]> git.ozlabs.org Git - ccan/blobdiff - ccan/timer/timer.c
timer: make timer_del() idempotent, add timer_init().
[ccan] / ccan / timer / timer.c
index 9486e6b92872ac22a50f38fd14f5077b2fd220e3..0abf05cd419ee8111312450872e80b53fee1ebb2 100644 (file)
@@ -12,41 +12,46 @@ struct timer_level {
        struct list_head list[PER_LEVEL];
 };
 
-static uint64_t time_to_grains(struct timespec ts)
+static uint64_t time_to_grains(struct timeabs t)
 {
-       return ts.tv_sec * ((uint64_t)1000000000 / TIMER_GRANULARITY)
-               + (ts.tv_nsec / TIMER_GRANULARITY);
+       return t.ts.tv_sec * ((uint64_t)1000000000 / TIMER_GRANULARITY)
+               + (t.ts.tv_nsec / TIMER_GRANULARITY);
 }
 
-static struct timespec grains_to_time(uint64_t grains)
+static struct timeabs grains_to_time(uint64_t grains)
 {
-       struct timespec ts;
+       struct timeabs t;
 
-       ts.tv_sec = grains / (1000000000 / TIMER_GRANULARITY);
-       ts.tv_nsec = (grains % (1000000000 / TIMER_GRANULARITY))
+       t.ts.tv_sec = grains / (1000000000 / TIMER_GRANULARITY);
+       t.ts.tv_nsec = (grains % (1000000000 / TIMER_GRANULARITY))
                * TIMER_GRANULARITY;
-       return ts;
+       return t;
 }
 
-void timers_init(struct timers *timers, struct timespec start)
+void timers_init(struct timers *timers, struct timeabs start)
 {
        unsigned int i;
 
        list_head_init(&timers->far);
        timers->base = time_to_grains(start);
+       timers->first = -1ULL;
        for (i = 0; i < ARRAY_SIZE(timers->level); i++)
                timers->level[i] = NULL;
 }
 
-static void timer_add_raw(struct timers *timers, struct timer *t)
+static unsigned int level_of(const struct timers *timers, uint64_t time)
 {
-       struct list_head *l;
        uint64_t diff;
-       unsigned int level;
 
        /* Level depends how far away it is. */
-       diff = t->time - timers->base;
-       level = ilog64(diff / 2) / TIMER_LEVEL_BITS;
+       diff = time - timers->base;
+       return ilog64(diff / 2) / TIMER_LEVEL_BITS;
+}
+
+static void timer_add_raw(struct timers *timers, struct timer *t)
+{
+       struct list_head *l;
+       unsigned int level = level_of(timers, t->time);
 
        if (!timers->level[level])
                l = &timers->far;
@@ -58,13 +63,27 @@ static void timer_add_raw(struct timers *timers, struct timer *t)
        list_add_tail(l, &t->list);
 }
 
-void timer_add(struct timers *timers, struct timer *t, struct timespec when)
+void timer_init(struct timer *t)
 {
+       list_node_init(&t->list);
+}
+
+static bool list_node_initted(const struct list_node *n)
+{
+       return n->prev == n;
+}
+
+void timer_add(struct timers *timers, struct timer *t, struct timeabs when)
+{
+       assert(list_node_initted(&t->list));
+
        t->time = time_to_grains(when);
 
        /* Added in the past?  Treat it as imminent. */
        if (t->time < timers->base)
                t->time = timers->base;
+       if (t->time < timers->first)
+               timers->first = t->time;
 
        timer_add_raw(timers, t);
 }
@@ -72,7 +91,7 @@ void timer_add(struct timers *timers, struct timer *t, struct timespec when)
 /* FIXME: inline */
 void timer_del(struct timers *timers, struct timer *t)
 {
-       list_del(&t->list);
+       list_del_init(&t->list);
 }
 
 static void timers_far_get(struct timers *timers,
@@ -112,41 +131,6 @@ static void add_level(struct timers *timers, unsigned int level)
                timer_add_raw(timers, t);
 }
 
-/* Take timers from level and distribute them down one. */
-static void cascade(struct timers *timers, unsigned int level)
-{
-       struct timer *i;
-       struct list_head from_far, *list;
-
-       if (level == ARRAY_SIZE(timers->level) || !timers->level[level]) {
-               list_head_init(&from_far);
-               timers_far_get(timers, &from_far,
-                              timers->base
-                              + (1ULL << (level*TIMER_LEVEL_BITS))-1);
-               list = &from_far;
-               if (level != ARRAY_SIZE(timers->level))
-                       add_level(timers, level);
-       } else {
-               unsigned src;
-
-               src = (timers->base >> (level * TIMER_LEVEL_BITS)) % PER_LEVEL;
-               if (src == 0)
-                       cascade(timers, level + 1);
-               list = &timers->level[level]->list[src];
-       }
-
-       while ((i = list_pop(list, struct timer, list)) != NULL) {
-               unsigned dst;
-
-               assert(i->time >= timers->base);
-               assert(i->time < (timers->base
-                                 + (1ULL << ((level+1)*TIMER_LEVEL_BITS))));
-
-               dst = (i->time >> ((level-1)*TIMER_LEVEL_BITS)) % PER_LEVEL;
-               list_add_tail(&timers->level[level-1]->list[dst], &i->list);
-       }
-}
-
 static const struct timer *find_first(const struct list_head *list,
                                      const struct timer *prev)
 {
@@ -159,17 +143,26 @@ static const struct timer *find_first(const struct list_head *list,
        return prev;
 }
 
-static struct timer *get_first(const struct timers *timers)
+static const struct timer *get_first(const struct timers *timers)
 {
-       unsigned int level = 0, i, off;
+       unsigned int level, i, off;
        bool need_next;
-       uint64_t base = timers->base;
+       uint64_t base;
        const struct timer *found = NULL;
        struct list_head *h;
 
