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Posted to commits@qpid.apache.org by ac...@apache.org on 2015/11/23 18:58:17 UTC

[49/50] [abbrv] qpid-proton git commit: Merge branch 'master' into go1

http://git-wip-us.apache.org/repos/asf/qpid-proton/blob/9e788b2d/electron/link.go
----------------------------------------------------------------------
diff --cc electron/link.go
index 4bef53b,0000000..91efa8e
mode 100644,000000..100644
--- a/electron/link.go
+++ b/electron/link.go
@@@ -1,247 -1,0 +1,245 @@@
 +/*
 +Licensed to the Apache Software Foundation (ASF) under one
 +or more contributor license agreements.  See the NOTICE file
 +distributed with this work for additional information
 +regarding copyright ownership.  The ASF licenses this file
 +to you 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 electron
 +
 +import (
- 	"qpid.apache.org/internal"
++	"fmt"
 +	"qpid.apache.org/proton"
 +)
 +
 +// Link is the common interface for AMQP links. Sender and Receiver provide
 +// more methods for the sending or receiving end of a link respectively.
 +type Link interface {
 +	Endpoint
 +
 +	// Source address that messages are coming from.
 +	Source() string
 +
 +	// Target address that messages are going to.
 +	Target() string
 +
 +	// Name is a unique name for the link among links between the same
 +	// containers in the same direction. By default generated automatically.
 +	LinkName() string
 +
 +	// IsSender is true if this is the sending end of the link.
 +	IsSender() bool
 +
 +	// IsReceiver is true if this is the receiving end of the link.
 +	IsReceiver() bool
 +
 +	// SndSettle defines when the sending end of the link settles message delivery.
 +	SndSettle() SndSettleMode
 +
 +	// RcvSettle defines when the sending end of the link settles message delivery.
 +	RcvSettle() RcvSettleMode
 +
 +	// Session containing the Link
 +	Session() Session
 +
 +	// Called in event loop on closed event.
 +	closed(err error)
 +	// Called to open a link (local or accepted incoming link)
 +	open()
 +}
 +
- // LinkSetting can be passed when creating a sender or receiver.
- // See functions that return LinkSetting for details
- type LinkSetting func(*link)
++// LinkOption can be passed when creating a sender or receiver link to set optional configuration.
++type LinkOption func(*link)
 +
- // Source sets address that messages are coming from.
- func Source(s string) LinkSetting { return func(l *link) { l.source = s } }
++// Source returns a LinkOption that sets address that messages are coming from.
++func Source(s string) LinkOption { return func(l *link) { l.source = s } }
 +
- // Target sets address that messages are going to.
- func Target(s string) LinkSetting { return func(l *link) { l.target = s } }
++// Target returns a LinkOption that sets address that messages are going to.
++func Target(s string) LinkOption { return func(l *link) { l.target = s } }
 +
- // LinkName sets the link name.
- func LinkName(s string) LinkSetting { return func(l *link) { l.target = s } }
++// LinkName returns a LinkOption that sets the link name.
++func LinkName(s string) LinkOption { return func(l *link) { l.target = s } }
 +
- // SndSettle sets the send settle mode
- func SndSettle(m SndSettleMode) LinkSetting { return func(l *link) { l.sndSettle = m } }
++// SndSettle returns a LinkOption that sets the send settle mode
++func SndSettle(m SndSettleMode) LinkOption { return func(l *link) { l.sndSettle = m } }
 +
- // RcvSettle sets the send settle mode
- func RcvSettle(m RcvSettleMode) LinkSetting { return func(l *link) { l.rcvSettle = m } }
++// RcvSettle returns a LinkOption that sets the send settle mode
++func RcvSettle(m RcvSettleMode) LinkOption { return func(l *link) { l.rcvSettle = m } }
 +
- // SndSettleMode defines when the sending end of the link settles message delivery.
++// SndSettleMode returns a LinkOption that defines when the sending end of the
++// link settles message delivery.
 +type SndSettleMode proton.SndSettleMode
 +
- // Capacity sets the link capacity
- func Capacity(n int) LinkSetting { return func(l *link) { l.capacity = n } }
++// Capacity returns a LinkOption that sets the link capacity
++func Capacity(n int) LinkOption { return func(l *link) { l.capacity = n } }
 +
- // Prefetch sets a receivers pre-fetch flag. Not relevant for a sender.
- func Prefetch(p bool) LinkSetting { return func(l *link) { l.prefetch = p } }
++// Prefetch returns a LinkOption that sets a receivers pre-fetch flag. Not relevant for a sender.
++func Prefetch(p bool) LinkOption { return func(l *link) { l.prefetch = p } }
 +
- // AtMostOnce sets "fire and forget" mode, messages are sent but no
- // acknowledgment is received, messages can be lost if there is a network
- // failure. Sets SndSettleMode=SendSettled and RcvSettleMode=RcvFirst
- func AtMostOnce() LinkSetting {
++// AtMostOnce returns a LinkOption that sets "fire and forget" mode, messages
++// are sent but no acknowledgment is received, messages can be lost if there is
++// a network failure. Sets SndSettleMode=SendSettled and RcvSettleMode=RcvFirst
++func AtMostOnce() LinkOption {
 +	return func(l *link) {
 +		SndSettle(SndSettled)(l)
 +		RcvSettle(RcvFirst)(l)
 +	}
 +}
 +
- // AtLeastOnce requests acknowledgment for every message, acknowledgment
- // indicates the message was definitely received. In the event of a
- // failure, unacknowledged messages can be re-sent but there is a chance
- // that the message will be received twice in this case.
- // Sets SndSettleMode=SndUnsettled and RcvSettleMode=RcvFirst
- func AtLeastOnce() LinkSetting {
++// AtLeastOnce returns a LinkOption that requests acknowledgment for every
++// message, acknowledgment indicates the message was definitely received. In the
++// event of a failure, unacknowledged messages can be re-sent but there is a
++// chance that the message will be received twice in this case.  Sets
++// SndSettleMode=SndUnsettled and RcvSettleMode=RcvFirst
++func AtLeastOnce() LinkOption {
 +	return func(l *link) {
 +		SndSettle(SndUnsettled)(l)
 +		RcvSettle(RcvFirst)(l)
 +	}
 +}
 +
 +const (
 +	// Messages are sent unsettled
 +	SndUnsettled = SndSettleMode(proton.SndUnsettled)
 +	// Messages are sent already settled
 +	SndSettled = SndSettleMode(proton.SndSettled)
 +	// Sender can send either unsettled or settled messages.
 +	SendMixed = SndSettleMode(proton.SndMixed)
 +)
 +
 +// RcvSettleMode defines when the receiving end of the link settles message delivery.
 +type RcvSettleMode proton.RcvSettleMode
 +
 +const (
 +	// Receiver settles first.
 +	RcvFirst = RcvSettleMode(proton.RcvFirst)
 +	// Receiver waits for sender to settle before settling.
 +	RcvSecond = RcvSettleMode(proton.RcvSecond)
 +)
 +
 +type link struct {
 +	endpoint
 +
 +	// Link settings.
 +	source    string
 +	target    string
 +	linkName  string
 +	isSender  bool
 +	sndSettle SndSettleMode
 +	rcvSettle RcvSettleMode
 +	capacity  int
 +	prefetch  bool
 +
 +	session *session
 +	eLink   proton.Link
- 	done    chan struct{} // Closed when link is closed
 +}
 +
 +func (l *link) Source() string           { return l.source }
 +func (l *link) Target() string           { return l.target }
 +func (l *link) LinkName() string         { return l.linkName }
 +func (l *link) IsSender() bool           { return l.isSender }
 +func (l *link) IsReceiver() bool         { return !l.isSender }
 +func (l *link) SndSettle() SndSettleMode { return l.sndSettle }
 +func (l *link) RcvSettle() RcvSettleMode { return l.rcvSettle }
 +func (l *link) Session() Session         { return l.session }
 +func (l *link) Connection() Connection   { return l.session.Connection() }
 +
 +func (l *link) engine() *proton.Engine { return l.session.connection.engine }
 +func (l *link) handler() *handler      { return l.session.connection.handler }
 +
 +// Set up link fields and open the proton.Link
- func localLink(sn *session, isSender bool, setting ...LinkSetting) (link, error) {
++func localLink(sn *session, isSender bool, setting ...LinkOption) (link, error) {
 +	l := link{
 +		session:  sn,
 +		isSender: isSender,
 +		capacity: 1,
 +		prefetch: false,
- 		done:     make(chan struct{}),
 +	}
 +	for _, set := range setting {
 +		set(&l)
 +	}
 +	if l.linkName == "" {
 +		l.linkName = l.session.connection.container.nextLinkName()
 +	}
 +	if l.IsSender() {
 +		l.eLink = l.session.eSession.Sender(l.linkName)
 +	} else {
 +		l.eLink = l.session.eSession.Receiver(l.linkName)
 +	}
 +	if l.eLink.IsNil() {
- 		l.err.Set(internal.Errorf("cannot create link %s", l))
++		l.err.Set(fmt.Errorf("cannot create link %s", l))
 +		return l, l.err.Get()
 +	}
 +	l.eLink.Source().SetAddress(l.source)
 +	l.eLink.Target().SetAddress(l.target)
 +	l.eLink.SetSndSettleMode(proton.SndSettleMode(l.sndSettle))
 +	l.eLink.SetRcvSettleMode(proton.RcvSettleMode(l.rcvSettle))
- 	l.str = l.eLink.String()
 +	l.eLink.Open()
++	l.endpoint = makeEndpoint(l.eLink.String())
 +	return l, nil
 +}
 +
 +type incomingLink struct {
 +	incoming
 +	link
 +}
 +
 +// Set up a link from an incoming proton.Link.
 +func makeIncomingLink(sn *session, eLink proton.Link) incomingLink {
 +	l := incomingLink{
++		incoming: makeIncoming(eLink),
 +		link: link{
 +			session:   sn,
 +			isSender:  eLink.IsSender(),
 +			eLink:     eLink,
 +			source:    eLink.RemoteSource().Address(),
 +			target:    eLink.RemoteTarget().Address(),
 +			linkName:  eLink.Name(),
 +			sndSettle: SndSettleMode(eLink.RemoteSndSettleMode()),
 +			rcvSettle: RcvSettleMode(eLink.RemoteRcvSettleMode()),
 +			capacity:  1,
 +			prefetch:  false,
- 			done:      make(chan struct{}),
++			endpoint:  makeEndpoint(eLink.String()),
 +		},
 +	}
- 	l.str = eLink.String()
 +	return l
 +}
 +
- // Called in proton goroutine on closed or disconnected
- func (l *link) closed(err error) {
- 	l.err.Set(err)
- 	l.err.Set(Closed) // If no error set, mark as closed.
