Poll for defaultAccount to update dapp & overlay subscriptions (#4417)

* Poll for defaultAccount (Fixes #4413)

* Fix nextTimeout on catch

* Store timers

* Re-enable default updates on change detection

js/src/api/subscriptions/eth.js

@@ -23,6 +23,7 @@ export default class Eth {
     this._started = false;
 
     this._lastBlock = new BigNumber(-1);
+    this._pollTimerId = null;
   }
 
   get isStarted () {
@@ -37,7 +38,7 @@ export default class Eth {
 
   _blockNumber = () => {
     const nextTimeout = (timeout = 1000) => {
-      setTimeout(() => {
+      this._pollTimerId = setTimeout(() => {
         this._blockNumber();
       }, timeout);
     };
@@ -57,6 +58,6 @@ export default class Eth {
 
         nextTimeout();
       })
-      .catch(nextTimeout);
+      .catch(() => nextTimeout());
   }
 }

js/src/api/subscriptions/personal.js

@@ -20,6 +20,9 @@ export default class Personal {
     this._api = api;
     this._updateSubscriptions = updateSubscriptions;
     this._started = false;
+
+    this._lastDefaultAccount = '0x0';
+    this._pollTimerId = null;
   }
 
   get isStarted () {
@@ -37,12 +40,35 @@ export default class Personal {
     ]);
   }
 
-  _defaultAccount = () => {
+  // FIXME: Because of the different API instances, the "wait for valid changes" approach
+  // doesn't work. Since the defaultAccount is critical to operation, we poll in exactly
+  // same way we do in ../eth (ala same as eth_blockNumber) and update. This should be moved
+  // to pub-sub as it becomes available
+  _defaultAccount = (timerDisabled = false) => {
+    const nextTimeout = (timeout = 1000) => {
+      if (!timerDisabled) {
+        this._pollTimerId = setTimeout(() => {
+          this._defaultAccount();
+        }, timeout);
+      }
+    };
+
+    if (!this._api.transport.isConnected) {
+      nextTimeout(500);
+      return;
+    }
+
     return this._api.parity
       .defaultAccount()
       .then((defaultAccount) => {
-        this._updateSubscriptions('parity_defaultAccount', null, defaultAccount);
-      });
+        if (this._lastDefaultAccount !== defaultAccount) {
+          this._lastDefaultAccount = defaultAccount;
+          this._updateSubscriptions('parity_defaultAccount', null, defaultAccount);
+        }
+
+        nextTimeout();
+      })
+      .catch(() => nextTimeout());
   }
 
   _listAccounts = () => {
@@ -95,7 +121,7 @@ export default class Personal {
 
         case 'parity_setDappsAddresses':
         case 'parity_setNewDappsWhitelist':
-          this._defaultAccount();
+          this._defaultAccount(true);
           return;
       }
     });

js/src/api/subscriptions/personal.spec.js

@@ -36,6 +36,9 @@ function stubApi (accounts, info) {
 
   return {
     _calls,
+    transport: {
+      isConnected: true
+    },
     parity: {
       accountsInfo: () => {
         const stub = sinon.stub().resolves(info || TEST_INFO)();