freebsd-nq/lib/libkse/thread/thr_spec.c
John Birrell 4a027d50c7 Change signal model to match POSIX (i.e. one set of signal handlers
for the process, not a separate set for each thread). By default, the
process now only has signal handlers installed for SIGVTALRM, SIGINFO
and SIGCHLD. The thread kernel signal handler is installed for other
signals on demand. This means that SIG_IGN and SIG_DFL processing is now
left to the kernel, not the thread kernel.

Change the signal dispatch to no longer use a signal thread, and
call the signal handler using the stack of the thread that has the
signal pending.

Change the atomic lock method to use test-and-set asm code with
a yield if blocked. This introduces separate locks for each type
of object instead of blocking signals to prevent a context
switch. It was this blocking of signals that caused the performance
degradation the people have noted.

This is a *big* change!
1998-04-29 09:59:34 +00:00

215 lines
5.7 KiB
C

/*
* Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
* 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, 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Birrell.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
*
*/
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#ifdef _THREAD_SAFE
#include <pthread.h>
#include "pthread_private.h"
/* Static variables: */
static struct pthread_key key_table[PTHREAD_KEYS_MAX];
static long key_table_lock = 0;
int
pthread_key_create(pthread_key_t * key, void (*destructor) (void *))
{
/* Lock the key table: */
_spinlock(&key_table_lock);
for ((*key) = 0; (*key) < PTHREAD_KEYS_MAX; (*key)++) {
if (key_table[(*key)].count == 0) {
key_table[(*key)].count++;
key_table[(*key)].destructor = destructor;
/* Unlock the key table: */
_atomic_unlock(&key_table_lock);
return (0);
}
}
/* Unlock the key table: */
_atomic_unlock(&key_table_lock);
return (EAGAIN);
}
int
pthread_key_delete(pthread_key_t key)
{
int ret;
/* Lock the key table: */
_spinlock(&key_table_lock);
if (key < PTHREAD_KEYS_MAX) {
switch (key_table[key].count) {
case 1:
key_table[key].destructor = NULL;
key_table[key].count = 0;
case 0:
ret = 0;
break;
default:
ret = EBUSY;
}
} else
ret = EINVAL;
/* Unlock the key table: */
_atomic_unlock(&key_table_lock);
return (ret);
}
void
_thread_cleanupspecific(void)
{
void *data;
int key;
int itr;
for (itr = 0; itr < PTHREAD_DESTRUCTOR_ITERATIONS; itr++) {
for (key = 0; key < PTHREAD_KEYS_MAX; key++) {
if (_thread_run->specific_data_count) {
/* Lock the key table entry: */
_spinlock(&key_table[key].access_lock);
if (_thread_run->specific_data[key]) {
data = (void *) _thread_run->specific_data[key];
_thread_run->specific_data[key] = NULL;
_thread_run->specific_data_count--;
if (key_table[key].destructor) {
key_table[key].destructor(data);
}
key_table[key].count--;
}
/* Unlock the key table entry: */
_atomic_unlock(&key_table[key].access_lock);
} else {
free(_thread_run->specific_data);
return;
}
}
}
free(_thread_run->specific_data);
}
static inline const void **
pthread_key_allocate_data(void)
{
const void **new_data;
if ((new_data = (const void **) malloc(sizeof(void *) * PTHREAD_KEYS_MAX)) != NULL) {
memset((void *) new_data, 0, sizeof(void *) * PTHREAD_KEYS_MAX);
}
return (new_data);
}
int
pthread_setspecific(pthread_key_t key, const void *value)
{
pthread_t pthread;
int ret = 0;
/* Point to the running thread: */
pthread = _thread_run;
if ((pthread->specific_data) ||
(pthread->specific_data = pthread_key_allocate_data())) {
if ((key < PTHREAD_KEYS_MAX) && (key_table)) {
/* Lock the key table entry: */
_spinlock(&key_table[key].access_lock);
if (key_table[key].count) {
if (pthread->specific_data[key] == NULL) {
if (value != NULL) {
pthread->specific_data_count++;
key_table[key].count++;
}
} else {
if (value == NULL) {
pthread->specific_data_count--;
key_table[key].count--;
}
}
pthread->specific_data[key] = value;
ret = 0;
} else
ret = EINVAL;
/* Unlock the key table entry: */
_atomic_unlock(&key_table[key].access_lock);
} else
ret = EINVAL;
} else
ret = ENOMEM;
return (ret);
}
void *
pthread_getspecific(pthread_key_t key)
{
pthread_t pthread;
void *data;
/* Point to the running thread: */
pthread = _thread_run;
/* Check if there is specific data: */
if (pthread->specific_data != NULL &&
(key < PTHREAD_KEYS_MAX) && (key_table)) {
/* Lock the key table entry: */
_spinlock(&key_table[key].access_lock);
/* Check if this key has been used before: */
if (key_table[key].count) {
/* Return the value: */
data = (void *) pthread->specific_data[key];
} else {
/*
* This key has not been used before, so return NULL
* instead:
*/
data = NULL;
}
/* Unlock the key table entry: */
_atomic_unlock(&key_table[key].access_lock);
} else
/* No specific data has been created, so just return NULL: */
data = NULL;
return (data);
}
#endif