src/lib/ioloop.c

	ioloop.c revision eb493a9993bce313e0750db6787459ef39067944
/* Copyright (c) 2002-2012 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "time-util.h"
#include "ioloop-private.h"

#include <unistd.h>

#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 ioloop *current_ioloop = NULL;

static void io_loop_initialize_handler(struct ioloop *ioloop)
{
    unsigned int initial_fd_count;

    initial_fd_count = ioloop->max_fd_count > 0 &&
        ioloop->max_fd_count < IOLOOP_INITIAL_FD_COUNT ?
        ioloop->max_fd_count : IOLOOP_INITIAL_FD_COUNT;
    io_loop_handler_init(ioloop, initial_fd_count);
}

#undef io_add
struct io *io_add(int fd, enum io_condition condition,
          unsigned int source_linenum,
          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->io.ioloop = current_ioloop;
    io->io.source_linenum = source_linenum;
    io->refcount = 1;
    io->fd = fd;

    if (io->io.ioloop->cur_ctx != NULL) {
        io->io.ctx = io->io.ioloop->cur_ctx;
        io_loop_context_ref(io->io.ctx);
    }

    if (io->io.ioloop->handler_context == NULL)
        io_loop_initialize_handler(io->io.ioloop);
    io_loop_handle_add(io);

    if (io->io.ioloop->io_files != NULL) {
        io->io.ioloop->io_files->prev = io;
        io->next = io->io.ioloop->io_files;
    }
    io->io.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
        io->io.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 (io->io.ioloop->next_io_file == io)
        io->io.ioloop->next_io_file = io->next;
}

static void io_remove_full(struct io **_io, bool closed)
{
    struct io *io = *_io;

    i_assert(io->callback != NULL);

    *_io = NULL;

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

    if (io->ctx != NULL)
        io_loop_context_unref(&io->ctx);

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

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

void io_remove(struct io **io)
{
    io_remove_full(io, FALSE);
}

void io_remove_closed(struct io **io)
{
    i_assert(((*io)->condition & IO_NOTIFY) == 0);

    io_remove_full(io, TRUE);
}

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, unsigned int source_linenum,
                timeout_callback_t *callback, void *context)
{
    struct timeout *timeout;

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

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

    if (timeout->ioloop->cur_ctx != NULL) {
        timeout->ctx = timeout->ioloop->cur_ctx;
        io_loop_context_ref(timeout->ctx);
    }

    timeout_update_next(timeout, timeout->ioloop->running ?
                NULL : &ioloop_timeval);
    priorityq_add(timeout->ioloop->timeouts, &timeout->item);
    return timeout;
}

static void timeout_free(struct timeout *timeout)
{
    if (timeout->ctx != NULL)
        io_loop_context_unref(&timeout->ctx);
    i_free(timeout);
}

void timeout_remove(struct timeout **_timeout)
{
    struct timeout *timeout = *_timeout;

    *_timeout = NULL;
    priorityq_remove(timeout->ioloop->timeouts, &timeout->item);
    timeout_free(timeout);
}

static void
timeout_reset_timeval(struct timeout *timeout, struct timeval *tv_now)
{
    timeout_update_next(timeout, tv_now);
    if (timeout->msecs == 0) {
        /* if we came here from io_loop_handle_timeouts(),
           next_run must be larger than tv_now or we could go to
           infinite loop. +1000 to get 1 ms further, another +1000 to
           account for timeout_update_next()'s truncation. */
        timeout->next_run.tv_usec += 2000;
        if (timeout->next_run.tv_usec >= 1000000) {
            timeout->next_run.tv_sec++;
            timeout->next_run.tv_usec -= 1000000;
        }
    }
    i_assert(tv_now == NULL ||
         timeout->next_run.tv_sec > tv_now->tv_sec ||
         (timeout->next_run.tv_sec == tv_now->tv_sec &&
          timeout->next_run.tv_usec > tv_now->tv_usec));
    priorityq_remove(timeout->ioloop->timeouts, &timeout->item);
    priorityq_add(timeout->ioloop->timeouts, &timeout->item);
}

void timeout_reset(struct timeout *timeout)
{
    timeout_reset_timeval(timeout, NULL);
}

static int timeout_get_wait_time(struct timeout *timeout, struct timeval *tv_r,
                 struct timeval *tv_now)
{
    int ret;

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

    i_assert(tv_r->tv_sec > 0);
    i_assert(timeout->next_run.tv_sec > 0);

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

    if (tv_r->tv_sec < 0 || (tv_r->tv_sec == 0 && tv_r->tv_usec < 1000)) {
        tv_r->tv_sec = 0;
        tv_r->tv_usec = 0;
        return 0;
    }
    if (tv_r->tv_sec > INT_MAX/1000-1)
        tv_r->tv_sec = INT_MAX/1000-1;

