pulseaudio/src/pulse/mainloop.c

/* $Id$ */

/***
  This file is part of PulseAudio.

  PulseAudio is free software; you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as published
  by the Free Software Foundation; either version 2 of the License,
  or (at your option) any later version.

  PulseAudio is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with PulseAudio; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  USA.
***/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <fcntl.h>
#include <errno.h>

#ifdef HAVE_SYS_POLL_H
#include <sys/poll.h>
#else
#include "../pulsecore/poll.h"
#endif

#include "../pulsecore/winsock.h"

#ifndef HAVE_PIPE
#include "../pulsecore/pipe.h"
#endif

#include <pulsecore/core-error.h>
#include <pulse/timeval.h>
#include <pulse/xmalloc.h>

#include <pulsecore/core-util.h>
#include <pulsecore/llist.h>
#include <pulsecore/log.h>

#include "mainloop.h"

struct pa_io_event {
    pa_mainloop *mainloop;
    int dead;

    int fd;
    pa_io_event_flags_t events;
    struct pollfd *pollfd;

    pa_io_event_cb_t callback;
    void *userdata;
    pa_io_event_destroy_cb_t destroy_callback;

    PA_LLIST_FIELDS(pa_io_event);
};

struct pa_time_event {
    pa_mainloop *mainloop;
    int dead;

    int enabled;
    struct timeval timeval;

    pa_time_event_cb_t callback;
    void *userdata;
    pa_time_event_destroy_cb_t destroy_callback;

    PA_LLIST_FIELDS(pa_time_event);
};

struct pa_defer_event {
    pa_mainloop *mainloop;
    int dead;

    int enabled;

    pa_defer_event_cb_t callback;
    void *userdata;
    pa_defer_event_destroy_cb_t destroy_callback;

    PA_LLIST_FIELDS(pa_defer_event);
};

struct pa_mainloop {
    PA_LLIST_HEAD(pa_io_event, io_events);
    PA_LLIST_HEAD(pa_time_event, time_events);
    PA_LLIST_HEAD(pa_defer_event, defer_events);

    int n_enabled_defer_events, n_enabled_time_events, n_io_events;
    int io_events_please_scan, time_events_please_scan, defer_events_please_scan;

    struct pollfd *pollfds;
    unsigned max_pollfds, n_pollfds;
    int rebuild_pollfds;

    int prepared_timeout;
    pa_time_event *cached_next_time_event;

    int quit, retval;
    pa_mainloop_api api;

    int wakeup_pipe[2];
    int wakeup_pipe_type;
    int wakeup_requested;

    enum {
        STATE_PASSIVE,
        STATE_PREPARED,
        STATE_POLLING,
        STATE_POLLED,
        STATE_QUIT
    } state;

    pa_poll_func poll_func;
    void *poll_func_userdata;
    int poll_func_ret;
};

static short map_flags_to_libc(pa_io_event_flags_t flags) {
    return
        (flags & PA_IO_EVENT_INPUT ? POLLIN : 0) |
        (flags & PA_IO_EVENT_OUTPUT ? POLLOUT : 0) |
        (flags & PA_IO_EVENT_ERROR ? POLLERR : 0) |
        (flags & PA_IO_EVENT_HANGUP ? POLLHUP : 0);
}

static pa_io_event_flags_t map_flags_from_libc(short flags) {
    return
        (flags & POLLIN ? PA_IO_EVENT_INPUT : 0) |
        (flags & POLLOUT ? PA_IO_EVENT_OUTPUT : 0) |
        (flags & POLLERR ? PA_IO_EVENT_ERROR : 0) |
        (flags & POLLHUP ? PA_IO_EVENT_HANGUP : 0);
}

/* IO events */
static pa_io_event* mainloop_io_new(
        pa_mainloop_api*a,
        int fd,
        pa_io_event_flags_t events,
        pa_io_event_cb_t callback,
        void *userdata) {

    pa_mainloop *m;
    pa_io_event *e;

    assert(a);
    assert(a->userdata);
    assert(fd >= 0);
    assert(callback);

    m = a->userdata;
    assert(a == &m->api);

    e = pa_xnew(pa_io_event, 1);
    e->mainloop = m;
    e->dead = 0;

    e->fd = fd;
    e->events = events;
    e->pollfd = NULL;

    e->callback = callback;
    e->userdata = userdata;
    e->destroy_callback = NULL;

