ctdb-daemon: Wait for eventd to be ready before connecting

[Samba.git] / lib / tevent / tevent_timed.c

/* 
   Unix SMB/CIFS implementation.

   common events code for timed events

   Copyright (C) Andrew Tridgell        2003-2006
   Copyright (C) Stefan Metzmacher      2005-2009

     ** NOTE! The following LGPL license applies to the tevent
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL

   This library 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 3 of the License, or (at your option) any later version.

   This library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

#include "replace.h"
#include "system/time.h"
#include "tevent.h"
#include "tevent_internal.h"
#include "tevent_util.h"

/**
  compare two timeval structures. 
  Return -1 if tv1 < tv2
  Return 0 if tv1 == tv2
  Return 1 if tv1 > tv2
*/
int tevent_timeval_compare(const struct timeval *tv1, const struct timeval *tv2)
{
        if (tv1->tv_sec  > tv2->tv_sec)  return 1;
        if (tv1->tv_sec  < tv2->tv_sec)  return -1;
        if (tv1->tv_usec > tv2->tv_usec) return 1;
        if (tv1->tv_usec < tv2->tv_usec) return -1;
        return 0;
}

/**
  return a zero timeval
*/
struct timeval tevent_timeval_zero(void)
{
        struct timeval tv;
        tv.tv_sec = 0;
        tv.tv_usec = 0;
        return tv;
}

/**
  return a timeval for the current time
*/
struct timeval tevent_timeval_current(void)
{
        struct timeval tv;
        gettimeofday(&tv, NULL);
        return tv;
}

/**
  return a timeval struct with the given elements
*/
struct timeval tevent_timeval_set(uint32_t secs, uint32_t usecs)
{
        struct timeval tv;
        tv.tv_sec = secs;
        tv.tv_usec = usecs;
        return tv;
}

/**
  return the difference between two timevals as a timeval
  if tv1 comes after tv2, then return a zero timeval
  (this is *tv2 - *tv1)
*/
struct timeval tevent_timeval_until(const struct timeval *tv1,
                                    const struct timeval *tv2)
{
        struct timeval t;
        if (tevent_timeval_compare(tv1, tv2) >= 0) {
                return tevent_timeval_zero();
        }
        t.tv_sec = tv2->tv_sec - tv1->tv_sec;
        if (tv1->tv_usec > tv2->tv_usec) {
                t.tv_sec--;
                t.tv_usec = 1000000 - (tv1->tv_usec - tv2->tv_usec);
        } else {
                t.tv_usec = tv2->tv_usec - tv1->tv_usec;
        }
        return t;
}

/**
  return true if a timeval is zero
*/
bool tevent_timeval_is_zero(const struct timeval *tv)
{
        return tv->tv_sec == 0 && tv->tv_usec == 0;
}

struct timeval tevent_timeval_add(const struct timeval *tv, uint32_t secs,
                                  uint32_t usecs)
{
        struct timeval tv2 = *tv;
        tv2.tv_sec += secs;
        tv2.tv_usec += usecs;
        tv2.tv_sec += tv2.tv_usec / 1000000;
        tv2.tv_usec = tv2.tv_usec % 1000000;

        return tv2;
}

/**
  return a timeval in the future with a specified offset
*/
struct timeval tevent_timeval_current_ofs(uint32_t secs, uint32_t usecs)
{
        struct timeval tv = tevent_timeval_current();
        return tevent_timeval_add(&tv, secs, usecs);
}

/*
  destroy a timed event
*/
static int tevent_common_timed_destructor(struct tevent_timer *te)
{
        if (te->destroyed) {
                tevent_common_check_double_free(te, "tevent_timer double free");
                goto done;
        }
        te->destroyed = true;

        if (te->event_ctx == NULL) {
                return 0;
        }

        tevent_debug(te->event_ctx, TEVENT_DEBUG_TRACE,
                     "Destroying timer event %p \"%s\"\n",
                     te, te->handler_name);

        if (te->event_ctx->last_zero_timer == te) {
                te->event_ctx->last_zero_timer = DLIST_PREV(te);
        }
        DLIST_REMOVE(te->event_ctx->timer_events, te);

        te->event_ctx = NULL;
done:
        if (te->busy) {
                return -1;
        }
        te->wrapper = NULL;

        return 0;
}

static void tevent_common_insert_timer(struct tevent_context *ev,
                                       struct tevent_timer *te,
                                       bool optimize_zero)
{
        struct tevent_timer *prev_te = NULL;

        if (te->destroyed) {
                tevent_abort(ev, "tevent_timer use after free");
                return;
        }

