Convert file-specific extern functions, variables and macros to static scope.

Previously, there were several functions, variables and macros declared
as extern in postgres_fdw_plus.h that were only used in connection.c or
postgres_fdw_plus.c. To enhance clarity and encapsulation,
this commit converts these functions, variables and macros to static scope
within their respective files. As a result, the extern declarations for
them are removed from postgres_fdw_plus.h,
further clarifying their limited visibility and usage.

Author: @MasaoFujii 
Reviewed-by: @YKatsuragi 
Discussion: #11

Author: MasaoFujii

connection.c

@@ -138,18 +138,22 @@ static void pgfdw_inval_callback(Datum arg, int cacheid, uint32 hashvalue);
 static void pgfdw_reject_incomplete_xact_state_change(ConnCacheEntry *entry);
 static void pgfdw_reset_xact_state(ConnCacheEntry *entry, bool toplevel);
 static bool pgfdw_cancel_query(PGconn *conn);
+#endif	/* NOT_USED_IN_PGFDWPLUS */
 static bool pgfdw_cancel_query_begin(PGconn *conn);
 static bool pgfdw_cancel_query_end(PGconn *conn, TimestampTz endtime,
 								   bool consume_input);
+#ifdef NOT_USED_IN_PGFDWPLUS
 static bool pgfdw_exec_cleanup_query(PGconn *conn, const char *query,
 									 bool ignore_errors);
 static bool pgfdw_exec_cleanup_query_begin(PGconn *conn, const char *query);
 static bool pgfdw_exec_cleanup_query_end(PGconn *conn, const char *query,
 										 TimestampTz endtime,
 										 bool consume_input,
 										 bool ignore_errors);
+#endif	/* NOT_USED_IN_PGFDWPLUS */
 static bool pgfdw_get_cleanup_result(PGconn *conn, TimestampTz endtime,
 									 PGresult **result, bool *timed_out);
+#ifdef NOT_USED_IN_PGFDWPLUS
 static void pgfdw_abort_cleanup(ConnCacheEntry *entry, bool toplevel);
 static bool pgfdw_abort_cleanup_begin(ConnCacheEntry *entry, bool toplevel,
 									  List **pending_entries,
@@ -1403,10 +1407,7 @@ pgfdw_cancel_query(PGconn *conn)
 	return pgfdw_cancel_query_end(conn, endtime, false);
 }
 
-#ifdef NOT_USED_IN_PGFDWPLUS
 static bool
-#endif	/* NOT_USED_IN_PGFDWPLUS */
-bool
 pgfdw_cancel_query_begin(PGconn *conn)
 {
 	PGcancel   *cancel;
@@ -1433,10 +1434,7 @@ pgfdw_cancel_query_begin(PGconn *conn)
 	return true;
 }
 
-#ifdef NOT_USED_IN_PGFDWPLUS
 static bool
-#endif	/* NOT_USED_IN_PGFDWPLUS */
-bool
 pgfdw_cancel_query_end(PGconn *conn, TimestampTz endtime, bool consume_input)
 {
 	PGresult   *result = NULL;

postgres_fdw_plus.c

@@ -12,15 +12,14 @@
 /*
  * GUC parameters
  */
-bool		pgfdw_two_phase_commit = false;
-bool		pgfdw_skip_commit_phase = false;
-bool		pgfdw_track_xact_commits = true;
-bool		pgfdw_use_read_committed = false;
+static bool		pgfdw_two_phase_commit = false;
+static bool		pgfdw_skip_commit_phase = false;
+static bool		pgfdw_track_xact_commits = true;
+static bool		pgfdw_use_read_committed = false;
 
 /*
  * Global variables
  */
-
 /*
  * This flag indicates whether the current local transaction uses
  * the read committed isolation level when starting remote transactions.
@@ -38,12 +37,38 @@ bool		pgfdw_use_read_committed_in_xact = false;
  * accesses to remote servers, which is not allowed when the read committed
  * isolation level is used for remote transactions.
  */
-CommandId	pgfdw_last_cid = InvalidCommandId;
+static CommandId	pgfdw_last_cid = InvalidCommandId;
+
+/*
+ * Private macros
+ */
+/*
+ * Construct the prepared transaction command like PREPARE TRANSACTION
+ * that's issued to the foreign server. It consists of full transaction ID,
+ * user mapping OID, process ID and cluster name.
+ */
+#define PreparedXactCommand(sql, cmd, entry)	\
+	snprintf(sql, sizeof(sql), "%s 'pgfdw_" UINT64_FORMAT "_%u_%d_%s'",	\
+			 cmd, U64FromFullTransactionId(entry->fxid),	\
+			 (Oid) entry->key, MyProcPid,	\
+			 (*cluster_name == '\0') ? "null" : cluster_name)
 