- 	close(l.done)
- }
- 
 +// Not part of Link interface but use by Sender and Receiver.
 +func (l *link) Credit() (credit int, err error) {
 +	err = l.engine().InjectWait(func() error {
++		if l.Error() != nil {
++			return l.Error()
++		}
 +		credit = l.eLink.Credit()
 +		return nil
 +	})
 +	return
 +}
 +
 +// Not part of Link interface but use by Sender and Receiver.
 +func (l *link) Capacity() int { return l.capacity }
 +
 +func (l *link) Close(err error) {
- 	l.engine().Inject(func() { localClose(l.eLink, err) })
++	l.engine().Inject(func() {
++		if l.Error() == nil {
++			localClose(l.eLink, err)
++		}
++	})
 +}
 +
 +func (l *link) open() {
 +	l.eLink.Open()
 +}

http://git-wip-us.apache.org/repos/asf/qpid-proton/blob/9e788b2d/electron/messaging_test.go
----------------------------------------------------------------------
diff --cc electron/messaging_test.go
index 36b0c24,0000000..5af57e8
mode 100644,000000..100644
--- a/electron/messaging_test.go
+++ b/electron/messaging_test.go
@@@ -1,416 -1,0 +1,426 @@@
 +/*
 +Licensed to the Apache Software Foundation (ASF) under one
 +or more contributor license agreements.  See the NOTICE file
 +distributed with this work for additional information
 +regarding copyright ownership.  The ASF licenses this file
 +to you 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 electron
 +
 +import (
 +	"fmt"
 +	"net"
 +	"path"
 +	"qpid.apache.org/amqp"
 +	"runtime"
 +	"testing"
 +	"time"
 +)
 +
 +func fatalIf(t *testing.T, err error) {
 +	if err != nil {
 +		_, file, line, ok := runtime.Caller(1) // annotate with location of caller.
 +		if ok {
 +			_, file = path.Split(file)
 +		}
 +		t.Fatalf("(from %s:%d) %v", file, line, err)
 +	}
 +}
 +
- // Start a server, return listening addr and channel for incoming Connection.
- func newServer(t *testing.T, cont Container, accept func(Endpoint) error) (net.Addr, <-chan Connection) {
++// Start a server, return listening addr and channel for incoming Connections.
++func newServer(t *testing.T, cont Container) (net.Addr, <-chan Connection) {
 +	listener, err := net.Listen("tcp", "")
 +	fatalIf(t, err)
 +	addr := listener.Addr()
 +	ch := make(chan Connection)
 +	go func() {
 +		conn, err := listener.Accept()
- 		c, err := cont.Connection(conn)
++		c, err := cont.Connection(conn, Server(), AllowIncoming())
 +		fatalIf(t, err)
- 		c.Server()
- 		c.Listen(accept)
- 		fatalIf(t, c.Open())
 +		ch <- c
 +	}()
 +	return addr, ch
 +}
 +
- // Return open an client connection and session, return the session.
++// Open a client connection and session, return the session.
 +func newClient(t *testing.T, cont Container, addr net.Addr) Session {
 +	conn, err := net.Dial(addr.Network(), addr.String())
 +	fatalIf(t, err)
 +	c, err := cont.Connection(conn)
 +	fatalIf(t, err)
- 	c.Open()
 +	sn, err := c.Session()
 +	fatalIf(t, err)
 +	return sn
 +}
 +
 +// Return client and server ends of the same connection.
- func newClientServer(t *testing.T, accept func(Endpoint) error) (client Session, server Connection) {
- 	addr, ch := newServer(t, NewContainer(""), accept)
- 	client = newClient(t, NewContainer(""), addr)
++func newClientServer(t *testing.T) (client Session, server Connection) {
++	addr, ch := newServer(t, NewContainer("test-server"))
++	client = newClient(t, NewContainer("test-client"), addr)
 +	return client, <-ch
 +}
 +
 +// Close client and server
 +func closeClientServer(client Session, server Connection) {
 +	client.Connection().Close(nil)
 +	server.Close(nil)
 +}
 +
 +// Send a message one way with a client sender and server receiver, verify ack.
 +func TestClientSendServerReceive(t *testing.T) {
- 	timeout := time.Second * 2
 +	nLinks := 3
 +	nMessages := 3
 +
 +	rchan := make(chan Receiver, nLinks)
- 	client, server := newClientServer(t, func(ep Endpoint) error {
- 		if r, ok := ep.(Receiver); ok {
- 			r.SetCapacity(1, false)
- 			rchan <- r
++	client, server := newClientServer(t)
++	go func() {
++		for in := range server.Incoming() {
++			switch in := in.(type) {
++			case *IncomingReceiver:
++				in.SetCapacity(1)
++				in.SetPrefetch(false)
++				rchan <- in.Accept().(Receiver)
++			default:
++				in.Accept()
++			}
 +		}
- 		return nil
- 	})
- 
- 	defer func() {
- 		closeClientServer(client, server)
 +	}()
 +
++	defer func() { closeClientServer(client, server) }()
++
 +	s := make([]Sender, nLinks)
 +	for i := 0; i < nLinks; i++ {
 +		var err error
 +		s[i], err = client.Sender(Target(fmt.Sprintf("foo%d", i)))
 +		if err != nil {
 +			t.Fatal(err)
 +		}
 +	}
 +	r := make([]Receiver, nLinks)
 +	for i := 0; i < nLinks; i++ {
 +		r[i] = <-rchan
 +	}
 +
 +	for i := 0; i < nLinks; i++ {
 +		for j := 0; j < nMessages; j++ {
- 			var sm SentMessage
- 
 +			// Client send
++			ack := make(chan Outcome, 1)
 +			sendDone := make(chan struct{})
 +			go func() {
 +				defer close(sendDone)
 +				m := amqp.NewMessageWith(fmt.Sprintf("foobar%v-%v", i, j))
 +				var err error
- 				sm, err = s[i].Send(m)
++				s[i].SendAsync(m, ack, "testing")
 +				if err != nil {
 +					t.Fatal(err)
 +				}
 +			}()
 +
 +			// Server recieve
 +			rm, err := r[i].Receive()
 +			if err != nil {
 +				t.Fatal(err)
 +			}
 +			if want, got := interface{}(fmt.Sprintf("foobar%v-%v", i, j)), rm.Message.Body(); want != got {
 +				t.Errorf("%#v != %#v", want, got)
 +			}
 +
 +			// Should not be acknowledged on client yet
 +			<-sendDone
- 			if d, err := sm.DispositionTimeout(0); err != Timeout || NoDisposition != d {
- 				t.Errorf("want [no-disposition/timeout] got [%v/%v]", d, err)
++			select {
++			case <-ack:
++				t.Errorf("unexpected ack")
++			default:
 +			}
- 			// Server ack
- 			if err := rm.Acknowledge(Rejected); err != nil {
++
++			// Server send ack
++			if err := rm.Reject(); err != nil {
 +				t.Error(err)
 +			}
 +			// Client get ack.
- 			if d, err := sm.DispositionTimeout(timeout); err != nil || Rejected != d {
- 				t.Errorf("want [rejected/nil] got [%v/%v]", d, err)
++			if a := <-ack; a.Value != "testing" || a.Error != nil || a.Status != Rejected {
++				t.Error("unexpected ack: ", a.Status, a.Error, a.Value)
 +			}
 +		}
 +	}
 +}
 +
 +func TestClientReceiver(t *testing.T) {
 +	nMessages := 3
- 	client, server := newClientServer(t, func(ep Endpoint) error {
- 		if s, ok := ep.(Sender); ok {
- 			go func() {
- 				for i := int32(0); i < int32(nMessages); i++ {
- 					sm, err := s.Send(amqp.NewMessageWith(i))
- 					if err != nil {
- 						t.Error(err)
- 						return
- 					} else {
- 						sm.Disposition() // Sync send.
++	client, server := newClientServer(t)
++	go func() {
++		for in := range server.Incoming() {
++			switch in := in.(type) {
++			case *IncomingSender:
++				s := in.Accept().(Sender)
++				go func() {
++					for i := int32(0); i < int32(nMessages); i++ {
++						out := s.SendSync(amqp.NewMessageWith(i))
++						if out.Error != nil {
++							t.Error(out.Error)
++							return
++						}
 +					}
- 				}
- 				s.Close(nil)
- 			}()
++					s.Close(nil)
++				}()
++			default:
++				in.Accept()
++			}
 +		}
- 		return nil
- 	})
++	}()
 +
 +	r, err := client.Receiver(Source("foo"))
 +	if err != nil {
 +		t.Fatal(err)
 +	}
 +	for i := int32(0); i < int32(nMessages); i++ {
 +		rm, err := r.Receive()
 +		if err != nil {
 +			if err != Closed {
 +				t.Error(err)
 +			}
 +			break
 +		}
 +		if err := rm.Accept(); err != nil {
 +			t.Error(err)
 +		}
 +		if b, ok := rm.Message.Body().(int32); !ok || b != i {
 +			t.Errorf("want %v, true got %v, %v", i, b, ok)
 +		}
 +	}
 +	server.Close(nil)
 +	client.Connection().Close(nil)
 +}
 +
 +// Test timeout versions of waiting functions.
 +func TestTimeouts(t *testing.T) {
 +	var err error
 +	rchan := make(chan Receiver, 1)
- 	client, server := newClientServer(t, func(ep Endpoint) error {
- 		if r, ok := ep.(Receiver); ok {
- 			r.SetCapacity(1, false) // Issue credit only on receive
- 			rchan <- r
++	client, server := newClientServer(t)
++	go func() {
++		for i := range server.Incoming() {
++			switch i := i.(type) {
++			case *IncomingReceiver:
++				i.SetCapacity(1)
++				i.SetPrefetch(false)
++				rchan <- i.Accept().(Receiver) // Issue credit only on receive
++			default:
++				i.Accept()
++			}
 +		}
- 		return nil
- 	})
++	}()
 +	defer func() { closeClientServer(client, server) }()
 +
 +	// Open client sender
 +	snd, err := client.Sender(Target("test"))
 +	if err != nil {
 +		t.Fatal(err)
 +	}
 +	rcv := <-rchan
 +
 +	// Test send with timeout
 +	short := time.Millisecond
 +	long := time.Second
 +	m := amqp.NewMessage()
- 	if _, err = snd.SendTimeout(m, 0); err != Timeout { // No credit, expect timeout.
++	if err := snd.SendSyncTimeout(m, 0).Error; err != Timeout { // No credit, expect timeout.
 +		t.Error("want Timeout got", err)
 +	}
- 	if _, err = snd.SendTimeout(m, short); err != Timeout { // No credit, expect timeout.
++	if err := snd.SendSyncTimeout(m, short).Error; err != Timeout { // No credit, expect timeout.