        /* keep the list ordered */
        if (optimize_zero && tevent_timeval_is_zero(&te->next_event)) {
                /*
                 * Some callers use zero tevent_timer
                 * instead of tevent_immediate events.
                 *
                 * As these can happen very often,
                 * we remember the last zero timer
                 * in the list.
                 */
                prev_te = ev->last_zero_timer;
                ev->last_zero_timer = te;
        } else {
                struct tevent_timer *cur_te;

                /*
                 * we traverse the list from the tail
                 * because it's much more likely that
                 * timers are added at the end of the list
                 */
                for (cur_te = DLIST_TAIL(ev->timer_events);
                     cur_te != NULL;
                     cur_te = DLIST_PREV(cur_te))
                {
                        int ret;

                        /*
                         * if the new event comes before the current
                         * we continue searching
                         */
                        ret = tevent_timeval_compare(&te->next_event,
                                                     &cur_te->next_event);
                        if (ret < 0) {
                                continue;
                        }

                        break;
                }

                prev_te = cur_te;
        }

        DLIST_ADD_AFTER(ev->timer_events, te, prev_te);
}

/*
  add a timed event
  return NULL on failure (memory allocation error)
*/
static struct tevent_timer *tevent_common_add_timer_internal(
                                        struct tevent_context *ev,
                                        TALLOC_CTX *mem_ctx,
                                        struct timeval next_event,
                                        tevent_timer_handler_t handler,
                                        void *private_data,
                                        const char *handler_name,
                                        const char *location,
                                        bool optimize_zero)
{
        struct tevent_timer *te;

        te = talloc(mem_ctx?mem_ctx:ev, struct tevent_timer);
        if (te == NULL) return NULL;

        *te = (struct tevent_timer) {
                .event_ctx      = ev,
                .next_event     = next_event,
                .handler        = handler,
                .private_data   = private_data,
                .handler_name   = handler_name,
                .location       = location,
        };

        if (ev->timer_events == NULL) {
                ev->last_zero_timer = NULL;
        }

        tevent_common_insert_timer(ev, te, optimize_zero);

        talloc_set_destructor(te, tevent_common_timed_destructor);

        tevent_debug(ev, TEVENT_DEBUG_TRACE,
                     "Added timed event \"%s\": %p\n",
                     handler_name, te);
        return te;
}

struct tevent_timer *tevent_common_add_timer(struct tevent_context *ev,
                                             TALLOC_CTX *mem_ctx,
                                             struct timeval next_event,
                                             tevent_timer_handler_t handler,
                                             void *private_data,
                                             const char *handler_name,
                                             const char *location)
{
        /*
         * do not use optimization, there are broken Samba
         * versions which use tevent_common_add_timer()
         * without using tevent_common_loop_timer_delay(),
         * it just uses DLIST_REMOVE(ev->timer_events, te)
         * and would leave ev->last_zero_timer behind.
         */
        return tevent_common_add_timer_internal(ev, mem_ctx, next_event,
                                                handler, private_data,
                                                handler_name, location,
                                                false);
}

struct tevent_timer *tevent_common_add_timer_v2(struct tevent_context *ev,
                                                TALLOC_CTX *mem_ctx,
                                                struct timeval next_event,
                                                tevent_timer_handler_t handler,
                                                void *private_data,
                                                const char *handler_name,
                                                const char *location)
{
        /*
         * Here we turn on last_zero_timer optimization
         */
        return tevent_common_add_timer_internal(ev, mem_ctx, next_event,
                                                handler, private_data,
                                                handler_name, location,
                                                true);
}

void tevent_update_timer(struct tevent_timer *te, struct timeval next_event)
{
        struct tevent_context *ev = te->event_ctx;

        if (ev->last_zero_timer == te) {
                te->event_ctx->last_zero_timer = DLIST_PREV(te);
        }
        DLIST_REMOVE(ev->timer_events, te);

        te->next_event = next_event;

