From 27b225794cf5774bc1c34ad431bbabd2cc3971b9 Mon Sep 17 00:00:00 2001
From: Sebastian Harl <sh@tokkee.org>
Date: Thu, 15 Nov 2012 13:29:20 +0100
Subject: [PATCH] postgresql plugin: Added support for "flushing" data.

This may be used to commit a PostgreSQL writer's transaction. Two different
types of flush callbacks are registered:

 - postgresql: Flush *all* databases.
 - postgresql-<database>: Flush the database named '<database>' only.
---
 src/postgresql.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/src/postgresql.c b/src/postgresql.c
index ef7a5ec1..9f4894ca 100644
--- a/src/postgresql.c
+++ b/src/postgresql.c
@@ -934,10 +934,41 @@ static int c_psql_write (const data_set_t *ds, const value_list_t *vl,
 	return 0;
 } /* c_psql_write */
 
+/* We cannot flush single identifiers as all we do is to commit the currently
+ * running transaction, thus making sure that all written data is actually
+ * visible to everybody. */
+static int c_psql_flush (cdtime_t timeout,
+		__attribute__((unused)) const char *ident,
+		user_data_t *ud)
+{
+	c_psql_database_t *dbs = databases;
+	size_t dbs_num = databases_num;
+	size_t i;
+
+	if ((ud != NULL) && (ud->data != NULL)) {
+		dbs = ud->data;
+		dbs_num = 1;
+	}
+
+	for (i = 0; i < dbs_num; ++i) {
+		c_psql_database_t *db = dbs + i;
+
+		/* don't commit if the timeout is larger than the regular commit
+		 * interval as in that case all requested data has already been
+		 * committed */
+		if ((db->next_commit > 0) && (db->commit_interval > timeout))
+			if (c_psql_commit (db) == 0)
+				c_psql_begin (db);
+	}
+	return 0;
+} /* c_psql_flush */
+
 static int c_psql_shutdown (void)
 {
 	size_t i = 0;
 
+	_Bool had_flush = 0;
+
 	plugin_unregister_read_group ("postgresql");
 
 	for (i = 0; i < databases_num; ++i) {
@@ -947,6 +978,13 @@ static int c_psql_shutdown (void)
 			char cb_name[DATA_MAX_NAME_LEN];
 			ssnprintf (cb_name, sizeof (cb_name), "postgresql-%s",
 					db->database);
+
+			if (! had_flush) {
+				plugin_unregister_flush ("postgresql");
+				had_flush = 1;
+			}
+
+			plugin_unregister_flush (cb_name);
 			plugin_unregister_write (cb_name);
 		}
 	}
@@ -1127,6 +1165,8 @@ static int c_psql_config_database (oconfig_item_t *ci)
 	struct timespec cb_interval = { 0, 0 };
 	user_data_t ud;
 
+	static _Bool have_flush = 0;
+
 	int i;
 
 	if ((1 != ci->values_num)
@@ -1223,6 +1263,17 @@ static int c_psql_config_database (oconfig_item_t *ci)
 	if (db->writers_num > 0) {
 		++db->ref_cnt;
 		plugin_register_write (cb_name, c_psql_write, &ud);
+
+		if (! have_flush) {
+			/* flush all */
+			plugin_register_flush ("postgresql",
+					c_psql_flush, /* user data = */ NULL);
+			have_flush = 1;
+		}
+
+		/* flush this connection only */
+		++db->ref_cnt;
+		plugin_register_flush (cb_name, c_psql_flush, &ud);
 	}
 	else if (db->commit_interval > 0) {
 		log_warn ("Database '%s': You do not have any writers assigned to "
-- 
2.30.2