close.go: Rewrite how the library handles closing

Far simpler now. Sorry this took a while.

Closes #427
Closes #429
Closes #434
Closes #436
Closes #437

Author: nhooyr

close.go

@@ -97,82 +97,106 @@ func CloseStatus(err error) StatusCode {
 //
 // Close will unblock all goroutines interacting with the connection once
 // complete.
-func (c *Conn) Close(code StatusCode, reason string) error {
-	defer c.wg.Wait()
-	return c.closeHandshake(code, reason)
+func (c *Conn) Close(code StatusCode, reason string) (err error) {
+	defer errd.Wrap(&err, "failed to close WebSocket")
+
+	if !c.casClosing() {
+		err = c.waitGoroutines()
+		if err != nil {
+			return err
+		}
+		return net.ErrClosed
+	}
+	defer func() {
+		if errors.Is(err, net.ErrClosed) {
+			err = nil
+		}
+	}()
+
+	err = c.closeHandshake(code, reason)
+
+	err2 := c.close()
+	if err == nil && err2 != nil {
+		err = err2
+	}
+
+	err2 = c.waitGoroutines()
+	if err == nil && err2 != nil {
+		err = err2
+	}
+
+	return err
 }
 
 // CloseNow closes the WebSocket connection without attempting a close handshake.
 // Use when you do not want the overhead of the close handshake.
 func (c *Conn) CloseNow() (err error) {
-	defer c.wg.Wait()
 	defer errd.Wrap(&err, "failed to close WebSocket")
 
-	if c.isClosed() {
+	if !c.casClosing() {
+		err = c.waitGoroutines()
+		if err != nil {
+			return err
+		}
 		return net.ErrClosed
 	}
+	defer func() {
+		if errors.Is(err, net.ErrClosed) {
+			err = nil
+		}
+	}()
 
-	c.close(nil)
-	c.closeMu.Lock()
-	defer c.closeMu.Unlock()
-	return c.closeErr
-}
-
-func (c *Conn) closeHandshake(code StatusCode, reason string) (err error) {
-	defer errd.Wrap(&err, "failed to close WebSocket")
-
-	writeErr := c.writeClose(code, reason)
-	closeHandshakeErr := c.waitCloseHandshake()
+	err = c.close()
 
-	if writeErr != nil {
-		return writeErr
+	err2 := c.waitGoroutines()
+	if err == nil && err2 != nil {
+		err = err2
 	}
+	return err
+}
 
-	if CloseStatus(closeHandshakeErr) == -1 && !errors.Is(net.ErrClosed, closeHandshakeErr) {
-		return closeHandshakeErr
+func (c *Conn) closeHandshake(code StatusCode, reason string) error {
+	err := c.writeClose(code, reason)
+	if err != nil {
+		return err
 	}
 
+	err = c.waitCloseHandshake()
+	if CloseStatus(err) != code {
+		return err
+	}
 	return nil
 }
 
 func (c *Conn) writeClose(code StatusCode, reason string) error {
-	c.closeMu.Lock()
-	wroteClose := c.wroteClose
-	c.wroteClose = true
-	c.closeMu.Unlock()
-	if wroteClose {
-		return net.ErrClosed
-	}
-
 	ce := CloseError{
 		Code:   code,
 		Reason: reason,
 	}
 
 	var p []byte
-	var marshalErr error
+	var err error
 	if ce.Code != StatusNoStatusRcvd {
-		p, marshalErr = ce.bytes()
-	}
-
-	writeErr := c.writeControl(context.Background(), opClose, p)
-	if CloseStatus(writeErr) != -1 {
-		// Not a real error if it's due to a close frame being received.
-		writeErr = nil
+		p, err = ce.bytes()
+		if err != nil {
+			return err
+		}
 	}
 
-	// We do this after in case there was an error writing the close frame.
-	c.setCloseErr(fmt.Errorf("sent close frame: %w", ce))
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	defer cancel()
 
-	if marshalErr != nil {
-		return marshalErr
+	err = c.writeControl(ctx, opClose, p)
+	// If the connection closed as we're writing we ignore the error as we might
+	// have written the close frame, the peer responded and then someone else read it
+	// and closed the connection.
+	if err != nil && !errors.Is(err, net.ErrClosed) {
+		return err
 	}
-	return writeErr
+	return nil
 }
 
 func (c *Conn) waitCloseHandshake() error {
-	defer c.close(nil)
-
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
 	defer cancel()
 
@@ -208,6 +232,36 @@ func (c *Conn) waitCloseHandshake() error {
 	}
 }
 
+func (c *Conn) waitGoroutines() error {
+	t := time.NewTimer(time.Second * 15)
+	defer t.Stop()
+
+	select {
+	case <-c.timeoutLoopDone:
+	case <-t.C:
+		return errors.New("failed to wait for timeoutLoop goroutine to exit")
+	}
+
+	c.closeReadMu.Lock()
+	ctx := c.closeReadCtx
+	c.closeReadMu.Unlock()
+	if ctx != nil {
+		select {
+		case <-ctx.Done():
+		case <-t.C:
+			return errors.New("failed to wait for close read goroutine to exit")
+		}
+	}
+
+	select {
+	case <-c.closed:
+	case <-t.C:
+		return errors.New("failed to wait for connection to be closed")
+	}
+
+	return nil
+}
+
 func parseClosePayload(p []byte) (CloseError, error) {
 	if len(p) == 0 {
 		return CloseError{
@@ -278,16 +332,14 @@ func (ce CloseError) bytesErr() ([]byte, error) {
 	return buf, nil
 }
 
