From 44de49ffa1adacf3b2a30f81877e84755453ec14 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Fri, 28 Dec 2018 12:25:59 -0600
Subject: [PATCH] Rename runtime params to parameter status

---
 base/conn.go | 22 ++++++++++++++--------
 conn.go      |  4 +++-
 query.go     |  4 ++--
 v4.md        |  4 ++--
 4 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/base/conn.go b/base/conn.go
index 99278839..b8867c18 100644
--- a/base/conn.go
+++ b/base/conn.go
@@ -103,12 +103,12 @@ func (cc *ConnConfig) assignDefaults() error {
 
 // PgConn is a low-level PostgreSQL connection handle. It is not safe for concurrent usage.
 type PgConn struct {
-	NetConn       net.Conn          // the underlying TCP or unix domain socket connection
-	PID           uint32            // backend pid
-	SecretKey     uint32            // key to use to send a cancel query message to the server
-	RuntimeParams map[string]string // parameters that have been reported by the server
-	TxStatus      byte
-	Frontend      *pgproto3.Frontend
+	NetConn           net.Conn          // the underlying TCP or unix domain socket connection
+	PID               uint32            // backend pid
+	SecretKey         uint32            // key to use to send a cancel query message to the server
+	parameterStatuses map[string]string // parameters that have been reported by the server
+	TxStatus          byte
+	Frontend          *pgproto3.Frontend
 
 	Config ConnConfig
 }
@@ -127,7 +127,7 @@ func Connect(cc ConnConfig) (*PgConn, error) {
 		return nil, err
 	}
 
-	pgConn.RuntimeParams = make(map[string]string)
+	pgConn.parameterStatuses = make(map[string]string)
 
 	if cc.TLSConfig != nil {
 		if err := pgConn.startTLS(cc.TLSConfig); err != nil {
@@ -260,8 +260,14 @@ func (pgConn *PgConn) ReceiveMessage() (pgproto3.BackendMessage, error) {
 	case *pgproto3.ReadyForQuery:
 		pgConn.TxStatus = msg.TxStatus
 	case *pgproto3.ParameterStatus:
-		pgConn.RuntimeParams[msg.Name] = msg.Value
+		pgConn.parameterStatuses[msg.Name] = msg.Value
 	}
 
 	return msg, nil
 }
+
+// ParameterStatus returns the value of a parameter reported by the server (e.g.
+// server_version). Returns an empty string for unknown parameters.
+func (pgConn *PgConn) ParameterStatus(key string) string {
+	return pgConn.parameterStatuses[key]
+}
diff --git a/conn.go b/conn.go
index a202fa4b..e550be98 100644
--- a/conn.go
+++ b/conn.go
@@ -933,8 +933,10 @@ func configTLS(args configTLSArgs, cc *ConnConfig) error {
 	return nil
 }
 
+// ParameterStatus returns the value of a parameter reported by the server (e.g.
+// server_version). Returns an empty string for unknown parameters.
 func (c *Conn) ParameterStatus(key string) string {
-	return c.pgConn.RuntimeParams[key]
+	return c.pgConn.ParameterStatus(key)
 }
 
 // Prepare creates a prepared statement with name and sql. sql can contain placeholders
diff --git a/query.go b/query.go
index b3bb56e3..0f1152c1 100644
--- a/query.go
+++ b/query.go
@@ -519,11 +519,11 @@ func (c *Conn) readUntilRowDescription() ([]FieldDescription, error) {
 }
 
 func (c *Conn) sanitizeAndSendSimpleQuery(sql string, args ...interface{}) (err error) {
-	if c.pgConn.RuntimeParams["standard_conforming_strings"] != "on" {
+	if c.pgConn.ParameterStatus("standard_conforming_strings") != "on" {
 		return errors.New("simple protocol queries must be run with standard_conforming_strings=on")
 	}
 
-	if c.pgConn.RuntimeParams["client_encoding"] != "UTF8" {
+	if c.pgConn.ParameterStatus("client_encoding") != "UTF8" {
 		return errors.New("simple protocol queries must be run with client_encoding=UTF8")
 	}
 
diff --git a/v4.md b/v4.md
index 50f76d56..63f5202b 100644
--- a/v4.md
+++ b/v4.md
@@ -34,8 +34,8 @@ Minor Potential Changes:
 
 ## Changes
 
-`base.Conn` now contains core PostgreSQL connection functionality.
+`base.PgConn` now contains core PostgreSQL connection functionality.
 
 ### Incompatible Changes
 
-* `RuntimeParams` removed from `pgx.Conn` and added to `base.Conn`
+* `RuntimeParams` `pgx.Conn`. Server reported status can now be queried with the `ParameterStatus` method. The rename aligns with the PostgreSQL protocol and standard libpq naming. Access via a method instead of direct access to the map protects against outside modification.