ggstd 0.1.0

// // Copyright 2009 The Go Authors. All rights reserved.
// // Use of this source code is governed by a BSD-style
// // license that can be found in the LICENSE file.

// // Pipe adapter to connect code expecting an io.Reader
// // with code expecting an ggio::Writer.

// package io

// import (
// 	"errors"
// 	"sync"
// )

// // onceError is an object that will only store an error once.
// type onceError struct {
// 	sync.Mutex // guards following
// 	err        error
// }

// func (a *onceError) Store(err error) {
// 	a.Lock()
// 	defer a.Unlock()
// 	if a.err != nil {
// 		return
// 	}
// 	a.err = err
// }
// func (a *onceError) Load() error {
// 	a.Lock()
// 	defer a.Unlock()
// 	return a.err
// }

// // ErrClosedPipe is the error used for read or write operations on a closed pipe.
// var ErrClosedPipe = errors.New("io: read/write on closed pipe")

// // A pipe is the shared pipe structure underlying PipeReader and PipeWriter.
// type pipe struct {
// 	wrMu sync.Mutex // Serializes Write operations
// 	wrCh chan [u8]
// 	rdCh chan int

// 	once sync.Once // Protects closing done
// 	done chan struct{}
// 	rerr onceError
// 	werr onceError
// }

// func (p *pipe) read(b [u8]) (n int, err error) {
// 	select {
// 	case <-p.done:
// 		return 0, p.readCloseError()
// 	default:
// 	}

// 	select {
// 	case bw := <-p.wrCh:
// 		nr := copy(b, bw)
// 		p.rdCh <- nr
// 		return nr, nil
// 	case <-p.done:
// 		return 0, p.readCloseError()
// 	}
// }

// func (p *pipe) closeRead(err error) error {
// 	if err == nil {
// 		err = ErrClosedPipe
// 	}
// 	p.rerr.Store(err)
// 	p.once.Do(func() { close(p.done) })
// 	return nil
// }

// func (p *pipe) write(b [u8]) (n int, err error) {
// 	select {
// 	case <-p.done:
// 		return 0, p.writeCloseError()
// 	default:
// 		p.wrMu.Lock()
// 		defer p.wrMu.Unlock()
// 	}

// 	for once := true; once || b.len() > 0; once = false {
// 		select {
// 		case p.wrCh <- b:
// 			nw := <-p.rdCh
// 			b = b[nw:]
// 			n += nw
// 		case <-p.done:
// 			return n, p.writeCloseError()
// 		}
// 	}
// 	return n, nil
// }

// func (p *pipe) closeWrite(err error) error {
// 	if err == nil {
// 		err = EOF
// 	}
// 	p.werr.Store(err)
// 	p.once.Do(func() { close(p.done) })
// 	return nil
// }

// // readCloseError is considered internal to the pipe type.
// func (p *pipe) readCloseError() error {
// 	rerr := p.rerr.Load()
// 	if werr := p.werr.Load(); rerr == nil && werr != nil {
// 		return werr
// 	}
// 	return ErrClosedPipe
// }

// // writeCloseError is considered internal to the pipe type.
// func (p *pipe) writeCloseError() error {
// 	werr := p.werr.Load()
// 	if rerr := p.rerr.Load(); werr == nil && rerr != nil {
// 		return rerr
// 	}
// 	return ErrClosedPipe
// }

// // A PipeReader is the read half of a pipe.
// type PipeReader struct {
// 	p *pipe
// }

// // Read implements the standard Read interface:
// // it reads data from the pipe, blocking until a writer
// // arrives or the write end is closed.
// // If the write end is closed with an error, that error is
// // returned as err; otherwise err is EOF.
// func (r *PipeReader) Read(data [u8]) (n int, err error) {
// 	return r.p.read(data)
// }

// // Close closes the reader; subsequent writes to the
// // write half of the pipe will return the error ErrClosedPipe.
// func (r *PipeReader) Close() error {
// 	return r.CloseWithError(nil)
// }

// // CloseWithError closes the reader; subsequent writes
// // to the write half of the pipe will return the error err.
// //
// // CloseWithError never overwrites the previous error if it exists
// // and always returns nil.
// func (r *PipeReader) CloseWithError(err error) error {
// 	return r.p.closeRead(err)
// }

// // A PipeWriter is the write half of a pipe.
// type PipeWriter struct {
// 	p *pipe
// }

// // Write implements the standard Write interface:
// // it writes data to the pipe, blocking until one or more readers
// // have consumed all the data or the read end is closed.
// // If the read end is closed with an error, that err is
// // returned as err; otherwise err is ErrClosedPipe.
// func (w *PipeWriter) Write(data [u8]) (n int, err error) {
// 	return w.p.write(data)
// }

// // Close closes the writer; subsequent reads from the
// // read half of the pipe will return no bytes and EOF.
// func (w *PipeWriter) Close() error {
// 	return w.CloseWithError(nil)
// }

// // CloseWithError closes the writer; subsequent reads from the
// // read half of the pipe will return no bytes and the error err,
// // or EOF if err is nil.
// //
// // CloseWithError never overwrites the previous error if it exists
// // and always returns nil.
// func (w *PipeWriter) CloseWithError(err error) error {
// 	return w.p.closeWrite(err)
// }

// // Pipe creates a synchronous in-memory pipe.
// // It can be used to connect code expecting an io.Reader
// // with code expecting an ggio::Writer.
// //
// // Reads and Writes on the pipe are matched one to one
// // except when multiple Reads are needed to consume a single Write.
// // That is, each Write to the PipeWriter blocks until it has satisfied
// // one or more Reads from the PipeReader that fully consume
// // the written data.
// // The data is copied directly from the Write to the corresponding
// // Read (or Reads); there is no internal buffering.
// //
// // It is safe to call Read and Write in parallel with each other or with Close.
// // Parallel calls to Read and parallel calls to Write are also safe:
// // the individual calls will be gated sequentially.
// func Pipe() (*PipeReader, *PipeWriter) {
// 	p := &pipe{
// 		wrCh: make(chan [u8]),
// 		rdCh: make(chan int),
// 		done: make(chan struct{}),
// 	}
// 	return &PipeReader{p}, &PipeWriter{p}
// }