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https://github.com/fluencelabs/redis
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Use flexible array in zskiplistNode to reduce memory usage
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6825491928
commit
2159782b51
11
src/redis.h
11
src/redis.h
@ -480,13 +480,14 @@ typedef struct _redisSortOperation {
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} redisSortOperation;
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/* ZSETs use a specialized version of Skiplists */
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typedef struct zskiplistNode {
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struct zskiplistNode **forward;
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struct zskiplistNode *backward;
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unsigned int *span;
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double score;
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robj *obj;
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double score;
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struct zskiplistNode *backward;
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struct zskiplistLevel {
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struct zskiplistNode *forward;
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unsigned int span;
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} level[];
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} zskiplistNode;
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typedef struct zskiplist {
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136
src/t_zset.c
136
src/t_zset.c
@ -24,13 +24,7 @@
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* from tail to head, useful for ZREVRANGE. */
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zskiplistNode *zslCreateNode(int level, double score, robj *obj) {
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zskiplistNode *zn = zmalloc(sizeof(*zn));
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zn->forward = zmalloc(sizeof(zskiplistNode*) * level);
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if (level > 1)
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zn->span = zmalloc(sizeof(unsigned int) * (level - 1));
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else
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zn->span = NULL;
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zskiplistNode *zn = zmalloc(sizeof(*zn)+level*sizeof(struct zskiplistLevel));
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zn->score = score;
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zn->obj = obj;
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return zn;
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@ -45,11 +39,8 @@ zskiplist *zslCreate(void) {
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zsl->length = 0;
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zsl->header = zslCreateNode(ZSKIPLIST_MAXLEVEL,0,NULL);
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for (j = 0; j < ZSKIPLIST_MAXLEVEL; j++) {
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zsl->header->forward[j] = NULL;
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/* span has space for ZSKIPLIST_MAXLEVEL-1 elements */
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if (j < ZSKIPLIST_MAXLEVEL-1)
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zsl->header->span[j] = 0;
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zsl->header->level[j].forward = NULL;
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zsl->header->level[j].span = 0;
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}
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zsl->header->backward = NULL;
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zsl->tail = NULL;
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@ -58,19 +49,15 @@ zskiplist *zslCreate(void) {
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void zslFreeNode(zskiplistNode *node) {
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decrRefCount(node->obj);
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zfree(node->forward);
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zfree(node->span);
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zfree(node);
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}
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void zslFree(zskiplist *zsl) {
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zskiplistNode *node = zsl->header->forward[0], *next;
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zskiplistNode *node = zsl->header->level[0].forward, *next;
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zfree(zsl->header->forward);
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zfree(zsl->header->span);
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zfree(zsl->header);
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while(node) {
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next = node->forward[0];
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next = node->level[0].forward;
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zslFreeNode(node);
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node = next;
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}
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@ -93,13 +80,12 @@ void zslInsert(zskiplist *zsl, double score, robj *obj) {
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for (i = zsl->level-1; i >= 0; i--) {
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/* store rank that is crossed to reach the insert position */
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rank[i] = i == (zsl->level-1) ? 0 : rank[i+1];
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while (x->forward[i] &&
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(x->forward[i]->score < score ||
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(x->forward[i]->score == score &&
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compareStringObjects(x->forward[i]->obj,obj) < 0))) {
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rank[i] += i > 0 ? x->span[i-1] : 1;
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x = x->forward[i];
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while (x->level[i].forward &&
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(x->level[i].forward->score < score ||
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(x->level[i].forward->score == score &&
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compareStringObjects(x->level[i].forward->obj,obj) < 0))) {
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rank[i] += x->level[i].span;
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x = x->level[i].forward;
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}
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update[i] = x;
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}
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@ -112,30 +98,28 @@ void zslInsert(zskiplist *zsl, double score, robj *obj) {
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for (i = zsl->level; i < level; i++) {
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rank[i] = 0;
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update[i] = zsl->header;
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update[i]->span[i-1] = zsl->length;
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update[i]->level[i].span = zsl->length;
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}
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zsl->level = level;
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}
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x = zslCreateNode(level,score,obj);
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for (i = 0; i < level; i++) {
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x->forward[i] = update[i]->forward[i];
