pollset.c   [plain text]

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifdef WIN32
/* POSIX defines 1024 for the FD_SETSIZE */
#define FD_SETSIZE 1024
#endif

#include "apr.h"
#include "apr_poll.h"
#include "apr_time.h"
#include "apr_portable.h"
#include "apr_arch_file_io.h"
#include "apr_arch_networkio.h"
#include "apr_arch_poll_private.h"
#include "apr_arch_inherit.h"

static apr_pollset_method_e pollset_default_method = POLLSET_DEFAULT_METHOD;

#if !APR_FILES_AS_SOCKETS
#if defined (WIN32)

/* Create a dummy wakeup socket pipe for interrupting the poller
 */
static apr_status_t create_wakeup_pipe(apr_pollset_t *pollset)
{
    apr_status_t rv;

    if ((rv = apr_file_socket_pipe_create(&pollset->wakeup_pipe[0],
                                          &pollset->wakeup_pipe[1],
                                          pollset->pool)) != APR_SUCCESS)
        return rv;

    pollset->wakeup_pfd.p = pollset->pool;
    pollset->wakeup_pfd.reqevents = APR_POLLIN;
    pollset->wakeup_pfd.desc_type = APR_POLL_FILE;
    pollset->wakeup_pfd.desc.f = pollset->wakeup_pipe[0];

    return apr_pollset_add(pollset, &pollset->wakeup_pfd);
}

#else  /* !WIN32 */
static apr_status_t create_wakeup_pipe(apr_pollset_t *pollset)
{
    return APR_ENOTIMPL;
}

static apr_status_t apr_file_socket_pipe_close(apr_file_t *file)
{
    return APR_ENOTIMPL;
}

#endif /* WIN32 */
#else  /* APR_FILES_AS_SOCKETS */

/* Create a dummy wakeup pipe for interrupting the poller
 */
static apr_status_t create_wakeup_pipe(apr_pollset_t *pollset)
{
    apr_status_t rv;

    if ((rv = apr_file_pipe_create(&pollset->wakeup_pipe[0],
                                   &pollset->wakeup_pipe[1],
                                   pollset->pool)) != APR_SUCCESS)
        return rv;

    pollset->wakeup_pfd.p = pollset->pool;
    pollset->wakeup_pfd.reqevents = APR_POLLIN;
    pollset->wakeup_pfd.desc_type = APR_POLL_FILE;
    pollset->wakeup_pfd.desc.f = pollset->wakeup_pipe[0];

    {
        int flags;

        if ((flags = fcntl(pollset->wakeup_pipe[0]->filedes, F_GETFD)) == -1)
            return errno;

        flags |= FD_CLOEXEC;
        if (fcntl(pollset->wakeup_pipe[0]->filedes, F_SETFD, flags) == -1)
            return errno;
    }
    {
        int flags;

        if ((flags = fcntl(pollset->wakeup_pipe[1]->filedes, F_GETFD)) == -1)
            return errno;

        flags |= FD_CLOEXEC;
        if (fcntl(pollset->wakeup_pipe[1]->filedes, F_SETFD, flags) == -1)
            return errno;
    }

    return apr_pollset_add(pollset, &pollset->wakeup_pfd);
}
#endif /* !APR_FILES_AS_SOCKETS */

/* Read and discard what's ever in the wakeup pipe.
 */
void apr_pollset_drain_wakeup_pipe(apr_pollset_t *pollset)
{
    char rb[512];
    apr_size_t nr = sizeof(rb);

    while (apr_file_read(pollset->wakeup_pipe[0], rb, &nr) == APR_SUCCESS) {
        /* Although we write just one byte to the other end of the pipe
         * during wakeup, multiple threads could call the wakeup.
         * So simply drain out from the input side of the pipe all
         * the data.
         */
        if (nr != sizeof(rb))
            break;
    }
}

static apr_status_t pollset_cleanup(void *p)
{
    apr_pollset_t *pollset = (apr_pollset_t *) p;
    if (pollset->provider->cleanup) {
        (*pollset->provider->cleanup)(pollset);
    }
    if (pollset->flags & APR_POLLSET_WAKEABLE) {
        /* Close both sides of the wakeup pipe */
        if (pollset->wakeup_pipe[0]) {
#if APR_FILES_AS_SOCKETS
            apr_file_close(pollset->wakeup_pipe[0]);
#else
            apr_file_socket_pipe_close(pollset->wakeup_pipe[0]);
#endif
            pollset->wakeup_pipe[0] = NULL;
        }
        if (pollset->wakeup_pipe[1]) {
#if APR_FILES_AS_SOCKETS
            apr_file_close(pollset->wakeup_pipe[1]);
#else
            apr_file_socket_pipe_close(pollset->wakeup_pipe[1]);
#endif
            pollset->wakeup_pipe[1] = NULL;
        }
    }

    return APR_SUCCESS;
}

#if defined(HAVE_KQUEUE)
extern apr_pollset_provider_t *apr_pollset_provider_kqueue;
#endif
#if defined(HAVE_PORT_CREATE)
extern apr_pollset_provider_t *apr_pollset_provider_port;
#endif
#if defined(HAVE_EPOLL)
extern apr_pollset_provider_t *apr_pollset_provider_epoll;
#endif
#if defined(HAVE_POLL)
extern apr_pollset_provider_t *apr_pollset_provider_poll;
#endif
extern apr_pollset_provider_t *apr_pollset_provider_select;

static apr_pollset_provider_t *pollset_provider(apr_pollset_method_e method)
{
    apr_pollset_provider_t *provider = NULL;
    switch (method) {
        case APR_POLLSET_KQUEUE:
#if defined(HAVE_KQUEUE)
            provider = apr_pollset_provider_kqueue;
#endif
        break;
        case APR_POLLSET_PORT:
#if defined(HAVE_PORT_CREATE)
            provider = apr_pollset_provider_port;
#endif
        break;
        case APR_POLLSET_EPOLL:
#if defined(HAVE_EPOLL)
            provider = apr_pollset_provider_epoll;
#endif
        break;
        case APR_POLLSET_POLL:
#if defined(HAVE_POLL)
            provider = apr_pollset_provider_poll;
#endif
        break;
        case APR_POLLSET_SELECT:
            provider = apr_pollset_provider_select;
        break;
        case APR_POLLSET_DEFAULT:
        break;
    }
    return provider;
}