#ifdef OS_IS_WIN32
    {
        fd_set xset;
        struct timeval tv;

        tv.tv_sec = 0;
        tv.tv_usec = 0;

        FD_ZERO (&xset);
        FD_SET (fd, &xset);

        if ((select((SELECT_TYPE_ARG1) fd, NULL, NULL, SELECT_TYPE_ARG234 &xset,
                    SELECT_TYPE_ARG5 &tv) == -1) &&
             (WSAGetLastError() == WSAENOTSOCK)) {
            pa_log_warn("WARNING: cannot monitor non-socket file descriptors.");
            e->dead = 1;
        }
    }
#endif

    PA_LLIST_PREPEND(pa_io_event, m->io_events, e);
    m->rebuild_pollfds = 1;
    m->n_io_events ++;

    pa_mainloop_wakeup(m);

    return e;
}

static void mainloop_io_enable(pa_io_event *e, pa_io_event_flags_t events) {
    assert(e);
    assert(!e->dead);

    if (e->events == events)
        return;

    e->events = events;

    if (e->pollfd)
        e->pollfd->events = map_flags_to_libc(events);
    else
        e->mainloop->rebuild_pollfds = 1;

    pa_mainloop_wakeup(e->mainloop);
}

static void mainloop_io_free(pa_io_event *e) {
    assert(e);
    assert(!e->dead);

    e->dead = 1;
    e->mainloop->io_events_please_scan ++;

    e->mainloop->n_io_events --;
    e->mainloop->rebuild_pollfds = 1;

    pa_mainloop_wakeup(e->mainloop);
}

static void mainloop_io_set_destroy(pa_io_event *e, pa_io_event_destroy_cb_t callback) {
    assert(e);

    e->destroy_callback = callback;
}

/* Defer events */
static pa_defer_event* mainloop_defer_new(
        pa_mainloop_api*a,
        pa_defer_event_cb_t callback,
        void *userdata) {

    pa_mainloop *m;
    pa_defer_event *e;

    assert(a);
    assert(a->userdata);
    assert(callback);

    m = a->userdata;
    assert(a == &m->api);

    e = pa_xnew(pa_defer_event, 1);
    e->mainloop = m;
    e->dead = 0;

    e->enabled = 1;
    m->n_enabled_defer_events++;

    e->callback = callback;
    e->userdata = userdata;
    e->destroy_callback = NULL;

    PA_LLIST_PREPEND(pa_defer_event, m->defer_events, e);

    pa_mainloop_wakeup(e->mainloop);

    return e;
}

static void mainloop_defer_enable(pa_defer_event *e, int b) {
    assert(e);
    assert(!e->dead);

    if (e->enabled && !b) {
        assert(e->mainloop->n_enabled_defer_events > 0);
        e->mainloop->n_enabled_defer_events--;
    } else if (!e->enabled && b) {
        e->mainloop->n_enabled_defer_events++;
        pa_mainloop_wakeup(e->mainloop);
    }

    e->enabled = b;
}

static void mainloop_defer_free(pa_defer_event *e) {
    assert(e);
    assert(!e->dead);

    e->dead = 1;
    e->mainloop->defer_events_please_scan ++;

    if (e->enabled) {
        assert(e->mainloop->n_enabled_defer_events > 0);
        e->mainloop->n_enabled_defer_events--;
    }
}

static void mainloop_defer_set_destroy(pa_defer_event *e, pa_defer_event_destroy_cb_t callback) {
    assert(e);
    assert(!e->dead);

    e->destroy_callback = callback;
}

/* Time events */
static pa_time_event* mainloop_time_new(
        pa_mainloop_api*a,
        const struct timeval *tv,
        pa_time_event_cb_t callback,
        void *userdata) {

    pa_mainloop *m;
    pa_time_event *e;

    assert(a);
    assert(a->userdata);
    assert(callback);

    m = a->userdata;
    assert(a == &m->api);

    e = pa_xnew(pa_time_event, 1);
    e->mainloop = m;
    e->dead = 0;

    if ((e->enabled = !!tv)) {
        e->timeval = *tv;

        m->n_enabled_time_events++;

        if (m->cached_next_time_event) {
            assert(m->cached_next_time_event->enabled);

            if (pa_timeval_cmp(tv, &m->cached_next_time_event->timeval) < 0)
                m->cached_next_time_event = e;
        }
    }

    e->callback = callback;
    e->userdata = userdata;
    e->destroy_callback = NULL;

