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source.go
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source.go
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package peco
import (
"bufio"
"context"
"io"
"sync"
"time"
"github.com/lestrrat-go/pdebug"
"github.com/peco/peco/internal/util"
"github.com/peco/peco/line"
"github.com/peco/peco/pipeline"
)
// Creates a new Source. Does not start processing the input until you
// call Setup()
func NewSource(name string, in io.Reader, isInfinite bool, idgen line.IDGenerator, capacity int, enableSep bool) *Source {
s := &Source{
name: name,
capacity: capacity,
enableSep: enableSep,
idgen: idgen,
in: in, // Note that this may be closed, so do not rely on it
inClosed: false,
isInfinite: isInfinite,
ready: make(chan struct{}),
setupDone: make(chan struct{}),
ChanOutput: pipeline.ChanOutput(make(chan interface{})),
}
s.Reset()
return s
}
func (s *Source) Name() string {
return s.name
}
func (s *Source) IsInfinite() bool {
return s.isInfinite && !s.inClosed
}
// Setup reads from the input os.File.
func (s *Source) Setup(ctx context.Context, state *Peco) {
s.setupOnce.Do(func() {
done := make(chan struct{})
refresh := make(chan struct{}, 1)
defer close(done)
defer close(refresh)
// And also, close the done channel so we can tell the consumers
// we have finished reading everything
defer close(s.setupDone)
draw := func(state *Peco) {
state.Hub().SendDraw(ctx, nil)
}
go func() {
ticker := time.NewTicker(100 * time.Millisecond)
defer ticker.Stop()
for {
select {
case <-done:
draw(state)
return
case <-ticker.C:
draw(state)
}
}
}()
// This sync.Once var is used to receive the notification
// that there was at least 1 line read from the source
// This is wrapped in a sync.Notify so we can safely call
// it in multiple places
var notify sync.Once
notifycb := func() {
// close the ready channel so others can be notified
// that there's at least 1 line in the buffer
state.Hub().SendStatusMsg(ctx, "")
close(s.ready)
}
// Register this to be called in a defer, just in case we could bailed
// out without reading a single line.
// Note: this will be a no-op if notify.Do has been called before
defer notify.Do(notifycb)
if pdebug.Enabled {
pdebug.Printf("Source: using buffer size of %dkb", state.maxScanBufferSize)
}
scanbuf := make([]byte, state.maxScanBufferSize*1024)
scanner := bufio.NewScanner(s.in)
scanner.Buffer(scanbuf, state.maxScanBufferSize*1024)
defer func() {
if util.IsTty(s.in) {
return
}
if closer, ok := s.in.(io.Closer); ok {
s.inClosed = true
closer.Close()
}
}()
lines := make(chan string)
go func() {
var scanned int
if pdebug.Enabled {
defer func() { pdebug.Printf("Source scanned %d lines", scanned) }()
}
defer close(lines)
for scanner.Scan() {
newLine := scanner.Text()
select {
case <-ctx.Done():
if pdebug.Enabled {
pdebug.Printf("Bailing out of source setup text reader loop, because ctx was canceled")
}
return
case lines <- newLine:
}
scanned++
}
}()
state.Hub().SendStatusMsg(ctx, "Waiting for input...")
readCount := 0
for loop := true; loop; {
select {
case <-ctx.Done():
if pdebug.Enabled {
pdebug.Printf("Bailing out of source setup, because ctx was canceled")
}
return
case l, ok := <-lines:
if !ok {
if pdebug.Enabled {
pdebug.Printf("No more lines to read...")
}
loop = false
break
}
readCount++
s.Append(line.NewRaw(s.idgen.Next(), l, s.enableSep))
notify.Do(notifycb)
}
}
if pdebug.Enabled {
pdebug.Printf("Read all %d lines from source", readCount)
}
})
}
// Start starts
func (s *Source) Start(ctx context.Context, out pipeline.ChanOutput) {
var sent int
// I should be the only one running this method until I bail out
if pdebug.Enabled {
g := pdebug.Marker("Source.Start (%d lines in buffer)", len(s.lines))
defer g.End()
defer func() { pdebug.Printf("Source sent %d lines", sent) }()
}
defer out.SendEndMark("end of input")
var resume bool
select {
case <-s.setupDone:
default:
resume = true
}
if !resume {
// no fancy resume handling needed. just go
for _, l := range s.lines {
select {
case <-ctx.Done():
if pdebug.Enabled {
pdebug.Printf("Source: context.Done detected")
}
return
default:
out.Send(l)
sent++
}
}
return
}
// For the first time we get called, we may possibly be in the
// middle of reading a really long input stream. In this case,
// we should resume where we left off.
var prev = 0
var setupDone bool
for {
// This is where we are ready up to
upto := s.Size()
// We bail out if we are done with the setup, and our
// buffer has not grown
if setupDone && upto == prev {
return
}
for i := prev; i < upto; i++ {
select {
case <-ctx.Done():
if pdebug.Enabled {
pdebug.Printf("Source: context.Done detected")
}
return
default:
l, _ := s.LineAt(i)
out.Send(l)
sent++
}
}
// Remember how far we have processed
prev = upto
// Check if we're done with setup
select {
case <-s.setupDone:
setupDone = true
default:
}
}
}
// Reset resets the state of the source object so that it
// is ready to feed the filters
func (s *Source) Reset() {
if pdebug.Enabled {
g := pdebug.Marker("Source.Reset")
defer g.End()
}
s.ChanOutput = pipeline.ChanOutput(make(chan interface{}))
}
// Ready returns the "input ready" channel. It will be closed as soon as
// the first line of input is processed via Setup()
func (s *Source) Ready() <-chan struct{} {
return s.ready
}
// SetupDone returns the "read all lines" channel. It will be closed as soon as
// the all input has been read
func (s *Source) SetupDone() <-chan struct{} {
return s.setupDone
}
func (s *Source) linesInRange(start, end int) []line.Line {
s.mutex.RLock()
defer s.mutex.RUnlock()
return s.lines[start:end]
}
func (s *Source) LineAt(n int) (line.Line, error) {
s.mutex.RLock()
defer s.mutex.RUnlock()
return bufferLineAt(s.lines, n)
}
func (s *Source) Size() int {
s.mutex.RLock()
defer s.mutex.RUnlock()
return bufferSize(s.lines)
}
func (s *Source) Append(l line.Line) {
s.mutex.Lock()
defer s.mutex.Unlock()
s.lines = append(s.lines, l)
if s.capacity > 0 && len(s.lines) > s.capacity {
diff := len(s.lines) - s.capacity
// Golang's version of array realloc
s.lines = s.lines[diff:s.capacity:s.capacity]
}
}