model encodings package more closely

mplexer/packer/encoder.go

@@ -7,23 +7,32 @@ import (
 	"sync"
 )
 
+// TODO: try to be more like encoding/csv, or more like encoding/pem and encoding/json?
+
+// Encoder converts TCP to MPLEXY-TCP
 type Encoder struct {
 	ctx        context.Context
 	subctx     context.Context
 	mux        sync.Mutex
-	w      io.WriteCloser
-	wErr   chan error
+	out        io.WriteCloser
+	outErr     chan error
+	bufferSize int
 }
 
-func NewEncoder(ctx context.Context, w io.WriteCloser) *Encoder {
+// NewEncoder returns an Encoder instance
+func NewEncoder(ctx context.Context, wout io.WriteCloser) *Encoder {
 	enc := &Encoder{
 		ctx:        ctx,
-		w:    w,
-		wErr: make(chan error),
+		out:        wout,
+		outErr:     make(chan error),
+		bufferSize: defaultBufferSize,
 	}
 	return enc
 }
 
+// Run loops over a select of contexts and error channels
+// to cancel and close south-side connections, if needed.
+// TODO should this be pushed elsewhere to handled?
 func (enc *Encoder) Run() error {
 	ctx, cancel := context.WithCancel(enc.ctx)
 	defer cancel()
@@ -35,35 +44,31 @@ func (enc *Encoder) Run() error {
 		// TODO: do children respond to children cancelling?
 		case <-enc.ctx.Done():
 			// TODO
-			_ = enc.w.Close()
+			_ = enc.out.Close()
 			return errors.New("context cancelled")
-		case err := <-enc.wErr:
+		case err := <-enc.outErr:
+			// if a write fails for one, it fail for all
 			return err
 		}
 	}
 }
 
+// Start will Run() the encoder in a goroutine
 func (enc *Encoder) Start() error {
 	go enc.Run()
 	return nil
 }
 
-// TODO inverse
-
-// StreamEncode can (and should) be called multiple times (once per client).
-func (enc *Encoder) StreamEncode(src Addr, r io.ReadCloser, bufferSize int) error {
+// Encode adds MPLEXY headers to raw net traffic, and is intended to be used on each client connection
+func (enc *Encoder) Encode(rin io.ReadCloser, src Addr) error {
 	rx := make(chan []byte)
 	rxErr := make(chan error)
 
-	if 0 == bufferSize {
-		bufferSize = 8192
-	}
-
 	go func() {
 		for {
-			b := make([]byte, bufferSize)
+			b := make([]byte, enc.bufferSize)
 			//fmt.Println("loopers gonna loop")
-			n, err := r.Read(b)
+			n, err := rin.Read(b)
 			if n > 0 {
 				rx <- b[:n]
 			}
@@ -81,52 +86,51 @@ func (enc *Encoder) StreamEncode(src Addr, r io.ReadCloser, bufferSize int) erro
 		// would it be sufficient to expect the reader to be closed by the caller instead?
 		case <-enc.ctx.Done():
 			// TODO: verify that closing the reader will cause the goroutine to be released
-			r.Close()
+			rin.Close()
 			return errors.New("cancelled by context")
 		case <-enc.subctx.Done():
-			r.Close()
+			rin.Close()
 			return errors.New("cancelled by context")
 		case b := <-rx:
 			header, _, err := Encode(src, Addr{}, "", b)
 			if nil != err {
-				r.Close()
+				rin.Close()
 				return err
 			}
-			_, err = enc.write(header)
+			_, err = enc.write(header, b)
 			if nil != err {
-				r.Close()
-				return err
-			}
-			_, err = enc.write(b)
-			if nil != err {
-				r.Close()
+				rin.Close()
 				return err
 			}
 		case err := <-rxErr:
 			// it can be assumed that err will close though, right?
-			r.Close()
+			rin.Close()
 			if io.EOF == err {
 				header, _, _ := Encode(src, Addr{scheme: "end"}, "", nil)
 				// ignore err, which may have already closed
-				_, _ = enc.write(header)
+				_, _ = enc.write(header, nil)
 				return nil
 			}
 			header, _, _ := Encode(src, Addr{scheme: "error"}, "", []byte(err.Error()))
 			// ignore err, which may have already closed
-			_, _ = enc.write(header)
+			_, _ = enc.write(header, nil)
 			return err
 		}
 
