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connmgr: adds cancellation of pending requests

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This commit extends the work started by roasbeef in the
 previous commit to bring full cancellation of pending
 connection requests. It also adds minor refactors to
 channel send/receives to help cleanup potentially
 lingering go routines.
This commit is contained in:
Conner Fromknecht 2017-11-28 00:31:12 -08:00 committed by Olaoluwa Osuntokun
parent 548c0f499b
commit b26daffac9
2 changed files with 229 additions and 42 deletions
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176
connmgr/connmanager.go
View file

@ -46,9 +46,10 @@ type ConnState uint8
// connection which was disconnected is categorized as disconnected.
const (
ConnPending ConnState = iota
ConnFailing
ConnCanceled
ConnEstablished
ConnDisconnected
ConnFailed
)
// ConnReq is the connection request to a network address. If permanent, the
@ -225,8 +226,16 @@ func (cm *ConnManager) handleFailedConn(c *ConnReq) {
// connections so that we remain connected to the network. Connection requests
// are processed and mapped by their assigned ids.
func (cm *ConnManager) connHandler() {
conns := make(map[uint64]*ConnReq, cm.cfg.TargetOutbound)
pendingConns := make(map[uint64]*ConnReq)
var (
// pending holds all registered conn requests that have yet to
// succeed.
pending = make(map[uint64]*ConnReq)
// conns represents the set of all actively connected peers.
conns = make(map[uint64]*ConnReq, cm.cfg.TargetOutbound)
)
out:
for {
select {
@ -234,11 +243,23 @@ out:
switch msg := req.(type) {
case registerPending:
pendingConns[msg.c.id] = msg.c
connReq := msg.c
connReq.updateState(ConnPending)
pending[msg.c.id] = connReq
close(msg.done)
case handleConnected:
connReq := msg.c
if _, ok := pending[connReq.id]; !ok {
if msg.conn != nil {
msg.conn.Close()
}
log.Debugf("Ignoring connection for "+
"canceled connreq=%v", connReq)
continue
}
connReq.updateState(ConnEstablished)
connReq.conn = msg.conn
conns[connReq.id] = connReq
@ -246,7 +267,7 @@ out:
connReq.retryCount = 0
cm.failedAttempts = 0
delete(pendingConns, connReq.id)
delete(pending, connReq.id)
if cm.cfg.OnConnection != nil {
go cm.cfg.OnConnection(connReq, msg.conn)
@ -255,39 +276,74 @@ out:
case handleDisconnected:
connReq, ok := conns[msg.id]
if !ok {
connReq, ok = pendingConns[msg.id]
if ok && !msg.retry {
connReq.updateState(ConnFailed)
log.Debugf("Cancelling: %v", connReq)
delete(pendingConns, msg.id)
return
connReq, ok = pending[msg.id]
if !ok {
log.Errorf("Unknown connid=%d",
msg.id)
continue
}
// Pending connection was found, remove
// it from pending map if we should
// ignore a later, successful
// connection.
connReq.updateState(ConnCanceled)
log.Debugf("Canceling: %v", connReq)
delete(pending, msg.id)
continue
}
if connReq != nil {
// An existing connection was located, mark as
// disconnected and execute disconnection
// callback.
log.Debugf("Disconnected from %v", connReq)
delete(conns, msg.id)
if connReq.conn != nil {
connReq.conn.Close()
}
if cm.cfg.OnDisconnection != nil {
go cm.cfg.OnDisconnection(connReq)
}
// All internal state has been cleaned up, if
// this connection is being removed, we will
// make no further attempts with this request.
if !msg.retry {
connReq.updateState(ConnDisconnected)
if connReq.conn != nil {
connReq.conn.Close()
}
log.Debugf("Disconnected from %v", connReq)
delete(conns, msg.id)
continue
}
if cm.cfg.OnDisconnection != nil {
go cm.cfg.OnDisconnection(connReq)
}
// Otherwise, we will attempt a reconnection if
// we do not have enough peers, or if this is a
// persistent peer. The connection request is
// re added to the pending map, so that
// subsequent processing of connections and
// failures do not ignore the request.
if uint32(len(conns)) < cm.cfg.TargetOutbound ||
connReq.Permanent {
if uint32(len(conns)) < cm.cfg.TargetOutbound && msg.retry {
cm.handleFailedConn(connReq)
}
} else {
log.Errorf("Unknown connection: %d", msg.id)
connReq.updateState(ConnPending)
log.Debugf("Reconnecting to %v",
connReq)
pending[msg.id] = connReq
cm.handleFailedConn(connReq)
}
case handleFailed:
connReq := msg.c
connReq.updateState(ConnFailed)
log.Debugf("Failed to connect to %v: %v", connReq, msg.err)
if _, ok := pending[connReq.id]; !ok {
log.Debugf("Ignoring connection for "+
"canceled conn req: %v", connReq)
continue
}
connReq.updateState(ConnFailing)
log.Debugf("Failed to connect to %v: %v",
connReq, msg.err)
cm.handleFailedConn(connReq)
}
@ -313,9 +369,31 @@ func (cm *ConnManager) NewConnReq() {
c := &ConnReq{}
atomic.StoreUint64(&c.id, atomic.AddUint64(&cm.connReqCount, 1))
// Submit a request of a pending connection attempt to the connection
// manager. By registering the id before the connection is even
// established, we'll be able to later cancel the connection via the
// Remove method.
done := make(chan struct{})
select {
case cm.requests <- registerPending{c, done}:
case <-cm.quit:
return
}
// Wait for the registration to successfully add the pending conn req to
// the conn manager's internal state.
select {
case <-done:
case <-cm.quit:
return
}
addr, err := cm.cfg.GetNewAddress()
if err != nil {
cm.requests <- handleFailed{c, err}
select {
case cm.requests <- handleFailed{c, err}:
case <-cm.quit:
}
return
}
@ -338,17 +416,35 @@ func (cm *ConnManager) Connect(c *ConnReq) {
// connection is even established, we'll be able to later
// cancel the connection via the Remove method.
done := make(chan struct{})
cm.requests <- registerPending{c, done}
<-done
select {
case cm.requests <- registerPending{c, done}:
case <-cm.quit:
return
}
// Wait for the registration to successfully add the pending
// conn req to the conn manager's internal state.
select {
case <-done:
case <-cm.quit:
return
}
}
log.Debugf("Attempting to connect to %v", c)
conn, err := cm.cfg.Dial(c.Addr)
if err != nil {
cm.requests <- handleFailed{c, err}
} else {
cm.requests <- handleConnected{c, conn}
select {
case cm.requests <- handleFailed{c, err}:
case <-cm.quit:
}
return
}
select {
case cm.requests <- handleConnected{c, conn}:
case <-cm.quit:
}
}
@ -359,7 +455,11 @@ func (cm *ConnManager) Disconnect(id uint64) {
if atomic.LoadInt32(&cm.stop) != 0 {
return
}
cm.requests <- handleDisconnected{id, true}
select {
case cm.requests <- handleDisconnected{id, true}:
case <-cm.quit:
}
}
// Remove removes the connection corresponding to the given connection id from
@ -371,7 +471,11 @@ func (cm *ConnManager) Remove(id uint64) {
if atomic.LoadInt32(&cm.stop) != 0 {
return
}
cm.requests <- handleDisconnected{id, false}
select {
case cm.requests <- handleDisconnected{id, false}:
case <-cm.quit:
}
}
// listenHandler accepts incoming connections on a given listener. It must be

