Fix potential race conditions for starting/stopping server add-ons

Reviewed By: mweststrate Differential Revision: D34301593 fbshipit-source-id: 2950de8a8567318cd3e87eff176657df5ba8fd1b
2022-02-28 03:50:34 -08:00
parent bdbf79e3e1
commit 81d0057a8d
6 changed files with 317 additions and 123 deletions
--- a/desktop/flipper-server-core/src/plugins/ServerAddManager.tsx
+++ b/desktop/flipper-server-core/src/plugins/ServerAddManager.tsx
@@ -0,0 +1,147 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {
+  ClientResponseType,
+  ExecuteMessage,
+  FlipperServerForServerAddOn,
+  ServerAddOnStartDetails,
+} from 'flipper-common';
+import {assertNotNull} from '../comms/Utilities';
+import {StateMachine} from '../utils/StateMachine';
+import {ServerAddOn} from './ServerAddOn';
+
+type TState =
+  | 'inactive'
+  | 'starting'
+  | 'active'
+  | 'fatal'
+  | 'stopping'
+  | 'zombie';
+
+export class ServerAddOnManager {
+  public readonly state = new StateMachine<TState, 'fatal'>('inactive');
+  private _serverAddOn?: ServerAddOn;
+  constructor(
+    public readonly pluginName: string,
+    details: ServerAddOnStartDetails,
+    initialOwner: string,
+    flipperServer: FlipperServerForServerAddOn,
+  ) {
+    this.startServerAddOn(details, initialOwner, flipperServer);
+  }
+
+  sendExpectResponse(message: ExecuteMessage): Promise<ClientResponseType> {
+    if (!this.state.is('active')) {
+      console.info(
+        'StateAddOnManager.sendExpectResponse -> error: server add-on is not active, Current state:',
+        this.state.currentState,
+      );
+      throw new Error(
+        'StateAddOnManager.sendExpectResponse -> error: server add-on is not active',
+      );
+    }
+    assertNotNull(
+      this._serverAddOn,
+      'StateAddOnManager.sendExpectResponse -> _serverAddOn is undefined',
+    );
+    return this._serverAddOn.connection.sendExpectResponse(message);
+  }
+
+  async addOwner(owner: string) {
+    if (this.state.is('starting')) {
+      await this.state.wait(['active', 'fatal']);
+    }
+
+    if (!this.state.is('active')) {
+      console.info(
+        'StateAddOnManager.addOwner -> error: server add-on is not active, Current state:',
+        this.state.currentState,
+      );
+      throw new Error(
+        'StateAddOnManager.addOwner -> error: server add-on is not active',
+      );
+    }
+    assertNotNull(
+      this._serverAddOn,
+      'StateAddOnManager.addOwner -> _serverAddOn is undefined',
+    );
+
+    this._serverAddOn.addOwner(owner);
+  }
+
+  async removeOwner(owner: string) {
+    if (this.state.is(['stopping', 'inactive'])) {
+      return this.state.wait(['zombie', 'inactive']);
+    }
+
+    if (this.state.is('starting')) {
+      await this.state.wait(['active', 'fatal']);
+    }
+
+    if (!this.state.is('active')) {
+      console.debug(
+        'StateAddOnManager.removeOwner -> error: server add-on failed to start, Current state:',
+        this.state.currentState,
+      );
+      return;
+    }
+
+    assertNotNull(
+      this._serverAddOn,
+      'StateAddOnManager.addOwner -> _serverAddOn is undefined',
+    );
+
+    const stopping = this._serverAddOn.removeOwner(owner);
+
+    if (stopping) {
+      this.state.set('stopping');
+      try {
+        await stopping;
+        this.state.set('inactive');
+      } catch (e) {
+        this.state.set('zombie');
+        console.error(
+          'ServerAddOnManager.removeOwner -> server add-on failed to clean up',
+          this.pluginName,
+          e,
+        );
+        throw e;
+      }
+    }
+  }
+
+  private async startServerAddOn(
+    details: ServerAddOnStartDetails,
+    initialOwner: string,
+    flipperServer: FlipperServerForServerAddOn,
+  ) {
+    try {
+      this.state.set('starting');
+
+      this._serverAddOn = await ServerAddOn.start(
+        this.pluginName,
+        details,
+        initialOwner,
+        flipperServer,
+      );
+
+      this.state.set('active');
+    } catch (e) {
+      this.state.set('fatal', e);
+      console.error(
+        'StateAddOnManager.startServerAddOn -> error',
+        this.pluginName,
+        details,
+        initialOwner,
+        e,
+      );
+    }
+  }
+}