forked from vadims/sslconn
/
nb_writer.go
125 lines (102 loc) · 1.91 KB
/
nb_writer.go
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package sslconn
import (
"bytes"
"io"
"sync"
)
type NonBlockingWriter struct {
writer io.Writer
cap int
lock *sync.Mutex
buffer *bytes.Buffer
readyCond *sync.Cond
unblockedCond *sync.Cond
closedChan chan bool
err error
closed bool
}
func NewNonBlockingWriter(writer io.Writer, cap int) *NonBlockingWriter {
w := &NonBlockingWriter{}
w.writer = writer
w.cap = cap
w.lock = &sync.Mutex{}
w.buffer = &bytes.Buffer{}
w.readyCond = sync.NewCond(w.lock)
w.unblockedCond = sync.NewCond(w.lock)
w.closedChan = make(chan bool, 1)
go w.loop()
return w
}
func (w *NonBlockingWriter) WaitUntilReady() {
w.lock.Lock()
defer w.lock.Unlock()
for w.cap-w.buffer.Len() == 0 && w.err == nil && !w.closed {
w.readyCond.Wait()
}
}
func (w *NonBlockingWriter) Close() {
w.lock.Lock()
if w.closed {
w.lock.Unlock()
return
}
w.closed = true
w.unblockedCond.Signal()
w.lock.Unlock()
<-w.closedChan
}
func (w *NonBlockingWriter) Write(b []byte) (int, error) {
w.lock.Lock()
defer w.lock.Unlock()
if w.closed {
return 0, ErrClosed
}
if w.err != nil {
return 0, w.err
}
space := w.cap - w.buffer.Len()
if space <= 0 {
return 0, ErrAgain
}
wrote := len(b)
if wrote > space {
wrote = space
}
w.buffer.Write(b[:wrote])
w.unblockedCond.Signal()
return wrote, nil
}
func (w *NonBlockingWriter) loop() {
buffer := make([]byte, w.cap)
for {
stop := func() bool {
w.lock.Lock()
defer w.lock.Unlock()
read := 0
for {
read, _ = w.buffer.Read(buffer)
if read > 0 {
break
}
if w.closed {
return true
}
w.unblockedCond.Wait()
}
w.readyCond.Broadcast()
w.lock.Unlock()
err := writeBytesTo(buffer[:read], w.writer)
w.lock.Lock()
if err != nil {
w.err = err
w.readyCond.Broadcast()
return true
}
return false
}()
if stop {
w.closedChan <- true
return
}
}
}