add history limitation

history.go

@@ -19,40 +19,81 @@ func (h *hisItem) Clean() {
 }
 
 type opHistory struct {
-	path       string
+	cfg        *Config
 	history    *list.List
 	historyVer int64
 	current    *list.Element
 	fd         *os.File
 }
 
-func newOpHistory(path string) (o *opHistory) {
+func newOpHistory(cfg *Config) (o *opHistory) {
 	o = &opHistory{
-		path:    path,
+		cfg:     cfg,
 		history: list.New(),
 	}
-	if o.path == "" {
-		return
+	if o.cfg.HistoryFile != "" {
+		o.historyUpdatePath(o.cfg.HistoryFile)
 	}
-	f, err := os.OpenFile(o.path, os.O_APPEND|os.O_CREATE|os.O_RDWR, 0666)
+	return
+}
+
+// only called by newOpHistory
+func (o *opHistory) historyUpdatePath(path string) {
+	f, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_RDWR, 0666)
 	if err != nil {
 		return
 	}
 	o.fd = f
 	r := bufio.NewReader(o.fd)
-	for {
+	total := 0
+	for ; ; total++ {
 		line, err := r.ReadSlice('\n')
 		if err != nil {
 			break
 		}
 		o.PushHistory([]rune(strings.TrimSpace(string(line))))
+		o.CompactHistory()
+	}
+	if total > o.cfg.HistoryLimit {
+		o.HistoryRewrite()
 	}
 	o.historyVer++
 	o.PushHistory(nil)
 	return
 }
 
-func (o *opHistory) Close() {
+func (o *opHistory) CompactHistory() {
+	for o.history.Len() > o.cfg.HistoryLimit {
+		o.history.Remove(o.history.Front())
+	}
+}
+
+func (o *opHistory) HistoryRewrite() {
+	if o.cfg.HistoryFile == "" {
+		return
+	}
+
+	tmpFile := o.cfg.HistoryFile + ".tmp"
+	fd, err := os.OpenFile(tmpFile, os.O_CREATE|os.O_WRONLY|os.O_TRUNC|os.O_APPEND, 0666)
+	if err != nil {
+		return
+	}
+	defer fd.Close()
+
+	buf := bufio.NewWriter(fd)
+	for elem := o.history.Front(); elem != nil; elem = elem.Next() {
+		buf.WriteString(string(elem.Value.(*hisItem).Source))
+	}
+	buf.Flush()
+
+	if o.fd != nil {
+		o.fd.Close()
+	}
+	// fd is write only, just satisfy what we need.
+	o.fd = fd
+}
+
+func (o *opHistory) CloseHistory() {
 	if o.fd != nil {
 		o.fd.Close()
 	}
@@ -197,7 +238,6 @@ func (o *opHistory) UpdateHistory(s []rune, commit bool) {
 }
 
 func (o *opHistory) PushHistory(s []rune) {
-	// copy
 	newCopy := make([]rune, len(s))
 	copy(newCopy, s)
 	elem := o.history.PushBack(&hisItem{Source: newCopy})

operation.go

@@ -55,8 +55,8 @@ func NewOperation(t *Terminal, cfg *Config) *Operation {
 		t:       t,
 		buf:     NewRuneBuffer(t, cfg.Prompt),
 		outchan: make(chan []rune),
-		opHistory: newOpHistory(cfg.HistoryFile),
 	}
+	op.SetHistoryPath(cfg.HistoryFile)
 	op.opVim = newVimMode(op)
 	op.w = op.buf.w
 	op.opSearch = newOpSearch(op.buf.w, op.buf, op.opHistory)
@@ -286,5 +286,13 @@ func (o *Operation) Slice() ([]byte, error) {
 }
 
 func (o *Operation) Close() {
-	o.opHistory.Close()
+	o.opHistory.CloseHistory()
+}
+
+func (o *Operation) SetHistoryPath(path string) {
+	if o.opHistory != nil {
+		o.opHistory.CloseHistory()
+	}
+	o.cfg.HistoryFile = path
+	o.opHistory = newOpHistory(o.cfg)
 }

readline.go

@@ -3,15 +3,26 @@ package readline
 import "io"
 
 type Instance struct {
+	Config    *Config
 	Terminal  *Terminal
 	Operation *Operation
 }
 
 type Config struct {
+	// prompt supports ANSI escape sequence, so we can color some characters even in windows
 	Prompt string
+
+	// readline will persist historys to file where HistoryFile specified
 	HistoryFile string
+	// specify the max length of historys, it's 500 by default
+	HistoryLimit int
+
+	// AutoCompleter will called once user press TAB
 	AutoComplete AutoCompleter
+
+	// If VimMode is true, readline will in vim.insert mode by default
 	VimMode bool
+
 	Stdout io.Writer
 	Stderr io.Writer
 
@@ -29,6 +40,9 @@ func (c *Config) Init() error {
 	if c.Stderr == nil {
 		c.Stderr = Stderr
 	}
+	if c.HistoryLimit < 0 {
+		c.HistoryLimit = 500
+	}
 	return nil
 }
 
@@ -39,6 +53,7 @@ func NewEx(cfg *Config) (*Instance, error) {
 	}
 	rl := t.Readline()
 	return &Instance{
+		Config:    cfg,
 		Terminal:  t,
 		Operation: rl,
 	}, nil
@@ -52,14 +67,22 @@ func (i *Instance) SetPrompt(s string) {
 	i.Operation.SetPrompt(s)
 }
 
+// change hisotry persistence in runtime
+func (i *Instance) SetHistoryPath(p string) {
+	i.Operation.SetHistoryPath(p)
+}
+
+// readline will refresh automatic when write through Stdout()
 func (i *Instance) Stdout() io.Writer {
 	return i.Operation.Stdout()
 }
 
+// readline will refresh automatic when write through Stdout()
 func (i *Instance) Stderr() io.Writer {
 	return i.Operation.Stderr()
 }
 
+// switch VimMode in runtime
 func (i *Instance) SetVimMode(on bool) {
 	i.Operation.SetVimMode(on)
 }
@@ -76,10 +99,12 @@ func (i *Instance) Readline() (string, error) {
 	return i.Operation.String()
 }
 
+// same as readline
 func (i *Instance) ReadSlice() ([]byte, error) {
 	return i.Operation.Slice()
 }
 
+// we must make sure that call Close() before process exit.
 func (i *Instance) Close() error {
 	if err := i.Terminal.Close(); err != nil {
 		return err