fetch only when clients are connected

lib/index.js

@@ -79,6 +79,17 @@ export default function slackin ({
     app.use(cors())
   }
 
+  // Temporarily increase the client connection count to allow
+  // slack to restart the fetch interval (if needed). This allows
+  // static connections to pull new data if dynamic clients are
+  // not connected and slack fetching has been paused.
+  let pingSlack = function() {
+    slack.clientConnected()
+    setTimeout(function() {
+      slack.clientDisconnected()
+    }, slack.interval * 4)
+  }
+
   // splash page
   app.get('/', (req, res) => {
     let { name, logo } = slack.org
@@ -101,6 +112,7 @@ export default function slackin ({
   })
 
   app.get('/data', (req, res) => {
+    pingSlack()
     let { name, logo } = slack.org
     let { active, total } = slack.users
     res.send({
@@ -262,6 +274,7 @@ export default function slackin ({
 
   // badge rendering
   app.get('/badge.svg', (req, res) => {
+    pingSlack()
     res.type('svg')
     res.set('Cache-Control', 'max-age=0, no-cache')
     res.set('Pragma', 'no-cache')
@@ -273,8 +286,10 @@ export default function slackin ({
     socket.emit('data', slack.users)
     let change = (key, val) => socket.emit(key, val)
     slack.on('change', change)
+    slack.clientConnected()
     socket.on('disconnect', () => {
       slack.removeListener('change', change)
+      slack.clientDisconnected()
     })
   })
 

lib/log.js

@@ -16,13 +16,18 @@ export default function log (slack, silent){
     out('fetching')
   })
 
+  slack.on('log', (message) => {
+    out(message)
+  })
+
   slack.on('data', online)
 
   // log online users
   function online (){
-    out('online %d, total %d %s',
+    out('online %d, total %d, clients %d %s',
       slack.users.active,
       slack.users.total,
+      slack.clientConnectionCount,
       last ? `(+${new Date - last}ms)` : '')
   }
 

lib/slack.js

@@ -11,6 +11,8 @@ export default class SlackData extends EventEmitter {
     this.ready = false
     this.org = {}
     this.users = {}
+    this.clientConnectionCount = 0
+    this.fetchTimeout = null
     this.channelsByName = {}
     this.init()
     this.fetch()
@@ -44,7 +46,36 @@ export default class SlackData extends EventEmitter {
     })
   }
 
+  clientConnected() {
+    if (this.clientConnectionCount == 0) {
+      this.emit('log', 'restarting fetch')
+      this.fetch()
+    }
+    this.clientConnectionCount++
+  }
+
+  clientDisconnected() {
+    this.clientConnectionCount--
+    if (this.clientConnectionCount == 0) {
+      this.emit('log', 'pausing fetch')
+      this.stopFetchTimeout()
+    }
+  }
+
+  stopFetchTimeout() {
+    if (this.fetchTimeout) {
+      clearTimeout(this.fetchTimeout)
+      this.fetchTimeout = null
+    }
+  }
+
+  retryFetch(interval) {
+    this.stopFetchTimeout()
+    this.fetchTimeout = setTimeout(this.fetch.bind(this), interval)
+  }
+
   fetch (){
+    this.stopFetchTimeout()
     request
     .get(`https://${this.host}.slack.com/api/users.list`)
     .query({ token: this.token, presence: 1 })
@@ -59,9 +90,9 @@ export default class SlackData extends EventEmitter {
     return channel ? channel.id: null
   }
 
-  retry (){
+  retry () {
     let interval = this.interval * 2
-    setTimeout(this.fetch.bind(this), interval)
+    this.retryFetch(interval)
     this.emit('retry')
   }
 
@@ -107,7 +138,9 @@ export default class SlackData extends EventEmitter {
       this.emit('ready')
     }
 
-    setTimeout(this.fetch.bind(this), this.interval)
+    if (this.clientConnectionCount > 0) {
+      this.retryFetch(this.interval)
+    }
     this.emit('data')
   }