mirror of
https://github.com/wavetermdev/waveterm.git
synced 2024-12-22 16:48:23 +01:00
252 lines
5.7 KiB
Go
252 lines
5.7 KiB
Go
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// Copyright 2024, Command Line Inc.
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// SPDX-License-Identifier: Apache-2.0
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package topicbus
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import (
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"fmt"
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"sync"
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)
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const (
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MaxMaxEntries = 1000
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MaxMaxDataLen = 1024 * 1024
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MaxTotalData = 50 * 1024 * 1024
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NotifyQueueLen = 100
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DefaultMaxEntries = 1
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DefaultMaxDataLen = 1024
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)
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type TopicOpts struct {
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MaxEntries int
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MaxDataLen int
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}
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type Topic struct {
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ZoneId string
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Name string
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Opts TopicOpts
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Data [][]byte
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StartPos int
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Size int
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DataSize int
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Subs map[string]bool
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}
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type topicKey struct {
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ZoneId string
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Name string
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}
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type TopicNotify struct {
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SubscribeId string
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ZoneId string
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Name string
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Data []byte
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}
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type Bus struct {
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lock *sync.Mutex
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topics map[topicKey]*Topic
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subsReverse map[string]map[topicKey]bool
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curDataLen int64
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notifyCh chan TopicNotify
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}
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var GlobalBus *Bus
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func InitGlobalBus(notifyCh chan TopicNotify) {
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GlobalBus = &Bus{
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lock: &sync.Mutex{},
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topics: make(map[topicKey]*Topic),
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subsReverse: make(map[string]map[topicKey]bool),
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curDataLen: 0,
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notifyCh: notifyCh,
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}
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}
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func (b *Bus) TopicSubscribe(zoneId string, name string, subscribeId string, opts TopicOpts) (*Topic, error) {
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if opts.MaxEntries < 0 {
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return nil, fmt.Errorf("max entries must not be negative")
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}
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if opts.MaxDataLen < 0 {
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return nil, fmt.Errorf("max data length must not be negative")
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}
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if opts.MaxEntries == 0 {
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opts.MaxEntries = DefaultMaxEntries
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}
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if opts.MaxDataLen == 0 {
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opts.MaxDataLen = DefaultMaxDataLen
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}
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if opts.MaxEntries > MaxMaxEntries {
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return nil, fmt.Errorf("max entries exceeds limit")
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}
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if opts.MaxDataLen > MaxMaxDataLen {
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return nil, fmt.Errorf("max data length exceeds limit")
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}
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if opts.MaxEntries <= 0 || opts.MaxDataLen <= 0 {
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return nil, fmt.Errorf("max entries and max data length must be positive")
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}
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if subscribeId == "" {
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return nil, fmt.Errorf("subscribe id must be provided")
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}
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b.lock.Lock()
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defer b.lock.Unlock()
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if b.curDataLen > MaxTotalData {
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return nil, fmt.Errorf("total data exceeds limit")
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}
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key := topicKey{ZoneId: zoneId, Name: name}
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topic := b.topics[key]
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if topic == nil {
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topic = &Topic{
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ZoneId: zoneId,
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Name: name,
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Opts: opts,
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Data: make([][]byte, opts.MaxEntries),
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StartPos: 0,
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Size: 0,
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Subs: make(map[string]bool),
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}
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b.curDataLen += int64(opts.MaxDataLen)
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}
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if topic.Opts.MaxDataLen < opts.MaxDataLen {
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b.curDataLen += int64(opts.MaxDataLen - topic.Opts.MaxDataLen)
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topic.Opts.MaxDataLen = opts.MaxDataLen
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}
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if topic.Opts.MaxEntries < opts.MaxEntries {
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topic.Opts.MaxEntries = opts.MaxEntries
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newData := make([][]byte, opts.MaxEntries)
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copy(newData, topic.Data)
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topic.Data = newData
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}
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topic.Subs[subscribeId] = true
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subMap := b.subsReverse[subscribeId]
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if subMap == nil {
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subMap = make(map[topicKey]bool)
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b.subsReverse[subscribeId] = subMap
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}
