Fix terminal resize race conditions

The runebuf, search and complete data structures all maintain their
own cache of the terminal width and height. When the terminal is
resized, a signal is sent to a go routine which calls a function
that sets the new width and height to each data structure instance.
However, this races with the main thread reading the sizes.

Instead of introducing more locks, it makes sense that the terminal
itself caches it's width and height and the other structures just
get it as necessary. This removes all the racing.

As part of this change, search, complete and runebuf constructor
changes to no longer require the initial sizes. Also each structure
needs a reference to the Terminal so they can get the width/height.
As the io.Writer parameter is actually the terminal anyway, the
simpliest option was just to change the type from the io.Writer to
Terminal. I don't believe that anyone would be calling these
functions directly so the signature changes should be ok. I also
removed the no longer used OnWidthChange() and OnSizeChange()
functions from these three structures.

complete.go

@@ -4,7 +4,6 @@ import (
 	"bufio"
 	"bytes"
 	"fmt"
-	"io"
 )
 
 type AutoCompleter interface {
@@ -25,10 +24,8 @@ func (t *TabCompleter) Do([]rune, int) ([][]rune, int) {
 }
 
 type opCompleter struct {
-	w               io.Writer
+	w               *Terminal
 	op              *Operation
-	width           int
-	height          int
 
 	inCompleteMode  bool
 	inSelectMode    bool
@@ -42,12 +39,10 @@ type opCompleter struct {
 	candidateColWidth  int           // width of candidate columns
 }
 
-func newOpCompleter(w io.Writer, op *Operation, width, height int) *opCompleter {
+func newOpCompleter(w *Terminal, op *Operation) *opCompleter {
 	return &opCompleter{
 		w:      w,
 		op:     op,
-		width:  width,
-		height: height,
 	}
 }
 
@@ -73,7 +68,8 @@ func (o *opCompleter) nextCandidate(i int) {
 // when tab pressed if cannot do complete for reason such as width unknown
 // or no candidates available.
 func (o *opCompleter) OnComplete() (ringBell bool) {
-	if o.width == 0 || o.height < 3 {
+	tWidth, tHeight := o.w.GetWidthHeight()
+	if tWidth == 0 || tHeight < 3 {
 		return false
 	}
 	if o.IsInCompleteSelectMode() {
@@ -246,15 +242,6 @@ func (o *opCompleter) getMatrixSize() int {
 	return line * colNum
 }
 
-func (o *opCompleter) OnWidthChange(newWidth int) {
-	o.width = newWidth
-}
-
-func (o *opCompleter) OnSizeChange(newWidth, newHeight int) {
-	o.width = newWidth
-	o.height = newHeight
-}
-
 // setColumnInfo calculates column width and number of columns required
 // to present the list of candidates on the terminal.
 func (o *opCompleter) setColumnInfo() {
@@ -270,8 +257,10 @@ func (o *opCompleter) setColumnInfo() {
 	}
 	colWidth++ // whitespace between cols
 
+	tWidth, _ := o.w.GetWidthHeight()
+
 	// -1 to avoid end of line issues
-	width := o.width - 1
+	width := tWidth - 1
 	colNum := width / colWidth
 	if colNum != 0 {
 		colWidth += (width - (colWidth * colNum)) / colNum
@@ -283,8 +272,9 @@ func (o *opCompleter) setColumnInfo() {
 
 // needPagerMode returns true if number of candidates would go off the page
 func (o *opCompleter) needPagerMode() bool {
+	tWidth, tHeight := o.w.GetWidthHeight()
 	buflineCnt := o.op.buf.LineCount()           // lines taken by buffer content
-	linesAvail := o.height - buflineCnt          // lines available without scrolling buffer off screen
+	linesAvail := tHeight - buflineCnt           // lines available without scrolling buffer off screen
 	if o.candidateColNum > 0 {
 		// Normal case where each candidate at least fits on a line
 		maxOrPage := linesAvail * o.candidateColNum  // max candiates without needing to page
@@ -299,9 +289,9 @@ func (o *opCompleter) needPagerMode() bool {
 	for _, c := range o.candidate {
 		cWidth := sameWidth + runes.WidthAll(c)
 		cLines := 1
-		if o.width > 0 {
-			cLines = cWidth / o.width
-			if cWidth % o.width > 0 {
+		if tWidth > 0 {
+			cLines = cWidth / tWidth
+			if cWidth % tWidth > 0 {
 				cLines++
 			}
 		}
@@ -326,6 +316,7 @@ func (o *opCompleter) CompleteRefresh() {
 	buf.WriteString("\033[J")
 