    PA_LLIST_PREPEND(pa_time_event, m->time_events, e);

    if (e->enabled)
        pa_mainloop_wakeup(m);

    return e;
}

static void mainloop_time_restart(pa_time_event *e, const struct timeval *tv) {
    assert(e);
    assert(!e->dead);

    if (e->enabled && !tv) {
        assert(e->mainloop->n_enabled_time_events > 0);
        e->mainloop->n_enabled_time_events--;
    } else if (!e->enabled && tv)
        e->mainloop->n_enabled_time_events++;

    if ((e->enabled = !!tv)) {
        e->timeval = *tv;
        pa_mainloop_wakeup(e->mainloop);
    }

    if (e->mainloop->cached_next_time_event && e->enabled) {
        assert(e->mainloop->cached_next_time_event->enabled);

        if (pa_timeval_cmp(tv, &e->mainloop->cached_next_time_event->timeval) < 0)
            e->mainloop->cached_next_time_event = e;
    } else if (e->mainloop->cached_next_time_event == e)
        e->mainloop->cached_next_time_event = NULL;
}

static void mainloop_time_free(pa_time_event *e) {
    assert(e);
    assert(!e->dead);

    e->dead = 1;
    e->mainloop->time_events_please_scan ++;

    if (e->enabled) {
        assert(e->mainloop->n_enabled_time_events > 0);
        e->mainloop->n_enabled_time_events--;
    }

    if (e->mainloop->cached_next_time_event == e)
        e->mainloop->cached_next_time_event = NULL;

    /* no wakeup needed here. Think about it! */
}

static void mainloop_time_set_destroy(pa_time_event *e, pa_time_event_destroy_cb_t callback) {
    assert(e);
    assert(!e->dead);

    e->destroy_callback = callback;
}

/* quit() */

static void mainloop_quit(pa_mainloop_api*a, int retval) {
    pa_mainloop *m;

    assert(a);
    assert(a->userdata);
    m = a->userdata;
    assert(a == &m->api);

    pa_mainloop_quit(m, retval);
}

static const pa_mainloop_api vtable = {
    .userdata = NULL,

    .io_new= mainloop_io_new,
    .io_enable= mainloop_io_enable,
    .io_free= mainloop_io_free,
    .io_set_destroy= mainloop_io_set_destroy,

    .time_new = mainloop_time_new,
    .time_restart = mainloop_time_restart,
    .time_free = mainloop_time_free,
    .time_set_destroy = mainloop_time_set_destroy,

    .defer_new = mainloop_defer_new,
    .defer_enable = mainloop_defer_enable,
    .defer_free = mainloop_defer_free,
    .defer_set_destroy = mainloop_defer_set_destroy,

    .quit = mainloop_quit,
};

pa_mainloop *pa_mainloop_new(void) {
    pa_mainloop *m;

    m = pa_xnew(pa_mainloop, 1);

    m->wakeup_pipe_type = 0;
    if (pipe(m->wakeup_pipe) < 0) {
        pa_log_error("ERROR: cannot create wakeup pipe");
        pa_xfree(m);
        return NULL;
    }

    pa_make_nonblock_fd(m->wakeup_pipe[0]);
    pa_make_nonblock_fd(m->wakeup_pipe[1]);
    m->wakeup_requested = 0;

