build: upgrade to go 1.17 and dependencies

vendor/github.com/eclipse/paho.mqtt.golang/messageids.go

@@ -28,6 +28,8 @@ type MId uint16
 type messageIds struct {
 	sync.RWMutex
 	index map[uint16]tokenCompletor
+
+	lastIssuedID uint16 // The most recently issued ID. Used so we cycle through ids rather than immediately reusing them (can make debugging easier)
 }
 
 const (
@@ -40,11 +42,11 @@ func (mids *messageIds) cleanUp() {
 	for _, token := range mids.index {
 		switch token.(type) {
 		case *PublishToken:
-			token.setError(fmt.Errorf("Connection lost before Publish completed"))
+			token.setError(fmt.Errorf("connection lost before Publish completed"))
 		case *SubscribeToken:
-			token.setError(fmt.Errorf("Connection lost before Subscribe completed"))
+			token.setError(fmt.Errorf("connection lost before Subscribe completed"))
 		case *UnsubscribeToken:
-			token.setError(fmt.Errorf("Connection lost before Unsubscribe completed"))
+			token.setError(fmt.Errorf("connection lost before Unsubscribe completed"))
 		case nil:
 			continue
 		}
@@ -71,18 +73,33 @@ func (mids *messageIds) claimID(token tokenCompletor, id uint16) {
 		old.flowComplete()
 		mids.index[id] = token
 	}
+	if id > mids.lastIssuedID {
+		mids.lastIssuedID = id
+	}
 }
 
+// getID will return an available id or 0 if none available
+// The id will generally be the previous id + 1 (because this makes tracing messages a bit simpler)
 func (mids *messageIds) getID(t tokenCompletor) uint16 {
 	mids.Lock()
 	defer mids.Unlock()
-	for i := midMin; i < midMax; i++ {
+	i := mids.lastIssuedID // note: the only situation where lastIssuedID is 0 the map will be empty
+	looped := false        // uint16 will loop from 65535->0
+	for {
+		i++
+		if i == 0 { // skip 0 because its not a valid id (Control Packets MUST contain a non-zero 16-bit Packet Identifier [MQTT-2.3.1-1])
+			i++
+			looped = true
+		}
 		if _, ok := mids.index[i]; !ok {
 			mids.index[i] = t
+			mids.lastIssuedID = i
 			return i
 		}
+		if (looped && i == mids.lastIssuedID) || (mids.lastIssuedID == 0 && i == midMax) { // lastIssuedID will be 0 at startup
+			return 0 // no free ids
+		}
 	}
-	return 0
 }
 
 func (mids *messageIds) getToken(id uint16) tokenCompletor {
@@ -98,14 +115,23 @@ type DummyToken struct {
 	id uint16
 }
 
+// Wait implements the Token Wait method.
 func (d *DummyToken) Wait() bool {
 	return true
 }
 
+// WaitTimeout implements the Token WaitTimeout method.
 func (d *DummyToken) WaitTimeout(t time.Duration) bool {
 	return true
 }
 
+// Done implements the Token Done method.
+func (d *DummyToken) Done() <-chan struct{} {
+	ch := make(chan struct{})
+	close(ch)
+	return ch
+}
+
 func (d *DummyToken) flowComplete() {
 	ERROR.Printf("A lookup for token %d returned nil\n", d.id)
 }
@@ -115,3 +141,36 @@ func (d *DummyToken) Error() error {
 }
 
 func (d *DummyToken) setError(e error) {}
+
+// PlaceHolderToken does nothing and was implemented to allow a messageid to be reserved
+// it differs from DummyToken in that calling flowComplete does not generate an error (it
+// is expected that flowComplete will be called when the token is overwritten with a real token)
+type PlaceHolderToken struct {
+	id uint16
+}
+
+// Wait implements the Token Wait method.
+func (p *PlaceHolderToken) Wait() bool {
+	return true
+}
+
+// WaitTimeout implements the Token WaitTimeout method.
+func (p *PlaceHolderToken) WaitTimeout(t time.Duration) bool {
+	return true
+}
+
+// Done implements the Token Done method.
+func (p *PlaceHolderToken) Done() <-chan struct{} {
+	ch := make(chan struct{})
+	close(ch)
+	return ch
+}
+
+func (p *PlaceHolderToken) flowComplete() {
+}
+
+func (p *PlaceHolderToken) Error() error {
+	return nil
+}
+
+func (p *PlaceHolderToken) setError(e error) {}