use compare function in the hash table;

add comments;

Author: nadbp

src/kv_fdw.h

@@ -34,7 +34,14 @@
 #define DATAAREASIZE sizeof(char)*BUFSIZE
 
 
-/* Shared memory for function requests */
+/* Shared memory for function requests: 
+ * mutex is used for the mutual exclusion of the request buffer;
+ * full is used to tell whether the request buffer is full;
+ * agent[2] are used to synchronize the creation of the worker process;
+ * worker is used to notify the worker process after a request is submitted;
+ * responseMutexes[RESPONSEQUEUELENGTH] are used for the mutual exclusion of the response buffer;
+ * responseSync[RESPONSEQUEUELENGTH] are used to notify child processes after the response is ready.
+ */
 typedef struct SharedMem {
     sem_t mutex;
     sem_t full;

src/kv_shm.c

@@ -168,9 +168,9 @@ void OpenResponseArea() {
 /*
  * Compare function for KVIterHash
  */
-/* int CompareKVIterHashKey(const void *key1, const void *key2, Size keysize) {
-    KVIterHashKey *k1 = (const KVIterHashKey *)key1;
-    KVIterHashKey *k2 = (const KVIterHashKey *)key2;
+int CompareKVIterHashKey(const void *key1, const void *key2, Size keysize) {
+    const KVIterHashKey *k1 = (const KVIterHashKey *)key1;
+    const KVIterHashKey *k2 = (const KVIterHashKey *)key2;
 
     if(k1 == NULL || k2 == NULL) {
         return -1;
@@ -181,7 +181,7 @@ void OpenResponseArea() {
     }
 
     return -1;
-}*/
+}
 
 void *KVStorageThreadFun(void *arg) {
     PthreadSetCancelState(PTHREAD_CANCEL_ENABLE, NULL, __func__);
@@ -259,13 +259,13 @@ static void KVWorkerMain(int argc, char *argv[]) {
     memset(&iterhash_ctl, 0, sizeof(iterhash_ctl));
     iterhash_ctl.keysize = sizeof(KVIterHashKey);
     iterhash_ctl.entrysize = sizeof(KVIterHashEntry);
-    //iterhash_ctl.match = CompareKVIterHashKey;
+    iterhash_ctl.match = CompareKVIterHashKey;
     kvIterHash = hash_create("kvIterHash",
                              HASHSIZE,
                              &iterhash_ctl,
-                             HASH_ELEM | HASH_BLOBS);
+                             HASH_ELEM | HASH_COMPARE);
 
-    char buff[DATAAREASIZE];
+    char buff[BUFSIZE];
     do {
         SemWait(&ptr->worker, __func__);