Merge branch 'prevent-account-data-cache-parallel-fetch'

3 files changed, 67 insertions, 33 deletions

diff --git a/gui/src/main/account-data-cache.ts b/gui/src/main/account-data-cache.ts
index 7db2c05ca8..ac829ca0f3 100644
--- a/gui/src/main/account-data-cache.ts
+++ b/gui/src/main/account-data-cache.ts
@@ -2,16 +2,14 @@ import log from 'electron-log';
 import moment from 'moment';
 import { AccountToken, IAccountData } from '../shared/daemon-rpc-types';
 import consumePromise from '../shared/promise';
+import { Scheduler } from '../shared/scheduler';
+import { InvalidAccountError } from './errors';
 
 const EXPIRED_ACCOUNT_REFRESH_PERIOD = 60_000;
 
-export enum AccountFetchRetryAction {
-  stop,
-  retry,
-}
 interface IAccountFetchWatcher {
   onFinish: () => void;
-  onError: (error: Error) => AccountFetchRetryAction;
+  onError: (error: Error) => void;
 }
 
 // An account data cache that helps to throttle RPC requests to get_account_data and retain the
@@ -19,8 +17,9 @@ interface IAccountFetchWatcher {
 export default class AccountDataCache {
   private currentAccount?: AccountToken;
   private expiresAt?: Date;
-  private fetchAttempt = 0;
-  private fetchRetryTimeout?: NodeJS.Timeout;
+  private performingFetch = false;
+  private waitStrategy = new WaitStrategy();
+  private fetchRetryScheduler = new Scheduler();
   private watchers: IAccountFetchWatcher[] = [];
 
   constructor(
@@ -35,25 +34,30 @@ export default class AccountDataCache {
       this.currentAccount = accountToken;
     }
 
-    // Only fetch is value has expired
+    // Only fetch if value has expired
     if (this.isExpired()) {
       if (watcher) {
         this.watchers.push(watcher);
       }
 
-      consumePromise(this.performFetch(accountToken));
+      this.fetchRetryScheduler.cancel();
+      // If a scheduled retry is cancelled the fetchAttempt shouldn't be increased.
+      this.waitStrategy.decrease();
+
+      // Only fetch if there's no fetch for this account number in progress.
+      if (!this.performingFetch) {
+        consumePromise(this.performFetch(accountToken));
+      }
     } else if (watcher) {
       watcher.onFinish();
     }
   }
 
   public invalidate() {
-    if (this.fetchRetryTimeout) {
-      clearTimeout(this.fetchRetryTimeout);
-      this.fetchRetryTimeout = undefined;
-      this.fetchAttempt = 0;
-    }
+    this.fetchRetryScheduler.cancel();
+    this.waitStrategy.reset();
 
+    this.performingFetch = false;
     this.expiresAt = undefined;
     this.updateHandler();
     this.notifyWatchers((watcher) => {
@@ -72,6 +76,7 @@ export default class AccountDataCache {
   }
 
   private async performFetch(accountToken: AccountToken) {
+    this.performingFetch = true;
     try {
       // it's possible for invalidate() to be called or for a fetch for a different account token
       // to start before this fetch completes, so checking if the current account token is the one
@@ -81,10 +86,13 @@ export default class AccountDataCache {
       if (this.currentAccount === accountToken) {
         this.setValue(accountData);
         this.scheduleRefetchIfExpired(accountToken, accountData);
+        this.waitStrategy.reset();
+        this.performingFetch = false;
       }
     } catch (error) {
       if (this.currentAccount === accountToken) {
         this.handleFetchError(accountToken, error);
+        this.performingFetch = false;
       }
     }
   }
@@ -97,24 +105,15 @@ export default class AccountDataCache {
   }
 
   private handleFetchError(accountToken: AccountToken, error: Error) {
-    let shouldRetry = true;
-
-    this.notifyWatchers((watcher) => {
-      if (watcher.onError(error) === AccountFetchRetryAction.stop) {
-        shouldRetry = false;
-      }
-    });
-
-    if (shouldRetry) {
+    this.notifyWatchers((w) => w.onError(error));
+    if (!(error instanceof InvalidAccountError)) {
       this.scheduleRetry(accountToken);
     }
   }
 
   private scheduleRetry(accountToken: AccountToken) {
-    this.fetchAttempt += 1;
-
-    // Max delay: 2^11 = 2048
-    const delay = Math.pow(2, Math.min(this.fetchAttempt + 2, 11)) * 1000;
+    this.waitStrategy.increase();
+    const delay = this.waitStrategy.delay();
 
     log.warn(`Failed to fetch account data. Retrying in ${delay} ms`);
 
@@ -122,8 +121,7 @@ export default class AccountDataCache {
   }
 
   private scheduleFetch(accountToken: AccountToken, delay: number) {
-    this.fetchRetryTimeout = global.setTimeout(() => {
-      this.fetchRetryTimeout = undefined;
+    this.fetchRetryScheduler.schedule(() => {
       consumePromise(this.performFetch(accountToken));
     }, delay);
   }
@@ -132,3 +130,29 @@ export default class AccountDataCache {
     this.watchers.splice(0).forEach(notify);
   }
 }
+
+const MAX_ATTEMPT = 9;
+
+class WaitStrategy {
+  private counter = 0;
+
+  public increase() {
+    if (this.counter < MAX_ATTEMPT) {
+      this.counter += 1;
+    }
+  }
+  public decrease() {
+    if (this.counter > 0) {
+      this.counter -= 1;
+    }
+  }
+
+  public reset() {
+    this.counter = 0;
+  }
+
+  public delay(): number {
+    // Max delay: 2^11 = 2048
+    return Math.pow(2, this.counter + 2) * 1000;
+  }
+}
diff --git a/gui/src/main/index.ts b/gui/src/main/index.ts
index 61b689456c..6f9185688a 100644
--- a/gui/src/main/index.ts
+++ b/gui/src/main/index.ts
@@ -36,7 +36,7 @@ import {
   setupLogging,
 } from '../shared/logging';
 import consumePromise from '../shared/promise';
-import AccountDataCache, { AccountFetchRetryAction } from './account-data-cache';
+import AccountDataCache from './account-data-cache';
 import { getOpenAtLogin, setOpenAtLogin } from './autostart';
 import {
   ConnectionObserver,
@@ -1139,13 +1139,11 @@ class ApplicationMain {
       this.accountDataCache.invalidate();
       this.accountDataCache.fetch(accountToken, {
         onFinish: () => resolve({ status: 'verified' }),
-        onError: (error): AccountFetchRetryAction => {
+        onError: (error) => {
           if (error instanceof InvalidAccountError) {
             reject(error);
-            return AccountFetchRetryAction.stop;
           } else {
             resolve({ status: 'deferred', error });
-            return AccountFetchRetryAction.retry;
           }
         },
       });
diff --git a/gui/src/shared/scheduler.ts b/gui/src/shared/scheduler.ts
new file mode 100644
index 0000000000..af28a7e95b
--- /dev/null
+++ b/gui/src/shared/scheduler.ts
@@ -0,0 +1,12 @@
+export class Scheduler {
+  private timer?: number;
+
+  public schedule(action: () => void, delay: number) {
+    this.cancel();
+    this.timer = setTimeout(action, delay);
+  }
+
+  public cancel() {
+    clearTimeout(this.timer);
+  }
+}