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|
package progress
import (
"context"
"io"
"sync"
)
type MultiReader struct {
mu sync.Mutex
main Reader
initialized bool
done chan struct{}
doneCause error
writers map[*progressWriter]func(error)
sent []*Progress
}
func NewMultiReader(pr Reader) *MultiReader {
mr := &MultiReader{
main: pr,
writers: make(map[*progressWriter]func(error)),
done: make(chan struct{}),
}
return mr
}
func (mr *MultiReader) Reader(ctx context.Context) Reader {
mr.mu.Lock()
defer mr.mu.Unlock()
pr, ctx, closeWriter := NewContext(ctx)
pw, _, ctx := NewFromContext(ctx)
w := pw.(*progressWriter)
isBehind := len(mr.sent) > 0
select {
case <-mr.done:
isBehind = true
default:
if !isBehind {
mr.writers[w] = closeWriter
}
}
go func() {
if isBehind {
close := func(err error) {
w.Close()
closeWriter(err)
}
i := 0
for {
mr.mu.Lock()
sent := mr.sent
count := len(sent) - i
if count == 0 {
select {
case <-ctx.Done():
close(context.Cause(ctx))
mr.mu.Unlock()
return
case <-mr.done:
close(mr.doneCause)
mr.mu.Unlock()
return
default:
}
mr.writers[w] = closeWriter
mr.mu.Unlock()
break
}
mr.mu.Unlock()
for i, p := range sent[i:] {
w.writeRawProgress(p)
if i%100 == 0 {
select {
case <-ctx.Done():
close(context.Cause(ctx))
return
default:
}
}
}
i += count
}
}
select {
case <-ctx.Done():
case <-mr.done:
}
mr.mu.Lock()
defer mr.mu.Unlock()
delete(mr.writers, w)
}()
if !mr.initialized {
go mr.handle()
mr.initialized = true
}
return pr
}
func (mr *MultiReader) handle() error {
for {
p, err := mr.main.Read(context.TODO())
if err != nil {
if err == io.EOF {
mr.mu.Lock()
cancelErr := context.Canceled
for w, c := range mr.writers {
w.Close()
c(cancelErr)
}
mr.doneCause = cancelErr
close(mr.done)
mr.mu.Unlock()
return nil
}
return err
}
mr.mu.Lock()
for _, p := range p {
for w := range mr.writers {
w.writeRawProgress(p)
}
}
mr.sent = append(mr.sent, p...)
mr.mu.Unlock()
}
}
|