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subMap[key] = true
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return topic, nil
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}
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func (t *Topic) nextIdx(idx int) int {
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return (t.StartPos + idx) % t.Opts.MaxEntries
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}
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func (t *Topic) writePos() int {
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return (t.StartPos + t.Size) % t.Opts.MaxEntries
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}
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// returns subscribers to notify
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func (b *Bus) Publish(zoneId string, name string, data []byte) error {
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b.lock.Lock()
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defer b.lock.Unlock()
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key := topicKey{ZoneId: zoneId, Name: name}
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topic := b.topics[key]
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if topic == nil {
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return nil
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}
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if len(data) > topic.Opts.MaxDataLen {
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return fmt.Errorf("data too large")
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}
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if topic.Size < topic.Opts.MaxEntries {
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topic.Data[topic.writePos()] = data
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topic.Size++
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topic.DataSize += len(data)
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} else {
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topic.DataSize += len(data) - len(topic.Data[topic.StartPos])
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topic.Data[topic.StartPos] = data
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topic.StartPos = topic.nextIdx(topic.StartPos)
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}
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// remove data items to make DataSize < MaxDataLen
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// we know it will fit because len(data) <= MaxDataLen
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for topic.DataSize > topic.Opts.MaxDataLen {
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topic.DataSize -= len(topic.Data[topic.StartPos])
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topic.Data[topic.StartPos] = nil
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topic.StartPos = topic.nextIdx(topic.StartPos)
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topic.Size--
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}
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for sub := range topic.Subs {
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// yes, this can block, it will lock then entire bus which will create backpressure
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// this implementation is good enough for now, but can be improved in the future
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b.notifyCh <- TopicNotify{
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SubscribeId: sub,
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ZoneId: zoneId,
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Name: name,
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Data: data,
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}
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}
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return nil
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}
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func (t *Topic) lastN(n int) [][]byte {
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if t == nil {
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return nil
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}
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if n > t.Size {
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n = t.Size
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}
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data := make([][]byte, n)
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for i := 0; i < n; i++ {
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idx := (t.StartPos + i) % t.Opts.MaxEntries
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data[i] = t.Data[idx]
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}
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return data
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}
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func (b *Bus) GetLastN(zoneId string, name string, n int) [][]byte {
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if n <= 0 {
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return nil
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}
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b.lock.Lock()
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defer b.lock.Unlock()
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key := topicKey{ZoneId: zoneId, Name: name}
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topic := b.topics[key]
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return topic.lastN(n)
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}
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func (b *Bus) GetAll(zoneId string, name string) [][]byte {
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b.lock.Lock()
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defer b.lock.Unlock()
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key := topicKey{ZoneId: zoneId, Name: name}
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topic := b.topics[key]
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return topic.lastN(topic.Size)
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}
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func (b *Bus) Subscribe(zoneId string, name string, subscribeId string) {
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b.lock.Lock()
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defer b.lock.Unlock()
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key := topicKey{ZoneId: zoneId, Name: name}
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topic := b.topics[key]
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if topic != nil {
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topic.Subs[subscribeId] = true
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}
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subMap := b.subsReverse[subscribeId]
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if subMap == nil {
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subMap = make(map[topicKey]bool)
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b.subsReverse[subscribeId] = subMap
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}
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subMap[key] = true
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}
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func (b *Bus) Unsubscribe(subscribeId string) {
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b.lock.Lock()
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defer b.lock.Unlock()
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subMap := b.subsReverse[subscribeId]
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if subMap == nil {
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return
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}
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for key := range subMap {
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topic := b.topics[key]
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if topic == nil {
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continue
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}
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delete(topic.Subs, subscribeId)
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if len(topic.Subs) == 0 {
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delete(b.topics, key)
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}
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}
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delete(b.subsReverse, subscribeId)
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}
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