 	}
 }
 
-func (enc *Encoder) write(b []byte) (int, error) {
+func (enc *Encoder) write(h, b []byte) (int, error) {
 	// mutex here so that we can get back error info
 	enc.mux.Lock()
-	n, err := enc.w.Write(b)
+	var m int
+	n, err := enc.out.Write(h)
+	if nil == err && len(b) > 0 {
+		m, err = enc.out.Write(b)
+	}
 	enc.mux.Unlock()
 	if nil != err {
-		enc.wErr <- err
+		enc.outErr <- err
 	}
-	return n, err
+	return n + m, err
 }

mplexer/packer/encoder_test.go

@@ -10,19 +10,47 @@ import (
 
 func TestEncodeWholeBlock(t *testing.T) {
 	ch := make(chan string)
+
+	a1 := "A.1: hello"
+	a2 := "A.2: smello"
+	b1 := "B.1: hello again"
+	b2 := "B.2: hello a third time"
+	m := map[string]bool{
+		a1: false,
+		a2: false,
+		b1: false,
+		b2: false,
+	}
+
 	go func() {
 		for {
 			str := <-ch
-			fmt.Printf("Read: %q\n", str)
+			// TODO check the headers too
+			if len(str) > 0 && 0xFE == str[0] {
+				fmt.Printf("TODO header: %q\n", str)
+				continue
+			}
+
+			b, ok := m[str]
+			if !ok {
+				// possible corruption
+				t.Fatalf("unexpected string %q", str)
+			}
+			if b {
+				// possible corruption also
+				t.Fatalf("duplicate string %q", str)
+			}
+
+			m[str] = true
 		}
 	}()
 
 	ctx := context.Background()
-	rp, wp := net.Pipe()
+	rin, wout := net.Pipe()
 	go func() {
 		for {
 			b := make([]byte, 1024)
-			n, err := rp.Read(b)
+			n, err := rin.Read(b)
 			if nil != err {
 				fmt.Printf("Error: %s\n", err)
 				return
@@ -31,25 +59,25 @@ func TestEncodeWholeBlock(t *testing.T) {
 			ch <- string(r)
 		}
 	}()
-	encoder := NewEncoder(ctx, wp)
+	encoder := NewEncoder(ctx, wout)
 	encoder.Start()
 
 	time.Sleep(time.Millisecond)
 
 	// single client
 	go func() {
-		wp, rp := net.Pipe()
+		wout, rin := net.Pipe()
 
 		go func() {
-			wp.Write([]byte("hello"))
-			wp.Write([]byte("smello"))
+			wout.Write([]byte(a1))
+			wout.Write([]byte(a2))
 		}()
 
-		err := encoder.StreamEncode(Addr{
+		err := encoder.Encode(rin, Addr{
 			family: "IPv4",
 			addr:   "192.168.1.102",
 			port:   4834,
-		}, rp, 0)
+		})
 		if nil != err {
 			fmt.Printf("Enc Err: %q\n", err)
 		}
@@ -57,22 +85,37 @@ func TestEncodeWholeBlock(t *testing.T) {
 
 	// single client
 	go func() {
-		wp, rp := net.Pipe()
+		wout, rin := net.Pipe()
 
 		go func() {
-			wp.Write([]byte("hello again"))
-			wp.Write([]byte("hello a third time"))
+			wout.Write([]byte(b1))
+			wout.Write([]byte(b2))
 		}()
 
-		err := encoder.StreamEncode(Addr{
+		err := encoder.Encode(rin, Addr{
 			family: "IPv4",
 			addr:   "192.168.1.103",
 			port:   4834,
-		}, rp, 0)
+		})
 		if nil != err {
 			fmt.Printf("Enc Err 2: %q\n", err)
 		}
 	}()
 
-	time.Sleep(time.Second)
+	// TODO must be a better way to do this
+	time.Sleep(10 * time.Millisecond)
+
+	for k, v := range m {
+		if !v {
+			t.Fatalf("failed to encode and transmit a value: %q", k)
 		}
+	}
+}
+
+/*
+func TestEncodeEnd(t *testing.T) {
+}
+
+func TestEncodeError(t *testing.T) {
+}
+*/