Revert nil context support

README.md

@@ -11,13 +11,13 @@ low-level access to PostgreSQL functionality.
 ## Example Usage
 
 ```go
-pgConn, err := pgconn.Connect(nil, os.Getenv("DATABASE_URL"))
+pgConn, err := pgconn.Connect(context.Background(), os.Getenv("DATABASE_URL"))
 if err != nil {
 	log.Fatalln("pgconn failed to connect:", err)
 }
 defer pgConn.Close()
 
-result := pgConn.ExecParams(nil, "SELECT email FROM users WHERE id=$1", [][]byte{[]byte("123")}, nil, nil, nil)
+result := pgConn.ExecParams(context.Background(), "SELECT email FROM users WHERE id=$1", [][]byte{[]byte("123")}, nil, nil, nil)
 for result.NextRow() {
 	fmt.Println("User 123 has email:", string(result.Values()[0]))
 }

benchmark_test.go

@@ -14,16 +14,9 @@ func BenchmarkConnect(b *testing.B) {
 	benchmarks := []struct {
 		name string
 		env  string
-		ctx  context.Context
 	}{
-		// The first benchmark in the list sometimes executes faster, no matter how
+		{"Unix socket", "PGX_TEST_UNIX_SOCKET_CONN_STRING"},
-		// you reorder it. Nil context is still faster on average.
+		{"TCP", "PGX_TEST_TCP_CONN_STRING"},
-		//
-		// Using and empty context other than context.Background() to compare.
-		{"Unix socket", "PGX_TEST_UNIX_SOCKET_CONN_STRING", context.TODO()},
-		{"TCP", "PGX_TEST_TCP_CONN_STRING", context.TODO()},
-		{"Unix socket nil context", "PGX_TEST_UNIX_SOCKET_CONN_STRING", nil},
-		{"TCP nil context", "PGX_TEST_TCP_CONN_STRING", nil},
 	}
 
 	for _, bm := range benchmarks {
@@ -35,10 +28,10 @@ func BenchmarkConnect(b *testing.B) {
 			}
 
 			for i := 0; i < b.N; i++ {
-				conn, err := pgconn.Connect(bm.ctx, connString)
+				conn, err := pgconn.Connect(context.Background(), connString)
 				require.Nil(b, err)
 
-				err = conn.Close(bm.ctx)
+				err = conn.Close(context.Background())
 				require.Nil(b, err)
 			}
 		})
@@ -51,9 +44,10 @@ func BenchmarkExec(b *testing.B) {
 		name string
 		ctx  context.Context
 	}{
-		// Using and empty context other than context.Background() to compare.
+		// Using an empty context other than context.Background() to compare
+		// performance
+		{"background context", context.Background()},
 		{"empty context", context.TODO()},
-		{"nil context", nil},
 	}
 
 	for _, bm := range benchmarks {
@@ -156,9 +150,10 @@ func BenchmarkExecPrepared(b *testing.B) {
 		name string
 		ctx  context.Context
 	}{
-		// Using and empty context other than context.Background() to compare.
+		// Using an empty context other than context.Background() to compare
+		// performance
+		{"background context", context.Background()},
 		{"empty context", context.TODO()},
-		{"nil context", nil},
 	}
 
 	for _, bm := range benchmarks {

doc.go

@@ -22,7 +22,6 @@ Context Support
 
 All potentially blocking operations take a context.Context. If a context is canceled while the method is in progress the
 method immediately returns. In most circumstances, this will close the underlying connection.
-A nil context can be passed for convenience. This has the same effect as passing context.Background().
 
 The CancelRequest method may be used to request the PostgreSQL server cancel an in-progress query without forcing the
 client to abort.

helper_test.go

@@ -29,25 +29,3 @@ func ensureConnValid(t *testing.T, pgConn *pgconn.PgConn) {
 	assert.Equal(t, "2", string(result.Rows[1][0]))
 	assert.Equal(t, "3", string(result.Rows[2][0]))
 }
-
-// Run subtest both with a context.Background() and nil context
-func splitOnContext(t *testing.T, test func(t *testing.T, ctx context.Context)) {
-	t.Helper()
-
-	cases := [...]struct {
-		name string
-		ctx  context.Context
-	}{
-		{"background context", context.Background()},
-		{"nil context", nil},
-	}
-
-	for i := range cases {
-		c := cases[i]
-		t.Run(c.name, func(t *testing.T) {
-			t.Helper()
-			t.Parallel()
-			test(t, c.ctx)
-		})
-	}
-}

pgconn.go

@@ -116,10 +116,6 @@ func ConnectConfig(ctx context.Context, config *Config) (pgConn *PgConn, err err
 		panic("config must be created by ParseConfig")
 	}
 
-	if ctx == nil {
-		ctx = context.Background()
-	}
-
 	// Simplify usage by treating primary config and fallbacks the same.
