/*

 * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014 Nicira, Inc.

 *

 * Licensed 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.

 */

#include <config.h>

#include "openvswitch/poll-loop.h"

#include <errno.h>

#include <inttypes.h>

#include <poll.h>

#include <stdlib.h>

#include <string.h>

#include "coverage.h"

#include "openvswitch/dynamic-string.h"

#include "fatal-signal.h"

#include "openvswitch/list.h"

#include "ovs-thread.h"

#include "seq.h"

#include "socket-util.h"

#include "timeval.h"

#include "openvswitch/vlog.h"

#include "openvswitch/hmap.h"

#include "hash.h"

VLOG_DEFINE_THIS_MODULE(poll_loop);

COVERAGE_DEFINE(poll_create_node);

COVERAGE_DEFINE(poll_zero_timeout);

struct poll_node {

    struct hmap_node hmap_node;

    struct pollfd pollfd;       /* Events to pass to time_poll(). */

    HANDLE wevent;              /* Events for WaitForMultipleObjects(). */

    const char *where;          /* Where poll_node was created. */

};

struct poll_loop {

    /* All active poll waiters. */

    struct hmap poll_nodes;

    /* Time at which to wake up the next call to poll_block(), LLONG_MIN to

     * wake up immediately, or LLONG_MAX to wait forever. */

    long long int timeout_when; /* In msecs as returned by time_msec(). */

    const char *timeout_where;  /* Where 'timeout_when' was set. */

};

static struct poll_loop *poll_loop(void);

/* Look up the node with same fd or wevent. */

static struct poll_node *

find_poll_node(struct poll_loop *loop, int fd, HANDLE wevent)

{

    struct poll_node *node;

    /* Both 'fd' and 'wevent' cannot be set. */

    ovs_assert(!fd != !wevent);

    HMAP_FOR_EACH_WITH_HASH (node, hmap_node,

                             hash_2words(fd, (uint32_t)wevent),

                             &loop->poll_nodes) {

        if ((fd && node->pollfd.fd == fd)

            || (wevent && node->wevent == wevent)) {

            return node;

        }

    }

    return NULL;

}

/* On Unix based systems:

 *

 *     Registers 'fd' as waiting for the specified 'events' (which should be

 *     POLLIN or POLLOUT or POLLIN | POLLOUT).  The following call to

 *     poll_block() will wake up when 'fd' becomes ready for one or more of the

 *     requested events. The 'fd's are given to poll() function later.

 *

 * On Windows system:

 *

 *     If 'fd' is specified, create a new 'wevent'. Association of 'fd' and

 *     'wevent' for 'events' happens in poll_block(). If 'wevent' is specified,

 *     it is assumed that it is unrelated to any sockets and poll_block()

 *     will wake up on any event on that 'wevent'. It is an error to pass

 *     both 'wevent' and 'fd'.

 *

 * The event registration is one-shot: only the following call to

 * poll_block() is affected.  The event will need to be re-registered after

 * poll_block() is called if it is to persist.

 *

 * ('where' is used in debug logging.  Commonly one would use poll_fd_wait() to

 * automatically provide the caller's source file and line number for

 * 'where'.) */

static void

poll_create_node(int fd, HANDLE wevent, short int events, const char *where)

{

    struct poll_loop *loop = poll_loop();

    struct poll_node *node;

    COVERAGE_INC(poll_create_node);

    /* Both 'fd' and 'wevent' cannot be set. */

    ovs_assert(!fd != !wevent);

    /* Check for duplicate.  If found, "or" the events. */

    node = find_poll_node(loop, fd, wevent);

    if (node) {

        node->pollfd.events |= events;

    } else {

        node = xzalloc(sizeof *node);

        hmap_insert(&loop->poll_nodes, &node->hmap_node,

                    hash_2words(fd, (uint32_t)wevent));

        node->pollfd.fd = fd;

        node->pollfd.events = events;

#ifdef _WIN32

        if (!wevent) {

            wevent = CreateEvent(NULL, FALSE, FALSE, NULL);

        }

#endif

        node->wevent = wevent;

        node->where = where;

    }

}

/* Registers 'fd' as waiting for the specified 'events' (which should be POLLIN

 * or POLLOUT or POLLIN | POLLOUT).  The following call to poll_block() will

 * wake up when 'fd' becomes ready for one or more of the requested events.

 *

 * On Windows, 'fd' must be a socket.

 *

 * The event registration is one-shot: only the following call to poll_block()

 * is affected.  The event will need to be re-registered after poll_block() is

 * called if it is to persist.

