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|
package tasks
import (
"bufio"
"fmt"
"io"
"os/exec"
"strings"
"sync"
"time"
"github.com/jesseduffield/gocui"
"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
"github.com/jesseduffield/lazygit/pkg/utils"
"github.com/sasha-s/go-deadlock"
"github.com/sirupsen/logrus"
)
// This file revolves around running commands that will be output to the main panel
// in the gui. If we're flicking through the commits panel, we want to invoke a
// `git show` command for each commit, but we don't want to read the entire output
// at once (because that would slow things down); we just want to fill the panel
// and then read more as the user scrolls down. We also want to ensure that we're only
// ever running one `git show` command at time, and that we only have one command
// writing its output to the main panel at a time.
const THROTTLE_TIME = time.Millisecond * 30
// we use this to check if the system is under stress right now. Hopefully this makes sense on other machines
const COMMAND_START_THRESHOLD = time.Millisecond * 10
type ViewBufferManager struct {
// this blocks until the task has been properly stopped
stopCurrentTask func()
// this is what we write the output of the task to. It's typically a view
writer io.Writer
waitingMutex deadlock.Mutex
taskIDMutex deadlock.Mutex
Log *logrus.Entry
newTaskID int
readLines chan LinesToRead
taskKey string
onNewKey func()
// beforeStart is the function that is called before starting a new task
beforeStart func()
refreshView func()
onEndOfInput func()
// see docs/dev/Busy.md
// A gocui task is not the same thing as the tasks defined in this file.
// A gocui task simply represents the fact that lazygit is busy doing something,
// whereas the tasks in this file are about rendering content to a view.
newGocuiTask func() gocui.Task
// if the user flicks through a heap of items, with each one
// spawning a process to render something to the main view,
// it can slow things down quite a bit. In these situations we
// want to throttle the spawning of processes.
throttle bool
}
type LinesToRead struct {
// Total number of lines to read
Total int
// Number of lines after which we have read enough to fill the view, and can
// do an initial refresh. Only set for the initial read request; -1 for
// subsequent requests.
InitialRefreshAfter int
}
func (m *ViewBufferManager) GetTaskKey() string {
return m.taskKey
}
func NewViewBufferManager(
log *logrus.Entry,
writer io.Writer,
beforeStart func(),
refreshView func(),
onEndOfInput func(),
onNewKey func(),
newGocuiTask func() gocui.Task,
) *ViewBufferManager {
return &ViewBufferManager{
Log: log,
writer: writer,
beforeStart: beforeStart,
refreshView: refreshView,
onEndOfInput: onEndOfInput,
readLines: make(chan LinesToRead, 1024),
onNewKey: onNewKey,
newGocuiTask: newGocuiTask,
}
}
func (self *ViewBufferManager) ReadLines(n int) {
go utils.Safe(func() {
self.readLines <- LinesToRead{Total: n, InitialRefreshAfter: -1}
})
}
func (self *ViewBufferManager) NewCmdTask(start func() (*exec.Cmd, io.Reader), prefix string, linesToRead LinesToRead, onDoneFn func()) func(TaskOpts) error {
return func(opts TaskOpts) error {
var onDoneOnce sync.Once
var onFirstPageShownOnce sync.Once
onFirstPageShown := func() {
onFirstPageShownOnce.Do(func() {
opts.InitialContentLoaded()
})
}
onDone := func() {
if onDoneFn != nil {
onDoneOnce.Do(onDoneFn)
}
onFirstPageShown()
}
if self.throttle {
self.Log.Info("throttling task")
time.Sleep(THROTTLE_TIME)
}
select {
case <-opts.Stop:
onDone()
return nil
default:
}
startTime := time.Now()
cmd, r := start()
timeToStart := time.Since(startTime)
go utils.Safe(func() {
<-opts.Stop
// we use the time it took to start the program as a way of checking if things
// are running slow at the moment. This is admittedly a crude estimate, but
// the point is that we only want to throttle when things are running slow
// and the user is flicking through a bunch of items.
self.throttle = time.Since(startTime) < THROTTLE_TIME && timeToStart > COMMAND_START_THRESHOLD
if err := oscommands.Kill(cmd); err != nil {
if !strings.Contains(err.Error(), "process already finished") {
self.Log.Errorf("error when running cmd task: %v", err)
}
}
// for pty's we need to call onDone here so that cmd.Wait() doesn't block forever
onDone()
})
loadingMutex := deadlock.Mutex{}
// not sure if it's the right move to redefine this or not
self.readLines = make(chan LinesToRead, 1024)
done := make(chan struct{})
scanner := bufio.NewScanner(r)
scanner.Split(bufio.ScanLines)
loaded := false
go utils.Safe(func() {
ticker := time.NewTicker(time.Millisecond * 200)
defer ticker.Stop()
select {
case <-opts.Stop:
return
case <-ticker.C:
loadingMutex.Lock()
if !loaded {
self.beforeStart()
_, _ = self.writer.Write([]byte("loading..."))
self.refreshView()
}
loadingMutex.Unlock()
}
})
go utils.Safe(func() {
isViewStale := true
writeToView := func(content []byte) {
isViewStale = true
_, _ = self.writer.Write(content)
}
refreshViewIfStale := func() {
if isViewStale {
self.refreshView()
isViewStale = false
}
}
outer:
for {
select {
case <-opts.Stop:
break outer
case linesToRead := <-self.readLines:
for i := 0; i < linesToRead.Total; i++ {
select {
case <-opts.Stop:
break outer
default:
}
ok := scanner.Scan()
loadingMutex.Lock()
if !loaded {
self.beforeStart()
if prefix != "" {
writeToView([]byte(prefix))
}
loaded = true
}
loadingMutex.Unlock()
if !ok {
// if we're here then there's nothing left to scan from the source
// so we're at the EOF and can flush the stale content
self.onEndOfInput()
break outer
}
writeToView(append(scanner.Bytes(), '\n'))
if i+1 == linesToRead.InitialRefreshAfter {
// We have read enough lines to fill the view, so do a first refresh
// here to show what we have. Continue reading and refresh again at
// the end to make sure the scrollbar has the right size.
refreshViewIfStale()
}
}
refreshViewIfStale()
onFirstPageShown()
}
}
refreshViewIfStale()
if err := cmd.Wait(); err != nil {
// it's fine if we've killed this program ourselves
if !strings.Contains(err.Error(), "signal: killed") {
self.Log.Errorf("Unexpected error when running cmd task: %v", err)
}
}
// calling this here again in case the program ended on its own accord
onDone()
close(done)
})
self.readLines <- linesToRead
<-done
return nil
}
}
// Close closes the task manager, killing whatever task may currently be running
func (self *ViewBufferManager) Close() {
if self.stopCurrentTask == nil {
return
}
c := make(chan struct{})
go utils.Safe
|