_DIR_UPPER()) {
start = native_main_thread.stack_start;
end = (char *)native_main_thread.stack_start + native_main_thread.stack_maxsize;
}
else {
start = (char *)native_main_thread.stack_start - native_main_thread.stack_maxsize;
end = native_main_thread.stack_start;
}
if ((void *)addr < start || (void *)addr > end) {
/* out of range */
native_main_thread.stack_start = (VALUE *)addr;
native_main_thread.stack_maxsize = 0; /* unknown */
}
}
}
#define CHECK_ERR(expr) \
{int err = (expr); if (err) {rb_bug_errno(#expr, err);}}
static int
native_thread_init_stack(rb_thread_t *th)
{
rb_nativethread_id_t curr = pthread_self();
if (pthread_equal(curr, native_main_thread.id)) {
th->ec->machine.stack_start = native_main_thread.stack_start;
th->ec->machine.stack_maxsize = native_main_thread.stack_maxsize;
}
else {
#ifdef STACKADDR_AVAILABLE
void *start;
size_t size;
if (get_stack(&start, &size) == 0) {
uintptr_t diff = (uintptr_t)start - (uintptr_t)&curr;
th->ec->machine.stack_start = (VALUE *)&curr;
th->ec->machine.stack_maxsize = size - diff;
}
#else
rb_raise(rb_eNotImpError, "ruby engine can initialize only in the main thread");
#endif
}
return 0;
}
#ifndef __CYGWIN__
#define USE_NATIVE_THREAD_INIT 1
#endif
static void *
thread_start_func_1(void *th_ptr)
{
rb_thread_t *th = th_ptr;
RB_ALTSTACK_INIT(void *altstack, th->nt->altstack);
#if USE_THREAD_CACHE
thread_start:
#endif
{
#if !defined USE_NATIVE_THREAD_INIT
VALUE stack_start;
#endif
#if defined USE_NATIVE_THREAD_INIT
native_thread_init_stack(th);
#endif
native_thread_init(th->nt);
RB_INTERNAL_THREAD_HOOK(RUBY_INTERNAL_THREAD_EVENT_STARTED);
/* run */
#if defined USE_NATIVE_THREAD_INIT
thread_start_func_2(th, th->ec->machine.stack_start);
#else
thread_start_func_2(th, &stack_start);
#endif
}
#if USE_THREAD_CACHE
/* cache thread */
if ((th = register_cached_thread_and_wait(RB_ALTSTACK(altstack))) != 0) {
goto thread_start;
}
#else
RB_ALTSTACK_FREE(altstack);
#endif
return 0;
}
struct cached_thread_entry {
rb_nativethread_cond_t cond;
rb_nativethread_id_t thread_id;
rb_thread_t *th;
void *altstack;
struct ccan_list_node node;
};
#if USE_THREAD_CACHE
static rb_nativethread_lock_t thread_cache_lock = RB_NATIVETHREAD_LOCK_INIT;
static CCAN_LIST_HEAD(cached_thread_head);
# if defined(HAVE_WORKING_FORK)
static void
thread_cache_reset(void)
{
rb_native_mutex_initialize(&thread_cache_lock);
ccan_list_head_init(&cached_thread_head);
}
# endif
/*
* number of seconds to cache for, I think 1-5s is sufficient to obviate
* the need for thread pool in many network programs (taking into account
* worst case network latency across the globe) without wasting memory
*/
#ifndef THREAD_CACHE_TIME
# define THREAD_CACHE_TIME ((rb_hrtime_t)3 * RB_HRTIME_PER_SEC)
#endif
static rb_thread_t *
register_cached_thread_and_wait(void *altstack)
{
rb_hrtime_t end = THREAD_CACHE_TIME;
struct cached_thread_entry entry;
rb_native_cond_initialize(&entry.cond);
entry.altstack = altstack;
entry.th = NULL;
entry.thread_id = pthread_self();
end = native_cond_timeout(&entry.cond, end);
rb_native_mutex_lock(&thread_cache_lock);
{
ccan_list_add(&cached_thread_head, &entry.node);
native_cond_timedwait(&entry.cond, &thread_cache_lock, &end);
if (entry.th == NULL) { /* unused */
ccan_list_del(&entry.node);
}
}
rb_native_mutex_unlock(&thread_cache_lock);
rb_native_cond_destroy(&entry.cond);
if (!entry.th) {
RB_ALTSTACK_FREE(entry.altstack);
}
return entry.th;
}
#else
# if defined(HAVE_WORKING_FORK)
static void thread_cache_reset(void) { }
# endif
#endif
static int
use_cached_thread(rb_thread_t *th)
{
#if USE_THREAD_CACHE
struct cached_thread_entry *entry;
rb_native_mutex_lock(&thread_cache_lock);
entry = ccan_list_pop(&cached_thread_head, struct cached_thread_entry, node);
if (entry) {
entry->th = th;
/* th->nt->thread_id must be set before signal for Thread#name= */
th->nt->thread_id = entry->thread_id;
rb_native_cond_signal(&entry->cond);
}
rb_native_mutex_unlock(&thread_cache_lock);
return !!entry;
#endif
return 0;
}
#if 0
// TODO
static void
clear_thread_cache_altstack(void)
{
#if USE_THREAD_CACHE
struct cached_thread_entry *entry;
rb_native_mutex_lock(&thread_cache_lock);
ccan_list_for_each(&cached_thread_head, entry, node) {
void MAYBE_UNUSED(*altstack) = entry->altstack;
entry->altstack = 0;
RB_ALTSTACK_FREE(altstack);
}
rb_native_mutex_unlock(&thread_cache_lock);
#endif
}
#endif
static int
native_thread_create(rb_thread_t *th)
{
int err = 0;
VM_ASSERT(th->nt == 0);
