Merge pull request 'feat(notify): New functionality for notify callback.' (#4) from development into master

Reviewed-on: #4

multiread_test.go

@@ -2,9 +2,11 @@ package multireader
 
 import (
 	"bytes"
+	"io"
 	"math/rand"
 	"sync"
 	"testing"
+	"time"
 )
 
 func TestMultiRead(t *testing.T) {
@@ -46,9 +48,10 @@ func TestReadWrite(t *testing.T) {
 
 	writeFunc := func(t *testing.T, m *MultiReader, data []byte, wg *sync.WaitGroup) {
 		var (
-			n  int
-			dl int
-			r  int
+			n        int
+			dl       int
+			r        int
+			loopFlag bool
 		)
 		defer wg.Done()
 
@@ -60,13 +63,21 @@ func TestReadWrite(t *testing.T) {
 				r, _ = m.Write(data[n : n+512+dl])
 			}
 			n += r
+			if rand.Intn(5) == 0 {
+				loopFlag = false
+				for !loopFlag {
+					if rand.Intn(100) == 0 {
+						loopFlag = true
+					}
+				}
+			}
 		}
 		_ = m.Close()
 	}
 	wg.Add(1)
 	go writeFunc(t, m, src, wg)
 
-	readFunc := func(t *testing.T, r *Reader, data []byte, wg *sync.WaitGroup) {
+	readFunc := func(t *testing.T, r *Reader, data []byte, wg *sync.WaitGroup, split bool) {
 		var (
 			offset int
 			n      int
@@ -77,10 +88,30 @@ func TestReadWrite(t *testing.T) {
 		offset = 0
 		for {
 			if offset+1024 < len(data) {
-				n, err = r.Read(data[offset : offset+1024])
-				if err != nil {
-					t.Logf("reader got error: %v", err)
-					break
+				if split {
+					_, err = r.WaitAvailable()
+					if err != nil {
+						t.Logf("reader got error on WaitAvailable: %v", err)
+						break
+					}
+					n, err = r.ReadAhead(data[offset : offset+1024])
+					if err != nil {
+						t.Logf("reader got error on ReadAhead: %v", err)
+						break
+					}
+
+					n -= 5
+					_, err = r.Seek(int64(n), io.SeekCurrent)
+					if err != nil {
+						t.Logf("reader got error on Seek: %v", err)
+						break
+					}
+				} else {
+					n, err = r.Read(data[offset : offset+1024])
+					if err != nil {
+						t.Logf("reader got error: %v", err)
+						break
+					}
 				}
 			} else {
 				n, err = r.Read(data[offset:])
@@ -95,11 +126,11 @@ func TestReadWrite(t *testing.T) {
 	}
 
 	wg.Add(1)
-	go readFunc(t, r1, dst1, wg)
+	go readFunc(t, r1, dst1, wg, false)
 	wg.Add(1)
-	go readFunc(t, r2, dst2, wg)
+	go readFunc(t, r2, dst2, wg, false)
 	wg.Add(1)
-	go readFunc(t, r3, dst3, wg)
+	go readFunc(t, r3, dst3, wg, true)
 
