128 lines
3.1 KiB
Go
128 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) initMessageWriter() {
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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().RLock()
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defer pc.locker().RUnlock()
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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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}
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func (pc *PeerConn) startMessageWriter() {
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pc.initMessageWriter()
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go pc.messageWriterRunner()
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}
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func (pc *PeerConn) messageWriterRunner() {
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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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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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lastWrite := time.Now()
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keepAliveTimer := time.NewTimer(keepAliveTimeout)
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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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cn.fillWriteBuffer()
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keepAlive := cn.keepAlive()
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cn.mu.Lock()
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if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout && 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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case <-keepAliveTimer.C:
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}
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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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if frontBuf.Len() == 0 {
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panic("expected non-empty front buffer")
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}
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var err error
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for frontBuf.Len() != 0 {
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// Limit write size for WebRTC. See https://github.com/pion/datachannel/issues/59.
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next := frontBuf.Next(1<<16 - 1)
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var n int
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n, err = cn.w.Write(next)
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if err == nil && n != len(next) {
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panic("expected full write")
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}
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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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lastWrite = time.Now()
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keepAliveTimer.Reset(keepAliveTimeout)
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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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