refactor(docs): async await version of examples/echo (#483)

* fix: performance bottleneck in stat.js (#463)

Array.shift seems to be very slow, perhaps linear, on some
engines, resulting in  _update consuming a lot of CPU.

* docs(fix): correct docs and example for pnet (#464)

* docs(fix): correct docs and example for pnet

* docs(fix): correct pnet docs

* docs(fix): update README.md language (#468)

* docs: reciprocate (#474)

* docs(example): fix ipfs cat (#475)

`ipfs.files.cat` is incorrect. the correct function is `ipfs.cat`

* fix: async await examples/echo

* fix: examples readme typos (#481)

* fix: simplify libp2p bundle for echo example

examples/echo/src/dialer.js

@@ -8,51 +8,54 @@
 const PeerId = require('peer-id')
 const PeerInfo = require('peer-info')
 const Node = require('./libp2p-bundle')
-const pull = require('pull-stream')
-const async = require('async')
+const pipe = require('it-pipe')
 
-async.parallel([
-  (cb) => PeerId.createFromJSON(require('./id-d'), cb),
-  (cb) => PeerId.createFromJSON(require('./id-l'), cb)
-], (err, ids) => {
-  if (err) { throw err }
+async function run() {
+  const [dialerId, listenerId] = await Promise.all([
+    PeerId.createFromJSON(require('./id-d')),
+    PeerId.createFromJSON(require('./id-l'))
+  ])
 
   // Dialer
-  const dialerId = ids[0]
   const dialerPeerInfo = new PeerInfo(dialerId)
   dialerPeerInfo.multiaddrs.add('/ip4/0.0.0.0/tcp/0')
   const dialerNode = new Node({
     peerInfo: dialerPeerInfo
   })
 
-  // Peer to Dial
-  const listenerPeerInfo = new PeerInfo(ids[1])
-  const listenerId = ids[1]
+  // Peer to Dial (the listener)
+  const listenerPeerInfo = new PeerInfo(listenerId)
   const listenerMultiaddr = '/ip4/127.0.0.1/tcp/10333/p2p/' +
       listenerId.toB58String()
   listenerPeerInfo.multiaddrs.add(listenerMultiaddr)
 
-  dialerNode.start((err) => {
-    if (err) { throw err }
+  // Start the dialer libp2p node
+  await dialerNode.start()
 
   console.log('Dialer ready, listening on:')
   dialerPeerInfo.multiaddrs.forEach((ma) => console.log(ma.toString() +
         '/p2p/' + dialerId.toB58String()))
 
+  // Dial the listener node
   console.log('Dialing to peer:', listenerMultiaddr.toString())
-    dialerNode.dialProtocol(listenerPeerInfo, '/echo/1.0.0', (err, conn) => {
-      if (err) { throw err }
+  const { stream } = await dialerNode.dialProtocol(listenerPeerInfo, '/echo/1.0.0')
 
   console.log('nodeA dialed to nodeB on protocol: /echo/1.0.0')
 
-      pull(
-        pull.values(['hey']),
-        conn,
-        pull.collect((err, data) => {
-          if (err) { throw err }
+  pipe(
+    // Source data
+    ['hey'],
+    // Write to the stream, and pass its output to the next function
+    stream,
+    // Sink function
+    async function (source) {
+      // For each chunk of data
+      for await (const data of source) {
+        // Output the data
         console.log('received echo:', data.toString())
-        })
+      }
+    }
   )
-    })
-  })
-})
+}
+
+run()

examples/echo/src/libp2p-bundle.js

@@ -1,41 +1,12 @@
 'use strict'
 
 const TCP = require('libp2p-tcp')
-const MulticastDNS = require('libp2p-mdns')
 const WS = require('libp2p-websockets')
-const Bootstrap = require('libp2p-bootstrap')
-const spdy = require('libp2p-spdy')
-const KadDHT = require('libp2p-kad-dht')
 const mplex = require('libp2p-mplex')
 const secio = require('libp2p-secio')
 const defaultsDeep = require('@nodeutils/defaults-deep')
 const libp2p = require('../../..')
 
-function mapMuxers (list) {
-  return list.map((pref) => {
-    if (typeof pref !== 'string') {
-      return pref
-    }
-    switch (pref.trim().toLowerCase()) {
-      case 'spdy': return spdy
-      case 'mplex': return mplex
-      default:
-        throw new Error(pref + ' muxer not available')
-    }
-  })
-}
-
-function getMuxers (muxers) {
-  const muxerPrefs = process.env.LIBP2P_MUXER
-  if (muxerPrefs && !muxers) {
-    return mapMuxers(muxerPrefs.split(','))
-  } else if (muxers) {
-    return mapMuxers(muxers)
-  } else {
-    return [mplex, spdy]
-  }
-}
-
 class Node extends libp2p {
   constructor (_options) {
     const defaults = {
@@ -44,29 +15,8 @@ class Node extends libp2p {
           TCP,
           WS
         ],
-        streamMuxer: getMuxers(_options.muxer),
-        connEncryption: [ secio ],
-        peerDiscovery: [
-          MulticastDNS,
-          Bootstrap
-        ],
-        dht: KadDHT
-      },
-      config: {
-        peerDiscovery: {
-          mdns: {
-            interval: 10000,
-            enabled: false
-          },
-          bootstrap: {
-            interval: 10000,
-            enabled: false,
-            list: _options.bootstrapList
-          }
-        },
-        dht: {
-          kBucketSize: 20
-        }
+        streamMuxer: [ mplex ],
+        connEncryption: [ secio ]
       }
     }
 

examples/echo/src/listener.js

@@ -8,39 +8,34 @@
 const PeerId = require('peer-id')
 const PeerInfo = require('peer-info')
 const Node = require('./libp2p-bundle')
-const pull = require('pull-stream')
-const series = require('async/series')
+const pipe = require('it-pipe')
 
-let listenerId
-let listenerNode
+async function run() {
+  const listenerId = await PeerId.createFromJSON(require('./id-l'))
 
-series([
-  (cb) => {
-    PeerId.createFromJSON(require('./id-l'), (err, id) => {
-      if (err) { return cb(err) }
-      listenerId = id
-      cb()
-    })
-  },
-  (cb) => {
+  // Listener libp2p node
   const listenerPeerInfo = new PeerInfo(listenerId)
   listenerPeerInfo.multiaddrs.add('/ip4/0.0.0.0/tcp/10333')
-    listenerNode = new Node({
+  const listenerNode = new Node({
     peerInfo: listenerPeerInfo
   })
 
+  // Log a message when we receive a connection
   listenerNode.on('peer:connect', (peerInfo) => {
     console.log('received dial to me from:', peerInfo.id.toB58String())
   })
 
-    listenerNode.handle('/echo/1.0.0', (protocol, conn) => pull(conn, conn))
-    listenerNode.start(cb)
-  }
-], (err) => {
-  if (err) { throw err }
+  // Handle incoming connections for the protocol by piping from the stream
+  // back to itself (an echo)
+  await listenerNode.handle('/echo/1.0.0', ({ stream }) => pipe(stream.source, stream.sink))
+
+  // Start listening
+  await listenerNode.start()
 
   console.log('Listener ready, listening on:')
   listenerNode.peerInfo.multiaddrs.forEach((ma) => {
     console.log(ma.toString() + '/p2p/' + listenerId.toB58String())
   })
-})
+}
+
+run()