BITOP bug when called against non existing keys fixed.

[redis.git] / src / bitops.c

diff --git a/src/bitops.c b/src/bitops.c
index 2f62ccc460494bd0f12b6482cc3fceea545f950c..00192b92b14fc13194ded59143b1f2a9582e8871 100644 (file)
--- a/src/bitops.c
+++ b/src/bitops.c
@@ -162,6 +162,7 @@ void bitopCommand(redisClient *c) {
     robj **objects;      /* Array of soruce objects. */
     unsigned char **src; /* Array of source strings pointers. */
     long *len, maxlen = 0; /* Array of length of src strings, and max len. */
+    long minlen = 0;    /* Min len among the input keys. */
     unsigned char *res = NULL; /* Resulting string. */
 
     /* Parse the operation name. */
@@ -196,6 +197,7 @@ void bitopCommand(redisClient *c) {
             objects[j] = NULL;
             src[j] = NULL;
             len[j] = 0;
+            minlen = 0;
             continue;
         }
         /* Return an error if one of the keys is not a string. */
@@ -213,6 +215,7 @@ void bitopCommand(redisClient *c) {
         src[j] = objects[j]->ptr;
         len[j] = sdslen(objects[j]->ptr);
         if (len[j] > maxlen) maxlen = len[j];
+        if (j == 0 || len[j] < minlen) minlen = len[j];
     }
 
     /* Compute the bit operation, if at least one string is not empty. */
@@ -221,7 +224,73 @@ void bitopCommand(redisClient *c) {
         unsigned char output, byte;
         long i;
 
-        for (j = 0; j < maxlen; j++) {
+        /* Fast path: as far as we have data for all the input bitmaps we
+         * can take a fast path that performs much better than the
+         * vanilla algorithm. */
+        j = 0;
+        if (minlen && numkeys <= 16) {
+            unsigned long *lp[16];
+            unsigned long *lres = (unsigned long*) res;
+
+            /* Note: sds pointer is always aligned to 8 byte boundary. */
+            memcpy(lp,src,sizeof(unsigned long*)*numkeys);
+            memcpy(res,src[0],minlen);
+
+            /* Different branches per different operations for speed (sorry). */
+            if (op == BITOP_AND) {
+                while(minlen >= sizeof(unsigned long)*4) {
+                    for (i = 1; i < numkeys; i++) {
+                        lres[0] &= lp[i][0];
+                        lres[1] &= lp[i][1];
+                        lres[2] &= lp[i][2];
+                        lres[3] &= lp[i][3];
+                        lp[i]+=4;
+                    }
+                    lres+=4;
+                    j += sizeof(unsigned long)*4;
+                    minlen -= sizeof(unsigned long)*4;
+                }
+            } else if (op == BITOP_OR) {
+                while(minlen >= sizeof(unsigned long)*4) {
+                    for (i = 1; i < numkeys; i++) {
+                        lres[0] |= lp[i][0];
+                        lres[1] |= lp[i][1];
+                        lres[2] |= lp[i][2];
+                        lres[3] |= lp[i][3];
+                        lp[i]+=4;
+                    }
+                    lres+=4;
+                    j += sizeof(unsigned long)*4;
+                    minlen -= sizeof(unsigned long)*4;
+                }
+            } else if (op == BITOP_XOR) {
+                while(minlen >= sizeof(unsigned long)*4) {
+                    for (i = 1; i < numkeys; i++) {
+                        lres[0] ^= lp[i][0];
+                        lres[1] ^= lp[i][1];
+                        lres[2] ^= lp[i][2];
+                        lres[3] ^= lp[i][3];
+                        lp[i]+=4;
+                    }
+                    lres+=4;
+                    j += sizeof(unsigned long)*4;
+                    minlen -= sizeof(unsigned long)*4;
+                }
+            } else if (op == BITOP_NOT) {
+                while(minlen >= sizeof(unsigned long)*4) {
+                    lres[0] = ~lres[0];
+                    lres[1] = ~lres[1];
+                    lres[2] = ~lres[2];
+                    lres[3] = ~lres[3];
+                    lres+=4;
+                    j += sizeof(unsigned long)*4;
+                    minlen -= sizeof(unsigned long)*4;
+                }
+            }
+        }
+
+        /* j is set to the next byte to process by the previous loop. */
+        for (; j < maxlen; j++) {
             output = (len[0] <= j) ? 0 : src[0][j];
             if (op == BITOP_NOT) output = ~output;
             for (i = 1; i < numkeys; i++) {