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/*
* Copyright (c) 2013 IBM Corp.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Seth Hoenig
* Allan Stockdill-Mander
* Mike Robertson
*/
package mqtt
import (
"fmt"
"sync"
"time"
)
// MId is 16 bit message id as specified by the MQTT spec.
// In general, these values should not be depended upon by
// the client application.
type MId uint16
type messageIds struct {
sync.RWMutex
index map[uint16]tokenCompletor
}
const (
midMin uint16 = 1
midMax uint16 = 65535
)
func (mids *messageIds) cleanUp() {
mids.Lock()
for _, token := range mids.index {
switch token.(type) {
case *PublishToken:
token.setError(fmt.Errorf("Connection lost before Publish completed"))
case *SubscribeToken:
token.setError(fmt.Errorf("Connection lost before Subscribe completed"))
case *UnsubscribeToken:
token.setError(fmt.Errorf("Connection lost before Unsubscribe completed"))
case nil:
continue
}
token.flowComplete()
}
mids.index = make(map[uint16]tokenCompletor)
mids.Unlock()
DEBUG.Println(MID, "cleaned up")
}
func (mids *messageIds) freeID(id uint16) {
mids.Lock()
delete(mids.index, id)
mids.Unlock()
}
func (mids *messageIds) claimID(token tokenCompletor, id uint16) {
mids.Lock()
defer mids.Unlock()
if _, ok := mids.index[id]; !ok {
mids.index[id] = token
} else {
old := mids.index[id]
old.flowComplete()
mids.index[id] = token
}
}
func (mids *messageIds) getID(t tokenCompletor) uint16 {
mids.Lock()
defer mids.Unlock()
for i := midMin; i < midMax; i++ {
if _, ok := mids.index[i]; !ok {
mids.index[i] = t
return i
}
}
return 0
}
func (mids *messageIds) getToken(id uint16) tokenCompletor {
mids.RLock()
defer mids.RUnlock()
if token, ok := mids.index[id]; ok {
return token
}
return &DummyToken{id: id}
}
type DummyToken struct {
id uint16
}
func (d *DummyToken) Wait() bool {
return true
}
func (d *DummyToken) WaitTimeout(t time.Duration) bool {
return true
}
func (d *DummyToken) flowComplete() {
ERROR.Printf("A lookup for token %d returned nil\n", d.id)
}
func (d *DummyToken) Error() error {
return nil
}
func (p *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
}
func (p *PlaceHolderToken) Wait() bool {
return true
}
func (p *PlaceHolderToken) WaitTimeout(t time.Duration) bool {
return true
}
func (p *PlaceHolderToken) flowComplete() {
}
func (p *PlaceHolderToken) Error() error {
return nil
}
func (p *PlaceHolderToken) setError(e error) {}
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