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freebsd/lib/libthr/thread/thr_list.c
2006-11-24 09:57:38 +00:00

345 lines
8.5 KiB
C

/*
* Copyright (c) 2005 David Xu <davidxu@freebsd.org>
* Copyright (C) 2003 Daniel M. Eischen <deischen@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <sys/types.h>
#include <sys/queue.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include "thr_private.h"
#include "libc_private.h"
/*#define DEBUG_THREAD_LIST */
#ifdef DEBUG_THREAD_LIST
#define DBG_MSG stdout_debug
#else
#define DBG_MSG(x...)
#endif
#define MAX_THREADS 100000
/*
* Define a high water mark for the maximum number of threads that
* will be cached. Once this level is reached, any extra threads
* will be free()'d.
*/
#define MAX_CACHED_THREADS 100
/*
* We've got to keep track of everything that is allocated, not only
* to have a speedy free list, but also so they can be deallocated
* after a fork().
*/
static TAILQ_HEAD(, pthread) free_threadq;
static struct umutex free_thread_lock = DEFAULT_UMUTEX;
static struct umutex tcb_lock = DEFAULT_UMUTEX;
static int free_thread_count = 0;
static int inited = 0;
static int total_threads;
LIST_HEAD(thread_hash_head, pthread);
#define HASH_QUEUES 128
static struct thread_hash_head thr_hashtable[HASH_QUEUES];
#define THREAD_HASH(thrd) (((unsigned long)thrd >> 8) % HASH_QUEUES)
static void thr_destroy(struct pthread *curthread, struct pthread *thread);
void
_thr_list_init(void)
{
int i;
_gc_count = 0;
total_threads = 1;
_thr_umutex_init(&_thr_list_lock);
TAILQ_INIT(&_thread_list);
TAILQ_INIT(&free_threadq);
_thr_umutex_init(&free_thread_lock);
_thr_umutex_init(&tcb_lock);
if (inited) {
for (i = 0; i < HASH_QUEUES; ++i)
LIST_INIT(&thr_hashtable[i]);
}
inited = 1;
}
void
_thr_gc(struct pthread *curthread)
{
struct pthread *td, *td_next;
TAILQ_HEAD(, pthread) worklist;
TAILQ_INIT(&worklist);
THREAD_LIST_LOCK(curthread);
/* Check the threads waiting for GC. */
TAILQ_FOREACH_SAFE(td, &_thread_gc_list, gcle, td_next) {
if (td->tid != TID_TERMINATED) {
/* make sure we are not still in userland */
continue;
}
_thr_stack_free(&td->attr);
if (((td->tlflags & TLFLAGS_DETACHED) != 0) &&
(td->refcount == 0)) {
THR_GCLIST_REMOVE(td);
/*
* The thread has detached and is no longer
* referenced. It is safe to remove all
* remnants of the thread.
*/
THR_LIST_REMOVE(td);
TAILQ_INSERT_HEAD(&worklist, td, gcle);
}
}
THREAD_LIST_UNLOCK(curthread);
while ((td = TAILQ_FIRST(&worklist)) != NULL) {
TAILQ_REMOVE(&worklist, td, gcle);
/*
* XXX we don't free initial thread, because there might
* have some code referencing initial thread.
*/
if (td == _thr_initial) {
DBG_MSG("Initial thread won't be freed\n");
continue;
}
_thr_free(curthread, td);
}
}
struct pthread *
_thr_alloc(struct pthread *curthread)
{
struct pthread *thread = NULL;
struct tcb *tcb;
if (curthread != NULL) {
if (GC_NEEDED())
_thr_gc(curthread);
if (free_thread_count > 0) {
THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
TAILQ_REMOVE(&free_threadq, thread, tle);
free_thread_count--;
}
THR_LOCK_RELEASE(curthread, &free_thread_lock);
}
}
if (thread == NULL) {
if (total_threads > MAX_THREADS)
return (NULL);
atomic_fetchadd_int(&total_threads, 1);
thread = malloc(sizeof(struct pthread));
if (thread == NULL) {
atomic_fetchadd_int(&total_threads, -1);
return (NULL);
}
}
if (curthread != NULL) {
THR_LOCK_ACQUIRE(curthread, &tcb_lock);
tcb = _tcb_ctor(thread, 0 /* not initial tls */);
THR_LOCK_RELEASE(curthread, &tcb_lock);
} else {
tcb = _tcb_ctor(thread, 1 /* initial tls */);
}
if (tcb != NULL) {
memset(thread, 0, sizeof(*thread));
thread->tcb = tcb;
} else {
thr_destroy(curthread, thread);
atomic_fetchadd_int(&total_threads, -1);
thread = NULL;
}
return (thread);
}
void
_thr_free(struct pthread *curthread, struct pthread *thread)
{
DBG_MSG("Freeing thread %p\n", thread);
/*
* Always free tcb, as we only know it is part of RTLD TLS
* block, but don't know its detail and can not assume how
* it works, so better to avoid caching it here.
