complete rewrite
This commit is contained in:
teizz
235
main.go
235
main.go
@@ -1,150 +1,159 @@
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package main
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import (
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"fmt"
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"io"
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"log"
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"net/http"
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"strconv"
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"sync"
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"sync/atomic"
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)
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var (
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// variables to set during build-time
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debugging = ""
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version = "0.0-undefined"
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buildtime = "0000-00-00T00:00:00+0000"
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queues = make(map[string]*Queue)
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mut = &sync.Mutex{}
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// actual business end of the device
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paths = &sync.Map{}
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)
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// Transfer holds a single tranferable connection to be read
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type Transfer struct {
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reader io.Reader
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size int
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reader *io.PipeReader
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done chan struct{}
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contentlength string
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}
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// Queue is where posts and gets can exchange transfers
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type Queue struct {
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ch chan Transfer
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producers int
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consumers int
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posts int32
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gets int32
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}
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func NewQueue() *Queue {
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return &Queue{
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ch: make(chan Transfer),
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func pathHandler(w http.ResponseWriter, r *http.Request) {
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pathID := r.URL.Path
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if len(pathID) < 2 {
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w.WriteHeader(400)
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w.Write([]byte("path to short"))
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return
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}
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if r.Method == "GET" {
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log.Printf("%s [GET] Connected", pathID)
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queue := &Queue{ch: make(chan Transfer)}
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if p, loaded := paths.LoadOrStore(pathID, queue); loaded {
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queue = p.(*Queue)
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debug("%s [GET] Loads path", pathID)
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} else {
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debug("%s [GET] Created path", pathID)
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}
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atomic.AddInt32(&queue.gets, 1)
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select {
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case transfer := <-queue.ch:
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debug("%s [GET] Reads from path", pathID)
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if transfer.contentlength != "" {
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w.Header().Set("Content-Length", transfer.contentlength)
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}
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_, err := io.Copy(w, transfer.reader)
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if err != nil {
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transfer.reader.Close()
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}
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debug("%s [GET] Sends done", pathID)
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close(transfer.done)
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case <-r.Context().Done():
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debug("%s [GET] Cancels path", pathID)
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}
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if atomic.AddInt32(&queue.gets, -1) <= 0 {
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if atomic.LoadInt32(&queue.posts) <= 0 {
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paths.Delete(pathID)
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debug("%s [GET] Removes path", pathID)
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}
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}
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log.Printf("%s [GET] Finishes", pathID)
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} else {
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log.Printf("%s [POST] Connected", pathID)
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queue := &Queue{ch: make(chan Transfer)}
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if p, loaded := paths.LoadOrStore(pathID, queue); loaded {
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queue = p.(*Queue)
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debug("%s [POST] Loads path", pathID)
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} else {
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debug("%s [POST] Creates path", pathID)
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}
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atomic.AddInt32(&queue.posts, 1)
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reader, writer := io.Pipe()
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transfer := Transfer{
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reader: reader,
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contentlength: r.Header.Get("Content-Length"),
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done: make(chan struct{}),
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}
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go func() {
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n, err := io.Copy(writer, r.Body)
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debug("%s [POST] Sends %d bytes", pathID, n)
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if err != nil {
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debug("%s [POST] Has error: %s", pathID, err.Error())
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}
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writer.Close()
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r.Body.Close()
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}()
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select {
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case queue.ch <- transfer:
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debug("%s [POST] Writes to path", pathID)
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case <-r.Context().Done():
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debug("%s [POST] Cancels path", pathID)
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close(transfer.done)
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}
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debug("%s [POST] Waits for done", pathID)
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<-transfer.done
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if atomic.AddInt32(&queue.posts, -1) <= 0 {
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if atomic.LoadInt32(&queue.gets) <= 0 {
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paths.Delete(pathID)
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debug("%s [POST] Removes path", pathID)
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}
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}
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log.Printf("%s [POST] Finishes", pathID)
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}
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}
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func (q *Queue) addConsumer() {
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q.consumers = q.consumers + 1
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func okHandler(w http.ResponseWriter, r *http.Request) {
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w.WriteHeader(http.StatusOK)
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w.Write([]byte("ok"))
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}
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func (q *Queue) remConsumer() {
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q.consumers = q.consumers - 1
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}
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func (q *Queue) addProducer() {
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q.producers = q.producers + 1
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}
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func (q *Queue) remProducer() {
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q.producers = q.producers - 1
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}
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func (q *Queue) isEmpty() bool {
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return q.producers == 0 && q.consumers == 0
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func emptyHandler(w http.ResponseWriter, r *http.Request) {
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w.WriteHeader(http.StatusOK)
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}
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func main() {
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log.Printf("pathway version:%s buildtime:%s", version, buildtime)
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handle := func(w http.ResponseWriter, r *http.Request) {
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channelId := r.URL.Path
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if r.Method == "GET" {
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log.Printf("GET: %s", channelId)
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mut.Lock()
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queue, exists := queues[channelId]
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if !exists {
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queue = NewQueue()
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queues[channelId] = queue
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}
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ch := queue.ch
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queue.addConsumer()
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mut.Unlock()
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select {
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case transfer := <-ch:
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w.Header().Set("Content-Length", fmt.Sprintf("%d", transfer.size))
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_, err := io.Copy(w, transfer.reader)
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if err != nil {
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if closer, ok := transfer.reader.(io.Closer); ok {
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closer.Close()
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}
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}
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case <-r.Context().Done():
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}
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mut.Lock()
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queue.remConsumer()
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if queue.isEmpty() {
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delete(queues, channelId)
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}
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mut.Unlock()
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} else {
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log.Printf("POST: %s", channelId)
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mut.Lock()
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queue, exists := queues[channelId]
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if !exists {
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queue = NewQueue()
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queues[channelId] = queue
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}
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ch := queue.ch
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queue.addProducer()
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mut.Unlock()
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reader, writer := io.Pipe()
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contentLength, err := strconv.Atoi(r.Header.Get("Content-Length"))
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if err != nil {
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contentLength = 0
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}
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transfer := Transfer{
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reader: reader,
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size: contentLength,
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}
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select {
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case ch <- transfer:
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io.Copy(writer, r.Body)
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case <-r.Context().Done():
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}
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writer.Close()
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mut.Lock()
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queue.remProducer()
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if queue.isEmpty() {
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delete(queues, channelId)
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}
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mut.Unlock()
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}
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}
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health := func(w http.ResponseWriter, r *http.Request) {
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w.WriteHeader(http.StatusOK)
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w.Write([]byte("OK"))
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}
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http.HandleFunc("/health", health)
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http.HandleFunc("/", handle)
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http.HandleFunc("/health", okHandler)
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http.HandleFunc("/favicon.ico", emptyHandler)
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http.HandleFunc("/robots.txt", emptyHandler)
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http.HandleFunc("/", pathHandler)
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err := http.ListenAndServe(":8080", nil)
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if err != nil {
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log.Println(err)
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}
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}
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func debug(msg string, args ...interface{}) {
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if len(debugging) > 0 {
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log.Printf(msg, args...)
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}
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}
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