chore(dht): add API to allow options in findProvs()

As discussed in: ipfs/js-ipfs#1322 (comment)

License: MIT
Signed-off-by: Pascal Precht <pascal.precht@gmail.com>

SPEC/DHT.md

@@ -39,10 +39,13 @@ A great source of [examples][] can be found in the tests for this API.
 
 ##### `Go` **WIP**
 
-##### `JavaScript` - ipfs.dht.findprovs(hash, [callback])
+##### `JavaScript` - ipfs.dht.findprovs(hash, [options], callback])
 
 Where `hash` is a multihash.
 
+`options` an optional object with the following properties
+  - `timeout` - a maximum timeout in milliseconds
+
 `callback` must follow `function (err, peerInfos) {}` signature, where `err` is an error if the operation was not successful. `peerInfos` is an array of objects of type [PeerInfo](https://github.com/libp2p/js-peer-info)
 
 If no `callback` is passed, a promise is returned.
@@ -51,6 +54,8 @@ If no `callback` is passed, a promise is returned.
 
 ```JavaScript
 ipfs.dht.findprovs(multihash, function (err, peerInfos) {})
+
+ipfs.dht.findprovs(multihash, { timeout: 4000 }, function (err, peerInfos) {})
 ```
 
 A great source of [examples][] can be found in the tests for this API.

js/src/dht/findprovs.js

@@ -1,12 +1,24 @@
 /* eslint-env mocha */
 'use strict'
 
+const multihashing = require('multihashing-async')
+const Crypto = require('crypto')
 const waterfall = require('async/waterfall')
 const CID = require('cids')
 const { spawnNodesWithId } = require('../utils/spawn')
 const { getDescribe, getIt, expect } = require('../utils/mocha')
 const { connect } = require('../utils/swarm')
 
+function fakeCid (cb) {
+  const bytes = Crypto.randomBytes(Math.round(Math.random() * 1000))
+  multihashing(bytes, 'sha2-256', (err, mh) => {
+    if (err) {
+      cb(err)
+    }
+    cb(null, new CID(0, 'dag-pb', mh))
+  })
+}
+
 module.exports = (createCommon, options) => {
   const describe = getDescribe(options)
   const it = getIt(options)
@@ -54,5 +66,18 @@ module.exports = (createCommon, options) => {
         }
       ], done)
     })
+
+    it('should take options to override timout config', function (done) {
+      const options = {
+        timeout: 1
+      }
+      waterfall([
+        (cb) => fakeCid(cb),
+        (cidV0, cb) => nodeA.dht.findprovs(cidV0, options, (err) => {
+          expect(err).to.exist()
+          cb(null)
+        }),
+      ], done)
+    });
   })
 }

package.json

@@ -38,6 +38,7 @@
     "chai": "^4.1.2",
     "cids": "~0.5.3",
     "concat-stream": "^1.6.2",
+    "crypto": "^1.0.1",
     "dirty-chai": "^2.0.1",
     "hat": "0.0.3",
     "ipfs-block": "~0.7.1",