 *

 * ('where' is used in debug logging.  Commonly one would use poll_fd_wait() to

 * automatically provide the caller's source file and line number for

 * 'where'.) */

void

poll_fd_wait_at(int fd, short int events, const char *where)

{

    poll_create_node(fd, 0, events, where);

}

#ifdef _WIN32

/* Registers for the next call to poll_block() to wake up when 'wevent' is

 * signaled.

 *

 * The event registration is one-shot: only the following call to poll_block()

 * is affected.  The event will need to be re-registered after poll_block() is

 * called if it is to persist.

 *

 * ('where' is used in debug logging.  Commonly one would use

 * poll_wevent_wait() to automatically provide the caller's source file and

 * line number for 'where'.) */

void

poll_wevent_wait_at(HANDLE wevent, const char *where)

{

    poll_create_node(0, wevent, 0, where);

}

#endif /* _WIN32 */

/* Causes the following call to poll_block() to block for no more than 'msec'

 * milliseconds.  If 'msec' is nonpositive, the following call to poll_block()

 * will not block at all.

 *

 * The timer registration is one-shot: only the following call to poll_block()

 * is affected.  The timer will need to be re-registered after poll_block() is

 * called if it is to persist.

 *

 * ('where' is used in debug logging.  Commonly one would use poll_timer_wait()

 * to automatically provide the caller's source file and line number for

 * 'where'.) */

void

poll_timer_wait_at(long long int msec, const char *where)

{

    long long int now = time_msec();

    long long int when;

    if (msec <= 0) {

        /* Wake up immediately. */

        when = LLONG_MIN;

    } else if ((unsigned long long int) now + msec <= LLONG_MAX) {

        /* Normal case. */

        when = now + msec;

    } else {

        /* now + msec would overflow. */

        when = LLONG_MAX;

    }

    poll_timer_wait_until_at(when, where);

}

/* Causes the following call to poll_block() to wake up when the current time,

 * as returned by time_msec(), reaches 'when' or later.  If 'when' is earlier

 * than the current time, the following call to poll_block() will not block at

 * all.

 *

 * The timer registration is one-shot: only the following call to poll_block()

 * is affected.  The timer will need to be re-registered after poll_block() is

 * called if it is to persist.

 *

 * ('where' is used in debug logging.  Commonly one would use

 * poll_timer_wait_until() to automatically provide the caller's source file

 * and line number for 'where'.) */

void

poll_timer_wait_until_at(long long int when, const char *where)

{

    struct poll_loop *loop = poll_loop();

    if (when < loop->timeout_when) {

        loop->timeout_when = when;

        loop->timeout_where = where;

    }

}

/* Causes the following call to poll_block() to wake up immediately, without

 * blocking.

 *

 * ('where' is used in debug logging.  Commonly one would use

 * poll_immediate_wake() to automatically provide the caller's source file and

 * line number for 'where'.) */

void

poll_immediate_wake_at(const char *where)

{

    poll_timer_wait_at(0, where);

}

/* Logs, if appropriate, that the poll loop was awakened by an event

 * registered at 'where' (typically a source file and line number).  The other

 * arguments have two possible interpretations:

 *

 *   - If 'pollfd' is nonnull then it should be the "struct pollfd" that caused

 *     the wakeup.  'timeout' is ignored.

 *

 *   - If 'pollfd' is NULL then 'timeout' is the number of milliseconds after

 *     which the poll loop woke up.

 */

static void

log_wakeup(const char *where, const struct pollfd *pollfd, int timeout)

{

    static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 10);

    enum vlog_level level;

    int cpu_usage;

    struct ds s;

    cpu_usage = get_cpu_usage();

    if (VLOG_IS_DBG_ENABLED()) {

        level = VLL_DBG;

    } else if (cpu_usage > 50

               && !thread_is_pmd()

               && !VLOG_DROP_INFO(&rl)) {

        level = VLL_INFO;

    } else {

        return;

    }

    ds_init(&s);

    ds_put_cstr(&s, "wakeup due to ");

    if (pollfd) {

        char *description = describe_fd(pollfd->fd);

        if (pollfd->revents & POLLIN) {

            ds_put_cstr(&s, "[POLLIN]");

        }

        if (pollfd->revents & POLLOUT) {

            ds_put_cstr(&s, "[POLLOUT]");

        }

        if (pollfd->revents & POLLERR) {

            ds_put_cstr(&s, "[POLLERR]");

        }

        if (pollfd->revents & POLLHUP) {

            ds_put_cstr(&s, "[POLLHUP]");