 	same := o.op.buf.RuneSlice(-o.candidateOff)
+	tWidth, _ := o.w.GetWidthHeight()
 
 	colIdx := 0
 	lines := 0
@@ -334,13 +325,13 @@ func (o *opCompleter) CompleteRefresh() {
 		inSelect := idx == o.candidateChoise && o.IsInCompleteSelectMode()
 		cWidth := sameWidth + runes.WidthAll(c)
 		cLines := 1
-		if o.width > 0 {
+		if tWidth > 0 {
 			sWidth := 0
 			if isWindows && inSelect {
 				sWidth = 1 // adjust for hightlighting on Windows
 			}
-			cLines = (cWidth + sWidth) / o.width
-			if (cWidth + sWidth) % o.width > 0 {
+			cLines = (cWidth + sWidth) / tWidth
+			if (cWidth + sWidth) % tWidth > 0 {
 				cLines++
 			}
 		}
@@ -408,6 +399,7 @@ func (o *opCompleter) pagerRefresh() (stayInMode bool) {
 
 	same := o.op.buf.RuneSlice(-o.candidateOff)
 	sameWidth := runes.WidthAll(same)
+	tWidth, tHeight := o.w.GetWidthHeight()
 
 	colIdx := 0
 	lines := 1
@@ -415,13 +407,13 @@ func (o *opCompleter) pagerRefresh() (stayInMode bool) {
 		c := o.candidate[o.candidateChoise]
 		cWidth := sameWidth + runes.WidthAll(c)
 		cLines := 1
-		if o.width > 0 {
-			cLines = cWidth / o.width
-			if cWidth % o.width > 0 {
+		if tWidth > 0 {
+			cLines = cWidth / tWidth
+			if cWidth % tWidth > 0 {
 				cLines++
 			}
 		}
-		if lines > 1 && lines + cLines > o.height {
+		if lines > 1 && lines + cLines > tHeight {
 			break // won't fit on page, stop early.
 		}
 		buf.WriteString(string(same))
@@ -460,7 +452,8 @@ func (o *opCompleter) pagerRefresh() (stayInMode bool) {
 // we rewrite the prompt it does not over write the page content. The code to rewrite
 // the prompt assumes the cursor is at the index line, so we add enough blank lines.
 func (o *opCompleter) scrollOutOfPagerMode() {
-	lineCnt := o.op.buf.IdxLine(o.width)
+	tWidth, _ := o.w.GetWidthHeight()
+	lineCnt := o.op.buf.IdxLine(tWidth)
 	if lineCnt > 0 {
 		buf := bufio.NewWriter(o.w)
 		buf.Write(bytes.Repeat([]byte("\n"), lineCnt))

operation.go

@@ -65,7 +65,8 @@ func (o *Operation) write(target io.Writer, b []byte) (int, error) {
 		n, err = target.Write(b)
 		// Adjust the prompt start position by b
 		rout := runes.ColorFilter([]rune(string(b[:])))
-		sp := SplitByLine(rout, []rune{}, o.buf.ppos, o.buf.width, 1)
+		tWidth, _ := o.t.GetWidthHeight()
+		sp := SplitByLine(rout, []rune{}, o.buf.ppos, tWidth, 1)
 		if len(sp) > 1 {
 			o.buf.ppos = len(sp[len(sp)-1])
 		} else {
@@ -83,24 +84,18 @@ func (o *Operation) write(target io.Writer, b []byte) (int, error) {
 }
 