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update[i]->forward[i] = x;
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x->level[i].forward = update[i]->level[i].forward;
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update[i]->level[i].forward = x;
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/* update span covered by update[i] as x is inserted here */
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if (i > 0) {
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x->span[i-1] = update[i]->span[i-1] - (rank[0] - rank[i]);
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update[i]->span[i-1] = (rank[0] - rank[i]) + 1;
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}
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x->level[i].span = update[i]->level[i].span - (rank[0] - rank[i]);
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update[i]->level[i].span = (rank[0] - rank[i]) + 1;
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}
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/* increment span for untouched levels */
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for (i = level; i < zsl->level; i++) {
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update[i]->span[i-1]++;
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update[i]->level[i].span++;
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}
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x->backward = (update[0] == zsl->header) ? NULL : update[0];
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if (x->forward[0])
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x->forward[0]->backward = x;
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if (x->level[0].forward)
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x->level[0].forward->backward = x;
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else
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zsl->tail = x;
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zsl->length++;
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@ -145,23 +129,19 @@ void zslInsert(zskiplist *zsl, double score, robj *obj) {
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void zslDeleteNode(zskiplist *zsl, zskiplistNode *x, zskiplistNode **update) {
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int i;
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for (i = 0; i < zsl->level; i++) {
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if (update[i]->forward[i] == x) {
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if (i > 0) {
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update[i]->span[i-1] += x->span[i-1] - 1;
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}
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update[i]->forward[i] = x->forward[i];
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if (update[i]->level[i].forward == x) {
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update[i]->level[i].span += x->level[i].span - 1;
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update[i]->level[i].forward = x->level[i].forward;
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} else {
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/* invariant: i > 0, because update[0]->forward[0]
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* is always equal to x */
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update[i]->span[i-1] -= 1;
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update[i]->level[i].span -= 1;
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}
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}
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if (x->forward[0]) {
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x->forward[0]->backward = x->backward;
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if (x->level[0].forward) {
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x->level[0].forward->backward = x->backward;
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} else {
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zsl->tail = x->backward;
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}
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while(zsl->level > 1 && zsl->header->forward[zsl->level-1] == NULL)
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while(zsl->level > 1 && zsl->header->level[zsl->level-1].forward == NULL)
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zsl->level--;
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zsl->length--;
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}
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@ -173,16 +153,16 @@ int zslDelete(zskiplist *zsl, double score, robj *obj) {
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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->forward[i] &&
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(x->forward[i]->score < score ||
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(x->forward[i]->score == score &&
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compareStringObjects(x->forward[i]->obj,obj) < 0)))
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x = x->forward[i];
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while (x->level[i].forward &&
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(x->level[i].forward->score < score ||
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(x->level[i].forward->score == score &&
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compareStringObjects(x->level[i].forward->obj,obj) < 0)))
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x = x->level[i].forward;
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update[i] = x;
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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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x = x->forward[0];
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x = x->level[0].forward;
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if (x && score == x->score && equalStringObjects(x->obj,obj)) {
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zslDeleteNode(zsl, x, update);
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zslFreeNode(x);
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@ -204,15 +184,15 @@ unsigned long zslDeleteRangeByScore(zskiplist *zsl, double min, double max, dict
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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->forward[i] && x->forward[i]->score < min)
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x = x->forward[i];
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while (x->level[i].forward && x->level[i].forward->score < min)
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x = x->level[i].forward;
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update[i] = x;
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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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x = x->forward[0];
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x = x->level[0].forward;
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while (x && x->score <= max) {
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zskiplistNode *next = x->forward[0];
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zskiplistNode *next = x->level[0].forward;
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zslDeleteNode(zsl, x, update);
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dictDelete(dict,x->obj);
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zslFreeNode(x);
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@ -231,17 +211,17 @@ unsigned long zslDeleteRangeByRank(zskiplist *zsl, unsigned int start, unsigned
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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->forward[i] && (traversed + (i > 0 ? x->span[i-1] : 1)) < start) {
