src/lib/ioloop.c

	ioloop.c revision c3ef0ca49561319d40095a4aefbec339683ea908
/* Copyright (c) 2002-2007 Timo Sirainen */

#include "lib.h"
#include "ioloop-internal.h"

#include <unistd.h>

/* If time moves backwards more than this, kill ourself instead of sleeping. */
#define IOLOOP_MAX_TIME_BACKWARDS_SLEEP 5

#define timer_is_larger(tvp, uvp) \
    ((tvp)->tv_sec > (uvp)->tv_sec || \
     ((tvp)->tv_sec == (uvp)->tv_sec && \
      (tvp)->tv_usec > (uvp)->tv_usec))

time_t ioloop_time = 0;
struct timeval ioloop_timeval;
struct timezone ioloop_timezone;

struct ioloop *current_ioloop = NULL;

#undef io_add
struct io *io_add(int fd, enum io_condition condition,
          io_callback_t *callback, void *context)
{
    struct io_file *io;

    i_assert(fd >= 0);
    i_assert(callback != NULL);
    i_assert((condition & IO_NOTIFY) == 0);

    io = i_new(struct io_file, 1);
        io->io.condition = condition;
    io->io.callback = callback;
        io->io.context = context;
    io->refcount = 1;
    io->fd = fd;

    if (current_ioloop->handler_context == NULL)
        io_loop_handler_init(current_ioloop);
    io_loop_handle_add(current_ioloop, io);

    if (current_ioloop->io_files != NULL) {
        current_ioloop->io_files->prev = io;
        io->next = current_ioloop->io_files;
    }
    current_ioloop->io_files = io;
    return &io->io;
}

static void io_file_unlink(struct io_file *io)
{
    if (io->prev != NULL)
        io->prev->next = io->next;
    else
        current_ioloop->io_files = io->next;

    if (io->next != NULL)
        io->next->prev = io->prev;

    /* if we got here from an I/O handler callback, make sure we
       don't try to handle this one next. */
    if (current_ioloop->next_io_file == io)
        current_ioloop->next_io_file = io->next;
}

void io_remove(struct io **_io)
{
    struct io *io = *_io;

    *_io = NULL;

    /* make sure the callback doesn't get called anymore.
       kqueue code relies on this. */
    io->callback = NULL;

    if ((io->condition & IO_NOTIFY) != 0)
        io_loop_notify_remove(current_ioloop, io);
    else {
        struct io_file *io_file = (struct io_file *)io;

        io_file_unlink(io_file);
        io_loop_handle_remove(current_ioloop, io_file);
    }
}

static void timeout_list_insert(struct ioloop *ioloop, struct timeout *timeout)
{
    struct timeout **t;
        struct timeval *next_run;

        next_run = &timeout->next_run;
    for (t = &ioloop->timeouts; *t != NULL; t = &(*t)->next) {
        if (timer_is_larger(&(*t)->next_run, next_run))
                        break;
    }

        timeout->next = *t;
        *t = timeout;
}

static void timeout_update_next(struct timeout *timeout, struct timeval *tv_now)
{
    if (tv_now == NULL) {
        if (gettimeofday(&timeout->next_run, NULL) < 0)
            i_fatal("gettimeofday(): %m");
    } else {
                timeout->next_run.tv_sec = tv_now->tv_sec;
                timeout->next_run.tv_usec = tv_now->tv_usec;
    }

    /* we don't want microsecond accuracy or this function will be
       called all the time - millisecond is more than enough */
    timeout->next_run.tv_usec -= timeout->next_run.tv_usec % 1000;

    timeout->next_run.tv_sec += timeout->msecs/1000;
    timeout->next_run.tv_usec += (timeout->msecs%1000)*1000;

    if (timeout->next_run.tv_usec > 1000000) {
                timeout->next_run.tv_sec++;
                timeout->next_run.tv_usec -= 1000000;
    }
}

#undef timeout_add
struct timeout *timeout_add(unsigned int msecs, timeout_callback_t *callback,
                void *context)
{
    struct timeout *timeout;

    timeout = i_new(struct timeout, 1);
        timeout->msecs = msecs;

    timeout->callback = callback;
    timeout->context = context;

    timeout_update_next(timeout, current_ioloop->running ?
                NULL : &ioloop_timeval);
        timeout_list_insert(current_ioloop, timeout);
    return timeout;
}

void timeout_remove(struct timeout **timeout)
{
    i_assert(*timeout != NULL);

    (*timeout)->destroyed = TRUE;
    *timeout = NULL;
}

int io_loop_get_wait_time(struct timeout *timeout, struct timeval *tv,
              struct timeval *tv_now)
{
    if (timeout == NULL) {
        /* no timeouts. give it INT_MAX msecs. */
        tv->tv_sec = INT_MAX / 1000;
        tv->tv_usec = 0;
        return INT_MAX;
    }

    if (tv_now == NULL) {
        if (gettimeofday(tv, NULL) < 0)
            i_fatal("gettimeofday(): %m");
    } else {
        tv->tv_sec = tv_now->tv_sec;
        tv->tv_usec = tv_now->tv_usec;
    }

    tv->tv_sec = timeout->next_run.tv_sec - tv->tv_sec;
    tv->tv_usec = timeout->next_run.tv_usec - tv->tv_usec;
    if (tv->tv_usec < 0) {
        tv->tv_sec--;
        tv->tv_usec += 1000000;
    }

    if (tv->tv_sec > 0 || (tv->tv_sec == 0 && tv->tv_usec > 0)) {
        /* round wait times up to next millisecond */
        return tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;
    }