        }

        if (pollfd->revents & POLLNVAL) {

            ds_put_cstr(&s, "[POLLNVAL]");

        }

        ds_put_format(&s, " on fd %d (%s)", pollfd->fd, description);

        free(description);

    } else {

        ds_put_format(&s, "%d-ms timeout", timeout);

    }

    if (where) {

        ds_put_format(&s, " at %s", where);

    }

    if (cpu_usage >= 0) {

        ds_put_format(&s, " (%d%% CPU usage)", cpu_usage);

    }

    VLOG(level, "%s", ds_cstr(&s));

    ds_destroy(&s);

}

static void

free_poll_nodes(struct poll_loop *loop)

{

    struct poll_node *node;

    HMAP_FOR_EACH_SAFE (node, hmap_node, &loop->poll_nodes) {

        hmap_remove(&loop->poll_nodes, &node->hmap_node);

#ifdef _WIN32

        if (node->wevent && node->pollfd.fd) {

            WSAEventSelect(node->pollfd.fd, NULL, 0);

            CloseHandle(node->wevent);

        }

#endif

        free(node);

    }

}

/* Blocks until one or more of the events registered with poll_fd_wait()

 * occurs, or until the minimum duration registered with poll_timer_wait()

 * elapses, or not at all if poll_immediate_wake() has been called. */

void

poll_block(void)

{

    struct poll_loop *loop = poll_loop();

    struct poll_node *node;

    struct pollfd *pollfds;

    HANDLE *wevents = NULL;

    int elapsed;

    int retval;

    int i;

    /* Register fatal signal events before actually doing any real work for

     * poll_block. */

    fatal_signal_wait();

    if (loop->timeout_when == LLONG_MIN) {

        COVERAGE_INC(poll_zero_timeout);

    }

    timewarp_run();

    pollfds = xmalloc(hmap_count(&loop->poll_nodes) * sizeof *pollfds);

#ifdef _WIN32

    wevents = xmalloc(hmap_count(&loop->poll_nodes) * sizeof *wevents);

#endif

    /* Populate with all the fds and events. */

    i = 0;

    HMAP_FOR_EACH (node, hmap_node, &loop->poll_nodes) {

        pollfds[i] = node->pollfd;

#ifdef _WIN32

        wevents[i] = node->wevent;

        if (node->pollfd.fd && node->wevent) {

            short int wsa_events = 0;

            if (node->pollfd.events & POLLIN) {

                wsa_events |= FD_READ | FD_ACCEPT | FD_CLOSE;

            }

            if (node->pollfd.events & POLLOUT) {

                wsa_events |= FD_WRITE | FD_CONNECT | FD_CLOSE;

            }

            WSAEventSelect(node->pollfd.fd, node->wevent, wsa_events);

        }

#endif

        i++;

    }

    retval = time_poll(pollfds, hmap_count(&loop->poll_nodes), wevents,

                       loop->timeout_when, &elapsed);

    if (retval < 0) {

        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);

        VLOG_ERR_RL(&rl, "poll: %s", ovs_strerror(-retval));

    } else if (!retval) {

        log_wakeup(loop->timeout_where, NULL, elapsed);

    } else if (get_cpu_usage() > 50 || VLOG_IS_DBG_ENABLED()) {

        i = 0;

        HMAP_FOR_EACH (node, hmap_node, &loop->poll_nodes) {

            if (pollfds[i].revents) {

                log_wakeup(node->where, &pollfds[i], 0);

            }

            i++;

        }

    }

    free_poll_nodes(loop);

    loop->timeout_when = LLONG_MAX;

    loop->timeout_where = NULL;

    free(pollfds);

    free(wevents);

    /* Handle any pending signals before doing anything else. */

    fatal_signal_run();

    seq_woke();

}

static void

free_poll_loop(void *loop_)

{

    struct poll_loop *loop = loop_;

    free_poll_nodes(loop);

    hmap_destroy(&loop->poll_nodes);

    free(loop);

}

static struct poll_loop *

poll_loop(void)

{

    static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;

    static pthread_key_t key;

    struct poll_loop *loop;

    if (ovsthread_once_start(&once)) {

        xpthread_key_create(&key, free_poll_loop);

        ovsthread_once_done(&once);

    }

    loop = pthread_getspecific(key);

    if (!loop) {

        loop = xzalloc(sizeof *loop);

        loop->timeout_when = LLONG_MAX;

        hmap_init(&loop->poll_nodes);

        xpthread_setspecific(key, loop);

    }

    return loop;

}