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connection_maker.go
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connection_maker.go
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package router
import (
"fmt"
"math/rand"
"net"
"time"
)
const (
InitialInterval = 2 * time.Second
MaxInterval = 6 * time.Minute
)
type peerAddrs map[string]*net.TCPAddr
type ConnectionMaker struct {
ourself *LocalPeer
peers *Peers
port int
discovery bool
targets map[string]*Target
directPeers peerAddrs
actionChan chan<- ConnectionMakerAction
}
// Information about an address where we may find a peer
type Target struct {
attempting bool // are we currently attempting to connect there?
lastError error // reason for disconnection last time
tryAfter time.Time // next time to try this address
tryInterval time.Duration // retry delay on next failure
}
type ConnectionMakerAction func() bool
func NewConnectionMaker(ourself *LocalPeer, peers *Peers, port int, discovery bool) *ConnectionMaker {
actionChan := make(chan ConnectionMakerAction, ChannelSize)
cm := &ConnectionMaker{
ourself: ourself,
peers: peers,
port: port,
discovery: discovery,
directPeers: peerAddrs{},
targets: make(map[string]*Target),
actionChan: actionChan}
go cm.queryLoop(actionChan)
return cm
}
func (cm *ConnectionMaker) InitiateConnections(peers []string, replace bool) []error {
errors := []error{}
addrs := peerAddrs{}
for _, peer := range peers {
host, port, err := net.SplitHostPort(peer)
if err != nil {
host = peer
port = "0" // we use that as an indication that "no port was supplied"
}
if addr, err := net.ResolveTCPAddr("tcp4", fmt.Sprintf("%s:%s", host, port)); err != nil {
errors = append(errors, err)
} else {
addrs[peer] = addr
}
}
cm.actionChan <- func() bool {
if replace {
cm.directPeers = peerAddrs{}
}
for peer, addr := range addrs {
cm.directPeers[peer] = addr
// curtail any existing reconnect interval
if target, found := cm.targets[addr.String()]; found {
target.tryNow()
}
}
return true
}
return errors
}
func (cm *ConnectionMaker) ForgetConnections(peers []string) {
cm.actionChan <- func() bool {
for _, peer := range peers {
delete(cm.directPeers, peer)
}
return false
}
}
func (cm *ConnectionMaker) ConnectionTerminated(address string, err error) {
cm.actionChan <- func() bool {
if target, found := cm.targets[address]; found {
target.attempting = false
target.lastError = err
target.retry()
}
return true
}
}
func (cm *ConnectionMaker) Refresh() {
cm.actionChan <- func() bool { return true }
}
func (cm *ConnectionMaker) queryLoop(actionChan <-chan ConnectionMakerAction) {
timer := time.NewTimer(MaxDuration)
run := func() { timer.Reset(cm.checkStateAndAttemptConnections()) }
for {
select {
case action := <-actionChan:
if action() {
run()
}
case <-timer.C:
run()
}
}
}
func (cm *ConnectionMaker) checkStateAndAttemptConnections() time.Duration {
var (
validTarget = make(map[string]struct{})
directTarget = make(map[string]struct{})
)
// Copy the set of things we are connected to, so we can access
// them without locking. Also clear out any entries in cm.targets
// for existing connections.
ourConnectedPeers, ourConnectedTargets, ourInboundIPs := cm.ourConnections()
addTarget := func(address string) {
if _, connected := ourConnectedTargets[address]; connected {
return
}
validTarget[address] = void
if _, found := cm.targets[address]; found {
return
}
target := &Target{}
target.tryNow()
cm.targets[address] = target
}
// Add direct targets that are not connected
for _, addr := range cm.directPeers {
completeAddr := *addr
attempt := true
if completeAddr.Port == 0 {
completeAddr.Port = cm.port
// If a peer was specified w/o a port, then we do not
// attempt to connect to it if we have any inbound
// connections from that IP.
