]> git.ozlabs.org Git - ccan/blobdiff - ccan/timer/timer.c
timer: put level-0 optimization directly into find_first.
[ccan] / ccan / timer / timer.c
index 991ec643926f330a897ba383265343f1ae280e65..208d8e6988f1a2d8871ecf40aecb64b8f7f4e282 100644 (file)
@@ -12,23 +12,23 @@ 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;
 
@@ -63,8 +63,20 @@ 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. */
@@ -79,7 +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,
@@ -119,7 +131,10 @@ static void add_level(struct timers *timers, unsigned int level)
                timer_add_raw(timers, t);
 }
 
+/* We don't need to search past the first at level 0, since the
+ * bucket range is 1; they're all the same. */
 static const struct timer *find_first(const struct list_head *list,
+                                     unsigned int level,
                                      const struct timer *prev)
 {
        struct timer *t;
@@ -127,6 +142,8 @@ static const struct timer *find_first(const struct list_head *list,
        list_for_each(list, t, list) {
                if (!prev || t->time < prev->time)
                        prev = t;
+               if (level == 0)
+                       break;
        }
        return prev;
 }
@@ -150,7 +167,7 @@ static const struct timer *get_first(const struct timers *timers)
 
 next:
        if (!timers->level[level])
-               return find_first(&timers->far, NULL);
+               return find_first(&timers->far, -1U, NULL);
 
        need_next = false;
        off = base % PER_LEVEL;
@@ -168,23 +185,33 @@ next:
        if (i == PER_LEVEL) {
                level++;
                base >>= TIMER_LEVEL_BITS;
+               if (off != 0)
+                       /* We need *next* bucket: we've started reusing the
+                        * one above */
+                       base++;
                goto next;
        }
 
        /* Level 0 is exact, so they're all the same. */
-       if (level == 0)
-               found = list_top(h, struct timer, list);
-       else
-               found = find_first(h, NULL);
+       found = find_first(h, level, NULL);
 
-       if (need_next) {
+       while (need_next) {
+               need_next = false;
                if (!timers->level[level+1]) {
-                       found = find_first(&timers->far, found);
+                       found = find_first(&timers->far, -1U, found);
                } else {
+                       /* Current upper bucket has emptied into this
+                        * bucket; we want *next* one. */
                        base >>= TIMER_LEVEL_BITS;
+                       base++;
                        off = base % PER_LEVEL;
-                       h = &timers->level[level+1]->list[off];
-                       found = find_first(h, found);
+
+                       if (off == 0) {
+                               need_next = true;
+                       } else {
+                               h = &timers->level[level+1]->list[off];
+                               found = find_first(h, level+1, found);
+                       }
                }
        }
        return found;
@@ -203,7 +230,7 @@ static bool update_first(struct timers *timers)
        return true;
 }
 
-bool timer_earliest(struct timers *timers, struct timespec *first)
+bool timer_earliest(struct timers *timers, struct timeabs *first)
 {
        if (!update_first(timers))
                return false;
@@ -259,37 +286,37 @@ 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;
+       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);
        }
 
        do {
                if (timers->first > now) {
                        timer_fast_forward(timers, now);
-                       break;
+                       return NULL;
                }
 
                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;
-       } while (update_first(timers));
+               /* 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,
@@ -306,7 +333,8 @@ 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;
@@ -315,7 +343,8 @@ static bool timer_list_check(const struct list_head *l,
                        if (abortstr) {
                                fprintf(stderr,
                                        "%s: timer %p %llu < minimum %llu\n",
-                                       abortstr, t, t->time, first);
+                                       abortstr, t, (long long)t->time,
+                                       (long long)first);
                                abort();
                        }
                        return false;
@@ -346,7 +375,7 @@ struct timers *timers_check(const struct timers *timers, const char *abortstr)
 
        /* For other levels, "current" bucket has been emptied, and may contain
         * entries for the current + level_size bucket. */
-       for (l = 1; timers->level[l] && l < PER_LEVEL; l++) {
+       for (l = 1; l < ARRAY_SIZE(timers->level) && timers->level[l]; l++) {
                uint64_t per_bucket = 1ULL << (TIMER_LEVEL_BITS * l);
 
                off = ((timers->base >> (l*TIMER_LEVEL_BITS)) % PER_LEVEL);
@@ -375,50 +404,84 @@ past_levels:
 }
 