    /* round wait times up to next millisecond */
    ret = tv_r->tv_sec * 1000 + (tv_r->tv_usec + 999) / 1000;
    i_assert(ret > 0 && tv_r->tv_sec >= 0 && tv_r->tv_usec >= 0);
    return ret;
}

int io_loop_get_wait_time(struct ioloop *ioloop, struct timeval *tv_r)
{
    struct timeval tv_now;
    struct priorityq_item *item;
    struct timeout *timeout;
    int msecs;

    item = priorityq_peek(ioloop->timeouts);
    timeout = (struct timeout *)item;
    if (timeout == NULL) {
        /* no timeouts. use INT_MAX msecs for timeval and
           return -1 for poll/epoll infinity. */
        tv_r->tv_sec = INT_MAX / 1000;
        tv_r->tv_usec = 0;
        ioloop->next_max_time = (1ULL << (TIME_T_MAX_BITS-1)) - 1;
        return -1;
    }

    tv_now.tv_sec = 0;
    msecs = timeout_get_wait_time(timeout, tv_r, &tv_now);
    ioloop->next_max_time = (tv_now.tv_sec + msecs/1000) + 1;
    return msecs;
}

static int timeout_cmp(const void *p1, const void *p2)
{
    const struct timeout *to1 = p1, *to2 = p2;

    return timeval_cmp(&to1->next_run, &to2->next_run);
}

static void io_loop_default_time_moved(time_t old_time, time_t new_time)
{
    if (old_time > new_time) {
        i_warning("Time moved backwards by %ld seconds.",
              (long)(old_time - new_time));
    }
}

static void io_loop_timeouts_update(struct ioloop *ioloop, long diff_secs)
{
    struct priorityq_item *const *items;
    unsigned int i, count;

    count = priorityq_count(ioloop->timeouts);
    items = priorityq_items(ioloop->timeouts);
    for (i = 0; i < count; i++) {
        struct timeout *to = (struct timeout *)items[i];

        to->next_run.tv_sec += diff_secs;
    }
}

static void io_loops_timeouts_update(long diff_secs)
{
    struct ioloop *ioloop;

    for (ioloop = current_ioloop; ioloop != NULL; ioloop = ioloop->prev)
        io_loop_timeouts_update(ioloop, diff_secs);
}

static void io_loop_handle_timeouts_real(struct ioloop *ioloop)
{
    struct priorityq_item *item;
    struct timeval tv, tv_call;
    unsigned int t_id;

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

    /* Don't bother comparing usecs. */
    if (unlikely(ioloop_time > ioloop_timeval.tv_sec)) {
        /* time moved backwards */
        io_loops_timeouts_update(-(long)(ioloop_time -
                         ioloop_timeval.tv_sec));
        ioloop->time_moved_callback(ioloop_time,
                        ioloop_timeval.tv_sec);
        /* the callback may have slept, so check the time again. */
        if (gettimeofday(&ioloop_timeval, NULL) < 0)
            i_fatal("gettimeofday(): %m");
    } else if (unlikely(ioloop_timeval.tv_sec >
                ioloop->next_max_time)) {
        io_loops_timeouts_update(ioloop_timeval.tv_sec -
                    ioloop->next_max_time);
        /* time moved forwards */
        ioloop->time_moved_callback(ioloop->next_max_time,
                        ioloop_timeval.tv_sec);
    }

    ioloop_time = ioloop_timeval.tv_sec;
    tv_call = ioloop_timeval;

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

        /* use tv_call to make sure we don't get to infinite loop in
           case callbacks update ioloop_timeval. */
        if (timeout_get_wait_time(timeout, &tv, &tv_call) > 0)
            break;

        /* update timeout's next_run and reposition it in the queue */
        timeout_reset_timeval(timeout, &tv_call);

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

void io_loop_handle_timeouts(struct ioloop *ioloop)
{
    T_BEGIN {
        io_loop_handle_timeouts_real(ioloop);
    } T_END;
}

void io_loop_call_io(struct io *io)
{
    struct ioloop *ioloop = io->ioloop;
    unsigned int t_id;

    if (io->ctx != NULL)
        io_loop_context_activate(io->ctx);
    t_id = t_push();
    io->callback(io->context);
    if (t_pop() != t_id) {
        i_panic("Leaked a t_pop() call in I/O handler %p",
            (void *)io->callback);
    }
    if (ioloop->cur_ctx != NULL)
        io_loop_context_deactivate(ioloop->cur_ctx);
}

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

    if (ioloop->cur_ctx != NULL)
        io_loop_context_unref(&ioloop->cur_ctx);

    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;
}

void io_loop_set_max_fd_count(struct ioloop *ioloop, unsigned int max_fds)
{
    ioloop->max_fd_count = max_fds;
}

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

void io_loop_time_refresh(void)
{
    if (gettimeofday(&ioloop_timeval, NULL) < 0)
        i_fatal("gettimeofday(): %m");
    ioloop_time = ioloop_timeval.tv_sec;
}

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

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

        ioloop = i_new(struct ioloop, 1);
    ioloop->timeouts = priorityq_init(timeout_cmp, 32);

    ioloop->time_moved_callback = current_ioloop != NULL ?
        current_ioloop->time_moved_callback :
        io_loop_default_time_moved;

    ioloop->prev = current_ioloop;
        current_ioloop = ioloop;

        return ioloop;
}

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

    *_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 (line %u, fd %d)",
              (void *)io->io.callback,
              io->io.source_linenum, io->fd);
        io_remove(&_io);
    }