    PA_LLIST_HEAD_INIT(pa_io_event, m->io_events);
    PA_LLIST_HEAD_INIT(pa_time_event, m->time_events);
    PA_LLIST_HEAD_INIT(pa_defer_event, m->defer_events);

    m->n_enabled_defer_events = m->n_enabled_time_events = m->n_io_events = 0;
    m->io_events_please_scan = m->time_events_please_scan = m->defer_events_please_scan = 0;

    m->cached_next_time_event = NULL;
    m->prepared_timeout = 0;

    m->pollfds = NULL;
    m->max_pollfds = m->n_pollfds = 0;
    m->rebuild_pollfds = 1;

    m->quit = m->retval = 0;

    m->api = vtable;
    m->api.userdata = m;

    m->state = STATE_PASSIVE;

    m->poll_func = NULL;
    m->poll_func_userdata = NULL;
    m->poll_func_ret = -1;

    return m;
}

static void cleanup_io_events(pa_mainloop *m, int force) {
    pa_io_event *e;

    e = m->io_events;
    while (e) {
        pa_io_event *n = e->next;

        if (!force && m->io_events_please_scan <= 0)
            break;

        if (force || e->dead) {
            PA_LLIST_REMOVE(pa_io_event, m->io_events, e);

            if (e->dead) {
                assert(m->io_events_please_scan > 0);
                m->io_events_please_scan--;
            }

            if (e->destroy_callback)
                e->destroy_callback(&m->api, e, e->userdata);

            pa_xfree(e);

            m->rebuild_pollfds = 1;
        }

        e = n;
    }

    assert(m->io_events_please_scan == 0);
}

static void cleanup_time_events(pa_mainloop *m, int force) {
    pa_time_event *e;

    e = m->time_events;
    while (e) {
        pa_time_event *n = e->next;

        if (!force && m->time_events_please_scan <= 0)
            break;

        if (force || e->dead) {
            PA_LLIST_REMOVE(pa_time_event, m->time_events, e);

            if (e->dead) {
                assert(m->time_events_please_scan > 0);
                m->time_events_please_scan--;
            }

            if (!e->dead && e->enabled) {
                assert(m->n_enabled_time_events > 0);
                m->n_enabled_time_events--;
            }

            if (e->destroy_callback)
                e->destroy_callback(&m->api, e, e->userdata);

            pa_xfree(e);
        }

        e = n;
    }

    assert(m->time_events_please_scan == 0);
}

static void cleanup_defer_events(pa_mainloop *m, int force) {
    pa_defer_event *e;

    e = m->defer_events;
    while (e) {
        pa_defer_event *n = e->next;

        if (!force && m->defer_events_please_scan <= 0)
            break;

        if (force || e->dead) {
            PA_LLIST_REMOVE(pa_defer_event, m->defer_events, e);

            if (e->dead) {
                assert(m->defer_events_please_scan > 0);
                m->defer_events_please_scan--;
            }

            if (!e->dead && e->enabled) {
                assert(m->n_enabled_defer_events > 0);
                m->n_enabled_defer_events--;
            }

            if (e->destroy_callback)
                e->destroy_callback(&m->api, e, e->userdata);

            pa_xfree(e);
        }

        e = n;
    }

    assert(m->defer_events_please_scan == 0);
}


void pa_mainloop_free(pa_mainloop* m) {
    assert(m);

    cleanup_io_events(m, 1);
    cleanup_defer_events(m, 1);
    cleanup_time_events(m, 1);

    pa_xfree(m->pollfds);

    if (m->wakeup_pipe[0] >= 0)
        close(m->wakeup_pipe[0]);
    if (m->wakeup_pipe[1] >= 0)
        close(m->wakeup_pipe[1]);

    pa_xfree(m);
}

static void scan_dead(pa_mainloop *m) {
    assert(m);

    if (m->io_events_please_scan)
        cleanup_io_events(m, 0);

    if (m->time_events_please_scan)
        cleanup_time_events(m, 0);

    if (m->defer_events_please_scan)
        cleanup_defer_events(m, 0);
}

static void rebuild_pollfds(pa_mainloop *m) {
    pa_io_event*e;
    struct pollfd *p;
    unsigned l;

    l = m->n_io_events + 1;
    if (m->max_pollfds < l) {
        l *= 2;
        m->pollfds = pa_xrealloc(m->pollfds, sizeof(struct pollfd)*l);
        m->max_pollfds = l;
    }

