fixed subscription handling for instances that disappeared

Author: bheisen

Diff for: CHANGELOG.md

@@ -33,6 +33,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Fixed
 
+- now unsubscribing from events on instances that aren't available anymore
 - invalid log message triggered when JSON return values are circular
 - multiple emitter registration under the same clientId
 - issue when loading files that are not ending with ".js"

Diff for: browser/vrpc.js

@@ -232,6 +232,9 @@ class VrpcClient extends EventEmitter {
         this._agents[agent].status = status
         this._agents[agent].hostname = hostname
         this._agents[agent].version = version
+        if (status === 'offline') {
+          this._clearCachedSubscriptions({ lostAgent: agent })
+        }
         this.emit('agent', { domain, agent, status, hostname, version })
         // ClassInfo message
       } else if (
@@ -251,6 +254,7 @@ class VrpcClient extends EventEmitter {
           json
         if (removed.length !== 0) {
           this.emit('instanceGone', removed, { domain, agent, className })
+          this._clearCachedSubscriptions({ lostInstance: removed })
         }
         if (added.length !== 0) {
           this.emit('instanceNew', added, { domain, agent, className })
@@ -1179,6 +1183,29 @@ class VrpcClient extends EventEmitter {
     return id
   }
 
+  _clearCachedSubscriptions ({ lostAgent, lostInstance }) {
+    const obsoleteTopics = Object.keys(this._cachedSubscriptions).filter(
+      topic => {
+        const [, agent, , instanceEvent] = topic.split('/')
+        const [instance] = instanceEvent.split(':')
+        if (agent === lostAgent || instance === lostInstance) {
+          return true
+        }
+        return false
+      }
+    )
+    obsoleteTopics.forEach(topic => {
+      const id = `__e__${topic}`
+      this._log.info(`Clearing subscriptions for obsolete topic: ${topic}`)
+      const subscriptions = this._cachedSubscriptions[topic]
+      subscriptions.forEach(({ handler }) => {
+        this._eventEmitter.removeListener(id, handler)
+      })
+      this._mqttUnsubscribe(topic)
+      delete this._cachedSubscriptions[topic]
+    })
+  }
+
   _stripSignature (method) {
     const pos = method.indexOf('-')
     if (pos > 0) return method.substring(0, pos)