*/
if (curthread != NULL) {
THR_LOCK_ACQUIRE(curthread, &tcb_lock);
_tcb_dtor(thread->tcb);
THR_LOCK_RELEASE(curthread, &tcb_lock);
} else {
_tcb_dtor(thread->tcb);
}
thread->tcb = NULL;
if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
thr_destroy(curthread, thread);
atomic_fetchadd_int(&total_threads, -1);
} else {
/*
* Add the thread to the free thread list, this also avoids
* pthread id is reused too quickly, may help some buggy apps.
*/
THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
free_thread_count++;
THR_LOCK_RELEASE(curthread, &free_thread_lock);
}
}
static void
thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
{
free(thread);
}
/*
* Add the thread to the list of all threads and increment
* number of active threads.
*/
void
_thr_link(struct pthread *curthread, struct pthread *thread)
{
THREAD_LIST_LOCK(curthread);
THR_LIST_ADD(thread);
_thread_active_threads++;
THREAD_LIST_UNLOCK(curthread);
}
/*
* Remove an active thread.
*/
void
_thr_unlink(struct pthread *curthread, struct pthread *thread)
{
THREAD_LIST_LOCK(curthread);
THR_LIST_REMOVE(thread);
_thread_active_threads--;
THREAD_LIST_UNLOCK(curthread);
}
void
_thr_hash_add(struct pthread *thread)
{
struct thread_hash_head *head;
head = &thr_hashtable[THREAD_HASH(thread)];
LIST_INSERT_HEAD(head, thread, hle);
}
void
_thr_hash_remove(struct pthread *thread)
{
LIST_REMOVE(thread, hle);
}
struct pthread *
_thr_hash_find(struct pthread *thread)
{
struct pthread *td;
struct thread_hash_head *head;
head = &thr_hashtable[THREAD_HASH(thread)];
LIST_FOREACH(td, head, hle) {
if (td == thread)
return (thread);
}
return (NULL);
}
/*
* Find a thread in the linked list of active threads and add a reference
* to it. Threads with positive reference counts will not be deallocated
* until all references are released.
*/
int
_thr_ref_add(struct pthread *curthread, struct pthread *thread,
int include_dead)
{
int ret;
if (thread == NULL)
/* Invalid thread: */
return (EINVAL);
THREAD_LIST_LOCK(curthread);
if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
thread->refcount++;
THR_CRITICAL_ENTER(curthread);
}
THREAD_LIST_UNLOCK(curthread);
/* Return zero if the thread exists: */
return (ret);
}
void
_thr_ref_delete(struct pthread *curthread, struct pthread *thread)
{
THREAD_LIST_LOCK(curthread);
_thr_ref_delete_unlocked(curthread, thread);
THREAD_LIST_UNLOCK(curthread);
}
void
_thr_ref_delete_unlocked(struct pthread *curthread,
struct pthread *thread)
{
if (thread != NULL) {
thread->refcount--;
if ((thread->refcount == 0) && thread->state == PS_DEAD &&
(thread->tlflags & TLFLAGS_DETACHED) != 0)
THR_GCLIST_ADD(thread);
THR_CRITICAL_LEAVE(curthread);
}
}
int
_thr_find_thread(struct pthread *curthread __unused, struct pthread *thread,
int include_dead)
{
struct pthread *pthread;
if (thread == NULL)
/* Invalid thread: */
return (EINVAL);
pthread = _thr_hash_find(thread);
if (pthread) {
if (include_dead == 0 && pthread->state == PS_DEAD) {
pthread = NULL;
}
}
/* Return zero if the thread exists: */
return ((pthread != NULL) ? 0 : ESRCH);
}