Initial database functions

2026-03-27 08:56:29 +00:00 · 2017-04-21 15:12:33 +09:00
parent 11b7dda778
commit 001d887e8d
9 changed files with 524 additions and 23 deletions
--- a/dbutils.c
+++ b/dbutils.c
@@ -0,0 +1,187 @@
+/*
+ * dbutils.c - Database connection/management functions
+ *
+ * Copyright (c) 2ndQuadrant, 2010-2017
+ *
+ */
+
+#include <unistd.h>
+#include <time.h>
+#include <sys/time.h>
+
+#include "repmgr.h"
+
+
+#include "catalog/pg_control.h"
+
+static PGconn *_establish_db_connection(const char *conninfo,
+										const bool exit_on_error,
+										const bool log_notice,
+										const bool verbose_only);
+static bool _set_config(PGconn *conn, const char *config_param, const char *sqlquery);
+/* ==================== */
+/* Connection functions */
+/* ==================== */
+
+/*
+ * _establish_db_connection()
+ *
+ * Connect to a database using a conninfo string.
+ *
+ * NOTE: *do not* use this for replication connections; instead use:
+ *   establish_db_connection_by_params()
+ */
+
+static PGconn *
+_establish_db_connection(const char *conninfo, const bool exit_on_error, const bool log_notice, const bool verbose_only)
+{
+	PGconn	   *conn = NULL;
+	char		connection_string[MAXLEN];
+
+	strncpy(connection_string, conninfo, MAXLEN);
+
+	/* TODO: only set if not already present */
+	strcat(connection_string, " fallback_application_name='repmgr'");
+
+	log_debug(_("connecting to: '%s'"), connection_string);
+
+	conn = PQconnectdb(connection_string);
+
+	/* Check to see that the backend connection was successfully made */
+	if ((PQstatus(conn) != CONNECTION_OK))
+	{
+		bool emit_log = true;
+
+		if (verbose_only == true && verbose_logging == false)
+			emit_log = false;
+
+		if (emit_log)
+		{
+			if (log_notice)
+			{
+				log_notice(_("connection to database failed: %s"),
+						   PQerrorMessage(conn));
+			}
+			else
+			{
+				log_error(_("connection to database failed: %s"),
+						  PQerrorMessage(conn));
+			}
+		}
+
+		if (exit_on_error)
+		{
+			PQfinish(conn);
+			exit(ERR_DB_CON);
+		}
+	}
+
+	/*
+	 * set "synchronous_commit" to "local" in case synchronous replication is in use
+	 *
+	 * XXX set this explicitly before any write operations
+	 */
+
+	else if (set_config(conn, "synchronous_commit", "local") == false)
+	{
+		if (exit_on_error)
+		{
+			PQfinish(conn);
+			exit(ERR_DB_CON);
+		}
+	}
+
+	return conn;
+}
+
+
+/*
+ * Establish a database connection, optionally exit on error
+ */
+PGconn *
+establish_db_connection(const char *conninfo, const bool exit_on_error)
+{
+	return _establish_db_connection(conninfo, exit_on_error, false, false);
+}
+
+/* ========================== */
+/* GUC manipulation functions */
+/* ========================== */
+
+static bool
+_set_config(PGconn *conn, const char *config_param, const char *sqlquery)
+{
+	PGresult   *res;
+
+	res = PQexec(conn, sqlquery);
+
+	if (PQresultStatus(res) != PGRES_COMMAND_OK)
+	{
+		log_error("unable to set '%s': %s", config_param, PQerrorMessage(conn));
+		PQclear(res);
+		return false;
+	}
+
+	PQclear(res);
+
+	return true;
+}
+
+bool
+set_config(PGconn *conn, const char *config_param,  const char *config_value)
+{
+	char		sqlquery[MAX_QUERY_LEN];
+
+	sqlquery_snprintf(sqlquery,
+					  "SET %s TO '%s'",
+					  config_param,
+					  config_value);
+
+	log_verbose(LOG_DEBUG, "set_config():\n%s", sqlquery);
+
+	return _set_config(conn, config_param, sqlquery);
+}
+
+bool
+set_config_bool(PGconn *conn, const char *config_param, bool state)
+{
+	char		sqlquery[MAX_QUERY_LEN];
+
+	sqlquery_snprintf(sqlquery,
+					  "SET %s TO %s",
+					  config_param,
+					  state ? "TRUE" : "FALSE");
+
+	log_verbose(LOG_DEBUG, "set_config_bool():\n%s\n", sqlquery);
+
+	return _set_config(conn, config_param, sqlquery);
+}
+
+/* ============================ */
+/* Server information functions */
+/* ============================ */
+
+/*
+ * Return the server version number for the connection provided
+ */
+int
+get_server_version(PGconn *conn, char *server_version)
+{
+	PGresult   *res;
+	res = PQexec(conn,
+				 "SELECT pg_catalog.current_setting('server_version_num'), "
+				 "       pg_catalog.current_setting('server_version')");
+
+	if (PQresultStatus(res) != PGRES_TUPLES_OK)
+	{
+		log_error(_("unable to determine server version number:\n%s"),
+				  PQerrorMessage(conn));
+		PQclear(res);
+		return -1;
+	}
+
+	if (server_version != NULL)
+		strcpy(server_version, PQgetvalue(res, 0, 0));
+
+	return atoi(PQgetvalue(res, 0, 0));
+}