 	fallbackConfigs := []*FallbackConfig{
 		{
@@ -366,9 +362,7 @@ func (pgConn *PgConn) SendBytes(ctx context.Context, buf []byte) error {
 	}
 	defer pgConn.unlock()
 
-	switch ctx {
+	if ctx != context.Background() {
-	case nil, context.Background():
-	default:
 		select {
 		case <-ctx.Done():
 			return &contextAlreadyDoneError{err: ctx.Err()}
@@ -400,9 +394,7 @@ func (pgConn *PgConn) ReceiveMessage(ctx context.Context) (pgproto3.BackendMessa
 	}
 	defer pgConn.unlock()
 
-	switch ctx {
+	if ctx != context.Background() {
-	case nil, context.Background():
-	default:
 		select {
 		case <-ctx.Done():
 			return nil, &contextAlreadyDoneError{err: ctx.Err()}
@@ -501,9 +493,7 @@ func (pgConn *PgConn) Close(ctx context.Context) error {
 
 	defer pgConn.conn.Close()
 
-	switch ctx {
+	if ctx != context.Background() {
-	case nil, context.Background():
-	default:
 		pgConn.contextWatcher.Watch(ctx)
 		defer pgConn.contextWatcher.Unwatch()
 	}
@@ -602,9 +592,7 @@ func (pgConn *PgConn) Prepare(ctx context.Context, name, sql string, paramOIDs [
 	}
 	defer pgConn.unlock()
 
-	switch ctx {
+	if ctx != context.Background() {
-	case nil, context.Background():
-	default:
 		select {
 		case <-ctx.Done():
 			return nil, &contextAlreadyDoneError{err: ctx.Err()}
@@ -693,19 +681,13 @@ func (pgConn *PgConn) CancelRequest(ctx context.Context) error {
 	// the connection config. This is important in high availability configurations where fallback connections may be
 	// specified or DNS may be used to load balance.
 	serverAddr := pgConn.conn.RemoteAddr()
-	_ctx := ctx
+	cancelConn, err := pgConn.config.DialFunc(ctx, serverAddr.Network(), serverAddr.String())
-	if _ctx == nil {
-		_ctx = context.Background()
-	}
-	cancelConn, err := pgConn.config.DialFunc(_ctx, serverAddr.Network(), serverAddr.String())
 	if err != nil {
 		return err
 	}
 	defer cancelConn.Close()
 
-	switch ctx {
+	if ctx != context.Background() {
-	case nil, context.Background():
-	default:
 		contextWatcher := ctxwatch.NewContextWatcher(
 			func() { cancelConn.SetDeadline(time.Date(1, 1, 1, 1, 1, 1, 1, time.UTC)) },
 			func() { cancelConn.SetDeadline(time.Time{}) },
@@ -740,9 +722,7 @@ func (pgConn *PgConn) WaitForNotification(ctx context.Context) error {
 	}
 	defer pgConn.unlock()
 
-	switch ctx {
+	if ctx != context.Background() {
-	case nil, context.Background():
-	default:
 		select {
 		case <-ctx.Done():
 			return ctx.Err()
@@ -784,11 +764,7 @@ func (pgConn *PgConn) Exec(ctx context.Context, sql string) *MultiResultReader {
 		ctx:    ctx,
 	}
 	multiResult := &pgConn.multiResultReader
-	switch ctx {
+	if ctx != context.Background() {
-	case nil:
-		pgConn.multiResultReader.ctx = context.Background()
-	case context.Background():
-	default:
 		select {
 		case <-ctx.Done():
 			multiResult.closed = true
@@ -882,9 +858,6 @@ func (pgConn *PgConn) execExtendedPrefix(ctx context.Context, paramValues [][]by
 		ctx:    ctx,
 	}
 	result := &pgConn.resultReader
-	if ctx == nil {
-		pgConn.resultReader.ctx = context.Background()
-	}
 
 	if err := pgConn.lock(); err != nil {
 		result.concludeCommand(nil, err)
@@ -899,9 +872,7 @@ func (pgConn *PgConn) execExtendedPrefix(ctx context.Context, paramValues [][]by
 		return result
 	}
 
-	switch ctx {
+	if ctx != context.Background() {
-	case nil, context.Background():
-	default:
 		select {
 		case <-ctx.Done():
 			result.concludeCommand(nil, &contextAlreadyDoneError{err: ctx.Err()})
@@ -937,9 +908,7 @@ func (pgConn *PgConn) CopyTo(ctx context.Context, w io.Writer, sql string) (Comm
 		return nil, err
 	}
 
-	switch ctx {
+	if ctx != context.Background() {
-	case nil, context.Background():
-	default:
 		select {
 		case <-ctx.Done():
 			pgConn.unlock()
@@ -1000,9 +969,7 @@ func (pgConn *PgConn) CopyFrom(ctx context.Context, r io.Reader, sql string) (Co
 	}
 	defer pgConn.unlock()
 
-	switch ctx {
+	if ctx != context.Background() {
-	case nil, context.Background():
-	default:
 		select {
 		case <-ctx.Done():
 			return nil, &contextAlreadyDoneError{err: ctx.Err()}
@@ -1396,11 +1363,8 @@ func (pgConn *PgConn) ExecBatch(ctx context.Context, batch *Batch) *MultiResultR
 		ctx:    ctx,
 	}
 	multiResult := &pgConn.multiResultReader
-	switch ctx {
+
-	case nil:
+	if ctx != context.Background() {
-		pgConn.multiResultReader.ctx = context.Background()
-	case context.Background():
-	default:
 		select {
 		case <-ctx.Done():
 			multiResult.closed = true