Stack allocate dict iterators

Replacing the get & release functions with an initiation
function. Simplifies the code and will make sure we
run subscription callbacks in OOM scenarios.

async.c

@@ -306,7 +306,7 @@ static void __redisRunPushCallback(redisAsyncContext *ac, redisReply *reply) {
 static void __redisAsyncFree(redisAsyncContext *ac) {
     redisContext *c = &(ac->c);
     redisCallback cb;
-    dictIterator *it;
+    dictIterator it;
     dictEntry *de;
 
     /* Execute pending callbacks with NULL reply. */
@@ -319,23 +319,17 @@ static void __redisAsyncFree(redisAsyncContext *ac) {
 
     /* Run subscription callbacks with NULL reply */
     if (ac->sub.channels) {
-        it = dictGetIterator(ac->sub.channels);
-        if (it != NULL) {
-            while ((de = dictNext(it)) != NULL)
-                __redisRunCallback(ac,dictGetEntryVal(de),NULL);
-            dictReleaseIterator(it);
-        }
+        dictInitIterator(&it,ac->sub.channels);
+        while ((de = dictNext(&it)) != NULL)
+            __redisRunCallback(ac,dictGetEntryVal(de),NULL);
 
         dictRelease(ac->sub.channels);
     }
 
     if (ac->sub.patterns) {
-        it = dictGetIterator(ac->sub.patterns);
-        if (it != NULL) {
-            while ((de = dictNext(it)) != NULL)
-                __redisRunCallback(ac,dictGetEntryVal(de),NULL);
-            dictReleaseIterator(it);
-        }
+        dictInitIterator(&it,ac->sub.patterns);
+        while ((de = dictNext(&it)) != NULL)
+            __redisRunCallback(ac,dictGetEntryVal(de),NULL);
 
         dictRelease(ac->sub.patterns);
     }

dict.c

@@ -267,16 +267,11 @@ static dictEntry *dictFind(dict *ht, const void *key) {
     return NULL;
 }
 
-static dictIterator *dictGetIterator(dict *ht) {
-    dictIterator *iter = hi_malloc(sizeof(*iter));
-    if (iter == NULL)
-        return NULL;
-
+static void dictInitIterator(dictIterator *iter, dict *ht) {
     iter->ht = ht;
     iter->index = -1;
     iter->entry = NULL;
     iter->nextEntry = NULL;
-    return iter;
 }
 
 static dictEntry *dictNext(dictIterator *iter) {
@@ -299,10 +294,6 @@ static dictEntry *dictNext(dictIterator *iter) {
     return NULL;
 }
 
-static void dictReleaseIterator(dictIterator *iter) {
-    hi_free(iter);
-}
-
 /* ------------------------- private functions ------------------------------ */
 
 /* Expand the hash table if needed */

dict.h

@@ -119,8 +119,7 @@ static int dictReplace(dict *ht, void *key, void *val);
 static int dictDelete(dict *ht, const void *key);
 static void dictRelease(dict *ht);
 static dictEntry * dictFind(dict *ht, const void *key);
-static dictIterator *dictGetIterator(dict *ht);
+static void dictInitIterator(dictIterator *iter, dict *ht);
 static dictEntry *dictNext(dictIterator *iter);
-static void dictReleaseIterator(dictIterator *iter);
 
 #endif /* __DICT_H */