Update hash table increment functions

Free the duplicated key in inc_su64() on failure.

Use the same pattern as in inc_su64() for inc_si32(), by duplicating the
key after an empty lookup result. This simplifies the call sites
ht_inc_cnt_overall() and ht_ins_seq() by avoiding a duplicate lookup.

src/gkhash.c

@@ -1040,8 +1040,10 @@ inc_su64 (khash_t (su64) *hash, const char *key, uint64_t inc) {
  dupkey = xstrdup (key);
  k = kh_put (su64, hash, dupkey, &ret);
  /* operation failed */
- if (ret == -1)
+ if (ret == -1) {
+ free(dupkey);
  return -1;
+ }
  } else {
  value = kh_val (hash, k) + inc;
  }
@@ -1087,17 +1089,24 @@ static uint32_t
 inc_si32 (khash_t (si32) *hash, const char *key, uint32_t inc) {
  khint_t k;
  int ret;
+ char *dupkey = NULL;
 
  if (!hash)
  return 0;
 
  k = kh_get (si32, hash, key);
  /* key not found, put a new hash with val=0 */
  if (k == kh_end (hash)) {
- k = kh_put (si32, hash, key, &ret);
+ dupkey = xstrdup(key);
+ k = kh_put (si32, hash, dupkey, &ret);
  /* operation failed */
- if (ret == -1)
+ if (ret == -1) {
+ free(dupkey);
  return 0;
+ }
+ /* concurrently added */
+ if (ret == 0)
+ free(dupkey);
  kh_val (hash, k) = 0;
  }
 
@@ -1484,9 +1493,7 @@ ht_inc_cnt_overall (const char *key, uint32_t val) {
  if (!hash)
  return 0;
 
- if (get_si32 (hash, key) != 0)
- return inc_si32 (hash, key, val);
- return inc_si32 (hash, xstrdup (key), val);
+ return inc_si32 (hash, key, val);
 }
 
 int
@@ -1509,9 +1516,7 @@ ht_ins_seq (khash_t (si32) *hash, const char *key) {
  if (!hash)
  return 0;
 
- if (get_si32 (hash, key) != 0)
- return inc_si32 (hash, key, 1);
- return inc_si32 (hash, xstrdup (key), 1);
+ return inc_si32 (hash, key, 1);
 }
 
 /* Insert an IP hostname mapped to the corresponding hostname.