th->nt = ZALLOC(struct rb_native_thread);
if (use_cached_thread(th)) {
RUBY_DEBUG_LOG("use cached nt. th:%u", rb_th_serial(th));
}
else {
pthread_attr_t attr;
const size_t stack_size = th->vm->default_params.thread_machine_stack_size + th->vm->default_params.thread_vm_stack_size;
const size_t space = space_size(stack_size);
#ifdef USE_SIGALTSTACK
th->nt->altstack = rb_allocate_sigaltstack();
#endif
th->ec->machine.stack_maxsize = stack_size - space;
CHECK_ERR(pthread_attr_init(&attr));
# ifdef PTHREAD_STACK_MIN
RUBY_DEBUG_LOG("stack size: %lu", (unsigned long)stack_size);
CHECK_ERR(pthread_attr_setstacksize(&attr, stack_size));
# endif
# ifdef HAVE_PTHREAD_ATTR_SETINHERITSCHED
CHECK_ERR(pthread_attr_setinheritsched(&attr, PTHREAD_INHERIT_SCHED));
# endif
CHECK_ERR(pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED));
err = pthread_create(&th->nt->thread_id, &attr, thread_start_func_1, th);
RUBY_DEBUG_LOG("th:%u err:%d", rb_th_serial(th), err);
/* should be done in the created thread */
CHECK_ERR(pthread_attr_destroy(&attr));
}
return err;
}
#if USE_NATIVE_THREAD_PRIORITY
static void
native_thread_apply_priority(rb_thread_t *th)
{
#if defined(_POSIX_PRIORITY_SCHEDULING) && (_POSIX_PRIORITY_SCHEDULING > 0)
struct sched_param sp;
int policy;
int priority = 0 - th->priority;
int max, min;
pthread_getschedparam(th->nt->thread_id, &policy, &sp);
max = sched_get_priority_max(policy);
min = sched_get_priority_min(policy);
if (min > priority) {
priority = min;
}
else if (max < priority) {
priority = max;
}
sp.sched_priority = priority;
pthread_setschedparam(th->nt->thread_id, policy, &sp);
#else
/* not touched */
#endif
}
#endif /* USE_NATIVE_THREAD_PRIORITY */
static int
native_fd_select(int n, rb_fdset_t *readfds, rb_fdset_t *writefds, rb_fdset_t *exceptfds, struct timeval *timeout, rb_thread_t *th)
{
return rb_fd_select(n, readfds, writefds, exceptfds, timeout);
}
static void
ubf_pthread_cond_signal(void *ptr)
{
rb_thread_t *th = (rb_thread_t *)ptr;
RUBY_DEBUG_LOG("th:%u", rb_th_serial(th));
rb_native_cond_signal(&th->nt->cond.intr);
}
static void
native_cond_sleep(rb_thread_t *th, rb_hrtime_t *rel)
{
rb_nativethread_lock_t *lock = &th->interrupt_lock;
rb_nativethread_cond_t *cond = &th->nt->cond.intr;
/* Solaris cond_timedwait() return EINVAL if an argument is greater than
* current_time + 100,000,000. So cut up to 100,000,000. This is
* considered as a kind of spurious wakeup. The caller to native_sleep
* should care about spurious wakeup.
*
* See also [Bug #1341] [ruby-core:29702]
* http://download.oracle.com/docs/cd/E19683-01/816-0216/6m6ngupgv/index.html
*/
const rb_hrtime_t max = (rb_hrtime_t)100000000 * RB_HRTIME_PER_SEC;
THREAD_BLOCKING_BEGIN(th);
{
rb_native_mutex_lock(lock);
th->unblock.func = ubf_pthread_cond_signal;
th->unblock.arg = th;
if (RUBY_VM_INTERRUPTED(th->ec)) {
/* interrupted. return immediate */
RUBY_DEBUG_LOG("interrupted before sleep th:%u", rb_th_serial(th));
}
else {
if (!rel) {
rb_native_cond_wait(cond, lock);
}
else {
rb_hrtime_t end;
if (*rel > max) {
*rel = max;
}
end = native_cond_timeout(cond, *rel);
native_cond_timedwait(cond, lock, &end);
}
}
th->unblock.func = 0;
rb_native_mutex_unlock(lock);
}
THREAD_BLOCKING_END(th);
RUBY_DEBUG_LOG("done th:%u", rb_th_serial(th));
}
#ifdef USE_UBF_LIST
static CCAN_LIST_HEAD(ubf_list_head);
static rb_nativethread_lock_t ubf_list_lock = RB_NATIVETHREAD_LOCK_INIT;
static void
ubf_list_atfork(void)
{
ccan_list_head_init(&ubf_list_head);
rb_native_mutex_initialize(&ubf_list_lock);
}
/* The thread 'th' is registered to be trying unblock. */
static void
register_ubf_list(rb_thread_t *th)
{
struct ccan_list_node *node = &th->sched.node.ubf;
if (ccan_list_empty((struct ccan_list_head*)node)) {
rb_native_mutex_lock(&ubf_list_lock);
ccan_list_add(&ubf_list_head, node);
rb_native_mutex_unlock(&ubf_list_lock);
}
}
/* The thread 'th' is unblocked. It no longer need to be registered. */
static void
unregister_ubf_list(rb_thread_t *th)
{
struct ccan_list_node *node = &th->sched.node.ubf;
/* we can't allow re-entry into ubf_list_head */
VM_ASSERT(th->unblock.func == 0);
if (!ccan_list_empty((struct ccan_list_head*)node)) {
rb_native_mutex_lock(&ubf_list_lock);
ccan_list_del_init(node);
if (ccan_list_empty(&ubf_list_head) && !rb_signal_buff_size()) {
ubf_timer_disarm();
}
rb_native_mutex_unlock(&ubf_list_lock);
}
}
/*
* send a signal to intent that a target thread return from blocking syscall.