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traversed += i > 0 ? x->span[i-1] : 1;
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x = x->forward[i];
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while (x->level[i].forward && (traversed + x->level[i].span) < start) {
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traversed += x->level[i].span;
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x = x->level[i].forward;
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}
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update[i] = x;
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}
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traversed++;
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x = x->forward[0];
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x = x->level[0].forward;
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while (x && traversed <= end) {
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zskiplistNode *next = x->forward[0];
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zskiplistNode *next = x->level[0].forward;
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zslDeleteNode(zsl, x, update);
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dictDelete(dict,x->obj);
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zslFreeNode(x);
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@ -260,12 +240,12 @@ zskiplistNode *zslFirstWithScore(zskiplist *zsl, double score) {
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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->forward[i] && x->forward[i]->score < score)
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x = x->forward[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->forward[0];
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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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@ -279,12 +259,12 @@ unsigned long zslistTypeGetRank(zskiplist *zsl, double score, robj *o) {
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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->forward[i] &&
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(x->forward[i]->score < score ||
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(x->forward[i]->score == score &&
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compareStringObjects(x->forward[i]->obj,o) <= 0))) {
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rank += i > 0 ? x->span[i-1] : 1;
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x = x->forward[i];
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while (x->level[i].forward &&
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(x->level[i].forward->score < score ||
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(x->level[i].forward->score == score &&
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compareStringObjects(x->level[i].forward->obj,o) <= 0))) {
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rank += x->level[i].span;
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x = x->level[i].forward;
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}
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/* x might be equal to zsl->header, so test if obj is non-NULL */
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@ -303,10 +283,10 @@ zskiplistNode* zslistTypeGetElementByRank(zskiplist *zsl, unsigned long rank) {
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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->forward[i] && (traversed + (i>0 ? x->span[i-1] : 1)) <= rank)
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while (x->level[i].forward && (traversed + x->level[i].span) <= rank)
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{
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traversed += i > 0 ? x->span[i-1] : 1;
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x = x->forward[i];
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traversed += x->level[i].span;
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x = x->level[i].forward;
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}
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if (traversed == rank) {
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return x;
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@ -778,7 +758,7 @@ void zrangeGenericCommand(redisClient *c, int reverse) {
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ln = start == 0 ? zsl->tail : zslistTypeGetElementByRank(zsl, llen-start);
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} else {
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ln = start == 0 ?
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zsl->header->forward[0] : zslistTypeGetElementByRank(zsl, start+1);
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zsl->header->level[0].forward : zslistTypeGetElementByRank(zsl, start+1);
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}
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/* Return the result in form of a multi-bulk reply */
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@ -789,7 +769,7 @@ void zrangeGenericCommand(redisClient *c, int reverse) {
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addReplyBulk(c,ele);
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if (withscores)
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addReplyDouble(c,ln->score);
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ln = reverse ? ln->backward : ln->forward[0];
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ln = reverse ? ln->backward : ln->level[0].forward;
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}
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}
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@ -872,7 +852,7 @@ void genericZrangebyscoreCommand(redisClient *c, int justcount) {
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/* Get the first node with the score >= min, or with
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* score > min if 'minex' is true. */
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ln = zslFirstWithScore(zsl,min);
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while (minex && ln && ln->score == min) ln = ln->forward[0];
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while (minex && ln && ln->score == min) ln = ln->level[0].forward;
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if (ln == NULL) {
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/* No element matching the speciifed interval */
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@ -893,7 +873,7 @@ void genericZrangebyscoreCommand(redisClient *c, int justcount) {
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while(ln && (maxex ? (ln->score < max) : (ln->score <= max))) {
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if (offset) {
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offset--;
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ln = ln->forward[0];
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ln = ln->level[0].forward;
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continue;
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}
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if (limit == 0) break;
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@ -903,7 +883,7 @@ void genericZrangebyscoreCommand(redisClient *c, int justcount) {
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if (withscores)
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addReplyDouble(c,ln->score);
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}
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ln = ln->forward[0];
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ln = ln->level[0].forward;
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rangelen++;
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if (limit > 0) limit--;
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}
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