Address code review comments

src/backend/distributed/connection/connection_configuration.c

@@ -85,21 +85,10 @@ ResetConnParams()
 		ConnParams.keywords[paramIdx] = ConnParams.values[paramIdx] = NULL;
 	}
 
-	if (ConnParamsHash != NULL)
-	{
-		ConnParamsHashEntry *entry = NULL;
-		HASH_SEQ_STATUS status;
-
-		hash_seq_init(&status, ConnParamsHash);
-		while ((entry = (ConnParamsHashEntry *) hash_seq_search(&status)) != NULL)
-		{
-			entry->isValid = false;
-		}
-	}
-
-
 	ConnParams.size = 0;
 
+	InvalidateConnParamsHashEntries();
+
 	AddConnParam("fallback_application_name", "citus");
 }
 
@@ -238,7 +227,7 @@ CheckConninfo(const char *conninfo, const char **whitelist,
  */
 void
 GetConnParams(ConnectionHashKey *key, char ***keywords, char ***values,
-			  Index *nonGlobalParamStart, MemoryContext context)
+			  Index *runtimeParamStart, MemoryContext context)
 {
 	/* make space for the port as a string: sign, 10 digits, NUL */
 	char *nodePortString = MemoryContextAlloc(context, 12 * sizeof(char *));
@@ -304,6 +293,9 @@ GetConnParams(ConnectionHashKey *key, char ***keywords, char ***values,
 		connValues[paramIndex] = ConnParams.values[paramIndex];
 	}
 
+	/* remember where global/GUC params end and runtime ones start */
+	*runtimeParamStart = ConnParams.size;
+
 	/* second step: begin at end of global params and copy runtime ones */
 	for (runtimeParamIndex = 0;
 		 runtimeParamIndex < lengthof(runtimeKeywords);
@@ -321,7 +313,6 @@ GetConnParams(ConnectionHashKey *key, char ***keywords, char ***values,
 
 	*keywords = connKeywords;
 	*values = connValues;
-	*nonGlobalParamStart = ConnParams.size;
 }
 
 

src/backend/distributed/connection/connection_management.c

@@ -42,6 +42,7 @@ MemoryContext ConnectionContext = NULL;
 static uint32 ConnectionHashHash(const void *key, Size keysize);
 static int ConnectionHashCompare(const void *a, const void *b, Size keysize);
 static MultiConnection * StartConnectionEstablishment(ConnectionHashKey *key);
+static void FreeConnParamsHashEntryFields(ConnParamsHashEntry *entry);
 static void AfterXactHostConnectionHandling(ConnectionHashEntry *entry, bool isCommit);
 static void DefaultCitusNoticeProcessor(void *arg, const char *message);
 static MultiConnection * FindAvailableConnection(dlist_head *connections, uint32 flags);
@@ -91,6 +92,26 @@ InitializeConnectionManagement(void)
 }
 
 
+/*
+ * InvalidateConnParamsHashEntries sets every hash entry's isValid flag to false.
+ */
+void
+InvalidateConnParamsHashEntries(void)
+{
+	if (ConnParamsHash != NULL)
+	{
+		ConnParamsHashEntry *entry = NULL;
+		HASH_SEQ_STATUS status;
+
+		hash_seq_init(&status, ConnParamsHash);
+		while ((entry = (ConnParamsHashEntry *) hash_seq_search(&status)) != NULL)
+		{
+			entry->isValid = false;
+		}
+	}
+}
+
+
 /*
  * Perform connection management activity after the end of a transaction. Both
  * COMMIT and ABORT paths are handled here.
@@ -694,29 +715,14 @@ StartConnectionEstablishment(ConnectionHashKey *key)
 	entry = hash_search(ConnParamsHash, key, HASH_ENTER, &found);
 	if (!found || !entry->isValid)
 	{
+		/* avoid leaking memory in the keys and values arrays */
 		if (found && !entry->isValid)
 		{
-			char **keyword = &entry->keywords[entry->nonGlobalParamStart];
+			FreeConnParamsHashEntryFields(entry);
-			char **value = &entry->values[entry->nonGlobalParamStart];
-
-			while (*keyword != NULL)
-			{
-				pfree(*keyword);
-				keyword++;
-			}
-
-			while (*value != NULL)
-			{
-				pfree(*value);
-				value++;
-			}
-
-			pfree(entry->keywords);
-			pfree(entry->values);
 		}
 
 		/* if not found or not valid, compute them from GUC, runtime, etc. */
-		GetConnParams(key, &entry->keywords, &entry->values, &entry->nonGlobalParamStart,
+		GetConnParams(key, &entry->keywords, &entry->values, &entry->runtimeParamStart,
 					  ConnectionContext);
 
 		entry->isValid = true;
@@ -748,6 +754,34 @@ StartConnectionEstablishment(ConnectionHashKey *key)
 }
 
