X-Git-Url: https://git.ozlabs.org/?a=blobdiff_plain;f=ccan%2Ftimer%2Ftimer.c;h=2c58a4e5238df00b7bd88abc8cee76feb284eab2;hb=63f770591286a5a61ef2857377eeab5e0e75d115;hp=f0e017ba6ed8decba4ac4abcf0ecce07f01abf48;hpb=bd9a48e7ffca063e21d580e9e0d94b1691c03687;p=ccan

diff --git a/ccan/timer/timer.c b/ccan/timer/timer.c
index f0e017ba..2c58a4e5 100644
--- a/ccan/timer/timer.c
+++ b/ccan/timer/timer.c
@@ -131,7 +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;
@@ -139,67 +142,56 @@ 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;
 }
 
-static const struct timer *get_first(const struct timers *timers)
+/* FIXME: Suboptimal */
+static const struct timer *brute_force_first(const struct timers *timers)
 {
-	unsigned int level, i, off;
-	bool need_next;
-	uint64_t base;
+	unsigned int l, i;
 	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 find_first(&timers->far, NULL);
-
-	need_next = false;
-	off = base % PER_LEVEL;
-	for (i = 0; i < PER_LEVEL; i++) {
-		h = &timers->level[level]->list[(i+off) % PER_LEVEL];
-
-		if (!list_empty(h))
-			break;
 
-		/* We haven't cascaded yet, so if we wrap, we'll need to
-		 * check next level, too. */
-		if (i + off == PER_LEVEL)
-			need_next = true;
-	}
-	if (i == PER_LEVEL) {
-		level++;
-		base >>= TIMER_LEVEL_BITS;
-		goto next;
+	for (l = 0; l < ARRAY_SIZE(timers->level) && timers->level[l]; l++) {
+		for (i = 0; i < PER_LEVEL; i++)
+			found = find_first(&timers->level[l]->list[i], l,
+					   found);
 	}
 
-	/* Level 0 is exact, so they're all the same. */
-	if (level == 0)
-		found = list_top(h, struct timer, list);
+	found = find_first(&timers->far, -1U, found);
+	return found;
+}
+			
+static const struct timer *get_first(const struct timers *timers)
+{
+	uint64_t time;
+	
+	/* Where can we start from? */
+	if (timers->first < timers->base)
+		time = timers->base;
 	else
-		found = find_first(h, NULL);
-
-	if (need_next) {
-		if (!timers->level[level+1]) {
-			found = find_first(&timers->far, found);
-		} else {
-			base >>= TIMER_LEVEL_BITS;
-			off = base % PER_LEVEL;
-			h = &timers->level[level+1]->list[off];
-			found = find_first(h, found);
+		time = timers->first;
+
+	/* We can have just far timers, for example. */
+	if (timers->level[0]) {
+		/* First search rest of lower buckets; we've already spilled
+		 * so if we find one there we don't need to search further. */
+		unsigned int i, off = time % PER_LEVEL;
+
+		for (i = off; i < PER_LEVEL; i++) {
+			struct list_head *h = &timers->level[0]->list[i];
+			if (!list_empty(h))
+				return find_first(h, 0, NULL);
 		}
 	}
-	return found;
+
+	/* From here on, we're searching non-normalized parts of the
+	 * data structure, which is much subtler.
+	 *
+	 * So we brute force. */
+	return brute_force_first(timers);
 }
 
 static bool update_first(struct timers *timers)