    /* no need to calculate the times again with this timeout */
        tv->tv_sec = tv->tv_usec = 0;
    timeout->run_now = TRUE;
        return 0;
}

void io_loop_handle_timeouts(struct ioloop *ioloop, bool update_run_now)
{
    struct timeout *called_timeouts;
    struct timeval tv;
        unsigned int t_id;

    if (gettimeofday(&ioloop_timeval, &ioloop_timezone) < 0)
        i_fatal("gettimeofday(): %m");

    /* Don't bother comparing usecs. */
    if (ioloop_time > ioloop_timeval.tv_sec) {
        time_t diff = ioloop_time - ioloop_timeval.tv_sec;

        /* Note that this code is here only because this is the easiest
           place to check for this. The I/O loop code itself could be
           easily fixed to work with time moving backwards, but there's
           really no point because there are a lot of other places
           which may break in more or less bad ways, such as files'
           timestamps moving backwards. */
        if (diff > IOLOOP_MAX_TIME_BACKWARDS_SLEEP) {
            i_fatal("Time just moved backwards by %ld seconds. "
                "This might cause a lot of problems, "
                "so I'll just kill myself now. "
                "http://wiki.dovecot.org/TimeMovedBackwards",
                (long)diff);
        } else {
            i_error("Time just moved backwards by %ld seconds. "
                "I'll sleep now until we're back in present. "
                "http://wiki.dovecot.org/TimeMovedBackwards",
                (long)diff);
            /* Sleep extra second to make sure usecs also grows. */
            diff++;

            while (diff > 0 && sleep(diff) != 0) {
                /* don't use sleep()'s return value, because
                   it could get us to a long loop in case
                   interrupts just keep coming */
                diff = ioloop_time - time(NULL) + 1;
            }

            /* Try again. */
            io_loop_handle_timeouts(ioloop, TRUE);
        }
    }

    ioloop_time = ioloop_timeval.tv_sec;

    if (ioloop->timeouts == NULL ||
        (!ioloop->timeouts->run_now && !update_run_now))
        return;

    called_timeouts = NULL;
    while (ioloop->timeouts != NULL) {
        struct timeout *t = ioloop->timeouts;

        if (t->destroyed) {
            ioloop->timeouts = t->next;
            i_free(t);
            continue;
        }

        if (!t->run_now) {
            io_loop_get_wait_time(t, &tv, &ioloop_timeval);

            if (!t->run_now)
                break;
        }

        /* move timeout to called_timeouts list */
        ioloop->timeouts = t->next;
        t->next = called_timeouts;
        called_timeouts = t;

                t->run_now = FALSE;
                timeout_update_next(t, &ioloop_timeval);

                t_id = t_push();
        t->callback(t->context);
        if (t_pop() != t_id) {
            i_panic("Leaked a t_pop() call in timeout handler %p",
                (void *)t->callback);
        }
    }

    /* move timeouts back to list so they get re-sorted again by next_run
       time, or destroy them if timeout_remove() was called for them. */
    while (called_timeouts != NULL) {
        struct timeout *t = called_timeouts;

        if (t->destroyed) {
            called_timeouts = t->next;
            i_free(t);
        } else {
            called_timeouts = t->next;
            timeout_list_insert(current_ioloop, t);
        }
    }
#ifdef DEBUG
    if (ioloop->timeouts != NULL) {
        struct timeout *t;

        for (t = ioloop->timeouts; t->next != NULL; t = t->next) {
            if (timer_is_larger(&t->next_run, &t->next->next_run))
                i_panic("broken timeout list");
        }
    }
#endif
}

void io_loop_run(struct ioloop *ioloop)
{
    if (ioloop->handler_context == NULL)
        io_loop_handler_init(ioloop);

    ioloop->running = TRUE;
    while (ioloop->running)
        io_loop_handler_run(ioloop);
}

void io_loop_stop(struct ioloop *ioloop)
{
        ioloop->running = FALSE;
}

void io_loop_set_running(struct ioloop *ioloop)
{
        ioloop->running = TRUE;
}

bool io_loop_is_running(struct ioloop *ioloop)
{
        return ioloop->running;
}

struct ioloop *io_loop_create(void)
{
    struct ioloop *ioloop;

    /* initialize time */
    if (gettimeofday(&ioloop_timeval, &ioloop_timezone) < 0)
        i_fatal("gettimeofday(): %m");
    ioloop_time = ioloop_timeval.tv_sec;

        ioloop = i_new(struct ioloop, 1);

    ioloop->prev = current_ioloop;
        current_ioloop = ioloop;

        return ioloop;
}

void io_loop_destroy(struct ioloop **_ioloop)
{
        struct ioloop *ioloop = *_ioloop;

    *_ioloop = NULL;

    if (ioloop->notify_handler_context != NULL)
        io_loop_notify_handler_deinit(ioloop);

    while (ioloop->io_files != NULL) {
        struct io_file *io = ioloop->io_files;
        struct io *_io = &io->io;

        i_warning("I/O leak: %p (%d)", (void *)io->io.callback, io->fd);
        io_remove(&_io);
    }

    while (ioloop->timeouts != NULL) {
        struct timeout *to = ioloop->timeouts;

        if (!to->destroyed)
            i_warning("Timeout leak: %p", (void *)to->callback);
        ioloop->timeouts = to->next;
        i_free(to);
    }

    if (current_ioloop->handler_context != NULL)
        io_loop_handler_deinit(ioloop);

        /* ->prev won't work unless loops are destroyed in create order */
        i_assert(ioloop == current_ioloop);
    current_ioloop = current_ioloop->prev;

    i_free(ioloop);
}