From badf0f008bede268d3235412243fc62d618e323c Mon Sep 17 00:00:00 2001
From: Matt Stancliff <matt@genges.com>
Date: Thu, 7 Aug 2014 09:43:16 -0400
Subject: Bitops: Stop overallocating storage space on set

Previously the string was created empty then re-sized
to fit the offset, but sds resize causes the sds to
over-allocate by at least 1 MB (which is a lot when
you are operating at bit-level access).

This also improves the speed of initial sets by 2% to 6%
based on quick testing.

Patch logic provided by @oranagra

Fixes #1918
---
 src/bitops.c   | 8 +++-----
 src/t_string.c | 2 +-
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/src/bitops.c b/src/bitops.c
index 4c8662244..ec912bc24 100644
--- a/src/bitops.c
+++ b/src/bitops.c
@@ -229,19 +229,17 @@ void setbitCommand(redisClient *c) {
         return;
     }
 
+    byte = bitoffset >> 3;
     o = lookupKeyWrite(c->db,c->argv[1]);
     if (o == NULL) {
-        o = createObject(REDIS_STRING,sdsempty());
+        o = createObject(REDIS_STRING,sdsnewlen(NULL, byte+1));
         dbAdd(c->db,c->argv[1],o);
     } else {
         if (checkType(c,o,REDIS_STRING)) return;
         o = dbUnshareStringValue(c->db,c->argv[1],o);
+        o->ptr = sdsgrowzero(o->ptr,byte+1);
     }
 
-    /* Grow sds value to the right length if necessary */
-    byte = bitoffset >> 3;
-    o->ptr = sdsgrowzero(o->ptr,byte+1);
-
     /* Get current values */
     byteval = ((uint8_t*)o->ptr)[byte];
     bit = 7 - (bitoffset & 0x7);
diff --git a/src/t_string.c b/src/t_string.c
index e3c1e5f4a..b61589961 100644
--- a/src/t_string.c
+++ b/src/t_string.c
@@ -194,7 +194,7 @@ void setrangeCommand(redisClient *c) {
         if (checkStringLength(c,offset+sdslen(value)) != REDIS_OK)
             return;
 
-        o = createObject(REDIS_STRING,sdsempty());
+        o = createObject(REDIS_STRING,sdsnewlen(NULL, offset+sdslen(value)));
         dbAdd(c->db,c->argv[1],o);
     } else {
         size_t olen;
-- 
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