From 867623708fb7684584977cfef9e9ba022b0fce64 Mon Sep 17 00:00:00 2001
From: Marko Kreen <markokr@gmail.com>
Date: Mon, 2 Apr 2012 13:12:11 +0300
Subject: [PATCH] New config var: 'default_user'

This allows to fall back to old default of 'session_user'.

New default is 'current_user'.
---
 doc/config.txt | 12 +++++++++++-
 src/cluster.c  | 25 +++++++++++++++++++++++--
 src/plproxy.h  |  1 +
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/doc/config.txt b/doc/config.txt
index 18cc6b0..b51fe23 100644
--- a/doc/config.txt
+++ b/doc/config.txt
@@ -20,7 +20,7 @@ The following plproxy schema functions are used to define the clusters:
 
 === plproxy.get_cluster_version(cluster_name) ===
 
-----------------------
+---------------------
 plproxy.get_cluster_version(cluster_name text)
 returns integer
 ----------------------
@@ -161,6 +161,16 @@ or NULL then the parameter is disabled (a default value will be used)
 	with same name.  Its better to just add the parameter to
 	connect string.
 
+  default_user::
+
+	Either `current_user` (default) or `session_user`.  They have same
+	meaning as SQL tokens.  The specified user is used to look up SQL/MED
+	user mapping.  In case of non-SQL/MED cluster, the user is put directly
+	to connect string, unless there already exist `user=` key.  The user is
+	also used to cache the connections.  Thus PL/Proxy 2.4+ supports connecting
+	to single cluster from same backend with different users.
+	+
+	*Deprecated*: it's use is to restore pre-2.4 default of `session_user`.
 
 Example function without the use of separate tables for storing parameters.
 
diff --git a/src/cluster.c b/src/cluster.c
index f32df7f..fc59c36 100644
--- a/src/cluster.c
+++ b/src/cluster.c
@@ -313,6 +313,8 @@ set_config_key(ProxyFunction *func, ProxyConfig *cf, const char *key, const char
 		cf->keepintvl = atoi(val);
 	else if (pg_strcasecmp("keepalive_count", key) == 0)
 		cf->keepcnt = atoi(val);
+	else if (pg_strcasecmp("default_user", key) == 0)
+		snprintf(cf->default_user, sizeof(cf->default_user), "%s", val);
 	else
 		plproxy_error(func, "Unknown config param: %s", key);
 }
@@ -968,12 +970,31 @@ static void
 refresh_cluster(ProxyFunction *func, ProxyCluster *cluster)
 {
 	ConnUserInfo *uinfo;
+	ProxyConfig *cf = &cluster->config;
 	Oid user_oid;
 
 	/*
-	 * Use current_user to pick user mapping
+	 * Decide which user to use for connections.
 	 */
-	user_oid = GetUserId();
+	if (cf->default_user[0])
+	{
+		if (strcmp(cf->default_user, "session_user") == 0)
+			user_oid = GetSessionUserId();
+		else if (strcmp(cf->default_user, "current_user") == 0)
+			user_oid = GetUserId();
+		else if (1)
+			/* dont support custom users, seems unnecessary */
+			elog(ERROR, "default_user: Expect 'current_user' or 'session_user', got '%s'",
+				 cf->default_user);
+		else
+			/* easy to support, but seems confusing conceptually */
+			user_oid = get_role_oid(cf->default_user, false);
+	}
+	else
+	{
+		/* default: current_user */
+		user_oid = GetUserId();
+	}
 
 	/* set up user cache */
 	uinfo = get_userinfo(cluster, user_oid);
diff --git a/src/plproxy.h b/src/plproxy.h
index f58c9cf..5f58321 100644
--- a/src/plproxy.h
+++ b/src/plproxy.h
@@ -134,6 +134,7 @@ typedef struct ProxyConfig
 	int			keepidle;
 	int			keepintvl;
 	int			keepcnt;
+	char		default_user[NAMEDATALEN];
 } ProxyConfig;
 
 typedef struct ConnUserInfo {
-- 
2.39.5