 	wg.Wait()
 	if !bytes.Equal(src, dst1) {
@@ -112,3 +143,149 @@ func TestReadWrite(t *testing.T) {
 		t.Error("src and dst3 mismatch")
 	}
 }
+
+func TestReaderClose(t *testing.T) {
+	var (
+		m                    *MultiReader
+		r1                   *Reader
+		r2                   *Reader
+		r3                   *Reader
+		src, dst, dst1, dst3 []byte
+		err                  error
+		found                bool
+		ctr                  int
+	)
+
+	src = make([]byte, 16)
+	dst = make([]byte, 32)
+	dst1 = dst[:16]
+	dst3 = dst[16:]
+	m = NewMultiReader(0)
+	r1 = m.NewReader()
+	r2 = m.NewReader()
+	r3 = m.NewReader()
+
+	_, _ = rand.Read(src)
+	_, err = m.Write(src)
+	if err != nil {
+		t.Fatalf("error setting up data: %v", err)
+	}
+
+	found = false
+	for ctr = range m.pos {
+		if m.pos[ctr].id == r2.id {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Error("unexpected behavior, r2 should exist in reader position list")
+	}
+
+	_ = r2.Close()
+	_, err = r2.Read(dst)
+	if err == nil && err != ErrReaderClosed {
+		t.Error("unexpected behavior, r2 should be closed")
+	}
+
+	found = false
+	for ctr = range m.pos {
+		if m.pos[ctr].id == r2.id {
+			found = true
+			break
+		}
+	}
+	if found {
+		t.Error("unexpected behavior, r2 should be removed from reader position list")
+	}
+
+	_, err = r1.Read(dst1)
+	if err != nil {
+		t.Errorf("failing to read from r1")
+	}
+	if !bytes.Equal(dst1, src) {
+		t.Error("invalid result reading from r1")
+	}
+
+	_ = m.Close()
+	_, err = r3.Read(dst3)
+	if err != nil {
+		t.Errorf("unexpected behavior, cannot read form r3: %v", err)
+	}
+	if !bytes.Equal(src, dst3) {
+		t.Error("invalid result reading from r3")
+	}
+
+	_, err = r3.WaitAvailable()
+	if err == nil {
+		t.Error("unexpected behavior; WaitAvailable when readpos == lastWritePos should fail")
+	}
+
+	_, err = r3.ReadAhead(dst3)
+	if err == nil {
+		t.Error("unexpected behavior; ReadAhead when readpos == lastWritePos should fail")
+	}
+
+}
+
+func TestNotify(t *testing.T) {
+	src := make([]byte, 16)
+	_, _ = rand.Read(src)
+
+	wg := &sync.WaitGroup{}
+	cr := make(chan int, 3)
+	m := NewMultiReader(0)
+	r := make([]*Reader, 0)
+	r = append(r, m.NewReader(), m.NewReader(), m.NewReader())
+	for i := range r {
+		r[i].NotifyFunc(func(ix int) {
+			wg.Add(1)
+			defer wg.Done()
+			cr <- ix
+		})
+	}
+	_, _ = m.Write(src)
+	time.Sleep(time.Millisecond)
+	wg.Wait()
+
+	nctr := 0
+	stop := false
+	for !stop {
+		select {
+		case rd := <-cr:
+			nctr++
+			if rd != 16 {
+				t.Error("unexpected notify value")
+			}
+		default:
+			stop = true
+		}
+	}
+	if nctr != 3 {
+		t.Error("unexpected number of notify event")
+	}
+
+	_, _ = r[0].Seek(16, io.SeekCurrent)
+	_, _ = r[1].Seek(8, io.SeekCurrent)
+	_, _ = r[2].Seek(16, io.SeekCurrent)
+
+	_, _ = m.Write(src[:8])
+	time.Sleep(time.Millisecond)
+	wg.Wait()
+	stop = false
+	nctr = 0
+	for !stop {
+		select {
+		case rd := <-cr:
+			nctr++
+			if rd != 8 {
+				t.Error("unexpected notify value")
+			}
+		default:
+			stop = true
+		}
+	}
+	if nctr != 2 {
+		t.Error("unexpected number of notify event")
+	}
+}

multireader.go

@@ -20,6 +20,7 @@ type MultiReader struct {
 	buffer       []byte
 	readers      []*Reader
 	pos          []*Reader
+	notif        []*Reader
 	lastWritePos int
 	closed       bool
 }
@@ -28,11 +29,13 @@ type Reader struct {
 	multiReader *MultiReader
 	mtx         *sync.Mutex
 	cond        *sync.Cond
+	notify      func(int)
 	id          int
 	readPos     int
 	closed      bool
 }
 
+//MultiReader initialize new MultiReader object. The object also implements WriteCloser.
 func NewMultiReader(len int) *MultiReader {
 	if len < 0 {
 		len = 0
@@ -46,23 +49,39 @@ func NewMultiReader(len int) *MultiReader {
 		buffer:       buff,
 		readers:      make([]*Reader, 0),
 		pos:          make([]*Reader, 0),
+		notif:        make([]*Reader, 0),
 		lastWritePos: 0,
 		closed:       false,
 	}
 }
 
+func (m *MultiReader) notify(dataLen int) {
+	m.cond.Broadcast()
+	for _, reader := range m.notif {
+		if reader.notify != nil && reader.readPos >= m.lastWritePos-dataLen && !reader.closed {
+			go func() {
+				reader.notify(dataLen)
+			}()
+		}
+	}
+}
+
+// Write implements Writer interface. The function will not return error. Error return only satisfy the interface.
 func (m *MultiReader) Write(data []byte) (int, error) {
 	m.mtx.Lock()
 	defer m.mtx.Unlock()
-	defer m.cond.Broadcast()
 
 	var (
 		tmpBuff []byte
+		dataLen int
 	)
 
 	if m.closed {
 		return 0, ErrMultiReaderClosed
 	}
+	defer func(ip *int) {
+		m.notify(*ip)
+	}(&dataLen)
 
 	if m.lastWritePos+len(data) > len(m.buffer) {
 		tmpBuff = make([]byte, m.lastWritePos+len(data)-len(m.buffer))
@@ -70,6 +89,8 @@ func (m *MultiReader) Write(data []byte) (int, error) {
 	}
 	copy(m.buffer[m.lastWritePos:], data)
 	m.lastWritePos += len(data)
+	dataLen = len(data)
+	//_ = dataLen //prevents lint complaining about ineffectual assignment
 
 	return len(data), nil
 }
@@ -116,6 +137,7 @@ func (m *MultiReader) removeReader(id int) {
 	m.pos = nb
 }
 