 func NewOperation(t *Terminal, cfg *Config) *Operation {
-	width, height := cfg.FuncGetSize()
 	op := &Operation{
 		t:       t,
-		buf:     NewRuneBuffer(t, cfg.Prompt, cfg, width, height),
+		buf:     NewRuneBuffer(t, cfg.Prompt, cfg),
 		outchan: make(chan []rune),
 		errchan: make(chan error, 1),
 	}
 	op.w = op.buf.w
 	op.SetConfig(cfg)
 	op.opVim = newVimMode(op)
-	op.opCompleter = newOpCompleter(op.buf.w, op, width, height)
+	op.opCompleter = newOpCompleter(op.buf.w, op)
 	op.opPassword = newOpPassword(op)
-	op.cfg.FuncOnWidthChanged(func() {
-		newWidth, newHeight := cfg.FuncGetSize()
-		op.opCompleter.OnSizeChange(newWidth, newHeight)
-		op.opSearch.OnSizeChange(newWidth, newHeight)
-		op.buf.OnSizeChange(newWidth, newHeight)
-	})
+	op.cfg.FuncOnWidthChanged(t.OnSizeChange)
 	go op.ioloop()
 	return op
 }
@@ -431,7 +426,7 @@ func (o *Operation) Runes() ([]rune, error) {
 	// maybe existing text on the same line that ideally we don't
 	// want to overwrite and cause prompt to jump left. Note that
 	// this is not perfect but works the majority of the time.
-	o.buf.getAndSetOffset(o.t)
+	o.buf.getAndSetOffset()
 	o.buf.Print() // print prompt & buffer contents
 	o.t.KickRead()
 
@@ -525,12 +520,11 @@ func (op *Operation) SetConfig(cfg *Config) (*Config, error) {
 	op.SetPrompt(cfg.Prompt)
 	op.SetMaskRune(cfg.MaskRune)
 	op.buf.SetConfig(cfg)
-	width, height := op.cfg.FuncGetSize()
 
 	if cfg.opHistory == nil {
 		op.SetHistoryPath(cfg.HistoryFile)
 		cfg.opHistory = op.history
-		cfg.opSearch = newOpSearch(op.buf.w, op.buf, op.history, cfg, width, height)
+		cfg.opSearch = newOpSearch(op.buf.w, op.buf, op.history, cfg)
 	}
 	op.history = cfg.opHistory
 
@@ -538,8 +532,8 @@ func (op *Operation) SetConfig(cfg *Config) (*Config, error) {
 	// so if we use it next time, we need to reopen it by `InitHistory()`
 	op.history.Init()
 
-	if op.cfg.AutoComplete != nil {
-		op.opCompleter = newOpCompleter(op.buf.w, op, width, height)
+	if op.cfg.AutoComplete != nil && op.opCompleter == nil {
+		op.opCompleter = newOpCompleter(op.buf.w, op)
 	}
 
 	op.opSearch = cfg.opSearch

runebuf.go

@@ -18,14 +18,11 @@ type RuneBuffer struct {
 	buf    []rune
 	idx    int
 	prompt []rune
-	w      io.Writer
+	w      *Terminal
 
 	interactive bool
 	cfg         *Config
 
-	width  int
-	height int
-
 	bck *runeBufferBck
 
 	offset string          // is offset useful? scrolling means row varies
@@ -40,19 +37,6 @@ func (r *RuneBuffer) pushKill(text []rune) {
 	r.lastKill = append([]rune{}, text...)
 }
 
-func (r *RuneBuffer) OnWidthChange(newWidth int) {
-	r.Lock()
-	r.width = newWidth
-	r.Unlock()
-}
-
-func (r *RuneBuffer) OnSizeChange(newWidth, newHeight int) {
-	r.Lock()
-	r.width = newWidth
-	r.height = newHeight
-	r.Unlock()
-}
-
 func (r *RuneBuffer) Backup() {
 	r.Lock()
 	r.bck = &runeBufferBck{r.buf, r.idx}
@@ -69,13 +53,11 @@ func (r *RuneBuffer) Restore() {
 	})
 }
 