 
+/*
+ * FreeConnParamsHashEntryFields frees any dynamically allocated memory reachable
+ * from the fields of the provided ConnParamsHashEntry. This includes all runtime
+ * libpq keywords and values, as well as the actual arrays storing them.
+ */
+static void
+FreeConnParamsHashEntryFields(ConnParamsHashEntry *entry)
+{
+	char **keyword = &entry->keywords[entry->runtimeParamStart];
+	char **value = &entry->values[entry->runtimeParamStart];
+
+	while (*keyword != NULL)
+	{
+		pfree(*keyword);
+		keyword++;
+	}
+
+	while (*value != NULL)
+	{
+		pfree(*value);
+		value++;
+	}
+
+	pfree(entry->keywords);
+	pfree(entry->values);
+}
+
+
 /*
  * Close all remote connections if necessary anymore (i.e. not session
  * lifetime), or if in a failed state.

src/backend/distributed/utils/metadata_cache.c

@@ -3178,15 +3178,7 @@ CreateDistTableCache(void)
 void
 InvalidateMetadataSystemCache(void)
 {
-	ConnParamsHashEntry *entry = NULL;
+	InvalidateConnParamsHashEntries();
-	HASH_SEQ_STATUS status;
-
-	hash_seq_init(&status, ConnParamsHash);
-
-	while ((entry = (ConnParamsHashEntry *) hash_seq_search(&status)) != NULL)
-	{
-		entry->isValid = false;
-	}
 
 	memset(&MetadataCache, 0, sizeof(MetadataCache));
 	workerNodeHashValid = false;

src/backend/distributed/worker/task_tracker.c

@@ -861,15 +861,7 @@ ManageWorkerTasksHash(HTAB *WorkerTasksHash)
 
 	if (!WorkerTasksSharedState->conninfosValid)
 	{
-		ConnParamsHashEntry *entry = NULL;
+		InvalidateConnParamsHashEntries();
-		HASH_SEQ_STATUS status;
-
-		hash_seq_init(&status, ConnParamsHash);
-
-		while ((entry = (ConnParamsHashEntry *) hash_seq_search(&status)) != NULL)
-		{
-			entry->isValid = false;
-		}
 	}
 
 	/* schedule new tasks if we have any */

src/include/distributed/connection_management.h

@@ -118,7 +118,7 @@ typedef struct ConnParamsHashEntry
 {
 	ConnectionHashKey key;
 	bool isValid;
-	Index nonGlobalParamStart;
+	Index runtimeParamStart;
 	char **keywords;
 	char **values;
 } ConnParamsHashEntry;
@@ -143,9 +143,10 @@ extern void InitializeConnectionManagement(void);
 
 extern void InitConnParams(void);
 extern void ResetConnParams(void);
+extern void InvalidateConnParamsHashEntries(void);
 extern void AddConnParam(const char *keyword, const char *value);
 extern void GetConnParams(ConnectionHashKey *key, char ***keywords, char ***values,
-						  Index *nonGlobalParamStart, MemoryContext context);
+						  Index *runtimeParamStart, MemoryContext context);
 extern const char * GetConnParam(const char *keyword);
 extern bool CheckConninfo(const char *conninfo, const char **whitelist,
 						  Size whitelistLength, char **errmsg);

src/test/regress/expected/multi_size_queries.out

@@ -125,5 +125,46 @@ ALTER TABLE supplier ALTER COLUMN s_suppkey SET NOT NULL;
 select citus_table_size('supplier');
 ERROR:  citus size functions cannot be called in transaction blocks which contain multi-shard data modifications
 END;
+show citus.node_conninfo;
+ citus.node_conninfo 
+---------------------
+ sslmode=require
+(1 row)
+
+ALTER SYSTEM SET citus.node_conninfo = 'sslmode=require';
+SELECT pg_reload_conf();
+ pg_reload_conf 
+----------------
+ t
+(1 row)
+
+-- make sure that any invalidation to the connection info
+-- wouldn't prevent future commands to fail
+SELECT citus_total_relation_size('customer_copy_hash');
+ citus_total_relation_size 
+---------------------------
+                   2646016
+(1 row)
+
+SELECT pg_reload_conf();
+ pg_reload_conf 
+----------------
+ t
+(1 row)
+
+SELECT citus_total_relation_size('customer_copy_hash');
+ citus_total_relation_size 
+---------------------------
+                   2646016
+(1 row)
+
+-- reset back to the original node_conninfo
+ALTER SYSTEM RESET citus.node_conninfo;
+SELECT pg_reload_conf();
+ pg_reload_conf 
+----------------
+ t
+(1 row)
+
 DROP INDEX index_1;
 DROP INDEX index_2;

src/test/regress/sql/multi_size_queries.sql

@@ -65,5 +65,19 @@ ALTER TABLE supplier ALTER COLUMN s_suppkey SET NOT NULL;
 select citus_table_size('supplier');
 END;
 
+show citus.node_conninfo;
+ALTER SYSTEM SET citus.node_conninfo = 'sslmode=require';
+SELECT pg_reload_conf();
+
+-- make sure that any invalidation to the connection info
+-- wouldn't prevent future commands to fail
+SELECT citus_total_relation_size('customer_copy_hash');
+SELECT pg_reload_conf();
+SELECT citus_total_relation_size('customer_copy_hash');
+
+-- reset back to the original node_conninfo
+ALTER SYSTEM RESET citus.node_conninfo;
+SELECT pg_reload_conf();
+
 DROP INDEX index_1;
 DROP INDEX index_2;