* Maybe any signal is ok, but we chose SIGVTALRM.
*/
static void
ubf_wakeup_thread(rb_thread_t *th)
{
RUBY_DEBUG_LOG("th:%u", rb_th_serial(th));
pthread_kill(th->nt->thread_id, SIGVTALRM);
}
static void
ubf_select(void *ptr)
{
rb_thread_t *th = (rb_thread_t *)ptr;
struct rb_thread_sched *sched = TH_SCHED(th);
const rb_thread_t *cur = ruby_thread_from_native(); /* may be 0 */
register_ubf_list(th);
/*
* ubf_wakeup_thread() doesn't guarantee to wake up a target thread.
* Therefore, we repeatedly call ubf_wakeup_thread() until a target thread
* exit from ubf function. We must have a timer to perform this operation.
* We use double-checked locking here because this function may be called
* while vm->gvl.lock is held in do_gvl_timer.
* There is also no need to start a timer if we're the designated
* sigwait_th thread, otherwise we can deadlock with a thread
* in unblock_function_clear.
*/
if (cur != sched->timer && cur != sigwait_th) {
/*
* Double-checked locking above was to prevent nested locking
* by the SAME thread. We use trylock here to prevent deadlocks
* between DIFFERENT threads
*/
if (rb_native_mutex_trylock(&sched->lock) == 0) {
if (!sched->timer) {
rb_thread_wakeup_timer_thread(-1);
}
rb_native_mutex_unlock(&sched->lock);
}
}
ubf_wakeup_thread(th);
}
static int
ubf_threads_empty(void)
{
return ccan_list_empty(&ubf_list_head);
}
static void
ubf_wakeup_all_threads(void)
{
if (!ubf_threads_empty()) {
rb_native_mutex_lock(&ubf_list_lock);
rb_thread_t *th;
ccan_list_for_each(&ubf_list_head, th, sched.node.ubf) {
ubf_wakeup_thread(th);
}
rb_native_mutex_unlock(&ubf_list_lock);
}
}
#else /* USE_UBF_LIST */
#define register_ubf_list(th) (void)(th)
#define unregister_ubf_list(th) (void)(th)
#define ubf_select 0
static void ubf_wakeup_all_threads(void) { return; }
static int ubf_threads_empty(void) { return 1; }
#define ubf_list_atfork() do {} while (0)
#endif /* USE_UBF_LIST */
#define TT_DEBUG 0
#define WRITE_CONST(fd, str) (void)(write((fd),(str),sizeof(str)-1)<0)
static struct {
/* pipes are closed in forked children when owner_process does not match */
int normal[2]; /* [0] == sigwait_fd */
int ub_main[2]; /* unblock main thread from native_ppoll_sleep */
/* volatile for signal handler use: */
volatile rb_pid_t owner_process;
} signal_self_pipe = {
{-1, -1},
{-1, -1},
};
/* only use signal-safe system calls here */
static void
rb_thread_wakeup_timer_thread_fd(int fd)
{
#if USE_EVENTFD
const uint64_t buff = 1;
#else
const char buff = '!';
#endif
ssize_t result;
/* already opened */
if (fd >= 0) {
retry:
if ((result = write(fd, &buff, sizeof(buff))) <= 0) {
int e = errno;
switch (e) {
case EINTR: goto retry;
case EAGAIN:
#if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN
case EWOULDBLOCK:
#endif
break;
default:
async_bug_fd("rb_thread_wakeup_timer_thread: write", e, fd);
}
}
if (TT_DEBUG) WRITE_CONST(2, "rb_thread_wakeup_timer_thread: write\n");
}
else {
/* ignore wakeup */
}
}
/*
* This ensures we get a SIGVTALRM in TIME_QUANTUM_MSEC if our
* process could not react to the original signal in time.
