mirror of
https://github.com/genuinetools/reg.git
synced 2024-08-21 06:10:23 -04:00
164 lines
3.8 KiB
Go
164 lines
3.8 KiB
Go
![]() |
// Copyright 2014 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.
|
||
|
|
||
|
package http2
|
||
|
|
||
|
import (
|
||
|
"errors"
|
||
|
"io"
|
||
|
"sync"
|
||
|
)
|
||
|
|
||
|
// pipe is a goroutine-safe io.Reader/io.Writer pair. It's like
|
||
|
// io.Pipe except there are no PipeReader/PipeWriter halves, and the
|
||
|
// underlying buffer is an interface. (io.Pipe is always unbuffered)
|
||
|
type pipe struct {
|
||
|
mu sync.Mutex
|
||
|
c sync.Cond // c.L lazily initialized to &p.mu
|
||
|
b pipeBuffer // nil when done reading
|
||
|
err error // read error once empty. non-nil means closed.
|
||
|
breakErr error // immediate read error (caller doesn't see rest of b)
|
||
|
donec chan struct{} // closed on error
|
||
|
readFn func() // optional code to run in Read before error
|
||
|
}
|
||
|
|
||
|
type pipeBuffer interface {
|
||
|
Len() int
|
||
|
io.Writer
|
||
|
io.Reader
|
||
|
}
|
||
|
|
||
|
func (p *pipe) Len() int {
|
||
|
p.mu.Lock()
|
||
|
defer p.mu.Unlock()
|
||
|
if p.b == nil {
|
||
|
return 0
|
||
|
}
|
||
|
return p.b.Len()
|
||
|
}
|
||
|
|
||
|
// Read waits until data is available and copies bytes
|
||
|
// from the buffer into p.
|
||
|
func (p *pipe) Read(d []byte) (n int, err error) {
|
||
|
p.mu.Lock()
|
||
|
defer p.mu.Unlock()
|
||
|
if p.c.L == nil {
|
||
|
p.c.L = &p.mu
|
||
|
}
|
||
|
for {
|
||
|
if p.breakErr != nil {
|
||
|
return 0, p.breakErr
|
||
|
}
|
||
|
if p.b != nil && p.b.Len() > 0 {
|
||
|
return p.b.Read(d)
|
||
|
}
|
||
|
if p.err != nil {
|
||
|
if p.readFn != nil {
|
||
|
p.readFn() // e.g. copy trailers
|
||
|
p.readFn = nil // not sticky like p.err
|
||
|
}
|
||
|
p.b = nil
|
||
|
return 0, p.err
|
||
|
}
|
||
|
p.c.Wait()
|
||
|
}
|
||
|
}
|
||
|
|
||
|
var errClosedPipeWrite = errors.New("write on closed buffer")
|
||
|
|
||
|
// Write copies bytes from p into the buffer and wakes a reader.
|
||
|
// It is an error to write more data than the buffer can hold.
|
||
|
func (p *pipe) Write(d []byte) (n int, err error) {
|
||
|
p.mu.Lock()
|
||
|
defer p.mu.Unlock()
|
||
|
if p.c.L == nil {
|
||
|
p.c.L = &p.mu
|
||
|
}
|
||
|
defer p.c.Signal()
|
||
|
if p.err != nil {
|
||
|
return 0, errClosedPipeWrite
|
||
|
}
|
||
|
if p.breakErr != nil {
|
||
|
return len(d), nil // discard when there is no reader
|
||
|
}
|
||
|
return p.b.Write(d)
|
||
|
}
|
||
|
|
||
|
// CloseWithError causes the next Read (waking up a current blocked
|
||
|
// Read if needed) to return the provided err after all data has been
|
||
|
// read.
|
||
|
//
|
||
|
// The error must be non-nil.
|
||
|
func (p *pipe) CloseWithError(err error) { p.closeWithError(&p.err, err, nil) }
|
||
|
|
||
|
// BreakWithError causes the next Read (waking up a current blocked
|
||
|
// Read if needed) to return the provided err immediately, without
|
||
|
// waiting for unread data.
|
||
|
func (p *pipe) BreakWithError(err error) { p.closeWithError(&p.breakErr, err, nil) }
|
||
|
|
||
|
// closeWithErrorAndCode is like CloseWithError but also sets some code to run
|
||
|
// in the caller's goroutine before returning the error.
|
||
|
func (p *pipe) closeWithErrorAndCode(err error, fn func()) { p.closeWithError(&p.err, err, fn) }
|
||
|
|
||
|
func (p *pipe) closeWithError(dst *error, err error, fn func()) {
|
||
|
if err == nil {
|
||
|
panic("err must be non-nil")
|
||
|
}
|
||
|
p.mu.Lock()
|
||
|
defer p.mu.Unlock()
|
||
|
if p.c.L == nil {
|
||
|
p.c.L = &p.mu
|
||
|
}
|
||
|
defer p.c.Signal()
|
||
|
if *dst != nil {
|
||
|
// Already been done.
|
||
|
return
|
||
|
}
|
||
|
p.readFn = fn
|
||
|
if dst == &p.breakErr {
|
||
|
p.b = nil
|
||
|
}
|
||
|
*dst = err
|
||
|
p.closeDoneLocked()
|
||
|
}
|
||
|
|
||
|
// requires p.mu be held.
|
||
|
func (p *pipe) closeDoneLocked() {
|
||
|
if p.donec == nil {
|
||
|
return
|
||
|
}
|
||
|
// Close if unclosed. This isn't racy since we always
|
||
|
// hold p.mu while closing.
|
||
|
select {
|
||
|
case <-p.donec:
|
||
|
default:
|
||
|
close(p.donec)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// Err returns the error (if any) first set by BreakWithError or CloseWithError.
|
||
|
func (p *pipe) Err() error {
|
||
|
p.mu.Lock()
|
||
|
defer p.mu.Unlock()
|
||
|
if p.breakErr != nil {
|
||
|
return p.breakErr
|
||
|
}
|
||
|
return p.err
|
||
|
}
|
||
|
|
||
|
// Done returns a channel which is closed if and when this pipe is closed
|
||
|
// with CloseWithError.
|
||
|
func (p *pipe) Done() <-chan struct{} {
|
||
|
p.mu.Lock()
|
||
|
defer p.mu.Unlock()
|
||
|
if p.donec == nil {
|
||
|
p.donec = make(chan struct{})
|
||
|
if p.err != nil || p.breakErr != nil {
|
||
|
// Already hit an error.
|
||
|
p.closeDoneLocked()
|
||
|
}
|
||
|
}
|
||
|
return p.donec
|
||
|
}
|