Fix HINCRBYFLOAT to work with long doubles.

During the refactoring needed for lazy free, specifically the conversion
of t_hash from struct robj to plain SDS strings, HINCRBFLOAT was
accidentally moved away from long doubles to doubles for internal
processing of increments and formatting.

The diminished precision created more obvious artifacts in the way small
numbers are formatted once we convert from decimal number in radix 10 to
double and back to its string in radix 10.

By using more precision, we now have less surprising results at least
with small numbers like "1.23", exactly like in the previous versions of
Redis.

See issue #2846.

3 files changed, 8 insertions, 8 deletions

diff --git a/src/t_hash.c b/src/t_hash.c
index 7da8fb171..c75b391d7 100644
--- a/src/t_hash.c
+++ b/src/t_hash.c
@@ -596,23 +596,23 @@ void hincrbyCommand(client *c) {
 }
 
 void hincrbyfloatCommand(client *c) {
-    double value, incr;
+    long double value, incr;
     long long ll;
     robj *o;
     sds new;
     unsigned char *vstr;
     unsigned int vlen;
 
-    if (getDoubleFromObjectOrReply(c,c->argv[3],&incr,NULL) != C_OK) return;
+    if (getLongDoubleFromObjectOrReply(c,c->argv[3],&incr,NULL) != C_OK) return;
     if ((o = hashTypeLookupWriteOrCreate(c,c->argv[1])) == NULL) return;
     if (hashTypeGetValue(o,c->argv[2]->ptr,&vstr,&vlen,&ll) == C_OK) {
         if (vstr) {
-            if (string2d((char*)vstr,vlen,&value) == 0) {
+            if (string2ld((char*)vstr,vlen,&value) == 0) {
                 addReplyError(c,"hash value is not a float");
                 return;
             }
         } else {
-            value = (double)ll;
+            value = (long double)ll;
         }
     } else {
         value = 0;
diff --git a/src/util.c b/src/util.c
index c734b1b6d..c1494e021 100644
--- a/src/util.c
+++ b/src/util.c
@@ -426,9 +426,9 @@ int string2l(const char *s, size_t slen, long *lval) {
  * Note that this function demands that the string strictly represents
  * a double: no spaces or other characters before or after the string
  * representing the number are accepted. */
-int string2d(const char *s, size_t slen, double *dp) {
+int string2ld(const char *s, size_t slen, long double *dp) {
     char buf[256];
-    double value;
+    long double value;
     char *eptr;
 
     if (slen >= sizeof(buf)) return 0;
@@ -436,7 +436,7 @@ int string2d(const char *s, size_t slen, double *dp) {
     buf[slen] = '\0';
 
     errno = 0;
-    value = strtod(buf, &eptr);
+    value = strtold(buf, &eptr);
     if (isspace(buf[0]) || eptr[0] != '\0' ||
         (errno == ERANGE &&
             (value == HUGE_VAL || value == -HUGE_VAL || value == 0)) ||
diff --git a/src/util.h b/src/util.h
index d28049eaf..d7784495b 100644
--- a/src/util.h
+++ b/src/util.h
@@ -41,7 +41,7 @@ uint32_t sdigits10(int64_t v);
 int ll2string(char *s, size_t len, long long value);
 int string2ll(const char *s, size_t slen, long long *value);
 int string2l(const char *s, size_t slen, long *value);
-int string2d(const char *s, size_t slen, double *dp);
+int string2ld(const char *s, size_t slen, long double *dp);
 int d2string(char *buf, size_t len, double value);
 int ld2string(char *buf, size_t len, long double value, int humanfriendly);
 sds getAbsolutePath(char *filename);