+// Close will not return error. The error return only satisfy the interface signature.
 func (m *MultiReader) Close() error {
 	m.mtx.Lock()
 	defer m.mtx.Unlock()
@@ -123,6 +145,7 @@ func (m *MultiReader) Close() error {
 	return nil
 }
 
+// NewReader initialize new Reader object. The object implements ReadCloser and Seeker interface.
 func (m *MultiReader) NewReader() *Reader {
 	m.mtx.Lock()
 	defer m.mtx.Unlock()
@@ -141,10 +164,44 @@ func (m *MultiReader) NewReader() *Reader {
 	return reader
 }
 
+// NotifyFunc sets up a callback function notify. The notify function will be called when there is a Write operation.
+// Notify function passed to the NotifyFunc will executed in a separate go routine for each notify function.
+// It's the caller responsibility to setup any synchronization to prevent data race.
+func (r *Reader) NotifyFunc(notify func(int)) {
+	r.mtx.Lock()
+	defer r.mtx.Unlock()
+
+	r.notify = notify
+
+	var x int
+	switch len(r.multiReader.notif) {
+	case 0:
+		r.multiReader.notif = append(r.multiReader.notif, r)
+	case 1:
+		if r.multiReader.notif[0].id != r.id {
+			goto notifyFuncAppend2
+		}
+	default:
+		goto notifyFuncAppend1
+	}
+	return
+
+notifyFuncAppend1:
+	x = sort.Search(len(r.multiReader.notif), func(i int) bool { return r.multiReader.notif[i].id >= r.id })
+	if x < len(r.multiReader.notif) && r.id == x {
+		return
+	}
+
+notifyFuncAppend2:
+	r.multiReader.notif = append(r.multiReader.notif, r)
+	sort.Slice(r.multiReader.notif, func(i, j int) bool { return r.multiReader.notif[i].id < r.multiReader.notif[j].id })
+}
+
+// Read implements Reader interface. If the reader reached the same position with the writer. It will wait.
+// Calling Read() is the same with calling WaitAvailable(), ReadAhead(), and Seek()
 func (r *Reader) Read(data []byte) (int, error) {
 	r.mtx.Lock()
 	defer r.mtx.Unlock()
-	defer r.cond.Broadcast()
 
 	var (
 		n   int
@@ -184,6 +241,8 @@ func (r *Reader) seek(offset int, whence int) (int, error) {
 	return r.readPos, nil
 }
 
+// Seek implements Seeker interface. The underlying function will move the reader position.
+// It only returns error when the whence parameter is not in io.SeekStart, io.SeekCurrent, io.SeekEnd
 func (r *Reader) Seek(offset int64, whence int) (int64, error) {
 	n, err := r.seek(int(offset), whence)
 	return int64(n), err
@@ -203,6 +262,7 @@ func (r *Reader) readAhead(data []byte) (int, error) {
 	return len(data), nil
 }
 
+// ReadAhead reads buffer ahead of current position without moving the reader position.
 func (r *Reader) ReadAhead(data []byte) (int, error) {
 	r.mtx.Lock()
 	defer r.mtx.Unlock()
@@ -210,10 +270,11 @@ func (r *Reader) ReadAhead(data []byte) (int, error) {
 }
 
 func (r *Reader) waitAvailable() (int, error) {
+	if r.closed {
+		return 0, ErrReaderClosed
+	}
+
 	for r.readPos >= r.multiReader.lastWritePos {
-		if r.closed {
-			return 0, ErrReaderClosed
-		}
 		if r.multiReader.closed {
 			return 0, ErrMultiReaderClosed
 		}
@@ -223,12 +284,14 @@ func (r *Reader) waitAvailable() (int, error) {
 	return r.multiReader.lastWritePos - r.readPos, nil
 }
 
+// WaitAvailable will only wait when Reader position reached Writer position.
 func (r *Reader) WaitAvailable() (int, error) {
 	r.mtx.Lock()
 	defer r.mtx.Unlock()
 	return r.waitAvailable()
 }
 
+// Close implements ReadCloser interface. It will not return error.
 func (r *Reader) Close() error {
 	r.mtx.Lock()
 	defer r.mtx.Unlock()