*/
static void
ubf_timer_arm(rb_pid_t current) /* async signal safe */
{
#if UBF_TIMER == UBF_TIMER_POSIX
if ((!current || timer_posix.owner == current) &&
timer_state_cas(RTIMER_DISARM, RTIMER_ARMING) == RTIMER_DISARM) {
struct itimerspec it;
it.it_interval.tv_sec = it.it_value.tv_sec = 0;
it.it_interval.tv_nsec = it.it_value.tv_nsec = TIME_QUANTUM_NSEC;
if (timer_settime(timer_posix.timerid, 0, &it, 0))
rb_async_bug_errno("timer_settime (arm)", errno);
switch (timer_state_cas(RTIMER_ARMING, RTIMER_ARMED)) {
case RTIMER_DISARM:
/* somebody requested a disarm while we were arming */
/* may race harmlessly with ubf_timer_destroy */
(void)timer_settime(timer_posix.timerid, 0, &zero, 0);
case RTIMER_ARMING: return; /* success */
case RTIMER_ARMED:
/*
* it is possible to have another thread disarm, and
* a third thread arm finish re-arming before we get
* here, so we wasted a syscall with timer_settime but
* probably unavoidable in a signal handler.
*/
return;
case RTIMER_DEAD:
/* may race harmlessly with ubf_timer_destroy */
(void)timer_settime(timer_posix.timerid, 0, &zero, 0);
return;
default:
rb_async_bug_errno("UBF_TIMER_POSIX unknown state", ERANGE);
}
}
#elif UBF_TIMER == UBF_TIMER_PTHREAD
if (!current || current == timer_pthread.owner) {
if (ATOMIC_EXCHANGE(timer_pthread.armed, 1) == 0)
rb_thread_wakeup_timer_thread_fd(timer_pthread.low[1]);
}
#endif
}
void
rb_thread_wakeup_timer_thread(int sig)
{
rb_pid_t current;
/* non-sighandler path */
if (sig <= 0) {
rb_thread_wakeup_timer_thread_fd(signal_self_pipe.normal[1]);
if (sig < 0) {
ubf_timer_arm(0);
}
return;
}
/* must be safe inside sighandler, so no mutex */
current = getpid();
if (signal_self_pipe.owner_process == current) {
rb_thread_wakeup_timer_thread_fd(signal_self_pipe.normal[1]);
/*
* system_working check is required because vm and main_thread are
* freed during shutdown
*/
if (system_working > 0) {
volatile rb_execution_context_t *ec;
rb_vm_t *vm = GET_VM();
rb_thread_t *mth;
/*
* FIXME: root VM and main_thread should be static and not
* on heap for maximum safety (and startup/shutdown speed)
*/
if (!vm) return;
mth = vm->ractor.main_thread;
if (!mth || system_working <= 0) return;
/* this relies on GC for grace period before cont_free */
ec = ACCESS_ONCE(rb_execution_context_t *, mth->ec);
if (ec) {
RUBY_VM_SET_TRAP_INTERRUPT(ec);
ubf_timer_arm(current);
/* some ubfs can interrupt single-threaded process directly */
if (vm->ubf_async_safe && mth->unblock.func) {
(mth->unblock.func)(mth->unblock.arg);
}
}
}
}
}
#define CLOSE_INVALIDATE_PAIR(expr) \
close_invalidate_pair(expr,"close_invalidate: "#expr)
static void
close_invalidate(int *fdp, const char *msg)
{
int fd = *fdp;
*fdp = -1;
if (close(fd) < 0) {
async_bug_fd(msg, errno, fd);
}
}
static void
close_invalidate_pair(int fds[2], const char *msg)
{
if (USE_EVENTFD && fds[0] == fds[1]) {
close_invalidate(&fds[0], msg);
fds[1] = -1;
}
else {
close_invalidate(&fds[0], msg);
close_invalidate(&fds[1], msg);
}
}
static void
set_nonblock(int fd)
{
int oflags;
int err;
oflags = fcntl(fd, F_GETFL);
if (oflags == -1)
rb_sys_fail(0);
oflags |= O_NONBLOCK;
err = fcntl(fd, F_SETFL, oflags);
if (err == -1)
rb_sys_fail(0);
}
/* communication pipe with timer thread and signal handler */
static int
setup_communication_pipe_internal(int pipes[2])
{
int err;
if (pipes[0] >= 0 || pipes[1] >= 0) {
VM_ASSERT(pipes[0] >= 0);
VM_ASSERT(pipes[1] >= 0);
return 0;
}
/*
* Don't bother with eventfd on ancient Linux 2.6.22..2.6.26 which were
* missing EFD_* flags, they can fall back to pipe
*/
#if USE_EVENTFD && defined(EFD_NONBLOCK) && defined(EFD_CLOEXEC)
pipes[0] = pipes[1] = eventfd(0, EFD_NONBLOCK|EFD_CLOEXEC);
if (pipes[0] >= 0) {
rb_update_max_fd(pipes[0]);
return 0;
}
#endif
err = rb_cloexec_pipe(pipes);
if (err != 0) {
rb_warn("pipe creation failed for timer: %s, scheduling broken",
strerror(errno));
return -1;
}
rb_update_max_fd(pipes[0]);
rb_update_max_fd(pipes[1]);
