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bufpipe.go
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bufpipe.go
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// Copyright 2022 Namespace Labs Inc; All rights reserved.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
package grpcstdio
import (
"bytes"
"sync"
"namespacelabs.dev/foundation/internal/fnerrors"
)
type pipe struct {
mu sync.Mutex
cond *sync.Cond
buf *bytes.Buffer
readErr error
writeErr error
}
type bufferedPipeReader struct {
*pipe
}
type bufferedPipeWriter struct {
*pipe
}
func newBufferedPipe() (*bufferedPipeReader, *bufferedPipeWriter) {
p := &pipe{buf: bytes.NewBuffer(nil)}
p.cond = sync.NewCond(&p.mu)
return &bufferedPipeReader{p}, &bufferedPipeWriter{p}
}
func (r *bufferedPipeReader) Read(data []byte) (int, error) {
if len(data) == 0 {
return 0, nil
}
r.mu.Lock()
defer r.mu.Unlock()
for {
if r.readErr != nil {
return 0, r.readErr
}
n, _ := r.buf.Read(data)
if n > 0 {
return n, nil
}
r.cond.Wait()
}
}
func (r *bufferedPipeReader) Close() error {
return r.closeWithError(fnerrors.New("pipe is closed"))
}
func (r *bufferedPipeReader) closeWithError(err error) error {
r.mu.Lock()
defer r.mu.Unlock()
if err == nil {
panic("no error")
}
if r.writeErr != nil {
return fnerrors.New("pipe is closed")
}
r.writeErr = err
return nil
}
func (w *bufferedPipeWriter) Write(data []byte) (int, error) {
w.mu.Lock()
defer w.mu.Unlock()
if w.writeErr != nil {
return 0, w.writeErr
}
n, err := w.buf.Write(data)
w.cond.Signal()
return n, err
}
func (w *bufferedPipeWriter) Close() error {
return w.closeWithError(fnerrors.New("already closed"))
}
func (w *bufferedPipeWriter) closeWithError(err error) error {
w.mu.Lock()
defer w.mu.Unlock()
if err == nil {
panic("no error")
}
if w.readErr != nil {
return fnerrors.New("already closed")
}
w.readErr = err
w.cond.Broadcast() // Wake up all readers.
return nil
}