 /*
  * Private functions
  */
+static void pgfdw_abort_cleanup_with_sql(ConnCacheEntry *entry,
+										 const char *sql, bool toplevel);
+static void pgfdw_prepare_xacts(ConnCacheEntry *entry,
+								List **pending_entries_prepare);
+static void pgfdw_finish_prepare_cleanup(List **pending_entries_prepare);
 static void pgfdw_cleanup_pending_entries(List **pending_entries_prepare);
+static void pgfdw_commit_prepared(ConnCacheEntry *entry,
+								  List **pending_entries_commit_prepared);
+static void pgfdw_finish_commit_prepared_cleanup(
+	List *pending_entries_commit_prepared);
+static bool pgfdw_rollback_prepared(ConnCacheEntry *entry);
+static void pgfdw_deallocate_all(ConnCacheEntry *entry);
+static void pgfdw_insert_xact_commits(List *umids);
 
 /*
  * Define GUC parameters for postgres_fdw_plus.
@@ -110,7 +135,7 @@ pgfdw_abort_cleanup(ConnCacheEntry *entry, bool toplevel)
 	pgfdw_abort_cleanup_with_sql(entry, sql, toplevel);
 }
 
-void
+static void
 pgfdw_abort_cleanup_with_sql(ConnCacheEntry *entry, const char *sql,
 							 bool toplevel)
 {
@@ -351,7 +376,7 @@ pgfdw_xact_two_phase(XactEvent event)
 	return true;
 }
 
-void
+static void
 pgfdw_prepare_xacts(ConnCacheEntry *entry, List **pending_entries_prepare)
 {
 	char		sql[256];
@@ -373,7 +398,7 @@ pgfdw_prepare_xacts(ConnCacheEntry *entry, List **pending_entries_prepare)
 	entry->changing_xact_state = false;
 }
 
-void
+static void
 pgfdw_finish_prepare_cleanup(List **pending_entries_prepare)
 {
 	ConnCacheEntry *entry;
@@ -433,7 +458,7 @@ pgfdw_cleanup_pending_entries(List **pending_entries_prepare)
 	*pending_entries_prepare = NIL;
 }
 
-void
+static void
 pgfdw_commit_prepared(ConnCacheEntry *entry,
 					  List **pending_entries_commit_prepared)
 {
@@ -470,7 +495,7 @@ pgfdw_commit_prepared(ConnCacheEntry *entry,
 		pgfdw_deallocate_all(entry);
 }
 
-void
+static void
 pgfdw_finish_commit_prepared_cleanup(List *pending_entries_commit_prepared)
 {
 	ConnCacheEntry *entry;
@@ -509,7 +534,7 @@ pgfdw_finish_commit_prepared_cleanup(List *pending_entries_commit_prepared)
 	}
 }
 
-bool
+static bool
 pgfdw_rollback_prepared(ConnCacheEntry *entry)
 {
 	char		sql[256];
@@ -534,7 +559,7 @@ pgfdw_rollback_prepared(ConnCacheEntry *entry)
  * Do a DEALLOCATE ALL to make sure we get rid of all prepared statements.
  * See comments in pgfdw_xact_callback().
  */
-void
+static void
 pgfdw_deallocate_all(ConnCacheEntry *entry)
 {
 	if (entry->have_prep_stmt && entry->have_error)
@@ -564,7 +589,7 @@ pgfdw_deallocate_all(ConnCacheEntry *entry)
  * If the transaction is rollbacked, the record inserted by this function
  * obviously gets unvisiable.
  */
-void
+static void
 pgfdw_insert_xact_commits(List *umids)
 {
 	Datum		values[PGFDW_PLUS_XACT_COMMITS_COLS];

postgres_fdw_plus.h

@@ -3,23 +3,12 @@
 
 #include "access/xact.h"
 #include "miscadmin.h"
-#include "nodes/pg_list.h"
 #include "postgres_fdw/postgres_fdw.h"
-#include "utils/guc.h"
-
-/*
- * GUC parameters
- */
-extern bool pgfdw_two_phase_commit;
-extern bool pgfdw_skip_commit_phase;
-extern bool pgfdw_track_xact_commits;
-extern bool pgfdw_use_read_committed;
 