set_nonblock(pipes[0]);
set_nonblock(pipes[1]);
return 0;
}
#if !defined(SET_CURRENT_THREAD_NAME) && defined(__linux__) && defined(PR_SET_NAME)
# define SET_CURRENT_THREAD_NAME(name) prctl(PR_SET_NAME, name)
#endif
enum {
THREAD_NAME_MAX =
#if defined(__linux__)
16
#elif defined(__APPLE__)
/* Undocumented, and main thread seems unlimited */
64
#else
16
#endif
};
static VALUE threadptr_invoke_proc_location(rb_thread_t *th);
static void
native_set_thread_name(rb_thread_t *th)
{
#ifdef SET_CURRENT_THREAD_NAME
VALUE loc;
if (!NIL_P(loc = th->name)) {
SET_CURRENT_THREAD_NAME(RSTRING_PTR(loc));
}
else if ((loc = threadptr_invoke_proc_location(th)) != Qnil) {
char *name, *p;
char buf[THREAD_NAME_MAX];
size_t len;
int n;
name = RSTRING_PTR(RARRAY_AREF(loc, 0));
p = strrchr(name, '/'); /* show only the basename of the path. */
if (p && p[1])
name = p + 1;
n = snprintf(buf, sizeof(buf), "%s:%d", name, NUM2INT(RARRAY_AREF(loc, 1)));
RB_GC_GUARD(loc);
len = (size_t)n;
if (len >= sizeof(buf)) {
buf[sizeof(buf)-2] = '*';
buf[sizeof(buf)-1] = '\0';
}
SET_CURRENT_THREAD_NAME(buf);
}
#endif
}
static void
native_set_another_thread_name(rb_nativethread_id_t thread_id, VALUE name)
{
#if defined SET_ANOTHER_THREAD_NAME || defined SET_CURRENT_THREAD_NAME
char buf[THREAD_NAME_MAX];
const char *s = "";
# if !defined SET_ANOTHER_THREAD_NAME
if (!pthread_equal(pthread_self(), thread_id)) return;
# endif
if (!NIL_P(name)) {
long n;
RSTRING_GETMEM(name, s, n);
if (n >= (int)sizeof(buf)) {
memcpy(buf, s, sizeof(buf)-1);
buf[sizeof(buf)-1] = '\0';
s = buf;
}
}
# if defined SET_ANOTHER_THREAD_NAME
SET_ANOTHER_THREAD_NAME(thread_id, s);
# elif defined SET_CURRENT_THREAD_NAME
SET_CURRENT_THREAD_NAME(s);
# endif
#endif
}
#if defined(RB_THREAD_T_HAS_NATIVE_ID) || defined(__APPLE__)
static VALUE
native_thread_native_thread_id(rb_thread_t *target_th)
{
#ifdef RB_THREAD_T_HAS_NATIVE_ID
int tid = target_th->nt->tid;
if (tid == 0) return Qnil;
return INT2FIX(tid);
#elif defined(__APPLE__)
uint64_t tid;
# if ((MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_6) || \
defined(__POWERPC__) /* never defined for PowerPC platforms */)
const bool no_pthread_threadid_np = true;
# define NO_PTHREAD_MACH_THREAD_NP 1
# elif MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_6
const bool no_pthread_threadid_np = false;
# else
# if !(defined(__has_attribute) && __has_attribute(availability))
/* __API_AVAILABLE macro does nothing on gcc */
__attribute__((weak)) int pthread_threadid_np(pthread_t, uint64_t*);
# endif
/* Check weakly linked symbol */
const bool no_pthread_threadid_np = !&pthread_threadid_np;
# endif
if (no_pthread_threadid_np) {
return ULL2NUM(pthread_mach_thread_np(pthread_self()));
}
# ifndef NO_PTHREAD_MACH_THREAD_NP
int e = pthread_threadid_np(target_th->nt->thread_id, &tid);
if (e != 0) rb_syserr_fail(e, "pthread_threadid_np");
return ULL2NUM((unsigned long long)tid);
# endif
#endif
}
# define USE_NATIVE_THREAD_NATIVE_THREAD_ID 1
#else
# define USE_NATIVE_THREAD_NATIVE_THREAD_ID 0
#endif
static void
ubf_timer_invalidate(void)
{
#if UBF_TIMER == UBF_TIMER_PTHREAD
CLOSE_INVALIDATE_PAIR(timer_pthread.low);
#endif
}
static void
ubf_timer_pthread_create(rb_pid_t current)
{
#if UBF_TIMER == UBF_TIMER_PTHREAD
int err;
if (timer_pthread.owner == current)
return;
if (setup_communication_pipe_internal(timer_pthread.low) < 0)
return;
err = pthread_create(&timer_pthread.thid, 0, timer_pthread_fn, GET_VM());
if (!err)
timer_pthread.owner = current;
else
rb_warn("pthread_create failed for timer: %s, signals racy",
strerror(err));
#endif
}
static void
ubf_timer_create(rb_pid_t current)
{
#if UBF_TIMER == UBF_TIMER_POSIX
# if defined(__sun)
# define UBF_TIMER_CLOCK CLOCK_REALTIME
# else /* Tested Linux and FreeBSD: */
# define UBF_TIMER_CLOCK CLOCK_MONOTONIC
# endif
struct sigevent sev;
sev.sigev_notify = SIGEV_SIGNAL;
sev.sigev_signo = SIGVTALRM;
sev.sigev_value.sival_ptr = &timer_posix;