95
connmgr/connmanager_test.go
View file

@ -9,7 +9,6 @@ import (
"fmt"
"io"
"net"
"runtime"
"sync/atomic"
"testing"
"time"
@ -268,7 +267,7 @@ func TestRetryPermanent(t *testing.T) {
t.Fatalf("retry: %v - want ID %v, got ID %v", cr.Addr, wantID, gotID)
}
gotState = cr.State()
wantState = ConnDisconnected
wantState = ConnPending
if gotState != wantState {
t.Fatalf("retry: %v - want state %v, got state %v", cr.Addr, wantState, gotState)
}
@ -451,24 +450,108 @@ func TestRemovePendingConnection(t *testing.T) {
}
go cmgr.Connect(cr)
runtime.Gosched()
time.Sleep(10 * time.Millisecond)
if cr.State() != ConnPending {
t.Fatalf("pending request hasn't been registered, status: %v",
cr.State())
}
// The request launched above will actually never be able to establish
// a connection. So we'll cancel it _before_ it's able to be completed.
cmgr.Remove(cr.ID())
runtime.Gosched()
time.Sleep(10 * time.Millisecond)
// Now examine the status of the connection request, it should read a
// status of failed.
if cr.State() != ConnFailed {
t.Fatalf("request wasn't cancelled, status is: %v", cr.State())
if cr.State() != ConnCanceled {
t.Fatalf("request wasn't canceled, status is: %v", cr.State())
}
close(wait)
cmgr.Stop()
}
// TestCancelIgnoreDelayedConnection tests that a canceled connection request will
// not execute the on connection callback, even if an outstanding retry
// succeeds.
func TestCancelIgnoreDelayedConnection(t *testing.T) {
retryTimeout := 10 * time.Millisecond
// Setup a dialer that will continue to return an error until the
// connect chan is signaled, the dial attempt immediately after will
// succeed in returning a connection.
connect := make(chan struct{})
failingDialer := func(addr net.Addr) (net.Conn, error) {
select {
case <-connect:
return mockDialer(addr)
default:
}
return nil, fmt.Errorf("error")
}
connected := make(chan *ConnReq)
cmgr, err := New(&Config{
Dial: failingDialer,
RetryDuration: retryTimeout,
OnConnection: func(c *ConnReq, conn net.Conn) {
connected <- c
},
})
if err != nil {
t.Fatalf("New error: %v", err)
}
cmgr.Start()
defer cmgr.Stop()
// Establish a connection request to a random IP we've chosen.
cr := &ConnReq{
Addr: &net.TCPAddr{
IP: net.ParseIP("127.0.0.1"),
Port: 18555,
},
}
cmgr.Connect(cr)
// Allow for the first retry timeout to elapse.
time.Sleep(2 * retryTimeout)
// Connection be marked as failed, even after reattempting to
// connect.
if cr.State() != ConnFailing {
t.Fatalf("failing request should have status failed, status: %v",
cr.State())
}
// Remove the connection, and then immediately allow the next connection
// to succeed.
cmgr.Remove(cr.ID())
close(connect)
// Allow the connection manager to process the removal.
time.Sleep(5 * time.Millisecond)
// Now examine the status of the connection request, it should read a
// status of canceled.
if cr.State() != ConnCanceled {
t.Fatalf("request wasn't canceled, status is: %v", cr.State())
}
// Finally, the connection manager should not signal the on-connection
// callback, since we explicitly canceled this request. We give a
// generous window to ensure the connection manager's lienar backoff is
// allowed to properly elapse.
select {
case <-connected:
t.Fatalf("on-connect should not be called for canceled req")
case <-time.After(5 * retryTimeout):
}
}
// mockListener implements the net.Listener interface and is used to test
// code that deals with net.Listeners without having to actually make any real
// connections.