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https://github.com/fluencelabs/redis
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Move logic concerned with zset ranges
This also optimizes ZREVRANGEBYSCORE for pathological cases where a sorted set contains many elements with the same score. Previously, it would traverse the list from back to front in such a case.
This commit is contained in:
Pieter Noordhuis
parent
a300477368
commit
22b9bf1594
163
src/t_zset.c
163
src/t_zset.c
@ -180,6 +180,78 @@ typedef struct {
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int minex, maxex; /* are min or max exclusive? */
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} zrangespec;
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static inline int zslValueInMinRange(double value, zrangespec *spec) {
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return spec->minex ? (value > spec->min) : (value >= spec->min);
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}
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static inline int zslValueInMaxRange(double value, zrangespec *spec) {
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return spec->maxex ? (value < spec->max) : (value <= spec->max);
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}
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static inline int zslValueInRange(double value, zrangespec *spec) {
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return zslValueInMinRange(value,spec) && zslValueInMaxRange(value,spec);
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}
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/* Returns if there is a part of the zset is in range. */
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int zslIsInRange(zskiplist *zsl, zrangespec *range) {
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zskiplistNode *x;
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x = zsl->tail;
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if (x == NULL || !zslValueInMinRange(x->score,range))
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return 0;
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x = zsl->header->level[0].forward;
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if (x == NULL || !zslValueInMaxRange(x->score,range))
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return 0;
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return 1;
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}
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/* Find the first node that is contained in the specified range.
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* Returns NULL when no element is contained in the range. */
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zskiplistNode *zslFirstInRange(zskiplist *zsl, zrangespec range) {
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zskiplistNode *x;
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int i;
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/* If everything is out of range, return early. */
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if (!zslIsInRange(zsl,&range)) return NULL;
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x = zsl->header;
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for (i = zsl->level-1; i >= 0; i--) {
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/* Go forward while *OUT* of range. */
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while (x->level[i].forward &&
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!zslValueInMinRange(x->level[i].forward->score,&range))
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x = x->level[i].forward;
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}
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/* The tail is in range, so the previous block should always return a
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* node that is non-NULL and the last one to be out of range. */
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x = x->level[0].forward;
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redisAssert(x != NULL && zslValueInRange(x->score,&range));
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return x;
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}
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/* Find the last node that is contained in the specified range.
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* Returns NULL when no element is contained in the range. */
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zskiplistNode *zslLastInRange(zskiplist *zsl, zrangespec range) {
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zskiplistNode *x;
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int i;
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/* If everything is out of range, return early. */
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if (!zslIsInRange(zsl,&range)) return NULL;
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x = zsl->header;
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for (i = zsl->level-1; i >= 0; i--) {
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/* Go forward while *IN* range. */
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while (x->level[i].forward &&
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zslValueInMaxRange(x->level[i].forward->score,&range))
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x = x->level[i].forward;
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}
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/* The header is in range, so the previous block should always return a
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* node that is non-NULL and in range. */
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redisAssert(x != NULL && zslValueInRange(x->score,&range));
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return x;
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}
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/* Delete all the elements with score between min and max from the skiplist.
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* Min and mx are inclusive, so a score >= min || score <= max is deleted.
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* Note that this function takes the reference to the hash table view of the
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@ -243,22 +315,6 @@ unsigned long zslDeleteRangeByRank(zskiplist *zsl, unsigned int start, unsigned
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return removed;
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}
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/* Find the first node having a score equal or greater than the specified one.
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* Returns NULL if there is no match. */
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zskiplistNode *zslFirstWithScore(zskiplist *zsl, double score) {
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zskiplistNode *x;
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int i;
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x = zsl->header;
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for (i = zsl->level-1; i >= 0; i--) {
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while (x->level[i].forward && x->level[i].forward->score < score)
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x = x->level[i].forward;
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}
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/* We may have multiple elements with the same score, what we need
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* is to find the element with both the right score and object. */
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return x->level[0].forward;
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}
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/* Find the rank for an element by both score and key.
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* Returns 0 when the element cannot be found, rank otherwise.