APR_DECLARE(apr_status_t) apr_pollset_create_ex(apr_pollset_t **ret_pollset,
                                                apr_uint32_t size,
                                                apr_pool_t *p,
                                                apr_uint32_t flags,
                                                apr_pollset_method_e method)
{
    apr_status_t rv;
    apr_pollset_t *pollset;
    apr_pollset_provider_t *provider = NULL;

    *ret_pollset = NULL;

 #ifdef WIN32
    /* Favor WSAPoll if supported.
     * This will work only if ws2_32.dll has WSAPoll funtion.
     * In other cases it will fall back to select() method unless
     * the APR_POLLSET_NODEFAULT is added to the flags.
     */
    if (method == APR_POLLSET_DEFAULT) {
        method = APR_POLLSET_POLL;
    }
 #endif

    if (method == APR_POLLSET_DEFAULT)
        method = pollset_default_method;
    while (provider == NULL) {
        provider = pollset_provider(method);
        if (!provider) {
            if ((flags & APR_POLLSET_NODEFAULT) == APR_POLLSET_NODEFAULT)
                return APR_ENOTIMPL;
            if (method == pollset_default_method)
                return APR_ENOTIMPL;
            method = pollset_default_method;
        }
    }
    if (flags & APR_POLLSET_WAKEABLE) {
        /* Add room for wakeup descriptor */
        size++;
    }

    pollset = apr_palloc(p, sizeof(*pollset));
    pollset->nelts = 0;
    pollset->nalloc = size;
    pollset->pool = p;
    pollset->flags = flags;
    pollset->provider = provider;

    rv = (*provider->create)(pollset, size, p, flags);
    if (rv == APR_ENOTIMPL) {
        if (method == pollset_default_method) {
            return rv;
        }
        provider = pollset_provider(pollset_default_method);
        if (!provider) {
            return APR_ENOTIMPL;
        }
        rv = (*provider->create)(pollset, size, p, flags);
        if (rv != APR_SUCCESS) {
            return rv;
        }
        pollset->provider = provider;
    }
    else if (rv != APR_SUCCESS) {
        return rv;
    }
    if (flags & APR_POLLSET_WAKEABLE) {
        /* Create wakeup pipe */
        if ((rv = create_wakeup_pipe(pollset)) != APR_SUCCESS) {
            return rv;
        }
    }
    if ((flags & APR_POLLSET_WAKEABLE) || provider->cleanup)
        apr_pool_cleanup_register(p, pollset, pollset_cleanup,
                                  apr_pool_cleanup_null);

    *ret_pollset = pollset;
    return APR_SUCCESS;
}

APR_DECLARE(const char *) apr_pollset_method_name(apr_pollset_t *pollset)
{
    return pollset->provider->name;
}

APR_DECLARE(const char *) apr_poll_method_defname()
{
    apr_pollset_provider_t *provider = NULL;

    provider = pollset_provider(pollset_default_method);
    if (provider)
        return provider->name;
    else
        return "unknown";
}

APR_DECLARE(apr_status_t) apr_pollset_create(apr_pollset_t **pollset,
                                             apr_uint32_t size,
                                             apr_pool_t *p,
                                             apr_uint32_t flags)
{
    apr_pollset_method_e method = APR_POLLSET_DEFAULT;
    return apr_pollset_create_ex(pollset, size, p, flags, method);
}

APR_DECLARE(apr_status_t) apr_pollset_destroy(apr_pollset_t * pollset)
{
    if (pollset->flags & APR_POLLSET_WAKEABLE ||
        pollset->provider->cleanup)
        return apr_pool_cleanup_run(pollset->pool, pollset,
                                    pollset_cleanup);
    else
        return APR_SUCCESS;
}

APR_DECLARE(apr_status_t) apr_pollset_wakeup(apr_pollset_t *pollset)
{
    if (pollset->flags & APR_POLLSET_WAKEABLE)
        return apr_file_putc(1, pollset->wakeup_pipe[1]);
    else
        return APR_EINIT;
}

APR_DECLARE(apr_status_t) apr_pollset_add(apr_pollset_t *pollset,
                                          const apr_pollfd_t *descriptor)
{
    return (*pollset->provider->add)(pollset, descriptor);
}

APR_DECLARE(apr_status_t) apr_pollset_remove(apr_pollset_t *pollset,
                                             const apr_pollfd_t *descriptor)
{
    return (*pollset->provider->remove)(pollset, descriptor);
}

APR_DECLARE(apr_status_t) apr_pollset_poll(apr_pollset_t *pollset,
                                           apr_interval_time_t timeout,
                                           apr_int32_t *num,
                                           const apr_pollfd_t **descriptors)
{
    return (*pollset->provider->poll)(pollset, timeout, num, descriptors);
}