Vendor dependencies with dep

vendor/github.com/pkg/sftp/packet-manager.go

@@ -0,0 +1,156 @@
+package sftp
+
+import (
+	"encoding"
+	"sync"
+)
+
+// The goal of the packetManager is to keep the outgoing packets in the same
+// order as the incoming. This is due to some sftp clients requiring this
+// behavior (eg. winscp).
+
+type packetSender interface {
+	sendPacket(encoding.BinaryMarshaler) error
+}
+
+type packetManager struct {
+	requests  chan requestPacket
+	responses chan responsePacket
+	fini      chan struct{}
+	incoming  requestPacketIDs
+	outgoing  responsePackets
+	sender    packetSender // connection object
+	working   *sync.WaitGroup
+}
+
+func newPktMgr(sender packetSender) packetManager {
+	s := packetManager{
+		requests:  make(chan requestPacket, sftpServerWorkerCount),
+		responses: make(chan responsePacket, sftpServerWorkerCount),
+		fini:      make(chan struct{}),
+		incoming:  make([]uint32, 0, sftpServerWorkerCount),
+		outgoing:  make([]responsePacket, 0, sftpServerWorkerCount),
+		sender:    sender,
+		working:   &sync.WaitGroup{},
+	}
+	go s.controller()
+	return s
+}
+
+// register incoming packets to be handled
+// send id of 0 for packets without id
+func (s packetManager) incomingPacket(pkt requestPacket) {
+	s.working.Add(1)
+	s.requests <- pkt // buffer == sftpServerWorkerCount
+}
+
+// register outgoing packets as being ready
+func (s packetManager) readyPacket(pkt responsePacket) {
+	s.responses <- pkt
+	s.working.Done()
+}
+
+// shut down packetManager controller
+func (s packetManager) close() {
+	// pause until current packets are processed
+	s.working.Wait()
+	close(s.fini)
+}
+
+// Passed a worker function, returns a channel for incoming packets.
+// The goal is to process packets in the order they are received as is
+// requires by section 7 of the RFC, while maximizing throughput of file
+// transfers.
+func (s *packetManager) workerChan(runWorker func(requestChan)) requestChan {
+
+	rwChan := make(chan requestPacket, sftpServerWorkerCount)
+	for i := 0; i < sftpServerWorkerCount; i++ {
+		runWorker(rwChan)
+	}
+
+	cmdChan := make(chan requestPacket)
+	runWorker(cmdChan)
+
+	pktChan := make(chan requestPacket, sftpServerWorkerCount)
+	go func() {
+		// start with cmdChan
+		curChan := cmdChan
+		for pkt := range pktChan {
+			// on file open packet, switch to rwChan
+			switch pkt.(type) {
+			case *sshFxpOpenPacket:
+				curChan = rwChan
+			// on file close packet, switch back to cmdChan
+			// after waiting for any reads/writes to finish
+			case *sshFxpClosePacket:
+				// wait for rwChan to finish
+				s.working.Wait()
+				// stop using rwChan
+				curChan = cmdChan
+			}
+			s.incomingPacket(pkt)
+			curChan <- pkt
+		}
+		close(rwChan)
+		close(cmdChan)
+		s.close()
+	}()
+
+	return pktChan
+}
+
+// process packets
+func (s *packetManager) controller() {
+	for {
+		select {
+		case pkt := <-s.requests:
+			debug("incoming id: %v", pkt.id())
+			s.incoming = append(s.incoming, pkt.id())
+			if len(s.incoming) > 1 {
+				s.incoming.Sort()
+			}
+		case pkt := <-s.responses:
+			debug("outgoing pkt: %v", pkt.id())
+			s.outgoing = append(s.outgoing, pkt)
+			if len(s.outgoing) > 1 {
+				s.outgoing.Sort()
+			}
+		case <-s.fini:
+			return
+		}
+		s.maybeSendPackets()
+	}
+}
+
+// send as many packets as are ready
+func (s *packetManager) maybeSendPackets() {
+	for {
+		if len(s.outgoing) == 0 || len(s.incoming) == 0 {
+			debug("break! -- outgoing: %v; incoming: %v",
+				len(s.outgoing), len(s.incoming))
+			break
+		}
+		out := s.outgoing[0]
+		in := s.incoming[0]
+		// 		debug("incoming: %v", s.incoming)
+		// 		debug("outgoing: %v", outfilter(s.outgoing))
+		if in == out.id() {
+			s.sender.sendPacket(out)
+			// pop off heads
+			copy(s.incoming, s.incoming[1:])            // shift left
+			s.incoming = s.incoming[:len(s.incoming)-1] // remove last
+			copy(s.outgoing, s.outgoing[1:])            // shift left
+			s.outgoing = s.outgoing[:len(s.outgoing)-1] // remove last
+		} else {
+			break
+		}
+	}
+}
+
+func outfilter(o []responsePacket) []uint32 {
+	res := make([]uint32, 0, len(o))
+	for _, v := range o {
+		res = append(res, v.id())
+	}
+	return res
+}