bind/lib/isc/thread.c

/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * SPDX-License-Identifier: MPL-2.0
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */

/*! \file */

#if defined(HAVE_SCHED_H)
#include <sched.h>
#endif /* if defined(HAVE_SCHED_H) */

#if defined(HAVE_CPUSET_H)
#include <sys/cpuset.h>
#include <sys/param.h>
#endif /* if defined(HAVE_CPUSET_H) */

#if defined(HAVE_SYS_PROCSET_H)
#include <sys/processor.h>
#include <sys/procset.h>
#include <sys/types.h>
#endif /* if defined(HAVE_SYS_PROCSET_H) */

#include <stdlib.h>

#include <isc/atomic.h>
#include <isc/iterated_hash.h>
#include <isc/strerr.h>
#include <isc/thread.h>
#include <isc/tid.h>
#include <isc/urcu.h>
#include <isc/util.h>

#ifndef THREAD_MINSTACKSIZE
#define THREAD_MINSTACKSIZE (1024U * 1024)
#endif /* ifndef THREAD_MINSTACKSIZE */

/*
 * We can't use isc_mem API here, because it's called too early and the
 * isc_mem_debugging flags can be changed later causing mismatch between flags
 * used for isc_mem_get() and isc_mem_put().
 */

struct thread_wrap {
	struct rcu_head rcu_head;
	isc_threadfunc_t func;
	void *arg;
};

static struct thread_wrap *
thread_wrap(isc_threadfunc_t func, void *arg) {
	struct thread_wrap *wrap = malloc(sizeof(*wrap));
	*wrap = (struct thread_wrap){
		.func = func,
		.arg = arg,
	};
	__tsan_release(wrap);
	return (wrap);
}

static void *
thread_body(struct thread_wrap *wrap) {
	isc_threadfunc_t func = wrap->func;
	void *arg = wrap->arg;
	void *ret = NULL;

	/*
	 * Every thread starts with a malloc() call to prevent memory bloat
	 * caused by a jemalloc quirk.  We use CMM_ACCESS_ONCE() To stop an
	 * optimizing compiler from stripping out free(malloc(1)).
	 */
	void *jemalloc_enforce_init = NULL;
	CMM_ACCESS_ONCE(jemalloc_enforce_init) = malloc(1);
	free(jemalloc_enforce_init);

	/* Reassure Thread Sanitizer that it is safe to free the wrapper */
	__tsan_acquire(wrap);
	free(wrap);

	ret = func(arg);

	return (ret);
}

static void *
thread_run(void *wrap) {
	/*
	 * Get a thread-local digest context only in new threads.
	 * The main thread is handled by isc__initialize().
	 */
	isc__iterated_hash_initialize();

	rcu_register_thread();

	void *ret = thread_body(wrap);

	isc__iterated_hash_shutdown();

	rcu_unregister_thread();

	return (ret);
}

void
isc_thread_main(isc_threadfunc_t func, void *arg) {
	/*
	 * Either this thread has not yet been started, so it can become the
	 * main thread, or it has already been annointed as the chosen zero
	 */
	REQUIRE(isc_tid() == ISC_TID_UNKNOWN || isc_tid() == 0);
	thread_body(thread_wrap(func, arg));
}

void
isc_thread_create(isc_threadfunc_t func, void *arg, isc_thread_t *thread) {
	int ret;
	pthread_attr_t attr;

	pthread_attr_init(&attr);

#if defined(HAVE_PTHREAD_ATTR_GETSTACKSIZE) && \
	defined(HAVE_PTHREAD_ATTR_SETSTACKSIZE)
	size_t stacksize;
	ret = pthread_attr_getstacksize(&attr, &stacksize);
	PTHREADS_RUNTIME_CHECK(pthread_attr_getstacksize, ret);

	if (stacksize < THREAD_MINSTACKSIZE) {
		ret = pthread_attr_setstacksize(&attr, THREAD_MINSTACKSIZE);
		PTHREADS_RUNTIME_CHECK(pthread_attr_setstacksize, ret);
	}
#endif /* if defined(HAVE_PTHREAD_ATTR_GETSTACKSIZE) && \
	* defined(HAVE_PTHREAD_ATTR_SETSTACKSIZE) */

	ret = pthread_create(thread, &attr, thread_run, thread_wrap(func, arg));
	PTHREADS_RUNTIME_CHECK(pthread_create, ret);

	pthread_attr_destroy(&attr);
}

void
isc_thread_join(isc_thread_t thread, void **resultp) {
	int ret = pthread_join(thread, resultp);

	PTHREADS_RUNTIME_CHECK(pthread_join, ret);
}

void
isc_thread_setname(isc_thread_t thread, const char *name) {
#if defined(HAVE_PTHREAD_SETNAME_NP) && !defined(__APPLE__)
	/*
	 * macOS has pthread_setname_np but only works on the
	 * current thread so it's not used here
	 */
#if defined(__NetBSD__)
	(void)pthread_setname_np(thread, name, NULL);
#else  /* if defined(__NetBSD__) */
	(void)pthread_setname_np(thread, name);
#endif /* if defined(__NetBSD__) */
#elif defined(HAVE_PTHREAD_SET_NAME_NP)
	(void)pthread_set_name_np(thread, name);
#else  /* if defined(HAVE_PTHREAD_SETNAME_NP) && !defined(__APPLE__) */
	UNUSED(thread);
	UNUSED(name);
#endif /* if defined(HAVE_PTHREAD_SETNAME_NP) && !defined(__APPLE__) */
}

void
isc_thread_yield(void) {
#if defined(HAVE_SCHED_YIELD)
	sched_yield();
#elif defined(HAVE_PTHREAD_YIELD)
	pthread_yield();
#elif defined(HAVE_PTHREAD_YIELD_NP)
	pthread_yield_np();
#endif /* if defined(HAVE_SCHED_YIELD) */
}