if (!timer_create(UBF_TIMER_CLOCK, &sev, &timer_posix.timerid)) {
rb_atomic_t prev = timer_state_exchange(RTIMER_DISARM);
if (prev != RTIMER_DEAD) {
rb_bug("timer_posix was not dead: %u\n", (unsigned)prev);
}
timer_posix.owner = current;
}
else {
rb_warn("timer_create failed: %s, signals racy", strerror(errno));
}
#endif
if (UBF_TIMER == UBF_TIMER_PTHREAD)
ubf_timer_pthread_create(current);
}
static void
rb_thread_create_timer_thread(void)
{
/* we only create the pipe, and lazy-spawn */
rb_pid_t current = getpid();
rb_pid_t owner = signal_self_pipe.owner_process;
if (owner && owner != current) {
CLOSE_INVALIDATE_PAIR(signal_self_pipe.normal);
CLOSE_INVALIDATE_PAIR(signal_self_pipe.ub_main);
ubf_timer_invalidate();
}
if (setup_communication_pipe_internal(signal_self_pipe.normal) < 0) return;
if (setup_communication_pipe_internal(signal_self_pipe.ub_main) < 0) return;
ubf_timer_create(current);
if (owner != current) {
/* validate pipe on this process */
sigwait_th = THREAD_INVALID;
signal_self_pipe.owner_process = current;
}
}
static void
ubf_timer_disarm(void)
{
#if UBF_TIMER == UBF_TIMER_POSIX
rb_atomic_t prev;
if (timer_posix.owner && timer_posix.owner != getpid()) return;
prev = timer_state_cas(RTIMER_ARMED, RTIMER_DISARM);
switch (prev) {
case RTIMER_DISARM: return; /* likely */
case RTIMER_ARMING: return; /* ubf_timer_arm will disarm itself */
case RTIMER_ARMED:
if (timer_settime(timer_posix.timerid, 0, &zero, 0)) {
int err = errno;
if (err == EINVAL) {
prev = timer_state_cas(RTIMER_DISARM, RTIMER_DISARM);
/* main thread may have killed the timer */
if (prev == RTIMER_DEAD) return;
rb_bug_errno("timer_settime (disarm)", err);
}
}
return;
case RTIMER_DEAD: return; /* stay dead */
default:
rb_bug("UBF_TIMER_POSIX bad state: %u\n", (unsigned)prev);
}
#elif UBF_TIMER == UBF_TIMER_PTHREAD
ATOMIC_SET(timer_pthread.armed, 0);
#endif
}
static void
ubf_timer_destroy(void)
{
#if UBF_TIMER == UBF_TIMER_POSIX
if (timer_posix.owner == getpid()) {
rb_atomic_t expect = RTIMER_DISARM;
size_t i, max = 10000000;
/* prevent signal handler from arming: */
for (i = 0; i < max; i++) {
switch (timer_state_cas(expect, RTIMER_DEAD)) {
case RTIMER_DISARM:
if (expect == RTIMER_DISARM) goto done;
expect = RTIMER_DISARM;
break;
case RTIMER_ARMING:
native_thread_yield(); /* let another thread finish arming */
expect = RTIMER_ARMED;
break;
case RTIMER_ARMED:
if (expect == RTIMER_ARMED) {
if (timer_settime(timer_posix.timerid, 0, &zero, 0))
rb_bug_errno("timer_settime (destroy)", errno);
goto done;
}
expect = RTIMER_ARMED;
break;
case RTIMER_DEAD:
rb_bug("RTIMER_DEAD unexpected");
}
}
rb_bug("timed out waiting for timer to arm");
done:
if (timer_delete(timer_posix.timerid) < 0)
rb_sys_fail("timer_delete");
VM_ASSERT(timer_state_exchange(RTIMER_DEAD) == RTIMER_DEAD);
}
#elif UBF_TIMER == UBF_TIMER_PTHREAD
int err;
timer_pthread.owner = 0;
ubf_timer_disarm();
rb_thread_wakeup_timer_thread_fd(timer_pthread.low[1]);
err = pthread_join(timer_pthread.thid, 0);
if (err) {
rb_raise(rb_eThreadError, "native_thread_join() failed (%d)", err);
}
#endif
}
static int
native_stop_timer_thread(void)
{
int stopped;
stopped = --system_working <= 0;
if (stopped)
ubf_timer_destroy();
if (TT_DEBUG) fprintf(stderr, "stop timer thread\n");
return stopped;
}
static void
native_reset_timer_thread(void)
{
if (TT_DEBUG) fprintf(stderr, "reset timer thread\n");
}
#ifdef HAVE_SIGALTSTACK
int
ruby_stack_overflowed_p(const rb_thread_t *th, const void *addr)
{
void *base;
size_t size;
const size_t water_mark = 1024 * 1024;
STACK_GROW_DIR_DETECTION;
#ifdef STACKADDR_AVAILABLE
if (get_stack(&base, &size) == 0) {
# ifdef __APPLE__
if (pthread_equal(th->nt->thread_id, native_main_thread.id)) {
struct rlimit rlim;
if (getrlimit(RLIMIT_STACK, &rlim) == 0 && rlim.rlim_cur > size) {
size = (size_t)rlim.rlim_cur;
}
}
# endif
base = (char *)base + STACK_DIR_UPPER(+size, -size);
}
else
#endif
if (th) {
size = th->ec->machine.stack_maxsize;
