fix: generate meaniful error when pubsub is called and not enabled

Author: richardschneider

src/core/components/no-floodsub.js

@@ -0,0 +1,25 @@
+'use strict'
+
+const EventEmitter = require('events')
+
+function fail() {
+  throw new Error('The daemon must be run with \'--enable-pubsub-experiment\'')
+}
+
+class NoFloodSub extends EventEmitter {
+  constructor () {
+    super()
+
+    this.peers = new Map()
+    this.subscriptions = new Set()
+  }
+
+  start (callback) { callback() }
+  stop (callback) { callback() }
+  publish () { fail() }
+  subscribe () { fail() }
+  unsubscribe () { fail() }
+
+}
+
+module.exports = NoFloodSub

src/core/components/start.js

@@ -3,6 +3,7 @@
 const series = require('async/series')
 const Bitswap = require('ipfs-bitswap')
 const FloodSub = require('libp2p-floodsub')
+const NoFloodSub = require('./no-floodsub')
 const setImmediate = require('async/setImmediate')
 const promisify = require('promisify-es6')
 
@@ -50,12 +51,10 @@ module.exports = (self) => {
       self._bitswap.start()
       self._blockService.setExchange(self._bitswap)
 
-      if (self._options.EXPERIMENTAL.pubsub) {
-        self._pubsub = new FloodSub(self._libp2pNode)
-        self._pubsub.start(done)
-      } else {
-        done()
-      }
+      self._pubsub = self._options.EXPERIMENTAL.pubsub
+        ? new FloodSub(self._libp2pNode)
+        : new NoFloodSub()
+      self._pubsub.start(done)
     })
   })
 }

src/core/components/stop.js

@@ -31,13 +31,7 @@ module.exports = (self) => {
     self._bitswap.stop()
 
     series([
-      (cb) => {
-        if (self._options.EXPERIMENTAL.pubsub) {
-          self._pubsub.stop(cb)
-        } else {
-          cb()
-        }
-      },
+      (cb) => self._pubsub.stop(cb),
       (cb) => self.libp2p.stop(cb),
       (cb) => self._repo.close(cb)
     ], done)