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* Note that the rank is 1-based due to the span of zsl->header to the
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@ -847,9 +903,18 @@ void genericZrangebyscoreCommand(redisClient *c, int reverse, int justcount) {
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int withscores = 0;
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unsigned long rangelen = 0;
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void *replylen = NULL;
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int minidx, maxidx;
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/* Parse the range arguments. */
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if (zslParseRange(c->argv[2],c->argv[3],&range) != REDIS_OK) {
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if (reverse) {
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/* Range is given as [max,min] */
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maxidx = 2; minidx = 3;
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} else {
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/* Range is given as [min,max] */
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minidx = 2; maxidx = 3;
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}
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if (zslParseRange(c->argv[minidx],c->argv[maxidx],&range) != REDIS_OK) {
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addReplyError(c,"min or max is not a double");
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return;
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}
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@ -882,33 +947,11 @@ void genericZrangebyscoreCommand(redisClient *c, int reverse, int justcount) {
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zsetobj = o->ptr;
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zsl = zsetobj->zsl;
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/* If reversed, assume the elements are sorted from high to low score. */
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ln = zslFirstWithScore(zsl,range.min);
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/* If reversed, get the last node in range as starting point. */
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if (reverse) {
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/* If range.min is out of range, ln will be NULL and we need to use
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* the tail of the skiplist as first node of the range. */
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if (ln == NULL) ln = zsl->tail;
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/* zslFirstWithScore returns the first element with where with
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* score >= range.min, so backtrack to make sure the element we use
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* here has score <= range.min. */
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while (ln && ln->score > range.min) ln = ln->backward;
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/* Move to the right element according to the range spec. */
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if (range.minex) {
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/* Find last element with score < range.min */
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while (ln && ln->score == range.min) ln = ln->backward;
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} else {
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/* Find last element with score <= range.min */
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while (ln && ln->level[0].forward &&
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ln->level[0].forward->score == range.min)
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ln = ln->level[0].forward;
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}
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ln = zslLastInRange(zsl,range);
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} else {
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if (range.minex) {
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/* Find first element with score > range.min */
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while (ln && ln->score == range.min) ln = ln->level[0].forward;
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}
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ln = zslFirstInRange(zsl,range);
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}
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/* No "first" element in the specified interval. */
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@ -917,40 +960,24 @@ void genericZrangebyscoreCommand(redisClient *c, int reverse, int justcount) {
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return;
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}
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/* We don't know in advance how many matching elements there
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* are in the list, so we push this object that will represent
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* the multi-bulk length in the output buffer, and will "fix"
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* it later */
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/* We don't know in advance how many matching elements there are in the
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* list, so we push this object that will represent the multi-bulk length
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* in the output buffer, and will "fix" it later */
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if (!justcount)
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replylen = addDeferredMultiBulkLength(c);
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/* If there is an offset, just traverse the number of elements without
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* checking the score because that is done in the next loop. */
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while(ln && offset--) {
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if (reverse)
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ln = ln->backward;
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else
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ln = ln->level[0].forward;
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ln = reverse ? ln->backward : ln->level[0].forward;
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}
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while (ln && limit--) {
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/* Check if this this element is in range. */
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/* Abort when the node is no longer in range. */
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if (reverse) {
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if (range.maxex) {
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/* Element should have score > range.max */
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if (ln->score <= range.max) break;
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} else {
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/* Element should have score >= range.max */
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if (ln->score < range.max) break;
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}
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if (!zslValueInMinRange(ln->score,&range)) break;
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} else {
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if (range.maxex) {
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/* Element should have score < range.max */
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if (ln->score >= range.max) break;
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} else {
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/* Element should have score <= range.max */
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if (ln->score > range.max) break;
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}
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if (!zslValueInMaxRange(ln->score,&range)) break;
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}
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/* Do our magic */
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@ -961,10 +988,8 @@ void genericZrangebyscoreCommand(redisClient *c, int reverse, int justcount) {
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addReplyDouble(c,ln->score);
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}
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if (reverse)
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ln = ln->backward;
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else
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ln = ln->level[0].forward;
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/* Move to next node */
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ln = reverse ? ln->backward : ln->level[0].forward;
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}
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if (justcount) {
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@ -227,6 +227,22 @@ start_server {tags {"zset"}} {
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assert_equal {f e} [r zrevrangebyscore zset (6 (3]
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assert_equal {f} [r zrevrangebyscore zset (+inf (4]
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assert_equal 2 [r zcount zset (0 (3]
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# test empty ranges
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r zrem zset a
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r zrem zset g
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# inclusive
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assert_equal {} [r zrangebyscore zset 6 +inf]
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assert_equal {} [r zrangebyscore zset -inf -6]
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assert_equal {} [r zrevrangebyscore zset +inf 6]
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assert_equal {} [r zrevrangebyscore zset -6 -inf]
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# exclusive
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assert_equal {} [r zrangebyscore zset (6 (+inf]
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assert_equal {} [r zrangebyscore zset (-inf (-6]
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assert_equal {} [r zrevrangebyscore zset (+inf (6]
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assert_equal {} [r zrevrangebyscore zset (-6 (-inf]
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}
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test "ZRANGEBYSCORE with WITHSCORES" {
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