 /*
  * Global variables
  */
 extern bool pgfdw_use_read_committed_in_xact;
-extern CommandId pgfdw_last_cid;
 
 /*
  * Connection cache hash table entry
@@ -84,61 +73,31 @@ extern HTAB *ConnectionHash;
 					 (entry)->xact_depth, (entry)->xact_depth); \
 	} while(0)
 
-/* option.c */
-extern void DefineCustomVariablesForPgFdwPlus(void);
-
 /* connection.c */
 extern void do_sql_command_begin(PGconn *conn, const char *sql);
 extern void do_sql_command_end(PGconn *conn, const char *sql,
 							   bool consume_input);
-
 extern void pgfdw_reject_incomplete_xact_state_change(ConnCacheEntry *entry);
 extern void pgfdw_reset_xact_state(ConnCacheEntry *entry, bool toplevel);
 extern bool pgfdw_cancel_query(PGconn *conn);
-extern bool pgfdw_cancel_query_begin(PGconn *conn);
-extern bool pgfdw_cancel_query_end(PGconn *conn, TimestampTz endtime,
-								   bool consume_input);
 extern bool pgfdw_exec_cleanup_query(PGconn *conn, const char *query,
 									 bool ignore_errors);
 extern bool pgfdw_exec_cleanup_query_begin(PGconn *conn, const char *query);
 extern bool pgfdw_exec_cleanup_query_end(PGconn *conn, const char *query,
 										 TimestampTz endtime,
 										 bool consume_input,
 										 bool ignore_errors);
-extern bool pgfdw_get_cleanup_result(PGconn *conn, TimestampTz endtime,
-									 PGresult **result, bool *timed_out);
-extern void pgfdw_abort_cleanup(ConnCacheEntry *entry, bool toplevel);
-extern void pgfdw_abort_cleanup_with_sql(ConnCacheEntry *entry,
-										 const char *sql, bool toplevel);
 extern bool pgfdw_abort_cleanup_begin(ConnCacheEntry *entry, bool toplevel,
 									  List **pending_entries,
 									  List **cancel_requested);
 extern void pgfdw_finish_abort_cleanup(List *pending_entries,
 									   List *cancel_requested,
 									   bool toplevel);
 
+/* postgres_fdw_plus.c */
+extern void DefineCustomVariablesForPgFdwPlus(void);
+extern void pgfdw_abort_cleanup(ConnCacheEntry *entry, bool toplevel);
 extern void pgfdw_arrange_read_committed(bool xact_got_connection);
 extern bool pgfdw_xact_two_phase(XactEvent event);
-extern void pgfdw_prepare_xacts(ConnCacheEntry *entry,
-								List **pending_entries_prepare);
-extern void pgfdw_finish_prepare_cleanup(List **pending_entries_prepare);
-extern void pgfdw_commit_prepared(ConnCacheEntry *entry,
-								  List **pending_entries_commit_prepared);
-extern void pgfdw_finish_commit_prepared_cleanup(
-	List *pending_entries_commit_prepared);
-extern bool pgfdw_rollback_prepared(ConnCacheEntry *entry);
-extern void pgfdw_deallocate_all(ConnCacheEntry *entry);
-extern void pgfdw_insert_xact_commits(List *umids);
-
-/*
- * Construct the prepared transaction command like PREPARE TRANSACTION
- * that's issued to the foreign server. It consists of full transaction ID,
- * user mapping OID, process ID and cluster name.
- */
-#define PreparedXactCommand(sql, cmd, entry)	\
-	snprintf(sql, sizeof(sql), "%s 'pgfdw_" UINT64_FORMAT "_%u_%d_%s'",	\
-			 cmd, U64FromFullTransactionId(entry->fxid),	\
-			 (Oid) entry->key, MyProcPid,	\
-			 (*cluster_name == '\0') ? "null" : cluster_name)
 
 #endif							/* POSTGRES_FDW_PLUS_H */