blob: a255903efe02426366ed67e5a5205c91f323d95f [file] [log] [blame] [edit]
/*
* Copyright (C) Igor Sysoev
* Copyright (C) Nginx, Inc.
*/
#include <ngx_config.h>
#include <ngx_core.h>
#if (NGX_HAVE_ATOMIC_OPS)
static void ngx_shmtx_wakeup(ngx_shmtx_t *mtx);
ngx_int_t
ngx_shmtx_create(ngx_shmtx_t *mtx, ngx_shmtx_sh_t *addr, u_char *name)
{
mtx->lock = &addr->lock;
if (mtx->spin == (ngx_uint_t) -1) {
return NGX_OK;
}
mtx->spin = 2048;
#if (NGX_HAVE_POSIX_SEM)
mtx->wait = &addr->wait;
if (sem_init(&mtx->sem, 1, 0) == -1) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
"sem_init() failed");
} else {
mtx->semaphore = 1;
}
#endif
return NGX_OK;
}
void
ngx_shmtx_destroy(ngx_shmtx_t *mtx)
{
#if (NGX_HAVE_POSIX_SEM)
if (mtx->semaphore) {
if (sem_destroy(&mtx->sem) == -1) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
"sem_destroy() failed");
}
}
#endif
}
ngx_uint_t
ngx_shmtx_trylock(ngx_shmtx_t *mtx)
{
return (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid));
}
void
ngx_shmtx_lock(ngx_shmtx_t *mtx)
{
ngx_uint_t i, n;
ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx lock");
for ( ;; ) {
if (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid)) {
return;
}
if (ngx_ncpu > 1) {
for (n = 1; n < mtx->spin; n <<= 1) {
for (i = 0; i < n; i++) {
ngx_cpu_pause();
}
if (*mtx->lock == 0
&& ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid))
{
return;
}
}
}
#if (NGX_HAVE_POSIX_SEM)
if (mtx->semaphore) {
(void) ngx_atomic_fetch_add(mtx->wait, 1);
if (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid)) {
(void) ngx_atomic_fetch_add(mtx->wait, -1);
return;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
"shmtx wait %uA", *mtx->wait);
while (sem_wait(&mtx->sem) == -1) {
ngx_err_t err;
err = ngx_errno;
if (err != NGX_EINTR) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, err,
"sem_wait() failed while waiting on shmtx");
break;
}
}
ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
"shmtx awoke");
continue;
}
#endif
ngx_sched_yield();
}
}
void
ngx_shmtx_unlock(ngx_shmtx_t *mtx)
{
if (mtx->spin != (ngx_uint_t) -1) {
ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx unlock");
}
if (ngx_atomic_cmp_set(mtx->lock, ngx_pid, 0)) {
ngx_shmtx_wakeup(mtx);
}
}
ngx_uint_t
ngx_shmtx_force_unlock(ngx_shmtx_t *mtx, ngx_pid_t pid)
{
ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
"shmtx forced unlock");
if (ngx_atomic_cmp_set(mtx->lock, pid, 0)) {
ngx_shmtx_wakeup(mtx);
return 1;
}
return 0;
}
static void
ngx_shmtx_wakeup(ngx_shmtx_t *mtx)
{
#if (NGX_HAVE_POSIX_SEM)
ngx_atomic_uint_t wait;
if (!mtx->semaphore) {
return;
}
for ( ;; ) {
wait = *mtx->wait;
if ((ngx_atomic_int_t) wait <= 0) {
return;
}
if (ngx_atomic_cmp_set(mtx->wait, wait, wait - 1)) {
break;
}
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
"shmtx wake %uA", wait);
if (sem_post(&mtx->sem) == -1) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
"sem_post() failed while wake shmtx");
}
#endif
}
#else
ngx_int_t
ngx_shmtx_create(ngx_shmtx_t *mtx, ngx_shmtx_sh_t *addr, u_char *name)
{
if (mtx->name) {
if (ngx_strcmp(name, mtx->name) == 0) {
mtx->name = name;
return NGX_OK;
}
ngx_shmtx_destroy(mtx);
}
mtx->fd = ngx_open_file(name, NGX_FILE_RDWR, NGX_FILE_CREATE_OR_OPEN,
NGX_FILE_DEFAULT_ACCESS);
if (mtx->fd == NGX_INVALID_FILE) {
ngx_log_error(NGX_LOG_EMERG, ngx_cycle->log, ngx_errno,
ngx_open_file_n " \"%s\" failed", name);
return NGX_ERROR;
}
if (ngx_delete_file(name) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
ngx_delete_file_n " \"%s\" failed", name);
}
mtx->name = name;
return NGX_OK;
}
void
ngx_shmtx_destroy(ngx_shmtx_t *mtx)
{
if (ngx_close_file(mtx->fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
ngx_close_file_n " \"%s\" failed", mtx->name);
}
}
ngx_uint_t
ngx_shmtx_trylock(ngx_shmtx_t *mtx)
{
ngx_err_t err;
err = ngx_trylock_fd(mtx->fd);
if (err == 0) {
return 1;
}
if (err == NGX_EAGAIN) {
return 0;
}
#if __osf__ /* Tru64 UNIX */
if (err == NGX_EACCES) {
return 0;
}
#endif
ngx_log_abort(err, ngx_trylock_fd_n " %s failed", mtx->name);
return 0;
}
void
ngx_shmtx_lock(ngx_shmtx_t *mtx)
{
ngx_err_t err;
err = ngx_lock_fd(mtx->fd);
if (err == 0) {
return;
}
ngx_log_abort(err, ngx_lock_fd_n " %s failed", mtx->name);
}
void
ngx_shmtx_unlock(ngx_shmtx_t *mtx)
{
ngx_err_t err;
err = ngx_unlock_fd(mtx->fd);
if (err == 0) {
return;
}
ngx_log_abort(err, ngx_unlock_fd_n " %s failed", mtx->name);
}
ngx_uint_t
ngx_shmtx_force_unlock(ngx_shmtx_t *mtx, ngx_pid_t pid)
{
return 0;
}
#endif