base = (char *)th->ec->machine.stack_start - STACK_DIR_UPPER(0, size);
}
else {
return 0;
}
size /= RUBY_STACK_SPACE_RATIO;
if (size > water_mark) size = water_mark;
if (IS_STACK_DIR_UPPER()) {
if (size > ~(size_t)base+1) size = ~(size_t)base+1;
if (addr > base && addr <= (void *)((char *)base + size)) return 1;
}
else {
if (size > (size_t)base) size = (size_t)base;
if (addr > (void *)((char *)base - size) && addr <= base) return 1;
}
return 0;
}
#endif
int
rb_reserved_fd_p(int fd)
{
/* no false-positive if out-of-FD at startup */
if (fd < 0)
return 0;
#if UBF_TIMER == UBF_TIMER_PTHREAD
if (fd == timer_pthread.low[0] || fd == timer_pthread.low[1])
goto check_pid;
#endif
if (fd == signal_self_pipe.normal[0] || fd == signal_self_pipe.normal[1])
goto check_pid;
if (fd == signal_self_pipe.ub_main[0] || fd == signal_self_pipe.ub_main[1])
goto check_pid;
return 0;
check_pid:
if (signal_self_pipe.owner_process == getpid()) /* async-signal-safe */
return 1;
return 0;
}
rb_nativethread_id_t
rb_nativethread_self(void)
{
return pthread_self();
}
int
rb_sigwait_fd_get(const rb_thread_t *th)
{
if (signal_self_pipe.normal[0] >= 0) {
VM_ASSERT(signal_self_pipe.owner_process == getpid());
/*
* no need to keep firing the timer if any thread is sleeping
* on the signal self-pipe
*/
ubf_timer_disarm();
if (ATOMIC_PTR_CAS(sigwait_th, THREAD_INVALID, th) == THREAD_INVALID) {
return signal_self_pipe.normal[0];
}
}
return -1; /* avoid thundering herd and work stealing/starvation */
}
void
rb_sigwait_fd_put(const rb_thread_t *th, int fd)
{
const rb_thread_t *old;
VM_ASSERT(signal_self_pipe.normal[0] == fd);
old = ATOMIC_PTR_EXCHANGE(sigwait_th, THREAD_INVALID);
if (old != th) assert(old == th);
}
#ifndef HAVE_PPOLL
/* TODO: don't ignore sigmask */
static int
ruby_ppoll(struct pollfd *fds, nfds_t nfds,
const struct timespec *ts, const sigset_t *sigmask)
{
int timeout_ms;
if (ts) {
int tmp, tmp2;
if (ts->tv_sec > INT_MAX/1000)
timeout_ms = INT_MAX;
else {
tmp = (int)(ts->tv_sec * 1000);
/* round up 1ns to 1ms to avoid excessive wakeups for <1ms sleep */
tmp2 = (int)((ts->tv_nsec + 999999L) / (1000L * 1000L));
if (INT_MAX - tmp < tmp2)
timeout_ms = INT_MAX;
else
timeout_ms = (int)(tmp + tmp2);
}
}
else
timeout_ms = -1;
return poll(fds, nfds, timeout_ms);
}
# define ppoll(fds,nfds,ts,sigmask) ruby_ppoll((fds),(nfds),(ts),(sigmask))
#endif
void
rb_sigwait_sleep(rb_thread_t *th, int sigwait_fd, const rb_hrtime_t *rel)
{
struct pollfd pfd;
struct timespec ts;
pfd.fd = sigwait_fd;
pfd.events = POLLIN;
if (!BUSY_WAIT_SIGNALS && ubf_threads_empty()) {
(void)ppoll(&pfd, 1, rb_hrtime2timespec(&ts, rel), 0);
check_signals_nogvl(th, sigwait_fd);
}
else {
rb_hrtime_t to = RB_HRTIME_MAX, end = 0;
int n = 0;
if (rel) {
to = *rel;
end = rb_hrtime_add(rb_hrtime_now(), to);
}
/*
* tricky: this needs to return on spurious wakeup (no auto-retry).
* But we also need to distinguish between periodic quantum
* wakeups, so we care about the result of consume_communication_pipe
*
* We want to avoid spurious wakeup for Mutex#sleep compatibility
* [ruby-core:88102]
*/
for (;;) {
const rb_hrtime_t *sto = sigwait_timeout(th, sigwait_fd, &to, &n);
if (n) return;
n = ppoll(&pfd, 1, rb_hrtime2timespec(&ts, sto), 0);
if (check_signals_nogvl(th, sigwait_fd))
return;
if (n || (th && RUBY_VM_INTERRUPTED(th->ec)))
return;
if (rel && hrtime_update_expire(&to, end))
return;
}
}
}
/*
* we need to guarantee wakeups from native_ppoll_sleep because
* ubf_select may not be going through ubf_list if other threads
* are all sleeping.
*/
static void
ubf_ppoll_sleep(void *ignore)
{
rb_thread_wakeup_timer_thread_fd(signal_self_pipe.ub_main[1]);
}
/*
* Single CPU setups benefit from explicit sched_yield() before ppoll(),
* since threads may be too starved to enter the GVL waitqueue for
* us to detect contention. Instead, we want to kick other threads
* so they can run and possibly prevent us from entering slow paths
* in ppoll() or similar syscalls.
