view src/core/ngx_shmtx.c @ 3992:a1dd9dc754ab

A new fix for the case when ssl_session_cache defined, but ssl is not enabled in any server. The previous r1033 does not help when unused zone becomes used after reconfiguration, so it is backed out. The initial thought was to make SSL modules independed from SSL implementation and to keep OpenSSL code dependance as much as in separate files.
author Igor Sysoev <igor@sysoev.ru>
date Thu, 04 Aug 2011 11:12:30 +0000
parents 0daede16d68b
children 3f6040cd731e 4919fb357a5d
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 */


#include <ngx_config.h>
#include <ngx_core.h>


#if (NGX_HAVE_ATOMIC_OPS)


ngx_int_t
ngx_shmtx_create(ngx_shmtx_t *mtx, void *addr, u_char *name)
{
    mtx->lock = addr;

    if (mtx->spin == (ngx_uint_t) -1) {
        return NGX_OK;
    }

    mtx->spin = 2048;

#if (NGX_HAVE_POSIX_SEM)

    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_destory(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)
{
    ngx_atomic_uint_t  val;

    val = *mtx->lock;

    return ((val & 0x80000000) == 0
            && ngx_atomic_cmp_set(mtx->lock, val, val | 0x80000000));
}


void
ngx_shmtx_lock(ngx_shmtx_t *mtx)
{
    ngx_uint_t         i, n;
    ngx_atomic_uint_t  val;

    ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx lock");

    for ( ;; ) {

        val = *mtx->lock;

        if ((val & 0x80000000) == 0
            && ngx_atomic_cmp_set(mtx->lock, val, val | 0x80000000))
        {
            return;
        }

        if (ngx_ncpu > 1) {

            for (n = 1; n < mtx->spin; n <<= 1) {

                for (i = 0; i < n; i++) {
                    ngx_cpu_pause();
                }

                val = *mtx->lock;

                if ((val & 0x80000000) == 0
                    && ngx_atomic_cmp_set(mtx->lock, val, val | 0x80000000))
                {
                    return;
                }
            }
        }

#if (NGX_HAVE_POSIX_SEM)

        if (mtx->semaphore) {
            val = *mtx->lock;

            if ((val & 0x80000000)
                && ngx_atomic_cmp_set(mtx->lock, val, val + 1))
            {
                ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
                               "shmtx wait %XA", val);

                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)
{
    ngx_atomic_uint_t  val, old, wait;

    if (mtx->spin != (ngx_uint_t) -1) {
        ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx unlock");
    }

    for ( ;; ) {

        old = *mtx->lock;
        wait = old & 0x7fffffff;
        val = wait ? wait - 1 : 0;

        if (ngx_atomic_cmp_set(mtx->lock, old, val)) {
            break;
        }
    }

#if (NGX_HAVE_POSIX_SEM)

    if (wait == 0 || !mtx->semaphore) {
        return;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
                   "shmtx wake %XA", old);

    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, void *addr, u_char *name)
{
    if (mtx->name) {

        if (ngx_strcmp(name, mtx->name) == 0) {
            mtx->name = name;
            return NGX_OK;
        }

        ngx_shmtx_destory(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_destory(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_EACCESS) {
        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);
}

#endif