From b69179cebbbf9a8498482d780b4f3623b2256ac3 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Wed, 10 Apr 2019 11:21:40 -0500
Subject: [PATCH] Remove Conn.Listen and Conn.Unlisten

Use Conn.Exec instead to listen or unlisten.
---
 conn.go               | 25 -------------------------
 conn_test.go          |  8 ++++----
 doc.go                |  2 +-
 examples/chat/main.go |  2 +-
 4 files changed, 6 insertions(+), 31 deletions(-)

diff --git a/conn.go b/conn.go
index 29dc924f..0fd42a8d 100644
--- a/conn.go
+++ b/conn.go
@@ -66,7 +66,6 @@ type Conn struct {
 	wbuf               []byte
 	config             *ConnConfig // config used when establishing this connection
 	preparedStatements map[string]*PreparedStatement
-	channels           map[string]struct{}
 	logger             Logger
 	logLevel           LogLevel
 	fp                 *fastpath
@@ -191,7 +190,6 @@ func connect(ctx context.Context, config *ConnConfig, connInfo *pgtype.ConnInfo)
 	}
 
 	c.preparedStatements = make(map[string]*PreparedStatement)
-	c.channels = make(map[string]struct{})
 	c.cancelQueryCompleted = make(chan struct{})
 	close(c.cancelQueryCompleted)
 	c.doneChan = make(chan struct{})
@@ -573,29 +571,6 @@ func (c *Conn) deallocateContext(ctx context.Context, name string) (err error) {
 	return err
 }
 
-// Listen establishes a PostgreSQL listen/notify to channel
-func (c *Conn) Listen(channel string) error {
-	_, err := c.Exec(context.TODO(), "listen "+quoteIdentifier(channel))
-	if err != nil {
-		return err
-	}
-
-	c.channels[channel] = struct{}{}
-
-	return nil
-}
-
-// Unlisten unsubscribes from a listen channel
-func (c *Conn) Unlisten(channel string) error {
-	_, err := c.Exec(context.TODO(), "unlisten "+quoteIdentifier(channel))
-	if err != nil {
-		return err
-	}
-
-	delete(c.channels, channel)
-	return nil
-}
-
 func (c *Conn) IsAlive() bool {
 	c.mux.Lock()
 	defer c.mux.Unlock()
diff --git a/conn_test.go b/conn_test.go
index db488f56..00698245 100644
--- a/conn_test.go
+++ b/conn_test.go
@@ -617,7 +617,7 @@ func TestSetLogger(t *testing.T) {
 		t.Fatalf("Expected conn.SetLogger to return %v, but it was %v", nil, oldLogger)
 	}
 
-	if err := conn.Listen("foo"); err != nil {
+	if _, err := conn.Exec(context.Background(), "listen foo"); err != nil {
 		t.Fatal(err)
 	}
 
@@ -631,7 +631,7 @@ func TestSetLogger(t *testing.T) {
 		t.Fatalf("Expected conn.SetLogger to return %v, but it was %v", l1, oldLogger)
 	}
 
-	if err := conn.Listen("bar"); err != nil {
+	if _, err := conn.Exec(context.Background(), "listen bar"); err != nil {
 		t.Fatal(err)
 	}
 
@@ -657,7 +657,7 @@ func TestSetLogLevel(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if err := conn.Listen("foo"); err != nil {
+	if _, err := conn.Exec(context.Background(), "listen foo"); err != nil {
 		t.Fatal(err)
 	}
 
@@ -669,7 +669,7 @@ func TestSetLogLevel(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if err := conn.Listen("bar"); err != nil {
+	if _, err := conn.Exec(context.Background(), "listen bar"); err != nil {
 		t.Fatal(err)
 	}
 
diff --git a/doc.go b/doc.go
index 5808c09d..7da1cd88 100644
--- a/doc.go
+++ b/doc.go
@@ -220,7 +220,7 @@ pgx can listen to the PostgreSQL notification system with the
 WaitForNotification function. It takes a maximum time to wait for a
 notification.
 
-    err := conn.Listen("channelname")
+    err := conn.Exec("listen channelname")
     if err != nil {
         return nil
     }
diff --git a/examples/chat/main.go b/examples/chat/main.go
index 83b16c02..35b73183 100644
--- a/examples/chat/main.go
+++ b/examples/chat/main.go
@@ -60,7 +60,7 @@ func listen() {
 	}
 	defer pool.Release(conn)
 
-	conn.Listen("chat")
+	conn.Exec(context.Background(), "listen chat")
 
 	for {
 		notification, err := conn.WaitForNotification(context.Background())