 +		t.Error("want Timeout got", err)
 +	}
 +	// Test receive with timeout
 +	if _, err = rcv.ReceiveTimeout(0); err != Timeout { // No credit, expect timeout.
 +		t.Error("want Timeout got", err)
 +	}
 +	// Test receive with timeout
 +	if _, err = rcv.ReceiveTimeout(short); err != Timeout { // No credit, expect timeout.
 +		t.Error("want Timeout got", err)
 +	}
 +	// There is now a credit on the link due to receive
- 	sm, err := snd.SendTimeout(m, long)
- 	if err != nil {
- 		t.Fatal(err)
- 	}
++	ack := make(chan Outcome)
++	snd.SendAsyncTimeout(m, ack, nil, short)
 +	// Disposition should timeout
- 	if _, err = sm.DispositionTimeout(long); err != Timeout {
- 		t.Error("want Timeout got", err)
- 	}
- 	if _, err = sm.DispositionTimeout(short); err != Timeout {
- 		t.Error("want Timeout got", err)
++	select {
++	case <-ack:
++		t.Errorf("want Timeout got %#v", ack)
++	case <-time.After(short):
 +	}
++
 +	// Receive and accept
 +	rm, err := rcv.ReceiveTimeout(long)
 +	if err != nil {
 +		t.Fatal(err)
 +	}
 +	rm.Accept()
 +	// Sender get ack
- 	d, err := sm.DispositionTimeout(long)
- 	if err != nil || d != Accepted {
- 		t.Errorf("want (rejected, nil) got (%v, %v)", d, err)
++	if a := <-ack; a.Status != Accepted || a.Error != nil {
++		t.Errorf("want (accepted, nil) got %#v", a)
 +	}
 +}
 +
 +// clientServer that returns sender/receiver pairs at opposite ends of link.
 +type pairs struct {
 +	t      *testing.T
 +	client Session
 +	server Connection
 +	rchan  chan Receiver
 +	schan  chan Sender
 +}
 +
 +func newPairs(t *testing.T) *pairs {
 +	p := &pairs{t: t, rchan: make(chan Receiver, 1), schan: make(chan Sender, 1)}
- 	p.client, p.server = newClientServer(t, func(ep Endpoint) error {
- 		switch ep := ep.(type) {
- 		case Receiver:
- 			ep.SetCapacity(1, false)
- 			p.rchan <- ep
- 		case Sender:
- 			p.schan <- ep
++	p.client, p.server = newClientServer(t)
++	go func() {
++		for i := range p.server.Incoming() {
++			switch i := i.(type) {
++			case *IncomingReceiver:
++				i.SetCapacity(1)
++				i.SetPrefetch(false)
++				p.rchan <- i.Accept().(Receiver)
++			case *IncomingSender:
++				p.schan <- i.Accept().(Sender)
++			default:
++				i.Accept()
++			}
 +		}
- 		return nil
- 	})
++	}()
 +	return p
 +}
 +
 +func (p *pairs) close() {
 +	closeClientServer(p.client, p.server)
 +}
 +
 +func (p *pairs) senderReceiver() (Sender, Receiver) {
 +	snd, err := p.client.Sender()
 +	fatalIf(p.t, err)
 +	rcv := <-p.rchan
 +	return snd, rcv
 +}
 +
 +func (p *pairs) receiverSender() (Receiver, Sender) {
 +	rcv, err := p.client.Receiver()
 +	fatalIf(p.t, err)
 +	snd := <-p.schan
 +	return rcv, snd
 +}
 +
 +type result struct {
 +	label string
 +	err   error
 +}
 +
 +func (r result) String() string { return fmt.Sprintf("%s(%s)", r.err, r.label) }
 +
 +func doSend(snd Sender, results chan result) {
- 	_, err := snd.Send(amqp.NewMessage())
++	err := snd.SendSync(amqp.NewMessage()).Error
 +	results <- result{"send", err}
 +}
 +
 +func doReceive(rcv Receiver, results chan result) {
 +	_, err := rcv.Receive()
 +	results <- result{"receive", err}
 +}
 +
- func doDisposition(sm SentMessage, results chan result) {
- 	_, err := sm.Disposition()
- 	results <- result{"disposition", err}
++func doDisposition(ack <-chan Outcome, results chan result) {
++	results <- result{"disposition", (<-ack).Error}
 +}
 +
 +// Test that closing Links interrupts blocked link functions.
 +func TestLinkCloseInterrupt(t *testing.T) {
 +	want := amqp.Errorf("x", "all bad")
 +	pairs := newPairs(t)
 +	results := make(chan result) // Collect expected errors
 +
 +	// Sender.Close() interrupts Send()
 +	snd, rcv := pairs.senderReceiver()
 +	go doSend(snd, results)
 +	snd.Close(want)
 +	if r := <-results; want != r.err {
 +		t.Errorf("want %#v got %#v", want, r)
 +	}
 +
 +	// Remote Receiver.Close() interrupts Send()
 +	snd, rcv = pairs.senderReceiver()
 +	go doSend(snd, results)
 +	rcv.Close(want)
 +	if r := <-results; want != r.err {
 +		t.Errorf("want %#v got %#v", want, r)
 +	}
 +
 +	// Receiver.Close() interrupts Receive()
 +	snd, rcv = pairs.senderReceiver()
 +	go doReceive(rcv, results)
 +	rcv.Close(want)
 +	if r := <-results; want != r.err {
 +		t.Errorf("want %#v got %#v", want, r)
 +	}
 +
 +	// Remote Sender.Close() interrupts Receive()
 +	snd, rcv = pairs.senderReceiver()
 +	go doReceive(rcv, results)
 +	snd.Close(want)
 +	if r := <-results; want != r.err {
 +		t.Errorf("want %#v got %#v", want, r)
 +	}
 +}
 +
 +// Test closing the server end of a connection.
 +func TestConnectionCloseInterrupt1(t *testing.T) {
 +	want := amqp.Errorf("x", "bad")
 +	pairs := newPairs(t)
 +	results := make(chan result) // Collect expected errors
 +
 +	// Connection.Close() interrupts Send, Receive, Disposition.
 +	snd, rcv := pairs.senderReceiver()
 +	go doReceive(rcv, results)
- 	sm, err := snd.Send(amqp.NewMessage())
- 	fatalIf(t, err)
- 	go doDisposition(sm, results)
++	ack := snd.SendWaitable(amqp.NewMessage())
++	go doDisposition(ack, results)
 +	snd, rcv = pairs.senderReceiver()
 +	go doSend(snd, results)
 +	rcv, snd = pairs.receiverSender()
 +	go doReceive(rcv, results)
 +	pairs.server.Close(want)
 +	for i := 0; i < 3; i++ {
 +		if r := <-results; want != r.err {
 +			// TODO aconway 2015-10-06: Not propagating the correct error, seeing nil and EOF.
- 			t.Logf("want %v got %v", want, r)
++			t.Logf("want %v got %v", want, r.err)
 +		}
 +	}
 +}
 +
 +// Test closing the client end of the connection.
 +func TestConnectionCloseInterrupt2(t *testing.T) {
 +	want := amqp.Errorf("x", "bad")
 +	pairs := newPairs(t)
 +	results := make(chan result) // Collect expected errors
 +
 +	// Connection.Close() interrupts Send, Receive, Disposition.
 +	snd, rcv := pairs.senderReceiver()
 +	go doReceive(rcv, results)
- 	sm, err := snd.Send(amqp.NewMessage())
- 	fatalIf(t, err)
- 	go doDisposition(sm, results)
++	ack := snd.SendWaitable(amqp.NewMessage())
++	go doDisposition(ack, results)
 +	snd, rcv = pairs.senderReceiver()
 +	go doSend(snd, results)
 +	rcv, snd = pairs.receiverSender()
 +	go doReceive(rcv, results)
 +	pairs.client.Close(want)
 +	for i := 0; i < 3; i++ {
 +		if r := <-results; want != r.err {
 +			// TODO aconway 2015-10-06: Not propagating the correct error, seeing nil.
- 			t.Logf("want %v got %v", want, r)
++			t.Logf("want %v got %v", want, r.err)
 +		}
 +	}
 +}

http://git-wip-us.apache.org/repos/asf/qpid-proton/blob/9e788b2d/electron/receiver.go
----------------------------------------------------------------------
diff --cc electron/receiver.go
index 59ac018,0000000..22bdc7e
mode 100644,000000..100644
--- a/electron/receiver.go
+++ b/electron/receiver.go
@@@ -1,238 -1,0 +1,244 @@@
 +/*
 +Licensed to the Apache Software Foundation (ASF) under one
 +or more contributor license agreements.  See the NOTICE file
 +distributed with this work for additional information
 +regarding copyright ownership.  The ASF licenses this file
 +to you 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 electron
 +
 +import (
++	"fmt"
 +	"qpid.apache.org/amqp"
- 	"qpid.apache.org/internal"
 +	"qpid.apache.org/proton"
 +	"time"
 +)
 +
 +// Receiver is a Link that receives messages.
 +//
 +type Receiver interface {
 +	Link
 +
 +	// Receive blocks until a message is available or until the Receiver is closed
 +	// and has no more buffered messages.
 +	Receive() (ReceivedMessage, error)
 +
 +	// ReceiveTimeout is like Receive but gives up after timeout, see Timeout.
 +	//
 +	// Note that that if Prefetch is false, after a Timeout the credit issued by
 +	// Receive remains on the link. It will be used by the next call to Receive.
 +	ReceiveTimeout(timeout time.Duration) (ReceivedMessage, error)
 +
 +	// Prefetch==true means the Receiver will automatically issue credit to the
 +	// remote sender to keep its buffer as full as possible, i.e. it will
 +	// "pre-fetch" messages independently of the application calling
 +	// Receive(). This gives good throughput for applications that handle a
 +	// continuous stream of messages. Larger capacity may improve throughput, the
 +	// optimal value depends on the characteristics of your application.
 +	//
 +	// Prefetch==false means the Receiver will issue only issue credit when you
 +	// call Receive(), and will only issue enough credit to satisfy the calls
 +	// actually made. This gives lower throughput but will not fetch any messages
 +	// in advance. It is good for synchronous applications that need to evaluate
 +	// each message before deciding whether to receive another. The
 +	// request-response pattern is a typical example.  If you make concurrent
 +	// calls to Receive with pre-fetch disabled, you can improve performance by
 +	// setting the capacity close to the expected number of concurrent calls.
 +	//
 +	Prefetch() bool
 +
 +	// Capacity is the size (number of messages) of the local message buffer
 +	// These are messages received but not yet returned to the application by a call to Receive()
 +	Capacity() int
 +}
 +
 +// Flow control policy for a receiver.
 +type policy interface {
 +	// Called at the start of Receive() to adjust credit before fetching a message.
