X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/2b37892e9b57d6d4c9d3f9a604e50cd8c15636de..a50ea45c841e980f7692a9cd97130f0f37e5917b:/redis.c

diff --git a/redis.c b/redis.c
index 0353940e..4f7d3efc 100644
--- a/redis.c
+++ b/redis.c
@@ -659,6 +659,7 @@ static void discardCommand(redisClient *c);
 static void blpopCommand(redisClient *c);
 static void brpopCommand(redisClient *c);
 static void appendCommand(redisClient *c);
+static void substrCommand(redisClient *c);
 static void zrankCommand(redisClient *c);
 
 /*================================= Globals ================================= */
@@ -670,6 +671,7 @@ static struct redisCommand cmdTable[] = {
     {"set",setCommand,3,REDIS_CMD_BULK|REDIS_CMD_DENYOOM,0,0,0},
     {"setnx",setnxCommand,3,REDIS_CMD_BULK|REDIS_CMD_DENYOOM,0,0,0},
     {"append",appendCommand,3,REDIS_CMD_BULK|REDIS_CMD_DENYOOM,1,1,1},
+    {"substr",substrCommand,4,REDIS_CMD_INLINE,1,1,1},
     {"del",delCommand,-2,REDIS_CMD_INLINE,0,0,0},
     {"exists",existsCommand,2,REDIS_CMD_INLINE,1,1,1},
     {"incr",incrCommand,2,REDIS_CMD_INLINE|REDIS_CMD_DENYOOM,1,1,1},
@@ -3764,6 +3766,50 @@ static void appendCommand(redisClient *c) {
     addReplySds(c,sdscatprintf(sdsempty(),":%lu\r\n",(unsigned long)totlen));
 }
 
+static void substrCommand(redisClient *c) {
+    robj *o;
+    long start = atoi(c->argv[2]->ptr);
+    long end = atoi(c->argv[3]->ptr);
+
+    o = lookupKeyRead(c->db,c->argv[1]);
+    if (o == NULL) {
+        addReply(c,shared.nullbulk);
+    } else {
+        if (o->type != REDIS_STRING) {
+            addReply(c,shared.wrongtypeerr);
+        } else {
+            size_t rangelen, strlen;
+            sds range;
+
+            o = getDecodedObject(o);
+            strlen = sdslen(o->ptr);
+
+            /* convert negative indexes */
+            if (start < 0) start = strlen+start;
+            if (end < 0) end = strlen+end;
+            if (start < 0) start = 0;
+            if (end < 0) end = 0;
+
+            /* indexes sanity checks */
+            if (start > end || (size_t)start >= strlen) {
+                /* Out of range start or start > end result in null reply */
+                addReply(c,shared.nullbulk);
+                decrRefCount(o);
+                return;
+            }
+            if ((size_t)end >= strlen) end = strlen-1;
+            rangelen = (end-start)+1;
+
+            /* Return the result */
+            addReplySds(c,sdscatprintf(sdsempty(),"$%lu\r\n",rangelen));
+            range = sdsnewlen((char*)o->ptr+start,rangelen);
+            addReplySds(c,range);
+            addReply(c,shared.crlf);
+            decrRefCount(o);
+        }
+    }
+}
+
 /* ========================= Type agnostic commands ========================= */
 
 static void delCommand(redisClient *c) {
@@ -4864,11 +4910,7 @@ static void zslInsert(zskiplist *zsl, double score, robj *obj) {
             (x->forward[i]->score < score ||
                 (x->forward[i]->score == score &&
                 compareStringObjects(x->forward[i]->obj,obj) < 0))) {
-            if (i > 0) {
-                rank[i] += x->span[i-1];
-            } else {
-                rank[i]++;
-            }
+            rank[i] += i > 0 ? x->span[i-1] : 1;
             x = x->forward[i];
         }
         update[i] = x;
@@ -5023,6 +5065,53 @@ static zskiplistNode *zslFirstWithScore(zskiplist *zsl, double score) {
     return x->forward[0];
 }
 
