virtcontainers: Initial import

This is a virtcontainers 1.0.8 import into Kata Containers runtime.

virtcontainers is a Go library designed to manage hardware virtualized
pods and containers. It is the core Clear Containers framework and will
become the core Kata Containers framework, as discussed at
https://github.com/kata-containers/runtime/issues/33

Some more more pointers:

virtcontainers README, including some design and architecure notes:
https://github.com/containers/virtcontainers/blob/master/README.md

virtcontainers 1.0 API:
https://github.com/containers/virtcontainers/blob/master/documentation/api/1.0/api.md

Fixes #40

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

virtcontainers/pkg/hyperstart/multicast.go

@@ -0,0 +1,175 @@
+//
+// Copyright (c) 2017 Intel Corporation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package hyperstart
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+	"sync"
+)
+
+type ctlDataType string
+
+const (
+	eventType ctlDataType = "ctlEvent"
+	replyType ctlDataType = "ctlReply"
+)
+
+type multicast struct {
+	bufReplies []*DecodedMessage
+	reply      []chan *DecodedMessage
+	event      map[string]chan *DecodedMessage
+	ctl        net.Conn
+	sync.Mutex
+}
+
+func newMulticast(ctlConn net.Conn) *multicast {
+	return &multicast{
+		bufReplies: []*DecodedMessage{},
+		reply:      []chan *DecodedMessage{},
+		event:      make(map[string]chan *DecodedMessage),
+		ctl:        ctlConn,
+	}
+}
+
+func startCtlMonitor(ctlConn net.Conn, done chan<- interface{}) *multicast {
+	ctlMulticast := newMulticast(ctlConn)
+
+	go func() {
+		for {
+			msg, err := ReadCtlMessage(ctlMulticast.ctl)
+			if err != nil {
+				hyperLog.Infof("Read on CTL channel ended: %s", err)
+				break
+			}
+
+			err = ctlMulticast.write(msg)
+			if err != nil {
+				hyperLog.Errorf("Multicaster write error: %s", err)
+				break
+			}
+		}
+
+		close(done)
+	}()
+
+	return ctlMulticast
+}
+
+func (m *multicast) buildEventID(containerID, processID string) string {
+	return fmt.Sprintf("%s-%s", containerID, processID)
+}
+
+func (m *multicast) sendEvent(msg *DecodedMessage) error {
+	var paeData PAECommand
+
+	err := json.Unmarshal(msg.Message, paeData)
+	if err != nil {
+		return err
+	}
+
+	uniqueID := m.buildEventID(paeData.Container, paeData.Process)
+	channel, exist := m.event[uniqueID]
+	if !exist {
+		return nil
+	}
+
+	channel <- msg
+
+	delete(m.event, uniqueID)
+
+	return nil
+}
+
+func (m *multicast) sendReply(msg *DecodedMessage) error {
+	m.Lock()
+	if len(m.reply) == 0 {
+		m.bufReplies = append(m.bufReplies, msg)
+		m.Unlock()
+		return nil
+	}
+
+	replyChannel := m.reply[0]
+	m.reply = m.reply[1:]
+
+	m.Unlock()
+
+	// The current reply channel has been removed from the list, that's why
+	// we can be out of the mutex to send through that channel. Indeed, there
+	// is no risk that someone else tries to write on this channel.
+	replyChannel <- msg
+
+	return nil
+}
+
+func (m *multicast) processBufferedReply(channel chan *DecodedMessage) {
+	m.Lock()
+
+	if len(m.bufReplies) == 0 {
+		m.reply = append(m.reply, channel)
+		m.Unlock()
+		return
+	}
+
+	msg := m.bufReplies[0]
+	m.bufReplies = m.bufReplies[1:]
+
+	m.Unlock()
+
+	// The current buffered reply message has been removed from the list, and
+	// the channel have not been added to the reply list, that's why we can be
+	// out of the mutex to send the buffered message through that channel.
+	// There is no risk that someone else tries to write this message on another
+	// channel, or another message on this channel.
+	channel <- msg
+}
+
+func (m *multicast) write(msg *DecodedMessage) error {
+	switch msg.Code {
+	case NextCode:
+		return nil
+	case ProcessAsyncEventCode:
+		return m.sendEvent(msg)
+	default:
+		return m.sendReply(msg)
+	}
+}
+
+func (m *multicast) listen(containerID, processID string, dataType ctlDataType) (chan *DecodedMessage, error) {
+	switch dataType {
+	case replyType:
+		newChan := make(chan *DecodedMessage)
+
+		go m.processBufferedReply(newChan)
+
+		return newChan, nil
+	case eventType:
+		uniqueID := m.buildEventID(containerID, processID)
+
+		_, exist := m.event[uniqueID]
+		if exist {
+			return nil, fmt.Errorf("Channel already assigned for ID %s", uniqueID)
+		}
+
+		m.event[uniqueID] = make(chan *DecodedMessage)
+
+		return m.event[uniqueID], nil
+	default:
+		return nil, fmt.Errorf("Unknown data type: %s", dataType)
+	}
+}