 +	Pre(*receiver)
 +	// Called after Receive() has received a message from Buffer() before it returns.
 +	// Non-nil error means no message was received because of an error.
 +	Post(*receiver, error)
 +}
 +
 +type prefetchPolicy struct{}
 +
 +func (p prefetchPolicy) Flow(r *receiver) {
 +	r.engine().Inject(func() {
++		if r.Error() != nil {
++			return
++		}
 +		_, _, max := r.credit()
 +		if max > 0 {
 +			r.eLink.Flow(max)
 +		}
 +	})
 +}
 +func (p prefetchPolicy) Pre(r *receiver) { p.Flow(r) }
 +func (p prefetchPolicy) Post(r *receiver, err error) {
 +	if err == nil {
 +		p.Flow(r)
 +	}
 +}
 +
 +type noPrefetchPolicy struct{ waiting int }
 +
 +func (p noPrefetchPolicy) Flow(r *receiver) { // Not called in proton goroutine
 +	r.engine().Inject(func() {
++		if r.Error() != nil {
++			return
++		}
 +		len, credit, max := r.credit()
 +		add := p.waiting - (len + credit)
 +		if add > max {
 +			add = max // Don't overflow
 +		}
 +		if add > 0 {
 +			r.eLink.Flow(add)
 +		}
 +	})
 +}
 +func (p noPrefetchPolicy) Pre(r *receiver) { p.waiting++; p.Flow(r) }
 +func (p noPrefetchPolicy) Post(r *receiver, err error) {
 +	p.waiting--
 +	if err == nil {
 +		p.Flow(r)
 +	}
 +}
 +
 +// Receiver implementation
 +type receiver struct {
 +	link
 +	buffer chan ReceivedMessage
 +	policy policy
 +}
 +
++// Call in proton goroutine
 +func newReceiver(l link) *receiver {
 +	r := &receiver{link: l}
 +	if r.capacity < 1 {
 +		r.capacity = 1
 +	}
 +	if r.prefetch {
 +		r.policy = &prefetchPolicy{}
 +	} else {
 +		r.policy = &noPrefetchPolicy{}
 +	}
 +	r.buffer = make(chan ReceivedMessage, r.capacity)
 +	r.handler().addLink(r.eLink, r)
 +	r.link.open()
 +	return r
 +}
 +
 +// call in proton goroutine.
 +func (r *receiver) credit() (buffered, credit, max int) {
 +	return len(r.buffer), r.eLink.Credit(), cap(r.buffer) - len(r.buffer)
 +}
 +
 +func (r *receiver) Capacity() int  { return cap(r.buffer) }
 +func (r *receiver) Prefetch() bool { return r.prefetch }
 +
 +func (r *receiver) Receive() (rm ReceivedMessage, err error) {
 +	return r.ReceiveTimeout(Forever)
 +}
 +
 +func (r *receiver) ReceiveTimeout(timeout time.Duration) (rm ReceivedMessage, err error) {
- 	internal.Assert(r.buffer != nil, "Receiver is not open: %s", r)
++	assert(r.buffer != nil, "Receiver is not open: %s", r)
 +	r.policy.Pre(r)
 +	defer func() { r.policy.Post(r, err) }()
 +	rmi, err := timedReceive(r.buffer, timeout)
 +	switch err {
 +	case Timeout:
 +		return ReceivedMessage{}, Timeout
 +	case Closed:
 +		return ReceivedMessage{}, r.Error()
 +	default:
 +		return rmi.(ReceivedMessage), nil
 +	}
 +}
 +
 +// Called in proton goroutine on MMessage event.
 +func (r *receiver) message(delivery proton.Delivery) {
 +	if r.eLink.State().RemoteClosed() {
 +		localClose(r.eLink, r.eLink.RemoteCondition().Error())
 +		return
 +	}
 +	if delivery.HasMessage() {
 +		m, err := delivery.Message()
 +		if err != nil {
 +			localClose(r.eLink, err)
 +			return
 +		}
- 		internal.Assert(m != nil)
++		assert(m != nil)
 +		r.eLink.Advance()
 +		if r.eLink.Credit() < 0 {
- 			localClose(r.eLink, internal.Errorf("received message in excess of credit limit"))
++			localClose(r.eLink, fmt.Errorf("received message in excess of credit limit"))
 +		} else {
 +			// We never issue more credit than cap(buffer) so this will not block.
 +			r.buffer <- ReceivedMessage{m, delivery, r}
 +		}
 +	}
 +}
 +
 +func (r *receiver) closed(err error) {
 +	r.link.closed(err)
 +	if r.buffer != nil {
 +		close(r.buffer)
 +	}
 +}
 +
 +// ReceivedMessage contains an amqp.Message and allows the message to be acknowledged.
 +type ReceivedMessage struct {
 +	// Message is the received message.
 +	Message amqp.Message
 +
 +	eDelivery proton.Delivery
 +	receiver  Receiver
 +}
 +
- // Acknowledge a ReceivedMessage with the given disposition code.
- func (rm *ReceivedMessage) Acknowledge(disposition Disposition) error {
- 	return rm.receiver.(*receiver).engine().InjectWait(func() error {
- 		// Settle doesn't return an error but if the receiver is broken the settlement won't happen.
- 		rm.eDelivery.SettleAs(uint64(disposition))
- 		return rm.receiver.Error()
++// Acknowledge a ReceivedMessage with the given delivery status.
++func (rm *ReceivedMessage) acknowledge(status uint64) error {
++	return rm.receiver.(*receiver).engine().Inject(func() {
++		// Deliveries are valid as long as the connection is, unless settled.
++		rm.eDelivery.SettleAs(uint64(status))
 +	})
 +}
 +
- // Accept is short for Acknowledge(Accpeted)
- func (rm *ReceivedMessage) Accept() error { return rm.Acknowledge(Accepted) }
++// Accept tells the sender that we take responsibility for processing the message.
++func (rm *ReceivedMessage) Accept() error { return rm.acknowledge(proton.Accepted) }
++
++// Reject tells the sender we consider the message invalid and unusable.
++func (rm *ReceivedMessage) Reject() error { return rm.acknowledge(proton.Rejected) }
 +
- // Reject is short for Acknowledge(Rejected)
- func (rm *ReceivedMessage) Reject() error { return rm.Acknowledge(Rejected) }
++// Release tells the sender we will not process the message but some other
++// receiver might.
++func (rm *ReceivedMessage) Release() error { return rm.acknowledge(proton.Released) }
 +
- // IncomingReceiver is passed to the accept() function given to Connection.Listen()
- // when there is an incoming request for a receiver link.
++// IncomingReceiver is sent on the Connection.Incoming() channel when there is
++// an incoming request to open a receiver link.
 +type IncomingReceiver struct {
 +	incomingLink
 +}
 +
- // Link provides information about the incoming link.
- func (i *IncomingReceiver) Link() Link { return i }
++// SetCapacity sets the capacity of the incoming receiver, call before Accept()
++func (in *IncomingReceiver) SetCapacity(capacity int) { in.capacity = capacity }
 +
- // AcceptReceiver sets Capacity and Prefetch of the accepted Receiver.
- func (i *IncomingReceiver) AcceptReceiver(capacity int, prefetch bool) Receiver {
- 	i.capacity = capacity
- 	i.prefetch = prefetch
- 	return i.Accept().(Receiver)
- }
++// SetPrefetch sets the pre-fetch mode of the incoming receiver, call before Accept()
++func (in *IncomingReceiver) SetPrefetch(prefetch bool) { in.prefetch = prefetch }
 +
- func (i *IncomingReceiver) Accept() Endpoint {
- 	i.accepted = true
- 	return newReceiver(i.link)
++// Accept accepts an incoming receiver endpoint
++func (in *IncomingReceiver) Accept() Endpoint {
++	return in.accept(func() Endpoint { return newReceiver(in.link) })
 +}

http://git-wip-us.apache.org/repos/asf/qpid-proton/blob/9e788b2d/electron/sender.go
----------------------------------------------------------------------
diff --cc electron/sender.go
index 68cfbb3,0000000..573e9da
mode 100644,000000..100644
--- a/electron/sender.go
+++ b/electron/sender.go
@@@ -1,315 -1,0 +1,274 @@@
 +/*
 +Licensed to the Apache Software Foundation (ASF) under one
 +or more contributor license agreements.  See the NOTICE file
 +distributed with this work for additional information
 +regarding copyright ownership.  The ASF licenses this file
 +to you 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 electron
 +
 +// #include <proton/disposition.h>
 +import "C"
 +
 +import (
 +	"qpid.apache.org/amqp"
- 	"qpid.apache.org/internal"
 +	"qpid.apache.org/proton"
- 	"reflect"
 +	"time"
 +)
 +
 +// Sender is a Link that sends messages.
++//
++// The result of sending a message is provided by an Outcome value.
++//
++// A sender can buffer messages up to the credit limit provided by the remote receiver.
++// Send* methods will block if the buffer is full until there is space.
++// Send*Timeout methods will give up after the timeout and set Timeout as Outcome.Error.
++//
 +type Sender interface {
 +	Link
 +
- 	// Send a message without waiting for acknowledgement. Returns a SentMessage.
- 	// use SentMessage.Disposition() to wait for acknowledgement and get the
- 	// disposition code.
- 	//
- 	// If the send buffer is full, send blocks until there is space in the buffer.
- 	Send(m amqp.Message) (sm SentMessage, err error)
++	// SendSync sends a message and blocks until the message is acknowledged by the remote receiver.
++	// Returns an Outcome, which may contain an error if the message could not be sent.
++	SendSync(m amqp.Message) Outcome
++
++	// SendWaitable puts a message in the send buffer and returns a channel that
++	// you can use to wait for the Outcome of just that message. The channel is
++	// buffered so you can receive from it whenever you want without blocking anything.
++	SendWaitable(m amqp.Message) <-chan Outcome
++
++	// SendForget buffers a message for sending and returns, with no notification of the outcome.
++	SendForget(m amqp.Message)
 +
- 	// SendTimeout is like send but only waits up to timeout for buffer space.
++	// SendAsync puts a message in the send buffer and returns immediately.  An
++	// Outcome with Value = value will be sent to the ack channel when the remote
++	// receiver has acknowledged the message or if there is an error.
 +	//
- 	// Returns Timeout error if the timeout expires and the message has not been sent.
- 	SendTimeout(m amqp.Message, timeout time.Duration) (sm SentMessage, err error)
++	// You can use the same ack channel for many calls to SendAsync(), possibly on
++	// many Senders. The channel will receive the outcomes in the order they
++	// become available. The channel should be buffered and/or served by dedicated
++	// goroutines to avoid blocking the connection.
++	//
++	// If ack == nil no Outcome is sent.
++	SendAsync(m amqp.Message, ack chan<- Outcome, value interface{})
 +
- 	// Send a message and forget it, there will be no acknowledgement.