+       if (timers->first < timers->base) {
+               base = timers->base;
+               level = 0;
+       } else {
+               /* May not be accurate, due to timer_del / expiry. */
+               level = level_of(timers, timers->first);
+               base = timers->first >> (TIMER_LEVEL_BITS * level);
+       }
+
 next:
        if (!timers->level[level])
-               return (struct timer *)find_first(&timers->far, NULL);
+               return find_first(&timers->far, NULL);
 
        need_next = false;
        off = base % PER_LEVEL;
@@ -206,17 +199,28 @@ next:
                        found = find_first(h, found);
                }
        }
-
-       return (struct timer *)found;
+       return found;
 }
 
-bool timer_earliest(const struct timers *timers, struct timespec *first)
+static bool update_first(struct timers *timers)
 {
-       struct timer *found = get_first(timers);
+       const struct timer *found = get_first(timers);
 
-       if (!found)
+       if (!found) {
+               timers->first = -1ULL;
                return false;
-       *first = grains_to_time(found->time);
+       }
+
+       timers->first = found->time;
+       return true;
+}
+
+bool timer_earliest(struct timers *timers, struct timeabs *first)
+{
+       if (!update_first(timers))
+               return false;
+
+       *first = grains_to_time(timers->first);
        return true;
 }
 
@@ -267,43 +271,41 @@ static void timer_fast_forward(struct timers *timers, uint64_t time)
                timer_add_raw(timers, i);
 }
 
-/* Fills list of expired timers. */
-void timers_expire(struct timers *timers,
-                  struct timespec expire,
-                  struct list_head *list)
+/* Returns an expired timer. */
+struct timer *timers_expire(struct timers *timers, struct timeabs expire)
 {
        uint64_t now = time_to_grains(expire);
        unsigned int off;
-       const struct timer *first;
+       struct timer *t;
 
        assert(now >= timers->base);
 
-       list_head_init(list);
-
        if (!timers->level[0]) {
                if (list_empty(&timers->far))
-                       return;
+                       return NULL;
                add_level(timers, 0);
        }
 
-       while ((first = get_first(timers)) != NULL) {
-               assert(first->time >= timers->base);
-               if (first->time > now) {
+       do {
+               if (timers->first > now) {
                        timer_fast_forward(timers, now);
-                       break;
+                       return NULL;
                }
 
-               timer_fast_forward(timers, first->time);
+               timer_fast_forward(timers, timers->first);
                off = timers->base % PER_LEVEL;
 
-               list_append_list(list, &timers->level[0]->list[off]);
-               if (timers->base == now)
-                       break;
-       }
+               /* This *may* be NULL, if we deleted the first timer */
+               t = list_pop(&timers->level[0]->list[off], struct timer, list);
+               if (t)
+                       list_node_init(&t->list);
+       } while (!t && update_first(timers));
+
+       return t;
 }
 
 static bool timer_list_check(const struct list_head *l,
-                            uint64_t min, uint64_t max,
+                            uint64_t min, uint64_t max, uint64_t first,
                             const char *abortstr)
 {
        const struct timer *t;
@@ -316,7 +318,18 @@ static bool timer_list_check(const struct list_head *l,
                        if (abortstr) {
                                fprintf(stderr,
                                        "%s: timer %p %llu not %llu-%llu\n",
-                                       abortstr, t, t->time, min, max);
+                                       abortstr, t, (long long)t->time,
+                                       (long long)min, (long long)max);
+                               abort();
+                       }
+                       return false;
+               }
+               if (t->time < first) {
+                       if (abortstr) {
+                               fprintf(stderr,
+                                       "%s: timer %p %llu < minimum %llu\n",
+                                       abortstr, t, (long long)t->time,
+                                       (long long)first);
                                abort();
                        }
                        return false;
@@ -341,7 +354,7 @@ struct timers *timers_check(const struct timers *timers, const char *abortstr)
 
                h = &timers->level[l]->list[(i+off) % PER_LEVEL];
                if (!timer_list_check(h, timers->base + i, timers->base + i,
-                                     abortstr))
+                                     timers->first, abortstr))
                        return NULL;
        }
 
@@ -359,7 +372,7 @@ struct timers *timers_check(const struct timers *timers, const char *abortstr)
 
                        h = &timers->level[l]->list[(i+off) % PER_LEVEL];
                        if (!timer_list_check(h, base, base + per_bucket - 1,
-                                             abortstr))
+                                             timers->first, abortstr))
                                return NULL;
                        base += per_bucket;
                }
@@ -368,13 +381,14 @@ struct timers *timers_check(const struct timers *timers, const char *abortstr)
 past_levels:
        base = (timers->base & ~((1ULL << (TIMER_LEVEL_BITS * l)) - 1))
                + (1ULL << (TIMER_LEVEL_BITS * l)) - 1;
-       if (!timer_list_check(&timers->far, base, -1ULL, abortstr))
+       if (!timer_list_check(&timers->far, base, -1ULL, timers->first,
+                             abortstr))
                return NULL;
 
        return (struct timers *)timers;
 }
 
-//#ifdef CCAN_TIMER_DEBUG
+#ifdef CCAN_TIMER_DEBUG
 void timers_dump(const struct timers *timers, FILE *fp)
 {
        unsigned int l, i;
@@ -420,7 +434,7 @@ void timers_dump(const struct timers *timers, FILE *fp)
        }
        fprintf(stderr, "Far: %llu (%llu-%llu)\n", num, min, max);
 }
-//#endif
+#endif
 
 void timers_cleanup(struct timers *timers)
 {