+/* Find the rank for an element by both score and key.
+ * Returns 0 when the element cannot be found, rank otherwise.
+ * Note that the rank is 1-based due to the span of zsl->header to the
+ * first element. */
+static unsigned long zslGetRank(zskiplist *zsl, double score, robj *o) {
+    zskiplistNode *x;
+    unsigned long rank = 0;
+    int i;
+
+    x = zsl->header;
+    for (i = zsl->level-1; i >= 0; i--) {
+        while (x->forward[i] &&
+            (x->forward[i]->score < score ||
+                (x->forward[i]->score == score &&
+                compareStringObjects(x->forward[i]->obj,o) <= 0))) {
+            rank += i > 0 ? x->span[i-1] : 1;
+            x = x->forward[i];
+        }
+
+        /* x might be equal to zsl->header, so test if obj is non-NULL */
+        if (x->obj && compareStringObjects(x->obj,o) == 0) {
+            return rank;
+        }
+    }
+    return 0;
+}
+
+/* Finds an element by its rank. The rank argument needs to be 1-based. */
+zskiplistNode* zslGetElementByRank(zskiplist *zsl, unsigned long rank) {
+    zskiplistNode *x;
+    unsigned long traversed = 0;
+    int i;
+
+    x = zsl->header;
+    for (i = zsl->level-1; i >= 0; i--) {
+        while (x->forward[i] && (traversed + (i > 0 ? x->span[i-1] : 1)) <= rank) {
+            traversed += i > 0 ? x->span[i-1] : 1;
+            x = x->forward[i];
+        }
+
+        if (traversed == rank) {
+            return x;
+        }
+    }
+    return NULL;
+}
+
 /* The actual Z-commands implementations */
 
 /* This generic command implements both ZADD and ZINCRBY.
@@ -5222,17 +5311,15 @@ static void zrangeGenericCommand(redisClient *c, int reverse) {
             if (end >= llen) end = llen-1;
             rangelen = (end-start)+1;
 
-            /* Return the result in form of a multi-bulk reply */
+            /* check if starting point is trivial, before searching
+             * the element in log(N) time */
             if (reverse) {
-                ln = zsl->tail;
-                while (start--)
-                    ln = ln->backward;
+                ln = start == 0 ? zsl->tail : zslGetElementByRank(zsl, llen - start);
             } else {
-                ln = zsl->header->forward[0];
-                while (start--)
-                    ln = ln->forward[0];
+                ln = start == 0 ? zsl->header->forward[0] : zslGetElementByRank(zsl, start + 1);
             }
 
+            /* Return the result in form of a multi-bulk reply */
             addReplySds(c,sdscatprintf(sdsempty(),"*%d\r\n",
                 withscores ? (rangelen*2) : rangelen));
             for (j = 0; j < rangelen; j++) {
@@ -5436,43 +5523,26 @@ static void zrankCommand(redisClient *c) {
     }
     if (o->type != REDIS_ZSET) {
         addReply(c,shared.wrongtypeerr);
-        return;
-    }
-
-    zset *zs = o->ptr;
-    zskiplist *zsl = zs->zsl;
-    dictEntry *de = dictFind(zs->dict,c->argv[2]);
-    if (!de) {
-        addReply(c,shared.nullbulk);
-        return;
-    }
-
-    double *score = dictGetEntryVal(de);
-    zskiplistNode *x;
-    unsigned int rank = 0;
-    int i;
+    } else {
+        zset *zs = o->ptr;
+        zskiplist *zsl = zs->zsl;
+        dictEntry *de;
+        unsigned long rank;
 
-    x = zsl->header;
-    for (i = zsl->level-1; i >= 0; i--) {
-        while (x->forward[i] &&
-            (x->forward[i]->score < *score ||
-                (x->forward[i]->score == *score &&
-                compareStringObjects(x->forward[i]->obj,c->argv[2]) < 0))) {
-            if (i > 0) {
-                rank += x->span[i-1];
-            } else {
-                rank++;
-            }
-            x = x->forward[i];
+        de = dictFind(zs->dict,c->argv[2]);
+        if (!de) {
+            addReply(c,shared.nullbulk);
+            return;
         }
 
-        if (x->forward[i] && compareStringObjects(x->forward[i]->obj,c->argv[2]) == 0) {
-            addReplyLong(c, rank);
-            return;
+        double *score = dictGetEntryVal(de);
+        rank = zslGetRank(zsl, *score, c->argv[2]);
+        if (rank) {
+            addReplyLong(c, rank-1);
+        } else {
+            addReply(c,shared.nullbulk);
         }
     }
-
-    addReply(c,shared.nullbulk);
 }
 
 /* ========================= Non type-specific commands  ==================== */