- 	// If the send buffer is full, send blocks until there is space in the buffer.
- 	SendForget(m amqp.Message) error
++	SendAsyncTimeout(m amqp.Message, ack chan<- Outcome, value interface{}, timeout time.Duration)
 +
- 	// SendForgetTimeout is like send but only waits up to timeout for buffer space.
- 	// Returns Timeout error if the timeout expires and the message has not been sent.
- 	SendForgetTimeout(m amqp.Message, timeout time.Duration) error
++	SendWaitableTimeout(m amqp.Message, timeout time.Duration) <-chan Outcome
 +
- 	// Credit indicates how many messages the receiving end of the link can accept.
- 	//
- 	// On a Sender credit can be negative, meaning that messages in excess of the
- 	// receiver's credit limit have been buffered locally till credit is available.
- 	Credit() (int, error)
- }
++	SendForgetTimeout(m amqp.Message, timeout time.Duration)
 +
- type sendMessage struct {
- 	m  amqp.Message
- 	sm SentMessage
++	SendSyncTimeout(m amqp.Message, timeout time.Duration) Outcome
 +}
 +
- type sender struct {
- 	link
- 	credit chan struct{} // Signal available credit.
++// Outcome provides information about the outcome of sending a message.
++type Outcome struct {
++	// Status of the message: was it sent, how was it acknowledged.
++	Status SentStatus
++	// Error is a local error if Status is Unsent or Unacknowledged, a remote error otherwise.
++	Error error
++	// Value provided by the application in SendAsync()
++	Value interface{}
 +}
 +
- // Disposition indicates the outcome of a settled message delivery.
- type Disposition uint64
++// SentStatus indicates the status of a sent message.
++type SentStatus int
 +
 +const (
- 	// No disposition available: pre-settled, not yet acknowledged or an error occurred
- 	NoDisposition Disposition = 0
++	// Message was never sent
++	Unsent SentStatus = iota
++	// Message was sent but never acknowledged. It may or may not have been received.
++	Unacknowledged
++	// Message was sent pre-settled, no remote outcome is available.
++	Presettled
 +	// Message was accepted by the receiver
- 	Accepted = proton.Accepted
++	Accepted
 +	// Message was rejected as invalid by the receiver
- 	Rejected = proton.Rejected
- 	// Message was not processed by the receiver but may be processed by some other receiver.
- 	Released = proton.Released
++	Rejected
++	// Message was not processed by the receiver but may be valid for a different receiver
++	Released
++	// Receiver responded with an unrecognized status.
++	Unknown
 +)
 +
- // String human readable name for a Disposition.
- func (d Disposition) String() string {
- 	switch d {
- 	case NoDisposition:
- 		return "no-disposition"
++// String human readable name for SentStatus.
++func (s SentStatus) String() string {
++	switch s {
++	case Unsent:
++		return "unsent"
++	case Unacknowledged:
++		return "unacknowledged"
 +	case Accepted:
 +		return "accepted"
 +	case Rejected:
 +		return "rejected"
 +	case Released:
 +		return "released"
- 	default:
++	case Unknown:
 +		return "unknown"
++	default:
++		return "invalid"
 +	}
 +}
 +
- func (s *sender) Send(m amqp.Message) (SentMessage, error) {
- 	return s.SendTimeout(m, Forever)
- }
- 
- func (s *sender) SendTimeout(m amqp.Message, timeout time.Duration) (SentMessage, error) {
- 	var sm SentMessage
- 	if s.sndSettle == SndSettled {
- 		sm = nil
- 	} else {
- 		sm = newSentMessage(s.session.connection)
++// Convert proton delivery state code to SentStatus value
++func sentStatus(d uint64) SentStatus {
++	switch d {
++	case proton.Accepted:
++		return Accepted
++	case proton.Rejected:
++		return Rejected
++	case proton.Released, proton.Modified:
++		return Released
++	default:
++		return Unknown
 +	}
- 	return s.sendInternal(sendMessage{m, sm}, timeout)
- }
- 
- func (s *sender) SendForget(m amqp.Message) error {
- 	return s.SendForgetTimeout(m, Forever)
 +}
 +
- func (s *sender) SendForgetTimeout(m amqp.Message, timeout time.Duration) error {
- 	snd := sendMessage{m, nil}
- 	_, err := s.sendInternal(snd, timeout)
- 	return err
++// Sender implementation, held by handler.
++type sender struct {
++	link
++	credit chan struct{} // Signal available credit.
 +}
 +
- func (s *sender) sendInternal(snd sendMessage, timeout time.Duration) (SentMessage, error) {
- 	if _, err := timedReceive(s.credit, timeout); err != nil { // Wait for credit
- 		if err == Closed {
++func (s *sender) SendAsyncTimeout(m amqp.Message, ack chan<- Outcome, v interface{}, t time.Duration) {
++	// wait for credit
++	if _, err := timedReceive(s.credit, t); err != nil {
++		if err == Closed && s.Error != nil {
 +			err = s.Error()
- 			internal.Assert(err != nil)
 +		}
- 		return nil, err
++		ack <- Outcome{Unsent, err, v}
++		return
 +	}
- 	if err := s.engine().Inject(func() { s.doSend(snd) }); err != nil {
- 		return nil, err
- 	}
- 	return snd.sm, nil
- }
- 
- // Send a message. Handler goroutine
- func (s *sender) doSend(snd sendMessage) {
- 	delivery, err := s.eLink.Send(snd.m)
- 	switch sm := snd.sm.(type) {
- 	case nil:
- 		delivery.Settle()
- 	case *sentMessage:
- 		sm.delivery = delivery
- 		if err != nil {
- 			sm.settled(err)
- 		} else {
- 			s.handler().sentMessages[delivery] = sm
++	// Send a message in handler goroutine
++	err := s.engine().Inject(func() {
++		if s.Error() != nil {
++			if ack != nil {
++				ack <- Outcome{Unsent, s.Error(), v}
++			}
++			return
 +		}
- 	default:
- 		internal.Assert(false, "bad SentMessage type %T", snd.sm)
- 	}
- 	if s.eLink.Credit() > 0 {
- 		s.sendable() // Signal credit.
++		if delivery, err := s.eLink.Send(m); err == nil {
++			if ack != nil { // We must report an outcome
++				if s.SndSettle() == SndSettled {
++					delivery.Settle() // Pre-settle if required
++					ack <- Outcome{Presettled, nil, v}
++				} else {
++					s.handler().sentMessages[delivery] = sentMessage{ack, v}
++				}
++			} else { // ack == nil, can't report outcome
++				if s.SndSettle() != SndUnsettled { // Pre-settle unless we are forced not to.
++					delivery.Settle()
++				}
++			}
++		} else { // err != nil
++			if ack != nil {
++				ack <- Outcome{Unsent, err, v}
++			}
++		}
++		if s.eLink.Credit() > 0 { // Signal there is still credit
++			s.sendable()
++		}
++	})
++	if err != nil && ack != nil {
++		ack <- Outcome{Unsent, err, v}
 +	}
 +}
 +
- // Signal the sender has credit. Any goroutine.
++// Set credit flag if not already set. Non-blocking, any goroutine
 +func (s *sender) sendable() {
 +	select { // Non-blocking
- 	case s.credit <- struct{}{}: // Set the flag if not already set.
++	case s.credit <- struct{}{}:
 +	default:
 +	}
 +}
 +
- func (s *sender) closed(err error) {
- 	s.link.closed(err)
- 	close(s.credit)
++func (s *sender) SendWaitableTimeout(m amqp.Message, t time.Duration) <-chan Outcome {
++	out := make(chan Outcome, 1)
++	s.SendAsyncTimeout(m, out, nil, t)
++	return out
 +}
 +
- func newSender(l link) *sender {
- 	s := &sender{link: l, credit: make(chan struct{}, 1)}
- 	s.handler().addLink(s.eLink, s)
- 	s.link.open()
- 	return s
- }
- 
- // SentMessage represents a previously sent message. It allows you to wait for acknowledgement.
- type SentMessage interface {
- 
- 	// Disposition blocks till the message is acknowledged and returns the
- 	// disposition state.
- 	//
- 	// NoDisposition with Error() != nil means the Connection was closed before
- 	// the message was acknowledged.
- 	//
- 	// NoDisposition with Error() == nil means the message was pre-settled or
- 	// Forget() was called.
- 	Disposition() (Disposition, error)
- 
- 	// DispositionTimeout is like Disposition but gives up after timeout, see Timeout.
- 	DispositionTimeout(time.Duration) (Disposition, error)
- 
- 	// Forget interrupts any call to Disposition on this SentMessage and tells the
- 	// peer we are no longer interested in the disposition of this message.
- 	Forget()
- 
- 	// Error returns the error that closed the disposition, or nil if there was no error.
- 	// If the disposition closed because the connection closed, it will return Closed.
- 	Error() error
- 
- 	// Value is an optional value you wish to associate with the SentMessage. It
- 	// can be the message itself or some form of identifier.
- 	Value() interface{}
- 	SetValue(interface{})
- }
- 
- // SentMessageSet is a concurrent-safe set of sent messages that can be checked
- // to get the next completed sent message
- type SentMessageSet struct {
- 	cases []reflect.SelectCase
- 	sm    []SentMessage
- 	done  chan SentMessage
- }
- 
- func (s *SentMessageSet) Add(sm SentMessage) {
- 	s.sm = append(s.sm, sm)
- 	s.cases = append(s.cases, reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(sm.(*sentMessage).done)})
++func (s *sender) SendForgetTimeout(m amqp.Message, t time.Duration) {
++	s.SendAsyncTimeout(m, nil, nil, t)
 +}
 +
- // Wait waits up to timeout and returns the next SentMessage that has a valid dispositionb
- // or an error.
- func (s *SentMessageSet) Wait(sm SentMessage, timeout time.Duration) (SentMessage, error) {
- 	s.cases = s.cases[:len(s.sm)] // Remove previous timeout cases
- 	if timeout == 0 {             // Non-blocking
- 		s.cases = append(s.cases, reflect.SelectCase{Dir: reflect.SelectDefault})
- 	} else {
- 		s.cases = append(s.cases,
- 			reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(After(timeout))})
++func (s *sender) SendSyncTimeout(m amqp.Message, t time.Duration) Outcome {
++	deadline := time.Now().Add(t)
++	ack := s.SendWaitableTimeout(m, t)
++	t = deadline.Sub(time.Now()) // Adjust for time already spent.
++	if t < 0 {
++		t = 0
 +	}
- 	chosen, _, _ := reflect.Select(s.cases)
- 	if chosen > len(s.sm) {
- 		return nil, Timeout
++	if out, err := timedReceive(ack, t); err == nil {
++		return out.(Outcome)
 +	} else {
- 		sm := s.sm[chosen]
- 		s.sm = append(s.sm[:chosen], s.sm[chosen+1:]...)