-func NewRuneBuffer(w io.Writer, prompt string, cfg *Config, width int, height int) *RuneBuffer {
+func NewRuneBuffer(w *Terminal, prompt string, cfg *Config) *RuneBuffer {
 	rb := &RuneBuffer{
 		w:           w,
 		interactive: cfg.useInteractive(),
 		cfg:         cfg,
-		width:       width,
-		height:      height,
 	}
 	rb.SetPrompt(prompt)
 	return rb
@@ -102,9 +84,8 @@ func (r *RuneBuffer) CurrentWidth(x int) int {
 
 func (r *RuneBuffer) PromptLen() int {
 	r.Lock()
-	width := r.promptLen()
-	r.Unlock()
-	return width
+	defer r.Unlock()
+	return r.promptLen()
 }
 
 func (r *RuneBuffer) promptLen() int {
@@ -448,12 +429,13 @@ func (r *RuneBuffer) isInLineEdge() bool {
 }
 
 func (r *RuneBuffer) getSplitByLine(rs []rune, nextWidth int) [][]rune {
+	tWidth, _ := r.w.GetWidthHeight()
 	if r.cfg.EnableMask {
 		w := runes.Width(r.cfg.MaskRune)
 		masked := []rune(strings.Repeat(string(r.cfg.MaskRune), len(rs)))
-		return SplitByLine(runes.ColorFilter(r.prompt), masked, r.ppos, r.width, w)
+		return SplitByLine(runes.ColorFilter(r.prompt), masked, r.ppos, tWidth, w)
 	} else {
-		return SplitByLine(runes.ColorFilter(r.prompt), rs, r.ppos, r.width, nextWidth)
+		return SplitByLine(runes.ColorFilter(r.prompt), rs, r.ppos, tWidth, nextWidth)
 	}
 }
 
@@ -476,7 +458,8 @@ func (r *RuneBuffer) idxLine(width int) int {
 }
 
 func (r *RuneBuffer) CursorLineCount() int {
-	return r.LineCount() - r.IdxLine(r.width)
+	tWidth, _ := r.w.GetWidthHeight()
+	return r.LineCount() - r.IdxLine(tWidth)
 }
 
 func (r *RuneBuffer) Refresh(f func()) {
@@ -506,7 +489,7 @@ func (r *RuneBuffer) refresh(f func()) {
 // will write the offset back to us via stdin and there may already be 
 // other data in the stdin buffer ahead of it.
 // This function is called at the start of readline each time.
-func (r *RuneBuffer) getAndSetOffset(t *Terminal) {
+func (r *RuneBuffer) getAndSetOffset() {
 	if !r.interactive {
 		return
 	}
@@ -517,7 +500,7 @@ func (r *RuneBuffer) getAndSetOffset(t *Terminal) {
 		// at the beginning of the next line.
 		r.w.Write([]byte(" \b"))
 	}
-	t.GetOffset(r.SetOffset)
+	r.w.GetOffset(r.SetOffset)
 }
 
 func (r *RuneBuffer) SetOffset(offset string) {
@@ -528,8 +511,9 @@ func (r *RuneBuffer) SetOffset(offset string) {
 
 func (r *RuneBuffer) setOffset(offset string) {
 	r.offset = offset
-	if _, c, ok := (&escapeKeyPair{attr:offset}).Get2(); ok && c > 0 && c < r.width {
-		r.ppos = c - 1  // c should be 1..width
+	tWidth, _ := r.w.GetWidthHeight()
+	if _, c, ok := (&escapeKeyPair{attr:offset}).Get2(); ok && c > 0 && c < tWidth {
+		r.ppos = c - 1  // c should be 1..tWidth
 	} else {
 		r.ppos = 0
 	}
@@ -703,7 +687,8 @@ func (r *RuneBuffer) SetPrompt(prompt string) {
 func (r *RuneBuffer) cleanOutput(w io.Writer, idxLine int) {
 	buf := bufio.NewWriter(w)
 
