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pipe.go
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pipe.go
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// Copyright 2016 CodisLabs. All Rights Reserved.
// Licensed under the MIT (MIT-LICENSE.txt) license.
package pipe
import (
"io"
"os"
"sync"
"pkg/libs/errors"
)
type buffer interface {
readSome(b []byte) (int, error)
writeSome(b []byte) (int, error)
buffered() int
available() int
rclose() error
wclose() error
}
type pipe struct {
rl sync.Mutex
wl sync.Mutex
mu sync.Mutex
rwait *sync.Cond
wwait *sync.Cond
rerr error
werr error
store buffer
}
func roffset(blen int, size, rpos, wpos uint64) (maxlen, offset uint64) {
maxlen = uint64(blen)
if n := wpos - rpos; n < maxlen {
maxlen = n
}
offset = rpos % size
if n := size - offset; n < maxlen {
maxlen = n
}
return
}
func woffset(blen int, size, rpos, wpos uint64) (maxlen, offset uint64) {
maxlen = uint64(blen)
if n := size + rpos - wpos; n < maxlen {
maxlen = n
}
offset = wpos % size
if n := size - offset; n < maxlen {
maxlen = n
}
return
}
func align(size, unit int) int {
if size < unit {
return unit
}
return (size + unit - 1) / unit * unit
}
func newPipe(store buffer) (Reader, Writer) {
p := &pipe{}
p.rwait = sync.NewCond(&p.mu)
p.wwait = sync.NewCond(&p.mu)
p.store = store
r := &reader{p}
w := &writer{p}
return r, w
}
func (p *pipe) Read(b []byte) (int, error) {
p.rl.Lock()
defer p.rl.Unlock()
for {
n, err := p.readSome(b)
if err != nil || n != 0 {
return n, err
}
if len(b) == 0 {
return 0, nil
}
}
}
func (p *pipe) readSome(b []byte) (int, error) {
p.mu.Lock()
defer p.mu.Unlock()
if p.rerr != nil {
return 0, errors.Trace(io.ErrClosedPipe)
}
if len(b) == 0 {
if p.store.buffered() != 0 {
return 0, nil
}
return 0, p.werr
}
n, err := p.store.readSome(b)
if err != nil || n != 0 {
p.wwait.Signal()
return n, err
}
if p.werr != nil {
return 0, p.werr
}
p.rwait.Wait()
return 0, nil
}
func (p *pipe) Write(b []byte) (int, error) {
p.wl.Lock()
defer p.wl.Unlock()
var nn int
for {
n, err := p.writeSome(b)
if err != nil {
return nn + n, err
}
nn, b = nn+n, b[n:]
if len(b) == 0 {
return nn, nil
}
}
}
func (p *pipe) writeSome(b []byte) (int, error) {
p.mu.Lock()
defer p.mu.Unlock()
if p.werr != nil {
return 0, errors.Trace(io.ErrClosedPipe)
}
if p.rerr != nil {
return 0, p.rerr
}
if len(b) == 0 {
return 0, nil
}
n, err := p.store.writeSome(b)
if err != nil || n != 0 {
p.rwait.Signal()
return n, err
}
p.wwait.Wait()
return 0, nil
}
func (p *pipe) RClose(err error) error {
if err == nil {
err = errors.Trace(io.ErrClosedPipe)
}
p.mu.Lock()
defer p.mu.Unlock()
if p.rerr == nil {
p.rerr = err
}
p.rwait.Signal()
p.wwait.Signal()
return p.store.rclose()
}
func (p *pipe) WClose(err error) error {
if err == nil {
err = errors.Trace(io.EOF)
}
p.mu.Lock()
defer p.mu.Unlock()
if p.werr == nil {
p.werr = err
}
p.rwait.Signal()
p.wwait.Signal()
return p.store.wclose()
}
func (p *pipe) Buffered() (int, error) {
p.mu.Lock()
defer p.mu.Unlock()
if p.rerr != nil {
return 0, p.rerr
}
if n := p.store.buffered(); n != 0 {
return n, nil
}
return 0, p.werr
}
func (p *pipe) Available() (int, error) {
p.mu.Lock()
defer p.mu.Unlock()
if p.werr != nil {
return 0, p.werr
}
if p.rerr != nil {
return 0, p.rerr
}
return p.store.available(), nil
}
func New() (Reader, Writer) {
return NewSize(BuffSizeAlign)
}
func NewSize(buffSize int) (Reader, Writer) {
return newPipe(newMemBuffer(buffSize))
}
func NewFilePipe(fileSize int, f *os.File) (Reader, Writer) {
return newPipe(newFileBuffer(fileSize, f))
}