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

        i_warning("Timeout leak: %p (line %u)", (void *)to->callback,
              to->source_linenum);
        timeout_free(to);
    }
    priorityq_deinit(&ioloop->timeouts);

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

    if (ioloop->cur_ctx != NULL)
        io_loop_context_deactivate(ioloop->cur_ctx);

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

    i_free(ioloop);
}

void io_loop_set_time_moved_callback(struct ioloop *ioloop,
                     io_loop_time_moved_callback_t *callback)
{
    ioloop->time_moved_callback = callback;
}

void io_loop_set_current(struct ioloop *ioloop)
{
    current_ioloop = ioloop;
}

struct ioloop_context *io_loop_context_new(struct ioloop *ioloop)
{
    struct ioloop_context *ctx;

    ctx = i_new(struct ioloop_context, 1);
    ctx->refcount = 2;
    ctx->ioloop = ioloop;
    i_array_init(&ctx->callbacks, 4);

    if (ioloop->cur_ctx != NULL)
        io_loop_context_unref(&ioloop->cur_ctx);
    ioloop->cur_ctx = ctx;
    return ctx;
}

void io_loop_context_ref(struct ioloop_context *ctx)
{
    i_assert(ctx->refcount > 0);

    ctx->refcount++;
}

void io_loop_context_unref(struct ioloop_context **_ctx)
{
    struct ioloop_context *ctx = *_ctx;

    *_ctx = NULL;

    i_assert(ctx->refcount > 0);
    if (--ctx->refcount > 0)
        return;

    /* cur_ctx itself keeps a reference */
    i_assert(ctx->ioloop->cur_ctx != ctx);

    array_free(&ctx->callbacks);
    i_free(ctx);
}

void io_loop_context_add_callbacks(struct ioloop_context *ctx,
                   io_callback_t *activate,
                   io_callback_t *deactivate, void *context)
{
    struct ioloop_context_callback cb;

    memset(&cb, 0, sizeof(cb));
    cb.activate = activate;
    cb.deactivate = deactivate;
    cb.context = context;

    array_append(&ctx->callbacks, &cb, 1);
}

void io_loop_context_remove_callbacks(struct ioloop_context *ctx,
                      io_callback_t *activate,
                      io_callback_t *deactivate, void *context)
{
    struct ioloop_context_callback *cb;

    array_foreach_modifiable(&ctx->callbacks, cb) {
        if (cb->context == context &&
            cb->activate == activate && cb->deactivate == deactivate) {
            /* simply mark it as deleted, since we could get
               here from activate/deactivate loop */
            cb->activate = NULL;
            cb->deactivate = NULL;
            cb->context = NULL;
            return;
        }
    }
    i_panic("io_loop_context_remove_callbacks() context not found");
}

static void
io_loop_context_remove_deleted_callbacks(struct ioloop_context *ctx)
{
    const struct ioloop_context_callback *cbs;
    unsigned int i, count;

    cbs = array_get(&ctx->callbacks, &count);
    for (i = 0; i < count; ) {
        if (cbs[i].activate != NULL)
            i++;
        else {
            array_delete(&ctx->callbacks, i, 1);
            cbs = array_get(&ctx->callbacks, &count);
        }
    }
}

void io_loop_context_activate(struct ioloop_context *ctx)
{
    const struct ioloop_context_callback *cb;

    i_assert(ctx->ioloop->cur_ctx == NULL);

    ctx->ioloop->cur_ctx = ctx;
    io_loop_context_ref(ctx);
    array_foreach(&ctx->callbacks, cb) {
        if (cb->activate != NULL)
            cb->activate(cb->context);
    }
}

void io_loop_context_deactivate(struct ioloop_context *ctx)
{
    const struct ioloop_context_callback *cb;

    array_foreach(&ctx->callbacks, cb) {
        if (cb->deactivate != NULL)
            cb->deactivate(cb->context);
    }
    ctx->ioloop->cur_ctx = NULL;
    io_loop_context_remove_deleted_callbacks(ctx);
    io_loop_context_unref(&ctx);
}

struct ioloop_context *io_loop_get_current_context(struct ioloop *ioloop)
{
    return ioloop->cur_ctx;
}

struct io *io_loop_move_io(struct io **_io)
{
    struct io *new_io, *old_io = *_io;
    struct io_file *old_io_file;

    i_assert((old_io->condition & IO_NOTIFY) == 0);

    if (old_io->ioloop == current_ioloop)
        return old_io;

    old_io_file = (struct io_file *)old_io;
    new_io = io_add(old_io_file->fd, old_io->condition,
            old_io->source_linenum,
            old_io->callback, old_io->context);
    io_remove(_io);
    return new_io;
}

struct timeout *io_loop_move_timeout(struct timeout **_timeout)
{
    struct timeout *new_to, *old_to = *_timeout;

    if (old_to->ioloop == current_ioloop)
        return old_to;

    new_to = timeout_add(old_to->msecs, old_to->source_linenum,
                 old_to->callback, old_to->context);
    timeout_remove(_timeout);
    return new_to;
}