134 lines
3.1 KiB
Go
134 lines
3.1 KiB
Go
package torrent
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import (
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"bytes"
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"io"
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"time"
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"github.com/anacrolix/chansync"
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"github.com/anacrolix/log"
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"github.com/anacrolix/sync"
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pp "github.com/anacrolix/torrent/peer_protocol"
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)
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func (pc *PeerConn) startWriter() {
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w := &pc.messageWriter
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*w = peerConnMsgWriter{
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fillWriteBuffer: func() {
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pc.locker().Lock()
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defer pc.locker().Unlock()
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if pc.closed.IsSet() {
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return
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}
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pc.fillWriteBuffer()
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},
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closed: &pc.closed,
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logger: pc.logger,
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w: pc.w,
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keepAlive: func() bool {
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pc.locker().Lock()
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defer pc.locker().Unlock()
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return pc.useful()
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},
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writeBuffer: new(bytes.Buffer),
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}
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go func() {
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defer pc.locker().Unlock()
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defer pc.close()
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defer pc.locker().Lock()
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pc.messageWriter.run(pc.t.cl.config.KeepAliveTimeout)
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}()
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}
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type peerConnMsgWriter struct {
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// Must not be called with the local mutex held, as it will call back into the write method.
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fillWriteBuffer func()
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closed *chansync.SetOnce
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logger log.Logger
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w io.Writer
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keepAlive func() bool
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mu sync.Mutex
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writeCond chansync.BroadcastCond
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// Pointer so we can swap with the "front buffer".
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writeBuffer *bytes.Buffer
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}
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// Routine that writes to the peer. Some of what to write is buffered by
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// activity elsewhere in the Client, and some is determined locally when the
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// connection is writable.
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func (cn *peerConnMsgWriter) run(keepAliveTimeout time.Duration) {
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var (
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lastWrite time.Time = time.Now()
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keepAliveTimer *time.Timer
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)
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cn.mu.Lock()
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defer cn.mu.Unlock()
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keepAliveTimer = time.AfterFunc(keepAliveTimeout, func() {
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cn.mu.Lock()
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defer cn.mu.Unlock()
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if time.Since(lastWrite) >= keepAliveTimeout {
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cn.writeCond.Broadcast()
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}
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keepAliveTimer.Reset(keepAliveTimeout)
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})
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defer keepAliveTimer.Stop()
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frontBuf := new(bytes.Buffer)
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for {
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if cn.closed.IsSet() {
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return
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}
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if cn.writeBuffer.Len() == 0 {
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func() {
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cn.mu.Unlock()
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defer cn.mu.Lock()
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cn.fillWriteBuffer()
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}()
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}
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if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout && cn.keepAlive() {
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cn.writeBuffer.Write(pp.Message{Keepalive: true}.MustMarshalBinary())
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torrent.Add("written keepalives", 1)
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}
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if cn.writeBuffer.Len() == 0 {
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writeCond := cn.writeCond.Signaled()
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cn.mu.Unlock()
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select {
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case <-cn.closed.Done():
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case <-writeCond:
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}
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cn.mu.Lock()
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continue
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}
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// Flip the buffers.
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frontBuf, cn.writeBuffer = cn.writeBuffer, frontBuf
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cn.mu.Unlock()
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n, err := cn.w.Write(frontBuf.Bytes())
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cn.mu.Lock()
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if n != 0 {
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lastWrite = time.Now()
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keepAliveTimer.Reset(keepAliveTimeout)
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}
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if err != nil {
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cn.logger.WithDefaultLevel(log.Debug).Printf("error writing: %v", err)
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return
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}
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if n != frontBuf.Len() {
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panic("short write")
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}
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frontBuf.Reset()
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}
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}
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func (cn *peerConnMsgWriter) write(msg pp.Message) bool {
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cn.mu.Lock()
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defer cn.mu.Unlock()
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cn.writeBuffer.Write(msg.MustMarshalBinary())
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cn.writeCond.Broadcast()
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return !cn.writeBufferFull()
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}
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func (cn *peerConnMsgWriter) writeBufferFull() bool {
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return cn.writeBuffer.Len() >= writeBufferHighWaterLen
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}
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