    m->n_pollfds = 0;
    p = m->pollfds;

    if (m->wakeup_pipe[0] >= 0) {
        m->pollfds[0].fd = m->wakeup_pipe[0];
        m->pollfds[0].events = POLLIN;
        m->pollfds[0].revents = 0;
        p++;
        m->n_pollfds++;
    }

    for (e = m->io_events; e; e = e->next) {
        if (e->dead) {
            e->pollfd = NULL;
            continue;
        }

        e->pollfd = p;
        p->fd = e->fd;
        p->events = map_flags_to_libc(e->events);
        p->revents = 0;

        p++;
        m->n_pollfds++;
    }

    m->rebuild_pollfds = 0;
}

static int dispatch_pollfds(pa_mainloop *m) {
    pa_io_event *e;
    int r = 0, k;

    assert(m->poll_func_ret > 0);

    for (e = m->io_events, k = m->poll_func_ret; e && !m->quit && k > 0; e = e->next) {
        if (e->dead || !e->pollfd || !e->pollfd->revents)
            continue;

        assert(e->pollfd->fd == e->fd && e->callback);
        e->callback(&m->api, e, e->fd, map_flags_from_libc(e->pollfd->revents), e->userdata);
        e->pollfd->revents = 0;
        r++;

        k--;
    }

    return r;
}

static int dispatch_defer(pa_mainloop *m) {
    pa_defer_event *e;
    int r = 0;

    if (m->n_enabled_defer_events <= 0)
        return 0;

    for (e = m->defer_events; e && !m->quit; e = e->next) {
        if (e->dead || !e->enabled)
            continue;

        assert(e->callback);
        e->callback(&m->api, e, e->userdata);
        r++;
    }

    return r;
}

static pa_time_event* find_next_time_event(pa_mainloop *m) {
    pa_time_event *t, *n = NULL;
    assert(m);

    if (m->cached_next_time_event)
        return m->cached_next_time_event;

    for (t = m->time_events; t; t = t->next) {

        if (t->dead || !t->enabled)
            continue;

        if (!n || pa_timeval_cmp(&t->timeval, &n->timeval) < 0) {
            n = t;

            /* Shortcut for tv = { 0, 0 } */
            if (n->timeval.tv_sec <= 0)
                break;
        }
    }

    m->cached_next_time_event = n;
    return n;
}

static int calc_next_timeout(pa_mainloop *m) {
    pa_time_event *t;
    struct timeval now;
    pa_usec_t usec;

    if (!m->n_enabled_time_events)
        return -1;

    t = find_next_time_event(m);
    assert(t);

    if (t->timeval.tv_sec <= 0)
        return 0;

    pa_gettimeofday(&now);

    if (pa_timeval_cmp(&t->timeval, &now) <= 0)
        return 0;

    usec = pa_timeval_diff(&t->timeval, &now);
    return (int) (usec / 1000);
}

static int dispatch_timeout(pa_mainloop *m) {
    pa_time_event *e;
    struct timeval now;
    int r = 0;
    assert(m);

    if (m->n_enabled_time_events <= 0)
        return 0;

    pa_gettimeofday(&now);

    for (e = m->time_events; e && !m->quit; e = e->next) {

        if (e->dead || !e->enabled)
            continue;

        if (pa_timeval_cmp(&e->timeval, &now) <= 0) {
            assert(e->callback);

            /* Disable time event */
            mainloop_time_restart(e, NULL);

            e->callback(&m->api, e, &e->timeval, e->userdata);

            r++;
        }
    }

    return r;
}

void pa_mainloop_wakeup(pa_mainloop *m) {
    char c = 'W';
    assert(m);

    if (m->wakeup_pipe[1] >= 0 && m->state == STATE_POLLING) {
        pa_write(m->wakeup_pipe[1], &c, sizeof(c), &m->wakeup_pipe_type);
        m->wakeup_requested++;
    }
}

static void clear_wakeup(pa_mainloop *m) {
    char c[10];

    assert(m);