-func (c *Conn) setCloseErr(err error) {
+func (c *Conn) casClosing() bool {
 	c.closeMu.Lock()
-	c.setCloseErrLocked(err)
-	c.closeMu.Unlock()
-}
-
-func (c *Conn) setCloseErrLocked(err error) {
-	if c.closeErr == nil && err != nil {
-		c.closeErr = fmt.Errorf("WebSocket closed: %w", err)
+	defer c.closeMu.Unlock()
+	if !c.closing {
+		c.closing = true
+		return true
 	}
+	return false
 }
 
 func (c *Conn) isClosed() bool {

conn.go

@@ -6,7 +6,6 @@ package websocket
 import (
 	"bufio"
 	"context"
-	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -53,8 +52,9 @@ type Conn struct {
 	br             *bufio.Reader
 	bw             *bufio.Writer
 
-	readTimeout  chan context.Context
-	writeTimeout chan context.Context
+	readTimeout     chan context.Context
+	writeTimeout    chan context.Context
+	timeoutLoopDone chan struct{}
 
 	// Read state.
 	readMu            *mu
@@ -70,11 +70,12 @@ type Conn struct {
 	writeHeaderBuf [8]byte
 	writeHeader    header
 
-	wg         sync.WaitGroup
-	closed     chan struct{}
-	closeMu    sync.Mutex
-	closeErr   error
-	wroteClose bool
+	closeReadMu  sync.Mutex
+	closeReadCtx context.Context
+
+	closed  chan struct{}
+	closeMu sync.Mutex
+	closing bool
 
 	pingCounter   int32
 	activePingsMu sync.Mutex
@@ -103,8 +104,9 @@ func newConn(cfg connConfig) *Conn {
 		br: cfg.br,
 		bw: cfg.bw,
 
-		readTimeout:  make(chan context.Context),
-		writeTimeout: make(chan context.Context),
+		readTimeout:     make(chan context.Context),
+		writeTimeout:    make(chan context.Context),
+		timeoutLoopDone: make(chan struct{}),
 
 		closed:      make(chan struct{}),
 		activePings: make(map[string]chan<- struct{}),
@@ -128,14 +130,10 @@ func newConn(cfg connConfig) *Conn {
 	}
 
 	runtime.SetFinalizer(c, func(c *Conn) {
-		c.close(errors.New("connection garbage collected"))
+		c.close()
 	})
 
-	c.wg.Add(1)
-	go func() {
-		defer c.wg.Done()
-		c.timeoutLoop()
-	}()
+	go c.timeoutLoop()
 
 	return c
 }
@@ -146,35 +144,29 @@ func (c *Conn) Subprotocol() string {
 	return c.subprotocol
 }
 
-func (c *Conn) close(err error) {
+func (c *Conn) close() error {
 	c.closeMu.Lock()
 	defer c.closeMu.Unlock()
 
 	if c.isClosed() {
-		return
-	}
-	if err == nil {
-		err = c.rwc.Close()
+		return net.ErrClosed
 	}
-	c.setCloseErrLocked(err)
-
-	close(c.closed)
 	runtime.SetFinalizer(c, nil)
+	close(c.closed)
 
 	// Have to close after c.closed is closed to ensure any goroutine that wakes up
 	// from the connection being closed also sees that c.closed is closed and returns
 	// closeErr.
-	c.rwc.Close()
-
-	c.wg.Add(1)
-	go func() {
-		defer c.wg.Done()
-		c.msgWriter.close()
-		c.msgReader.close()
-	}()
+	err := c.rwc.Close()
+	// With the close of rwc, these become safe to close.
+	c.msgWriter.close()
+	c.msgReader.close()
+	return err
 }
 
 func (c *Conn) timeoutLoop() {
+	defer close(c.timeoutLoopDone)
+
 	readCtx := context.Background()
 	writeCtx := context.Background()
 
@@ -187,14 +179,10 @@ func (c *Conn) timeoutLoop() {
 		case readCtx = <-c.readTimeout:
 
 		case <-readCtx.Done():
-			c.setCloseErr(fmt.Errorf("read timed out: %w", readCtx.Err()))
-			c.wg.Add(1)
-			go func() {
-				defer c.wg.Done()
-				c.writeError(StatusPolicyViolation, errors.New("read timed out"))
-			}()
+			c.close()
+			return
 		case <-writeCtx.Done():
-			c.close(fmt.Errorf("write timed out: %w", writeCtx.Err()))
+			c.close()
 			return
 		}
 	}
@@ -243,9 +231,7 @@ func (c *Conn) ping(ctx context.Context, p string) error {
 	case <-c.closed:
 		return net.ErrClosed
 	case <-ctx.Done():
-		err := fmt.Errorf("failed to wait for pong: %w", ctx.Err())
-		c.close(err)
-		return err
+		return fmt.Errorf("failed to wait for pong: %w", ctx.Err())
 	case <-pong:
 		return nil
 	}
@@ -281,9 +267,7 @@ func (m *mu) lock(ctx context.Context) error {
 	case <-m.c.closed:
 		return net.ErrClosed
 	case <-ctx.Done():
-		err := fmt.Errorf("failed to acquire lock: %w", ctx.Err())
-		m.c.close(err)
-		return err
+		return fmt.Errorf("failed to acquire lock: %w", ctx.Err())
 	case m.ch <- struct{}{}:
 		// To make sure the connection is certainly alive.
 		// As it's possible the send on m.ch was selected

conn_test.go

@@ -345,6 +345,9 @@ func TestConn(t *testing.T) {
 
 func TestWasm(t *testing.T) {
 	t.Parallel()
+	if os.Getenv("CI") == "" {
+		t.Skip()
+	}
 
 	s := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		err := echoServer(w, r, &websocket.AcceptOptions{