fix: migrate LruMap from collections to lru-cache. (mqttjs#1396)

lib/topic-alias-send.js

@@ -3,7 +3,7 @@
 /**
  * Module dependencies
  */
-const LruMap = require('collections/lru-map')
+const LruMap = require('lru-cache')
 const NumberAllocator = require('number-allocator').NumberAllocator
 
 /**
@@ -17,7 +17,7 @@ function TopicAliasSend (max) {
   }
 
   if (max > 0) {
-    this.aliasToTopic = new LruMap()
+    this.aliasToTopic = new LruMap({ max: max })
     this.topicToAlias = {}
     this.numberAllocator = new NumberAllocator(1, max)
     this.max = max
@@ -37,9 +37,9 @@ TopicAliasSend.prototype.put = function (topic, alias) {
   }
   const entry = this.aliasToTopic.get(alias)
   if (entry) {
-    delete this.topicToAlias[entry.topic]
+    delete this.topicToAlias[entry]
   }
-  this.aliasToTopic.set(alias, { topic: topic, alias: alias })
+  this.aliasToTopic.set(alias, topic)
   this.topicToAlias[topic] = alias
   this.numberAllocator.use(alias)
   this.length = this.aliasToTopic.length
@@ -52,9 +52,7 @@ TopicAliasSend.prototype.put = function (topic, alias) {
  * @returns {String} - if mapped topic exists return topic, otherwise return undefined
  */
 TopicAliasSend.prototype.getTopicByAlias = function (alias) {
-  const entry = this.aliasToTopic.get(alias)
-  if (typeof entry === 'undefined') return entry
-  return entry.topic
+  return this.aliasToTopic.get(alias)
 }
 
 /**
@@ -74,7 +72,7 @@ TopicAliasSend.prototype.getAliasByTopic = function (topic) {
  * Clear all entries
  */
 TopicAliasSend.prototype.clear = function () {
-  this.aliasToTopic.clear()
+  this.aliasToTopic.reset()
   this.topicToAlias = {}
   this.numberAllocator.clear()
   this.length = 0
@@ -87,7 +85,7 @@ TopicAliasSend.prototype.clear = function () {
 TopicAliasSend.prototype.getLruAlias = function () {
   const alias = this.numberAllocator.firstVacant()
   if (alias) return alias
-  return this.aliasToTopic.min().alias
+  return this.aliasToTopic.keys()[this.aliasToTopic.length - 1]
 }
 
 module.exports = TopicAliasSend

package.json

@@ -62,13 +62,13 @@
     "net": false
   },
   "dependencies": {
-    "collections": "^5.1.13",
     "commist": "^1.0.0",
     "concat-stream": "^2.0.0",
     "debug": "^4.1.1",
     "duplexify": "^4.1.1",
     "help-me": "^3.0.0",
     "inherits": "^2.0.3",
+    "lru-cache": "^6.0.0",
     "minimist": "^1.2.5",
     "mqtt-packet": "^6.8.0",
     "number-allocator": "^1.0.9",