From 92c5ab40295260352f0da09616ff15b499251bad Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Tue, 2 Dec 2014 18:19:30 +0100
Subject: Use exp format and more precision output for ZSCAN.

Ref: issue #2175
---
 src/db.c       |  2 +-
 src/object.c   | 28 +++++++++++++++++-----------
 src/redis.h    |  2 +-
 src/t_hash.c   |  2 +-
 src/t_string.c |  2 +-
 5 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/src/db.c b/src/db.c
index d5a381daf..2982c0166 100644
--- a/src/db.c
+++ b/src/db.c
@@ -381,7 +381,7 @@ void scanCallback(void *privdata, const dictEntry *de) {
     } else if (o->type == REDIS_ZSET) {
         key = dictGetKey(de);
         incrRefCount(key);
-        val = createStringObjectFromLongDouble(*(double*)dictGetVal(de));
+        val = createStringObjectFromLongDouble(*(double*)dictGetVal(de),0);
     } else {
         redisPanic("Type not handled in SCAN callback.");
     }
diff --git a/src/object.c b/src/object.c
index 6b8e42477..2b2d463f6 100644
--- a/src/object.c
+++ b/src/object.c
@@ -109,9 +109,11 @@ robj *createStringObjectFromLongLong(long long value) {
     return o;
 }
 
-/* Note: this function is defined into object.c since here it is where it
- * belongs but it is actually designed to be used just for INCRBYFLOAT */
-robj *createStringObjectFromLongDouble(long double value) {
+/* Create a string object from a long double. If humanfriendly is non-zero
+ * it does not use exponential format and trims trailing zeroes at the end,
+ * however this result in loss of precision. Otherwise exp format is used
+ * and the output of snprintf() is not modified. */
+robj *createStringObjectFromLongDouble(long double value, int humanfriendly) {
     char buf[256];
     int len;
 
@@ -120,15 +122,19 @@ robj *createStringObjectFromLongDouble(long double value) {
      * that is "non surprising" for the user (that is, most small decimal
      * numbers will be represented in a way that when converted back into
      * a string are exactly the same as what the user typed.) */
-    len = snprintf(buf,sizeof(buf),"%.17Lf", value);
-    /* Now remove trailing zeroes after the '.' */
-    if (strchr(buf,'.') != NULL) {
-        char *p = buf+len-1;
-        while(*p == '0') {
-            p--;
-            len--;
+    if (humanfriendly) {
+        len = snprintf(buf,sizeof(buf),"%.17Lf", value);
+        /* Now remove trailing zeroes after the '.' */
+        if (strchr(buf,'.') != NULL) {
+            char *p = buf+len-1;
+            while(*p == '0') {
+                p--;
+                len--;
+            }
+            if (*p == '.') len--;
         }
-        if (*p == '.') len--;
+    } else {
+        len = snprintf(buf,sizeof(buf),"%.17Lg", value);
     }
     return createStringObject(buf,len);
 }
diff --git a/src/redis.h b/src/redis.h
index 855ae5742..5b1b33a84 100644
--- a/src/redis.h
+++ b/src/redis.h
@@ -1116,7 +1116,7 @@ robj *tryObjectEncoding(robj *o);
 robj *getDecodedObject(robj *o);
 size_t stringObjectLen(robj *o);
 robj *createStringObjectFromLongLong(long long value);
-robj *createStringObjectFromLongDouble(long double value);
+robj *createStringObjectFromLongDouble(long double value, int humanfriendly);
 robj *createListObject(void);
 robj *createZiplistObject(void);
 robj *createSetObject(void);
diff --git a/src/t_hash.c b/src/t_hash.c
index f5ceb36e9..7f33bba0c 100644
--- a/src/t_hash.c
+++ b/src/t_hash.c
@@ -565,7 +565,7 @@ void hincrbyfloatCommand(redisClient *c) {
     }
 
     value += incr;
-    new = createStringObjectFromLongDouble(value);
+    new = createStringObjectFromLongDouble(value,1);
     hashTypeTryObjectEncoding(o,&c->argv[2],NULL);
     hashTypeSet(o,c->argv[2],new);
     addReplyBulk(c,new);
diff --git a/src/t_string.c b/src/t_string.c
index 74c05793c..e3c1e5f4a 100644
--- a/src/t_string.c
+++ b/src/t_string.c
@@ -397,7 +397,7 @@ void incrbyfloatCommand(redisClient *c) {
         addReplyError(c,"increment would produce NaN or Infinity");
         return;
     }
-    new = createStringObjectFromLongDouble(value);
+    new = createStringObjectFromLongDouble(value,1);
     if (o)
         dbOverwrite(c->db,c->argv[1],new);
     else
-- 
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