fix: use pubsub seenCache (#75)

The inherited PubSubProtocol class already contains a time-cache for
latest seen messages. Use the existing cache instead of creating a
duplicate.

package.json

@@ -65,8 +65,7 @@
     "protons": "^1.0.1",
     "pull-length-prefixed": "^1.3.2",
     "pull-pushable": "^2.2.0",
-    "pull-stream": "^3.6.9",
-    "time-cache": "~0.3.0"
+    "pull-stream": "^3.6.9"
   },
   "contributors": [
     "Alan Shaw <alan.shaw@protocol.ai>",

src/index.js

@@ -1,6 +1,5 @@
 'use strict'
 
-const TimeCache = require('time-cache')
 const pull = require('pull-stream')
 const lp = require('pull-length-prefixed')
 const assert = require('assert')
@@ -27,13 +26,6 @@ class FloodSub extends BaseProtocol {
   constructor (libp2p) {
     super('libp2p:floodsub', multicodec, libp2p)
 
-    /**
-     * Time based cache for sequence numbers.
-     *
-     * @type {TimeCache}
-     */
-    this.cache = new TimeCache()
-
     /**
      * List of our subscriptions
      * @type {Set<string>}
@@ -109,11 +101,11 @@ class FloodSub extends BaseProtocol {
     msgs.forEach((msg) => {
       const seqno = utils.msgId(msg.from, msg.seqno)
       // 1. check if I've seen the message, if yes, ignore
-      if (this.cache.has(seqno)) {
+      if (this.seenCache.has(seqno)) {
         return
       }
 
-      this.cache.put(seqno)
+      this.seenCache.put(seqno)
 
       // 2. emit to self
       this._emitMessages(msg.topicIDs, [msg])
@@ -182,7 +174,7 @@ class FloodSub extends BaseProtocol {
 
     const buildMessage = (msg) => {
       const seqno = utils.randomSeqno()
-      this.cache.put(utils.msgId(from, seqno))
+      this.seenCache.put(utils.msgId(from, seqno))
 
       return {
         from: from,