-	if r.width == 0 {
+	tWidth, _ := r.w.GetWidthHeight()
+	if tWidth == 0 {
 		buf.WriteString(strings.Repeat("\r\b", len(r.buf)+r.promptLen()))
 		buf.Write([]byte("\033[J"))
 	} else {
@@ -724,7 +709,8 @@ func (r *RuneBuffer) Clean() {
 }
 
 func (r *RuneBuffer) clean() {
-	r.cleanWithIdxLine(r.idxLine(r.width))
+	tWidth, _ := r.w.GetWidthHeight()
+	r.cleanWithIdxLine(r.idxLine(tWidth))
 }
 
 func (r *RuneBuffer) cleanWithIdxLine(idxLine int) {

search.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"container/list"
 	"fmt"
-	"io"
 )
 
 const (
@@ -22,36 +21,24 @@ type opSearch struct {
 	state     int
 	dir       int
 	source    *list.Element
-	w         io.Writer
+	w         *Terminal
 	buf       *RuneBuffer
 	data      []rune
 	history   *opHistory
 	cfg       *Config
 	markStart int
 	markEnd   int
-	width     int
-	height    int
 }
 
-func newOpSearch(w io.Writer, buf *RuneBuffer, history *opHistory, cfg *Config, width int, height int) *opSearch {
+func newOpSearch(w *Terminal, buf *RuneBuffer, history *opHistory, cfg *Config) *opSearch {
 	return &opSearch{
 		w:       w,
 		buf:     buf,
 		cfg:     cfg,
 		history: history,
-		width:   width,
-		height:  height,
 	}
 }
 
-func (o *opSearch) OnWidthChange(newWidth int) {
-	o.width = newWidth
-}
-func (o *opSearch) OnSizeChange(newWidth, newHeight int) {
-	o.width = newWidth
-	o.height = newHeight
-}
-
 func (o *opSearch) IsSearchMode() bool {
 	return o.inMode
 }
@@ -103,7 +90,8 @@ func (o *opSearch) SearchChar(r rune) {
 }
 
 func (o *opSearch) SearchMode(dir int) bool {
-	if o.width == 0 {
+	tWidth, _ := o.w.GetWidthHeight()
+	if tWidth == 0 {
 		return false
 	}
 	alreadyInMode := o.inMode
@@ -131,6 +119,7 @@ func (o *opSearch) ExitSearchMode(revert bool) {
 }
 
 func (o *opSearch) SearchRefresh(x int) {
+	tWidth, _ := o.w.GetWidthHeight()
 	if x == -2 {
 		o.state = S_STATE_FAILING
 	} else if x >= 0 {
@@ -141,7 +130,7 @@ func (o *opSearch) SearchRefresh(x int) {
 	}
 	x = o.buf.CurrentWidth(x)
 	x += o.buf.PromptLen()
-	x = x % o.width
+	x = x % tWidth
 
 	if o.markStart > 0 {
 		o.buf.SetStyle(o.markStart, o.markEnd, "4")

terminal.go

@@ -19,6 +19,8 @@ type Terminal struct {
 	wg        sync.WaitGroup
 	sleeping  int32
 
+	width     int                 // terminal width
+	height    int                 // terminal height
 	sizeChan  chan string
 }
 
@@ -33,6 +35,8 @@ func NewTerminal(cfg *Config) (*Terminal, error) {
 		stopChan: make(chan struct{}, 1),
 		sizeChan: make(chan string, 1),
 	}
+	// Get and cache the current terminal size.
+	t.OnSizeChange()
 
 	go t.ioloop()
 	return t, nil
@@ -244,3 +248,17 @@ func (t *Terminal) SetConfig(c *Config) error {
 	t.m.Unlock()
 	return nil
 }
+
+// OnSizeChange gets the current terminal size and caches it
+func (t *Terminal) OnSizeChange() {
+	t.m.Lock()
+	defer t.m.Unlock()
+	t.width, t.height = t.cfg.FuncGetSize()
+}
+
+// GetWidthHeight returns the cached width, height values from the terminal
+func (t *Terminal) GetWidthHeight() (width, height int) {
+	t.m.Lock()
+	defer t.m.Unlock()
+	return t.width, t.height
+}