- 		return sm, nil
++		if err == Closed && s.Error() != nil {
++			err = s.Error()
++		}
++		return Outcome{Unacknowledged, err, nil}
 +	}
 +}
 +
- // SentMessage implementation
- type sentMessage struct {
- 	connection  *connection
- 	done        chan struct{}
- 	delivery    proton.Delivery
- 	disposition Disposition
- 	err         error
- 	value       interface{}
++func (s *sender) SendAsync(m amqp.Message, ack chan<- Outcome, v interface{}) {
++	s.SendAsyncTimeout(m, ack, v, Forever)
 +}
 +
- func newSentMessage(c *connection) *sentMessage {
- 	return &sentMessage{connection: c, done: make(chan struct{})}
++func (s *sender) SendWaitable(m amqp.Message) <-chan Outcome {
++	return s.SendWaitableTimeout(m, Forever)
 +}
 +
- func (sm *sentMessage) SetValue(v interface{}) { sm.value = v }
- func (sm *sentMessage) Value() interface{}     { return sm.value }
- func (sm *sentMessage) Disposition() (Disposition, error) {
- 	<-sm.done
- 	return sm.disposition, sm.err
++func (s *sender) SendForget(m amqp.Message) {
++	s.SendForgetTimeout(m, Forever)
 +}
 +
- func (sm *sentMessage) DispositionTimeout(timeout time.Duration) (Disposition, error) {
- 	if _, err := timedReceive(sm.done, timeout); err == Timeout {
- 		return sm.disposition, Timeout
- 	} else {
- 		return sm.disposition, sm.err
- 	}
++func (s *sender) SendSync(m amqp.Message) Outcome {
++	return <-s.SendWaitable(m)
 +}
 +
- func (sm *sentMessage) Forget() {
- 	sm.connection.engine.Inject(func() {
- 		sm.delivery.Settle()
- 		delete(sm.connection.handler.sentMessages, sm.delivery)
- 	})
- 	sm.finish()
++// handler goroutine
++func (s *sender) closed(err error) {
++	s.link.closed(err)
++	close(s.credit)
 +}
 +
- func (sm *sentMessage) settled(err error) {
- 	if sm.delivery.Settled() {
- 		sm.disposition = Disposition(sm.delivery.Remote().Type())
- 	}
- 	sm.err = err
- 	sm.finish()
++func newSender(l link) *sender {
++	s := &sender{link: l, credit: make(chan struct{}, 1)}
++	s.handler().addLink(s.eLink, s)
++	s.link.open()
++	return s
 +}
 +
- func (sm *sentMessage) finish() {
- 	select {
- 	case <-sm.done: // No-op if already closed
- 	default:
- 		close(sm.done)
- 	}
++// sentMessage records a sent message on the handler.
++type sentMessage struct {
++	ack   chan<- Outcome
++	value interface{}
 +}
 +
- func (sm *sentMessage) Error() error { return sm.err }
- 
- // IncomingSender is passed to the accept() function given to Connection.Listen()
- // when there is an incoming request for a sender link.
++// IncomingSender is sent on the Connection.Incoming() channel when there is
++// an incoming request to open a sender link.
 +type IncomingSender struct {
 +	incomingLink
 +}
 +
- // Link provides information about the incoming link.
- func (i *IncomingSender) Link() Link { return i }
- 
- func (i *IncomingSender) AcceptSender() Sender { return i.Accept().(Sender) }
++// Accept accepts an incoming sender endpoint
++func (in *IncomingSender) Accept() Endpoint {
++	return in.accept(func() Endpoint { return newSender(in.link) })
++}
 +
- func (i *IncomingSender) Accept() Endpoint {
- 	i.accepted = true
- 	return newSender(i.link)
++// Call in injected functions to check if the sender is valid.
++func (s *sender) valid() bool {
++	s2, ok := s.handler().links[s.eLink].(*sender)
++	return ok && s2 == s
 +}

http://git-wip-us.apache.org/repos/asf/qpid-proton/blob/9e788b2d/electron/session.go
----------------------------------------------------------------------
diff --cc electron/session.go
index 3531da6,0000000..18d8bc8
mode 100644,000000..100644
--- a/electron/session.go
+++ b/electron/session.go
@@@ -1,125 -1,0 +1,128 @@@
 +/*
 +Licensed to the Apache Software Foundation (ASF) under one
 +or more contributor license agreements.  See the NOTICE file
 +distributed with this work for additional information
 +regarding copyright ownership.  The ASF licenses this file
 +to you 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 electron
 +
 +import (
 +	"qpid.apache.org/proton"
 +)
 +
 +// Session is an AMQP session, it contains Senders and Receivers.
 +type Session interface {
 +	Endpoint
 +
- 	// Sender opens a new sender. v can be a string, which is used as the Target
- 	// address, or a SenderSettings struct containing more details settings.
- 	Sender(...LinkSetting) (Sender, error)
- 
- 	// Receiver opens a new Receiver. v can be a string, which is used as the
- 	// Source address, or a ReceiverSettings struct containing more details
- 	// settings.
- 	Receiver(...LinkSetting) (Receiver, error)
++	// Sender opens a new sender.
++	Sender(...LinkOption) (Sender, error)
++
++	// Receiver opens a new Receiver.
++	Receiver(...LinkOption) (Receiver, error)
 +}
 +
 +type session struct {
 +	endpoint
 +	eSession   proton.Session
 +	connection *connection
 +	capacity   uint
 +}
 +
- // SessionSetting can be passed when creating a sender or receiver.
- // See functions that return SessionSetting for details
- type SessionSetting func(*session)
++// SessionOption can be passed when creating a Session
++type SessionOption func(*session)
 +
- // IncomingCapacity sets the size (in bytes) of the sessions incoming data buffer..
- func IncomingCapacity(cap uint) SessionSetting { return func(s *session) { s.capacity = cap } }
++// IncomingCapacity returns a Session Option that sets the size (in bytes) of
++// the sessions incoming data buffer..
++func IncomingCapacity(cap uint) SessionOption { return func(s *session) { s.capacity = cap } }
 +
 +// in proton goroutine
- func newSession(c *connection, es proton.Session, setting ...SessionSetting) *session {
++func newSession(c *connection, es proton.Session, setting ...SessionOption) *session {
 +	s := &session{
 +		connection: c,
 +		eSession:   es,
- 		endpoint:   endpoint{str: es.String()},
++		endpoint:   makeEndpoint(es.String()),
 +	}
 +	for _, set := range setting {
 +		set(s)
 +	}
 +	c.handler.sessions[s.eSession] = s
 +	s.eSession.SetIncomingCapacity(s.capacity)
 +	s.eSession.Open()
 +	return s
 +}
 +
 +func (s *session) Connection() Connection     { return s.connection }
 +func (s *session) eEndpoint() proton.Endpoint { return s.eSession }
 +func (s *session) engine() *proton.Engine     { return s.connection.engine }
++
 +func (s *session) Close(err error) {
- 	s.engine().Inject(func() { localClose(s.eSession, err) })
++	s.engine().Inject(func() {
++		if s.Error() == nil {
++			localClose(s.eSession, err)
++		}
++	})
 +}
 +
- func (s *session) SetCapacity(bytes uint) { s.capacity = bytes }
- 
- func (s *session) Sender(setting ...LinkSetting) (snd Sender, err error) {
++func (s *session) Sender(setting ...LinkOption) (snd Sender, err error) {
 +	err = s.engine().InjectWait(func() error {
++		if s.Error() != nil {
++			return s.Error()
++		}
 +		l, err := localLink(s, true, setting...)
 +		if err == nil {
 +			snd = newSender(l)
 +		}
 +		return err
 +	})
 +	return
 +}
 +
- func (s *session) Receiver(setting ...LinkSetting) (rcv Receiver, err error) {
++func (s *session) Receiver(setting ...LinkOption) (rcv Receiver, err error) {
 +	err = s.engine().InjectWait(func() error {
++		if s.Error() != nil {
++			return s.Error()
++		}
 +		l, err := localLink(s, false, setting...)
 +		if err == nil {
 +			rcv = newReceiver(l)
 +		}
 +		return err
 +	})
 +	return
 +}
 +
- // Called from handler on closed.
- func (s *session) closed(err error) {
- 	s.err.Set(err)
- 	s.err.Set(Closed)
- }
- 
- // IncomingSession is passed to the accept() function given to Connection.Listen()
- // when there is an incoming session request.
++// IncomingSender is sent on the Connection.Incoming() channel when there is an
++// incoming request to open a session.
 +type IncomingSession struct {
 +	incoming
 +	h        *handler
 +	pSession proton.Session
 +	capacity uint
 +}
 +
- // AcceptCapacity sets the session buffer capacity of an incoming session in bytes.
- func (i *IncomingSession) AcceptSession(bytes uint) Session {
- 	i.capacity = bytes
- 	return i.Accept().(Session)
++func newIncomingSession(h *handler, ps proton.Session) *IncomingSession {
++	return &IncomingSession{incoming: makeIncoming(ps), h: h, pSession: ps}
 +}
 +
- func (i *IncomingSession) Accept() Endpoint {
- 	i.accepted = true
- 	return newSession(i.h.connection, i.pSession, IncomingCapacity(i.capacity))
++// SetCapacity sets the session buffer capacity of an incoming session in bytes.
++func (in *IncomingSession) SetCapacity(bytes uint) { in.capacity = bytes }
++
++// Accept an incoming session endpoint.
++func (in *IncomingSession) Accept() Endpoint {
++	return in.accept(func() Endpoint {
++		return newSession(in.h.connection, in.pSession, IncomingCapacity(in.capacity))
++	})
 +}

http://git-wip-us.apache.org/repos/asf/qpid-proton/blob/9e788b2d/electron/time.go
----------------------------------------------------------------------
diff --cc electron/time.go
index 3407b82,0000000..51bfbc5
mode 100644,000000..100644
--- a/electron/time.go
+++ b/electron/time.go
@@@ -1,82 -1,0 +1,83 @@@
 +/*
 +Licensed to the Apache Software Foundation (ASF) under one
 +or more contributor license agreements.  See the NOTICE file
 +distributed with this work for additional information
 +regarding copyright ownership.  The ASF licenses this file
 +to you 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 electron
 +
 +import (
- 	"qpid.apache.org/internal"
++	"fmt"
++	"math"
 +	"reflect"
 +	"time"
 +)
 +
 +// Timeout is the error returned if an operation does not complete on time.
 +//
 +// Methods named *Timeout in this package take time.Duration timeout parameter.
 +//
 +// If timeout > 0 and there is no result available before the timeout, they
 +// return a zero or nil value and Timeout as an error.
