fix: limit concurrent HTTP requests (backport for 0.2.x)

package.json

@@ -27,6 +27,7 @@
   },
   "dependencies": {
     "ipfs-http-client": "^33.0.1",
+    "p-queue": "^6.1.0",
     "peer-id": "^0.12.2",
     "peer-info": "^0.15.1"
   },

src/index.js

@@ -3,18 +3,22 @@
 const PeerId = require('peer-id')
 const dht = require('ipfs-http-client/src/dht')
 const defaultConfig = require('ipfs-http-client/src/utils/default-config')
+const { default: PQueue } = require('p-queue')
 
 const DEFAULT_MAX_TIMEOUT = 30e3 // 30 second default
 const DEFAULT_IPFS_API = {
   protocol: 'https',
   port: 443,
-  host: 'ipfs.io'
+  host: 'node0.delegate.ipfs.io'
 }
 
 class DelegatedPeerRouting {
   constructor (api) {
     this.api = Object.assign({}, defaultConfig(), DEFAULT_IPFS_API, api)
     this.dht = dht(this.api)
+    // limit concurrency to avoid request flood in web browser
+    // (backport of: https://github.com/libp2p/js-libp2p-delegated-peer-routing/pull/12)
+    this._httpQueue = new PQueue({ concurrency: 4 })
   }
 
   /**
@@ -44,17 +48,13 @@ class DelegatedPeerRouting {
 
     options.maxTimeout = options.maxTimeout || DEFAULT_MAX_TIMEOUT
 
-    this.dht.findPeer(id, {
+    this._httpQueue.add(() => this.dht.findPeer(id, {
       timeout: `${options.maxTimeout}ms`// The api requires specification of the time unit (s/ms)
-    }, (err, info) => {
-      if (err) {
-        if (err.message.includes('not found')) {
-          return callback()
-        }
-        return callback(err)
+    })).then(res => callback(null, res), err => {
+      if (err.message.includes('not found')) {
+        return callback()
       }
-
-      callback(null, info)
+      return callback(err)
     })
   }
 }

test/index.spec.js

@@ -81,14 +81,14 @@ describe('DelegatedPeerRouting', function () {
   })
 
   describe('create', () => {
-    it('should default to https://ipfs.io as the delegate', () => {
+    it('should default to https://node0.delegate.ipfs.io as the delegate', () => {
       const router = new DelegatedPeerRouting()
 
       expect(router.api).to.include({
         'api-path': '/api/v0/',
         protocol: 'https',
         port: 443,
-        host: 'ipfs.io'
+        host: 'node0.delegate.ipfs.io'
       })
     })