    if (m->wakeup_pipe[0] < 0)
        return;

    if (m->wakeup_requested) {
        while (pa_read(m->wakeup_pipe[0], &c, sizeof(c), &m->wakeup_pipe_type) == sizeof(c));
        m->wakeup_requested = 0;
    }
}

int pa_mainloop_prepare(pa_mainloop *m, int timeout) {
    assert(m);
    assert(m->state == STATE_PASSIVE);

    clear_wakeup(m);
    scan_dead(m);

    if (m->quit)
        goto quit;

    if (m->n_enabled_defer_events <= 0) {
        if (m->rebuild_pollfds)
            rebuild_pollfds(m);

        m->prepared_timeout = calc_next_timeout(m);
        if (timeout >= 0 && (timeout < m->prepared_timeout || m->prepared_timeout < 0))
            m->prepared_timeout = timeout;
    }

    m->state = STATE_PREPARED;
    return 0;

quit:
    m->state = STATE_QUIT;
    return -2;
}

int pa_mainloop_poll(pa_mainloop *m) {
    assert(m);
    assert(m->state == STATE_PREPARED);

    if (m->quit)
        goto quit;

    m->state = STATE_POLLING;

    if (m->n_enabled_defer_events )
        m->poll_func_ret = 0;
    else {
        assert(!m->rebuild_pollfds);

        if (m->poll_func)
            m->poll_func_ret = m->poll_func(m->pollfds, m->n_pollfds, m->prepared_timeout, m->poll_func_userdata);
        else
            m->poll_func_ret = poll(m->pollfds, m->n_pollfds, m->prepared_timeout);

        if (m->poll_func_ret < 0) {
            if (errno == EINTR)
                m->poll_func_ret = 0;
            else
                pa_log("poll(): %s", pa_cstrerror(errno));
        }
    }

    m->state = m->poll_func_ret < 0 ? STATE_PASSIVE : STATE_POLLED;
    return m->poll_func_ret;

quit:
    m->state = STATE_QUIT;
    return -2;
}

int pa_mainloop_dispatch(pa_mainloop *m) {
    int dispatched = 0;

    assert(m);
    assert(m->state == STATE_POLLED);

    if (m->quit)
        goto quit;

    if (m->n_enabled_defer_events)
        dispatched += dispatch_defer(m);
    else {
        if (m->n_enabled_time_events)
            dispatched += dispatch_timeout(m);

        if (m->quit)
            goto quit;

        if (m->poll_func_ret > 0)
            dispatched += dispatch_pollfds(m);
    }

    if (m->quit)
        goto quit;

    m->state = STATE_PASSIVE;

    return dispatched;

quit:
    m->state = STATE_QUIT;
    return -2;
}

int pa_mainloop_get_retval(pa_mainloop *m) {
    assert(m);
    return m->retval;
}

int pa_mainloop_iterate(pa_mainloop *m, int block, int *retval) {
    int r;
    assert(m);

    if ((r = pa_mainloop_prepare(m, block ? -1 : 0)) < 0)
        goto quit;

    if ((r = pa_mainloop_poll(m)) < 0)
        goto quit;

    if ((r = pa_mainloop_dispatch(m)) < 0)
        goto quit;

    return r;

quit:

    if ((r == -2) && retval)
        *retval = pa_mainloop_get_retval(m);
    return r;
}

int pa_mainloop_run(pa_mainloop *m, int *retval) {
    int r;

    while ((r = pa_mainloop_iterate(m, 1, retval)) >= 0);

    if (r == -2)
        return 1;
    else if (r < 0)
        return -1;
    else
        return 0;
}

void pa_mainloop_quit(pa_mainloop *m, int retval) {
    assert(m);

    m->quit = 1;
    m->retval = retval;
    pa_mainloop_wakeup(m);
}

pa_mainloop_api* pa_mainloop_get_api(pa_mainloop*m) {
    assert(m);
    return &m->api;
}

void pa_mainloop_set_poll_func(pa_mainloop *m, pa_poll_func poll_func, void *userdata) {
    assert(m);

    m->poll_func = poll_func;
    m->poll_func_userdata = userdata;
}