 +//
 +// If timeout == 0 they will return a result if one is immediatley available or
 +// nil/zero and Timeout as an error if not.
 +//
 +// If timeout == Forever the function will return only when there is a result or
 +// some non-timeout error occurs.
 +//
- var Timeout = internal.Errorf("timeout")
++var Timeout = fmt.Errorf("timeout")
 +
 +// Forever can be used as a timeout parameter to indicate wait forever.
- const Forever time.Duration = -1
++const Forever time.Duration = math.MaxInt64
 +
 +// timedReceive receives on channel (which can be a chan of any type), waiting
 +// up to timeout.
 +//
 +// timeout==0 means do a non-blocking receive attempt. timeout < 0 means block
 +// forever. Other values mean block up to the timeout.
 +//
 +// Returns error Timeout on timeout, Closed on channel close.
 +func timedReceive(channel interface{}, timeout time.Duration) (interface{}, error) {
 +	cases := []reflect.SelectCase{
 +		reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(channel)},
 +	}
 +	if timeout == 0 { // Non-blocking
 +		cases = append(cases, reflect.SelectCase{Dir: reflect.SelectDefault})
 +	} else { // Block up to timeout
 +		cases = append(cases,
 +			reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(After(timeout))})
 +	}
 +	chosen, value, ok := reflect.Select(cases)
 +	switch {
- 	case !ok:
- 		return nil, Closed
- 	case chosen == 0:
++	case chosen == 0 && ok:
 +		return value.Interface(), nil
++	case chosen == 0 && !ok:
++		return nil, Closed
 +	default:
 +		return nil, Timeout
 +	}
 +}
 +
 +// After is like time.After but returns a nil channel if timeout == Forever
 +// since selecting on a nil channel will never return.
 +func After(timeout time.Duration) <-chan time.Time {
 +	if timeout == Forever {
 +		return nil
 +	} else {
 +		return time.After(timeout)
 +	}
 +}

http://git-wip-us.apache.org/repos/asf/qpid-proton/blob/9e788b2d/proton/engine.go
----------------------------------------------------------------------
diff --cc proton/engine.go
index 2cebb49,0000000..2e67ef7
mode 100644,000000..100644
--- a/proton/engine.go
+++ b/proton/engine.go
@@@ -1,402 -1,0 +1,403 @@@
 +/*
 +Licensed to the Apache Software Foundation (ASF) under one
 +or more contributor license agreements.  See the NOTICE file
 +distributed with this work for additional information
 +regarding copyright ownership.  The ASF licenses this file
 +to you 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 proton
 +
 +// #include <proton/connection.h>
 +// #include <proton/event.h>
 +// #include <proton/handlers.h>
 +// #include <proton/session.h>
 +// #include <proton/transport.h>
 +// #include <memory.h>
 +// #include <stdlib.h>
 +//
 +// PN_HANDLE(REMOTE_ADDR)
 +import "C"
 +
 +import (
 +	"fmt"
 +	"io"
 +	"net"
- 	"qpid.apache.org/internal"
 +	"sync"
 +	"unsafe"
 +)
 +
 +// Injecter allows functions to be "injected" into the event-processing loop, to
 +// be called in the same goroutine as event handlers.
 +type Injecter interface {
 +	// Inject a function into the engine goroutine.
 +	//
 +	// f() will be called in the same goroutine as event handlers, so it can safely
 +	// use values belonging to event handlers without synchronization. f() should
 +	// not block, no further events or injected functions can be processed until
 +	// f() returns.
 +	//
 +	// Returns a non-nil error if the function could not be injected and will
 +	// never be called. Otherwise the function will eventually be called.
 +	//
 +	// Note that proton values (Link, Session, Connection etc.) that existed when
 +	// Inject(f) was called may have become invalid by the time f() is executed.
 +	// Handlers should handle keep track of Closed events to ensure proton values
 +	// are not used after they become invalid. One technique is to have map from
 +	// proton values to application values. Check that the map has the correct
 +	// proton/application value pair at the start of the injected function and
 +	// delete the value from the map when handling a Closed event.
 +	Inject(f func()) error
 +
 +	// InjectWait is like Inject but does not return till f() has completed.
 +	// If f() cannot be injected it returns the error from Inject(), otherwise
 +	// it returns the error from f()
 +	InjectWait(f func() error) error
 +}
 +
 +// bufferChan manages a pair of ping-pong buffers to pass bytes through a channel.
 +type bufferChan struct {
 +	buffers    chan []byte
 +	buf1, buf2 []byte
 +}
 +
 +func newBufferChan(size int) *bufferChan {
 +	return &bufferChan{make(chan []byte), make([]byte, size), make([]byte, size)}
 +}
 +
 +func (b *bufferChan) buffer() []byte {
 +	b.buf1, b.buf2 = b.buf2, b.buf1 // Alternate buffers.
 +	return b.buf1[:cap(b.buf1)]
 +}
 +
 +// Engine reads from a net.Conn, decodes AMQP events and calls the appropriate
 +// Handler functions sequentially in a single goroutine. Actions taken by
 +// Handler functions (such as sending messages) are encoded and written to the
 +// net.Conn. You can create multiple Engines to handle multiple connections
 +// concurrently.
 +//
 +// You implement the EventHandler and/or MessagingHandler interfaces and provide
 +// those values to NewEngine(). Their HandleEvent method will be called in the
 +// event-handling goroutine.
 +//
 +// Handlers can pass values from an event (Connections, Links, Deliveries etc.) to
 +// other goroutines, store them, or use them as map indexes. Effectively they are
 +// just pointers.  Other goroutines cannot call their methods directly but they can
 +// can create a function closure to call such methods and pass it to Engine.Inject()
 +// to have it evaluated in the engine goroutine.
 +//
 +// You are responsible for ensuring you don't use an event value after it is
 +// invalid. The handler methods will tell you when a value is no longer valid. For
 +// example after a LinkClosed event, that link is no longer valid. If you do
 +// Link.Close() yourself (in a handler or injected function) the link remains valid
 +// until the corresponing LinkClosed event is received by the handler.
 +//
 +// Engine.Close() will take care of cleaning up any remaining values when you are
 +// done with the Engine. All values associated with a engine become invalid when you
 +// call Engine.Close()
 +//
 +// The qpid.apache.org/proton/concurrent package will do all this for you, so it
 +// may be a better choice for some applications.
 +//
 +type Engine struct {
 +	// Error is set on exit from Run() if there was an error.
- 	err    internal.ErrorHolder
++	err    ErrorHolder
 +	inject chan func()
 +
 +	conn       net.Conn
 +	connection Connection
 +	transport  Transport
 +	collector  *C.pn_collector_t
 +	read       *bufferChan    // Read buffers channel.
 +	write      *bufferChan    // Write buffers channel.
 +	handlers   []EventHandler // Handlers for proton events.
 +	running    chan struct{}  // This channel will be closed when the goroutines are done.
 +	closeOnce  sync.Once
 +}
 +
 +const bufferSize = 4096
 +
- // Map of Connection to *Engine
- var engines = internal.MakeSafeMap()
- 
 +// NewEngine initializes a engine with a connection and handlers. To start it running:
 +//    eng := NewEngine(...)
 +//    go run eng.Run()
 +// The goroutine will exit when the engine is closed or disconnected.
 +// You can check for errors on Engine.Error.
 +//
 +func NewEngine(conn net.Conn, handlers ...EventHandler) (*Engine, error) {
 +	// Save the connection ID for Connection.String()
 +	eng := &Engine{
 +		inject:     make(chan func()),
 +		conn:       conn,
 +		transport:  Transport{C.pn_transport()},
 +		connection: Connection{C.pn_connection()},
 +		collector:  C.pn_collector(),
 +		handlers:   handlers,
 +		read:       newBufferChan(bufferSize),
 +		write:      newBufferChan(bufferSize),
 +		running:    make(chan struct{}),
 +	}
 +	if eng.transport.IsNil() || eng.connection.IsNil() || eng.collector == nil {
- 		return nil, internal.Errorf("failed to allocate engine")
++		return nil, fmt.Errorf("failed to allocate engine")
 +	}
 +
 +	// TODO aconway 2015-06-25: connection settings for user, password, container etc.
 +	// before transport.Bind() Set up connection before Engine, allow Engine or Reactor
 +	// to run connection.
 +
 +	// Unique container-id by default.
- 	eng.connection.SetContainer(internal.UUID4().String())
++	eng.connection.SetContainer(UUID4().String())
 +	pnErr := eng.transport.Bind(eng.connection)
 +	if pnErr != 0 {
- 		return nil, internal.Errorf("cannot setup engine: %s", internal.PnErrorCode(pnErr))
++		return nil, fmt.Errorf("cannot setup engine: %s", PnErrorCode(pnErr))
 +	}
 +	C.pn_connection_collect(eng.connection.pn, eng.collector)
 +	eng.connection.Open()
- 	connectionContexts.Put(eng.connection, connectionContext{eng.String()})
 +	return eng, nil
 +}
 +
 +func (eng *Engine) String() string {
 +	return fmt.Sprintf("%s-%s", eng.conn.LocalAddr(), eng.conn.RemoteAddr())
 +}
 +
 +func (eng *Engine) Id() string {
 +	return fmt.Sprintf("%eng", &eng)
 +}
 +
 +func (eng *Engine) Error() error {
 +	return eng.err.Get()
 +}
 +
 +// Inject a function into the Engine's event loop.
 +//
 +// f() will be called in the same event-processing goroutine that calls Handler
 +// methods. f() can safely call methods on values that belong to this engine
 +// (Sessions, Links etc)
 +//
 +// The injected function has no parameters or return values. It is normally a
 +// closure and can use channels to communicate with the injecting goroutine if
 +// necessary.
 +//
 +// Returns a non-nil error if the engine is closed before the function could be
 +// injected.
 +func (eng *Engine) Inject(f func()) error {
 +	select {
 +	case eng.inject <- f:
 +		return nil
 +	case <-eng.running:
 +		return eng.Error()
 +	}
 +}
 +
 +// InjectWait is like Inject but does not return till f() has completed or the
 +// engine is closed, and returns an error value from f()
 +func (eng *Engine) InjectWait(f func() error) error {
 +	done := make(chan error)
 +	defer close(done)
 +	err := eng.Inject(func() { done <- f() })
 +	if err != nil {
 +		return err
 +	}
 +	select {
 +	case <-eng.running:
 +		return eng.Error()
 +	case err := <-done:
 +		return err
 +	}
 +}
 +
 +// Server puts the Engine in server mode, meaning it will auto-detect security settings on
 +// the incoming connnection such as use of SASL and SSL.
 +// Must be called before Run()
 +//
 +func (eng *Engine) Server() { eng.transport.SetServer() }
 +
 +// Close the engine's connection, returns when the engine has exited.