 #ifdef CCAN_TIMER_DEBUG
-void timers_dump(const struct timers *timers, FILE *fp)
+static void dump_bucket_stats(FILE *fp, const struct list_head *h)
 {
-       unsigned int l, i;
-       uint64_t min, max, num;
+       unsigned long long min, max, num;
        struct timer *t;
 
-       if (!fp)
-               fp = stderr;
-
-       fprintf(fp, "Base: %llu\n", timers->base);
-
-       for (l = 0; timers->level[l] && l < ARRAY_SIZE(timers->level); l++) {
-               fprintf(fp, "Level %i (+%llu):\n",
-                       l, (uint64_t)1 << (TIMER_LEVEL_BITS * l));
-               for (i = 0; i < (1 << TIMER_LEVEL_BITS); i++) {
-
-                       if (list_empty(&timers->level[l]->list[i]))
-                               continue;
-                       min = -1ULL;
-                       max = 0;
-                       num = 0;
-                       list_for_each(&timers->level[l]->list[i], t, list) {
-                               if (t->time < min)
-                                       min = t->time;
-                               if (t->time > max)
-                                       max = t->time;
-                               num++;
-                       }
-                       fprintf(stderr, "  %llu (+%llu-+%llu)\n",
-                               num, min - timers->base, max - timers->base);
-               }
+       if (list_empty(h)) {
+               printf("\n");
+               return;
        }
 
        min = -1ULL;
        max = 0;
        num = 0;
-       list_for_each(&timers->far, t, list) {
+       list_for_each(h, t, list) {
                if (t->time < min)
                        min = t->time;
                if (t->time > max)
                        max = t->time;
                num++;
        }
-       fprintf(stderr, "Far: %llu (%llu-%llu)\n", num, min, max);
+       fprintf(fp, " %llu (%llu-%llu)\n",
+               num, min, max);
+}
+
+void timers_dump(const struct timers *timers, FILE *fp)
+{
+       unsigned int l, i, off;
+       unsigned long long base;
+
+       if (!fp)
+               fp = stderr;
+
+       fprintf(fp, "Base: %llu\n", (unsigned long long)timers->base);
+
+       if (!timers->level[0])
+               goto past_levels;
+
+       fprintf(fp, "Level 0:\n");
+
+       /* First level is simple. */
+       off = timers->base % PER_LEVEL;
+       for (i = 0; i < PER_LEVEL; i++) {
+               const struct list_head *h;
+
+               fprintf(fp, "  Bucket %llu (%lu):",
+                       (i+off) % PER_LEVEL, timers->base + i);
+               h = &timers->level[0]->list[(i+off) % PER_LEVEL];
+               dump_bucket_stats(fp, h);
+       }
+
+       /* For other levels, "current" bucket has been emptied, and may contain
+        * entries for the current + level_size bucket. */
+       for (l = 1; l < ARRAY_SIZE(timers->level) && timers->level[l]; l++) {
+               uint64_t per_bucket = 1ULL << (TIMER_LEVEL_BITS * l);
+
+               off = ((timers->base >> (l*TIMER_LEVEL_BITS)) % PER_LEVEL);
+               /* We start at *next* bucket. */
+               base = (timers->base & ~(per_bucket - 1)) + per_bucket;
+
+               fprintf(fp, "Level %u:\n", l);
+               for (i = 1; i <= PER_LEVEL; i++) {
+                       const struct list_head *h;
+
+                       fprintf(fp, "  Bucket %llu (%llu - %llu):",
+                               (i+off) % PER_LEVEL,
+                               base, base + per_bucket - 1);
+
+                       h = &timers->level[l]->list[(i+off) % PER_LEVEL];
+                       dump_bucket_stats(fp, h);
+                       base += per_bucket;
+               }
+       }
+
+past_levels:
+       if (!list_empty(&timers->far)) {
+               fprintf(fp, "Far timers:");
+               dump_bucket_stats(fp, &timers->far);
+       }
 }
 #endif