*
* Confirmed on FreeBSD 11.2 and Linux 4.19.
* [ruby-core:90417] [Bug #15398]
*/
#define THREAD_BLOCKING_YIELD(th) do { \
const rb_thread_t *next; \
struct rb_thread_sched *sched = TH_SCHED(th); \
RB_GC_SAVE_MACHINE_CONTEXT(th); \
rb_native_mutex_lock(&sched->lock); \
next = thread_sched_to_waiting_common(sched); \
rb_native_mutex_unlock(&sched->lock); \
if (!next && rb_ractor_living_thread_num(th->ractor) > 1) { \
native_thread_yield(); \
}
/*
* This function does not exclusively acquire sigwait_fd, so it
* cannot safely read from it. However, it can be woken up in
* 4 ways:
*
* 1) ubf_ppoll_sleep (from another thread)
* 2) rb_thread_wakeup_timer_thread (from signal handler)
* 3) any unmasked signal hitting the process
* 4) periodic ubf timer wakeups (after 3)
*/
static void
native_ppoll_sleep(rb_thread_t *th, rb_hrtime_t *rel)
{
rb_native_mutex_lock(&th->interrupt_lock);
th->unblock.func = ubf_ppoll_sleep;
rb_native_mutex_unlock(&th->interrupt_lock);
THREAD_BLOCKING_YIELD(th);
{
if (!RUBY_VM_INTERRUPTED(th->ec)) {
struct pollfd pfd[2];
struct timespec ts;
pfd[0].fd = signal_self_pipe.normal[0]; /* sigwait_fd */
pfd[1].fd = signal_self_pipe.ub_main[0];
pfd[0].events = pfd[1].events = POLLIN;
if (ppoll(pfd, 2, rb_hrtime2timespec(&ts, rel), 0) > 0) {
if (pfd[1].revents & POLLIN) {
(void)consume_communication_pipe(pfd[1].fd);
}
}
/*
* do not read the sigwait_fd, here, let uplevel callers
* or other threads that, otherwise we may steal and starve
* other threads
*/
}
unblock_function_clear(th);
}
THREAD_BLOCKING_END(th);
}
static void
native_sleep(rb_thread_t *th, rb_hrtime_t *rel)
{
int sigwait_fd = rb_sigwait_fd_get(th);
rb_ractor_blocking_threads_inc(th->ractor, __FILE__, __LINE__);
RB_INTERNAL_THREAD_HOOK(RUBY_INTERNAL_THREAD_EVENT_SUSPENDED);
if (sigwait_fd >= 0) {
rb_native_mutex_lock(&th->interrupt_lock);
th->unblock.func = ubf_sigwait;
rb_native_mutex_unlock(&th->interrupt_lock);
THREAD_BLOCKING_YIELD(th);
{
if (!RUBY_VM_INTERRUPTED(th->ec)) {
rb_sigwait_sleep(th, sigwait_fd, rel);
}
else {
check_signals_nogvl(th, sigwait_fd);
}
unblock_function_clear(th);
}
THREAD_BLOCKING_END(th);
rb_sigwait_fd_put(th, sigwait_fd);
rb_sigwait_fd_migrate(th->vm);
}
else if (th == th->vm->ractor.main_thread) { /* always able to handle signals */
native_ppoll_sleep(th, rel);
}
else {
native_cond_sleep(th, rel);
}
rb_ractor_blocking_threads_dec(th->ractor, __FILE__, __LINE__);
}
#if UBF_TIMER == UBF_TIMER_PTHREAD
static void *
timer_pthread_fn(void *p)
{
rb_vm_t *vm = p;
pthread_t main_thread_id = vm->ractor.main_thread->nt->thread_id;
struct pollfd pfd;
int timeout = -1;
int ccp;
pfd.fd = timer_pthread.low[0];
pfd.events = POLLIN;
while (system_working > 0) {
(void)poll(&pfd, 1, timeout);
ccp = consume_communication_pipe(pfd.fd);
if (system_working > 0) {
if (ATOMIC_CAS(timer_pthread.armed, 1, 1)) {
pthread_kill(main_thread_id, SIGVTALRM);
if (rb_signal_buff_size() || !ubf_threads_empty()) {
timeout = TIME_QUANTUM_MSEC;
}
else {
ATOMIC_SET(timer_pthread.armed, 0);
timeout = -1;
}
}
else if (ccp) {
pthread_kill(main_thread_id, SIGVTALRM);
ATOMIC_SET(timer_pthread.armed, 0);
timeout = -1;
}
}
}
return 0;
}
#endif /* UBF_TIMER_PTHREAD */
static VALUE
ubf_caller(void *ignore)
{
rb_thread_sleep_forever();
return Qfalse;
}
/*
* Called if and only if one thread is running, and
* the unblock function is NOT async-signal-safe
* This assumes USE_THREAD_CACHE is true for performance reasons
*/
static VALUE
rb_thread_start_unblock_thread(void)
{
return rb_thread_create(ubf_caller, 0);
}
#endif /* THREAD_SYSTEM_DEPENDENT_IMPLEMENTATION */
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