Full support for websocket reconnection/resubscription

package.json

@@ -120,6 +120,7 @@
         "lerna": "^2.11.0",
         "mocha": "^6.2.1",
         "npm-auth-to-token": "^1.0.0",
+        "pify": "^4.0.1",
         "puppeteer": "^1.20.0",
         "sandboxed-module": "^2.0.3",
         "typescript": "next",

packages/web3-core-requestmanager/src/index.js

@@ -103,13 +103,16 @@ RequestManager.prototype.setProvider = function (p, net) {
                 _this.subscriptions[result.params.subscription].callback(null, result.params.result);
             }
         });
-        // TODO add error, end, timeout, connect??
-        // this.provider.on('error', function requestManagerNotification(result){
-        //     Object.keys(_this.subscriptions).forEach(function(id){
-        //         if(_this.subscriptions[id].callback)
-        //             _this.subscriptions[id].callback(err);
-        //     });
-        // }
+
+        // notify all subscriptions about the error condition
+        this.provider.on('error', function (event) {
+            Object.keys(_this.subscriptions).forEach(function(id){
+                if(_this.subscriptions[id] && _this.subscriptions[id].callback)
+                _this.subscriptions[id].callback(event.code || new Error('Provider error'));
+            });
+        });
+
+        // TODO add end, timeout, connect??
     }
 };
 
@@ -205,17 +208,20 @@ RequestManager.prototype.addSubscription = function (id, name, type, callback) {
  * @param {Function} callback   fired once the subscription is removed
  */
 RequestManager.prototype.removeSubscription = function (id, callback) {
-    var _this = this;
-
     if(this.subscriptions[id]) {
+        var type = this.subscriptions[id].type;
+
+        // remove subscription first to avoid reentry
+        delete this.subscriptions[id];
 
+        // then, try to actually unsubscribe
         this.send({
-            method: this.subscriptions[id].type + '_unsubscribe',
+            method: type + '_unsubscribe',
             params: [id]
         }, callback);
-
-        // remove subscription
-        delete _this.subscriptions[id];
+    } else if (typeof callback === 'function') {
+        // call the callback if the subscription was already removed
+        callback(null);
     }
 };