        /*
         * Not doing the zero_timer optimization. This is for new code
         * that should know about immediates.
         */
        tevent_common_insert_timer(ev, te, false);
}

int tevent_common_invoke_timer_handler(struct tevent_timer *te,
                                       struct timeval current_time,
                                       bool *removed)
{
        struct tevent_context *handler_ev = te->event_ctx;

        if (removed != NULL) {
                *removed = false;
        }

        if (te->event_ctx == NULL) {
                return 0;
        }

        /*
         * We need to remove the timer from the list before calling the
         * handler because in a semi-async inner event loop called from the
         * handler we don't want to come across this event again -- vl
         */
        if (te->event_ctx->last_zero_timer == te) {
                te->event_ctx->last_zero_timer = DLIST_PREV(te);
        }
        DLIST_REMOVE(te->event_ctx->timer_events, te);

        tevent_debug(te->event_ctx, TEVENT_DEBUG_TRACE,
                     "Running timer event %p \"%s\"\n",
                     te, te->handler_name);

        /*
         * If the timed event was registered for a zero current_time,
         * then we pass a zero timeval here too! To avoid the
         * overhead of gettimeofday() calls.
         *
         * otherwise we pass the current time
         */
        te->busy = true;
        if (te->wrapper != NULL) {
                handler_ev = te->wrapper->wrap_ev;

                tevent_wrapper_push_use_internal(handler_ev, te->wrapper);
                te->wrapper->ops->before_timer_handler(
                                        te->wrapper->wrap_ev,
                                        te->wrapper->private_state,
                                        te->wrapper->main_ev,
                                        te,
                                        te->next_event,
                                        current_time,
                                        te->handler_name,
                                        te->location);
        }
        te->handler(handler_ev, te, current_time, te->private_data);
        if (te->wrapper != NULL) {
                te->wrapper->ops->after_timer_handler(
                                        te->wrapper->wrap_ev,
                                        te->wrapper->private_state,
                                        te->wrapper->main_ev,
                                        te,
                                        te->next_event,
                                        current_time,
                                        te->handler_name,
                                        te->location);
                tevent_wrapper_pop_use_internal(handler_ev, te->wrapper);
        }
        te->busy = false;

        tevent_debug(te->event_ctx, TEVENT_DEBUG_TRACE,
                     "Ending timer event %p \"%s\"\n",
                     te, te->handler_name);

        te->wrapper = NULL;
        te->event_ctx = NULL;
        talloc_set_destructor(te, NULL);
        TALLOC_FREE(te);

        if (removed != NULL) {
                *removed = true;
        }

        return 0;
}
/*
  do a single event loop using the events defined in ev

  return the delay until the next timed event,
  or zero if a timed event was triggered
*/
struct timeval tevent_common_loop_timer_delay(struct tevent_context *ev)
{
        struct timeval current_time = tevent_timeval_zero();
        struct tevent_timer *te = ev->timer_events;
        int ret;

        if (!te) {
                /* have a default tick time of 30 seconds. This guarantees
                   that code that uses its own timeout checking will be
                   able to proceed eventually */
                return tevent_timeval_set(30, 0);
        }

        /*
         * work out the right timeout for the next timed event
         *
         * avoid the syscall to gettimeofday() if the timed event should
         * be triggered directly
         *
         * if there's a delay till the next timed event, we're done
         * with just returning the delay
         */
        if (!tevent_timeval_is_zero(&te->next_event)) {
                struct timeval delay;

                current_time = tevent_timeval_current();

                delay = tevent_timeval_until(&current_time, &te->next_event);
                if (!tevent_timeval_is_zero(&delay)) {
                        return delay;
                }
        }

        /*
         * ok, we have a timed event that we'll process ...
         */
        ret = tevent_common_invoke_timer_handler(te, current_time, NULL);
        if (ret != 0) {
                tevent_abort(ev, "tevent_common_invoke_timer_handler() failed");
        }

        return tevent_timeval_zero();
}