 +func (eng *Engine) Close(err error) {
 +	eng.err.Set(err)
 +	eng.Inject(func() {
 +		CloseError(eng.connection, err)
 +	})
 +	<-eng.running
 +}
 +
 +// Disconnect the engine's connection without and AMQP close, returns when the engine has exited.
 +func (eng *Engine) Disconnect(err error) {
 +	eng.err.Set(err)
 +	eng.conn.Close()
 +	<-eng.running
 +}
 +
 +// Run the engine. Engine.Run() will exit when the engine is closed or
 +// disconnected.  You can check for errors after exit with Engine.Error().
 +//
 +func (eng *Engine) Run() error {
 +	wait := sync.WaitGroup{}
 +	wait.Add(2) // Read and write goroutines
 +
 +	readErr := make(chan error, 1) // Don't block
 +	go func() {                    // Read goroutine
 +		defer wait.Done()
 +		for {
 +			rbuf := eng.read.buffer()
 +			n, err := eng.conn.Read(rbuf)
 +			if n > 0 {
 +				eng.read.buffers <- rbuf[:n]
 +			}
 +			if err != nil {
 +				readErr <- err
 +				close(readErr)
 +				close(eng.read.buffers)
 +				return
 +			}
 +		}
 +	}()
 +
 +	writeErr := make(chan error, 1) // Don't block
 +	go func() {                     // Write goroutine
 +		defer wait.Done()
 +		for {
 +			wbuf, ok := <-eng.write.buffers
 +			if !ok {
 +				return
 +			}
 +			_, err := eng.conn.Write(wbuf)
 +			if err != nil {
 +				writeErr <- err
 +				close(writeErr)
 +				return
 +			}
 +		}
 +	}()
 +
 +	wbuf := eng.write.buffer()[:0]
 +
 +	for eng.err.Get() == nil {
 +		if len(wbuf) == 0 {
 +			eng.pop(&wbuf)
 +		}
 +		// Don't set wchan unless there is something to write.
 +		var wchan chan []byte
 +		if len(wbuf) > 0 {
 +			wchan = eng.write.buffers
 +		}
 +
 +		select {
 +		case buf, ok := <-eng.read.buffers: // Read a buffer
 +			if ok {
 +				eng.push(buf)
 +			}
 +		case wchan <- wbuf: // Write a buffer
 +			wbuf = eng.write.buffer()[:0]
 +		case f, ok := <-eng.inject: // Function injected from another goroutine
 +			if ok {
 +				f()
 +			}
 +		case err := <-readErr:
 +			eng.netError(err)
 +		case err := <-writeErr:
 +			eng.netError(err)
 +		}
 +		eng.process()
 +	}
 +	close(eng.write.buffers)
 +	eng.conn.Close() // Make sure connection is closed
 +	wait.Wait()
 +	close(eng.running) // Signal goroutines have exited and Error is set.
 +
- 	connectionContexts.Delete(eng.connection)
++	// Execute any injected functions for side effects on application data structures.
++	inject := eng.inject
++	eng.inject = nil // Further calls to Inject() will return an error.
++	for f := range inject {
++		f()
++	}
++
 +	if !eng.connection.IsNil() {
 +		eng.connection.Free()
 +	}
 +	if !eng.transport.IsNil() {
 +		eng.transport.Free()
 +	}
 +	if eng.collector != nil {
 +		C.pn_collector_free(eng.collector)
 +	}
 +	for _, h := range eng.handlers {
 +		switch h := h.(type) {
 +		case cHandler:
 +			C.pn_handler_free(h.pn)
 +		}
 +	}
 +	return eng.err.Get()
 +}
 +
 +func (eng *Engine) netError(err error) {
 +	eng.err.Set(err)
 +	eng.transport.CloseHead()
 +	eng.transport.CloseTail()
 +}
 +
 +func minInt(a, b int) int {
 +	if a < b {
 +		return a
 +	} else {
 +		return b
 +	}
 +}
 +
 +func (eng *Engine) pop(buf *[]byte) {
 +	pending := int(eng.transport.Pending())
 +	switch {
 +	case pending == int(C.PN_EOS):
 +		*buf = (*buf)[:]
 +		return
 +	case pending < 0:
- 		panic(internal.Errorf("%s", internal.PnErrorCode(pending)))
++		panic(fmt.Errorf("%s", PnErrorCode(pending)))
 +	}
 +	size := minInt(pending, cap(*buf))
 +	*buf = (*buf)[:size]
 +	if size == 0 {
 +		return
 +	}
 +	C.memcpy(unsafe.Pointer(&(*buf)[0]), eng.transport.Head(), C.size_t(size))
- 	internal.Assert(size > 0)
++	assert(size > 0)
 +	eng.transport.Pop(uint(size))
 +}
 +
 +func (eng *Engine) push(buf []byte) {
 +	buf2 := buf
 +	for len(buf2) > 0 {
 +		n := eng.transport.Push(buf2)
 +		if n <= 0 {
- 			panic(internal.Errorf("error in transport: %s", internal.PnErrorCode(n)))
++			panic(fmt.Errorf("error in transport: %s", PnErrorCode(n)))
 +		}
 +		buf2 = buf2[n:]
 +	}
 +}
 +
 +func (eng *Engine) handle(e Event) {
 +	for _, h := range eng.handlers {
 +		h.HandleEvent(e)
 +	}
 +	if e.Type() == ETransportClosed {
 +		eng.err.Set(io.EOF)
 +	}
 +}
 +
 +func (eng *Engine) process() {
 +	for ce := C.pn_collector_peek(eng.collector); ce != nil; ce = C.pn_collector_peek(eng.collector) {
 +		eng.handle(makeEvent(ce, eng))
 +		C.pn_collector_pop(eng.collector)
 +	}
 +}
 +
 +func (eng *Engine) Connection() Connection { return eng.connection }

http://git-wip-us.apache.org/repos/asf/qpid-proton/blob/9e788b2d/proton/error.go
----------------------------------------------------------------------
diff --cc proton/error.go
index f9cc948,0000000..80d9680
mode 100644,000000..100644
--- a/proton/error.go
+++ b/proton/error.go
@@@ -1,96 -1,0 +1,96 @@@
 +/*
 +Licensed to the Apache Software Foundation (ASF) under one
 +or more contributor license agreements.  See the NOTICE file
 +distributed with this work for additional information
 +regarding copyright ownership.  The ASF licenses this file
 +to you 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.
 +*/
 +
++// Internal implementation details - ignore.
 +package proton
 +
++// #cgo LDFLAGS: -lqpid-proton
 +// #include <proton/error.h>
 +// #include <proton/codec.h>
 +import "C"
 +
 +import (
 +	"fmt"
- 	"reflect"
- 	"runtime"
++	"sync"
++	"sync/atomic"
 +)
 +
- var pnErrorNames = map[int]string{
- 	C.PN_EOS:        "end of data",
- 	C.PN_ERR:        "error",
- 	C.PN_OVERFLOW:   "overflow",
- 	C.PN_UNDERFLOW:  "underflow",
- 	C.PN_STATE_ERR:  "bad state",
- 	C.PN_ARG_ERR:    "invalid argument",
- 	C.PN_TIMEOUT:    "timeout",
- 	C.PN_INTR:       "interrupted",
- 	C.PN_INPROGRESS: "in progress",
- }
++type PnErrorCode int
 +
- func pnErrorName(code int) string {
- 	name := pnErrorNames[code]
- 	if name != "" {
- 		return name
- 	} else {
- 		return "unknown error code"
++func (e PnErrorCode) String() string {
++	switch e {
++	case C.PN_EOS:
++		return "end-of-data"
++	case C.PN_ERR:
++		return "error"
++	case C.PN_OVERFLOW:
++		return "overflow"
++	case C.PN_UNDERFLOW:
++		return "underflow"
++	case C.PN_STATE_ERR:
++		return "bad-state"
++	case C.PN_ARG_ERR:
++		return "invalid-argument"
++	case C.PN_TIMEOUT:
++		return "timeout"
++	case C.PN_INTR:
++		return "interrupted"
++	case C.PN_INPROGRESS:
++		return "in-progress"
++	default:
++		return fmt.Sprintf("unknown-error(%d)", e)
 +	}
 +}
 +
- type BadUnmarshal struct {
- 	AMQPType C.pn_type_t
- 	GoType   reflect.Type
++func PnError(e *C.pn_error_t) error {
++	if e == nil || C.pn_error_code(e) == 0 {
++		return nil
++	}
++	return fmt.Errorf("%s: %s", PnErrorCode(C.pn_error_code(e)), C.GoString(C.pn_error_text(e)))
 +}
 +
- func newBadUnmarshal(pnType C.pn_type_t, v interface{}) *BadUnmarshal {
- 	return &BadUnmarshal{pnType, reflect.TypeOf(v)}
++// ErrorHolder is a goroutine-safe error holder that keeps the first error that is set.
++type ErrorHolder struct {
++	once  sync.Once
++	value atomic.Value
 +}
 +
- func (e BadUnmarshal) Error() string {
- 	if e.GoType.Kind() != reflect.Ptr {
- 		return fmt.Sprintf("proton: cannot unmarshal to type %s, not a pointer", e.GoType)
- 	} else {
- 		return fmt.Sprintf("proton: cannot unmarshal AMQP %s to %s", getPnType(e.AMQPType), e.GoType)
++// Set the error if not already set, return the error in the Holder.
++func (e *ErrorHolder) Set(err error) {
++	if err != nil {
++		e.once.Do(func() { e.value.Store(err) })
 +	}
 +}
 +
- // errorf creates an error with a formatted message
- func errorf(format string, a ...interface{}) error {
- 	return fmt.Errorf("proton: %s", fmt.Sprintf(format, a...))
++// Get the error.
++func (e *ErrorHolder) Get() (err error) {
++	err, _ = e.value.Load().(error)
++	return
 +}
 +
- func pnDataError(data *C.pn_data_t) string {
- 	err := C.pn_data_error(data)
- 	if err != nil && int(C.pn_error_code(err)) != 0 {
- 		return C.GoString(C.pn_error_text(err))
- 	}
- 	return ""
- }
- 
- // doRecover is called to recover from internal panics
- func doRecover(err *error) {
- 	r := recover()
- 	switch r := r.(type) {
- 	case nil:
- 		return
- 	case runtime.Error:
- 		panic(r)
- 	case error:
- 		*err = r
- 	default:
- 		panic(r)
++// assert panics if condition is false with optional formatted message
++func assert(condition bool, format ...interface{}) {
++	if !condition {
++		if len(format) > 0 {
++			panic(fmt.Errorf(format[0].(string), format[1:]...))
++		} else {
++			panic(fmt.Errorf("assertion failed"))
++		}
 +	}
 +}


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