doc: add godoc format documentation

multireader.go

@@ -1,3 +1,4 @@
+//Package multireader provides capability for single writer to multiple reader
 package multireader
 
 import (
@@ -33,6 +34,7 @@ type Reader struct {
 	closed      bool
 }
 
+//MultiReader initialize new MultiReader object. The object also implements WriteCloser.
 func NewMultiReader(len int) *MultiReader {
 	if len < 0 {
 		len = 0
@@ -51,6 +53,7 @@ func NewMultiReader(len int) *MultiReader {
 	}
 }
 
+// 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()
@@ -116,6 +119,7 @@ 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 +127,7 @@ 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()
@@ -141,6 +146,8 @@ func (m *MultiReader) NewReader() *Reader {
 	return reader
 }
 
+// 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()
@@ -184,6 +191,8 @@ 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 +212,7 @@ 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()
@@ -223,12 +233,14 @@ 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()