if _, connected := ourInboundIPs[completeAddr.IP.String()]; connected {
attempt = false
}
}
address := completeAddr.String()
directTarget[address] = void
if attempt {
addTarget(address)
}
}
// Add targets for peers that someone else is connected to, but we
// aren't
if cm.discovery {
cm.addPeerTargets(ourConnectedPeers, addTarget)
}
return cm.connectToTargets(validTarget, directTarget)
}
func (cm *ConnectionMaker) ourConnections() (PeerNameSet, map[string]struct{}, map[string]struct{}) {
var (
ourConnectedPeers = make(PeerNameSet)
ourConnectedTargets = make(map[string]struct{})
ourInboundIPs = make(map[string]struct{})
)
for conn := range cm.ourself.Connections() {
address := conn.RemoteTCPAddr()
delete(cm.targets, address)
ourConnectedPeers[conn.Remote().Name] = void
ourConnectedTargets[address] = void
if conn.Outbound() {
continue
}
if ip, _, err := net.SplitHostPort(address); err == nil { // should always succeed
ourInboundIPs[ip] = void
}
}
return ourConnectedPeers, ourConnectedTargets, ourInboundIPs
}
func (cm *ConnectionMaker) addPeerTargets(ourConnectedPeers PeerNameSet, addTarget func(string)) {
cm.peers.ForEach(func(peer *Peer) {
if peer == cm.ourself.Peer {
return
}
// Modifying peer.connections requires a write lock on Peers,
// and since we are holding a read lock (due to the ForEach),
// access without locking the peer is safe.
for otherPeer, conn := range peer.connections {
if otherPeer == cm.ourself.Name {
continue
}
if _, connected := ourConnectedPeers[otherPeer]; connected {
continue
}
address := conn.RemoteTCPAddr()
if conn.Outbound() {
addTarget(address)
} else if ip, _, err := net.SplitHostPort(address); err == nil {
// There is no point connecting to the (likely
// ephemeral) remote port of an inbound connection
// that some peer has. Let's try to connect to on the
// weave port instead.
addTarget(fmt.Sprintf("%s:%d", ip, cm.port))
}
}
})
}
func (cm *ConnectionMaker) connectToTargets(validTarget map[string]struct{}, directTarget map[string]struct{}) time.Duration {
now := time.Now() // make sure we catch items just added
after := MaxDuration
for address, target := range cm.targets {
if target.attempting {
continue
}
if _, valid := validTarget[address]; !valid {
delete(cm.targets, address)
continue
}
if target.tryAfter.IsZero() {
continue
}
switch duration := target.tryAfter.Sub(now); {
case duration <= 0:
target.attempting = true
_, isCmdLineTarget := directTarget[address]
go cm.attemptConnection(address, isCmdLineTarget)
case duration < after:
after = duration
}
}
return after
}
func (cm *ConnectionMaker) attemptConnection(address string, acceptNewPeer bool) {
log.Printf("->[%s] attempting connection", address)
if err := cm.ourself.CreateConnection(address, acceptNewPeer); err != nil {
log.Errorf("->[%s] error during connection attempt: %v", address, err)
cm.ConnectionTerminated(address, err)
}
}
func (t *Target) tryNow() {
t.tryAfter = time.Now()
t.tryInterval = InitialInterval
}
// The delay at the nth retry is a random value in the range
// [i-i/2,i+i/2], where i = InitialInterval * 1.5^(n-1).
func (t *Target) retry() {
if t.lastError == ErrConnectToSelf {
t.tryAfter = time.Time{}
t.tryInterval = MaxInterval
return
}
t.tryAfter = time.Now().Add(t.tryInterval/2 + time.Duration(rand.Int63n(int64(t.tryInterval))))
t.tryInterval = t.tryInterval * 3 / 2
if t.tryInterval > MaxInterval {
t.tryInterval = MaxInterval
}
}