| // Copyright (C) 2018 The Android Open Source Project |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| import {applyPatches, Patch} from 'immer'; |
| |
| import {assertExists} from '../base/logging'; |
| import {DeferredAction} from '../common/actions'; |
| import {createEmptyState} from '../common/empty_state'; |
| import {State} from '../common/state'; |
| import {globals as frontendGlobals} from '../frontend/globals'; |
| |
| import {ControllerAny} from './controller'; |
| |
| export interface App { |
| state: State; |
| dispatch(action: DeferredAction): void; |
| } |
| |
| /** |
| * Global accessors for state/dispatch in the controller. |
| */ |
| class Globals implements App { |
| private _state?: State; |
| private _rootController?: ControllerAny; |
| private _runningControllers = false; |
| |
| initialize(rootController: ControllerAny) { |
| this._rootController = rootController; |
| this._state = createEmptyState(); |
| } |
| |
| dispatch(action: DeferredAction): void { |
| frontendGlobals.dispatch(action); |
| } |
| |
| // Send the passed dispatch actions to the frontend. The frontend logic |
| // will run the actions, compute the new state and invoke patchState() so |
| // our copy is updated. |
| dispatchMultiple(actions: DeferredAction[]): void { |
| for (const action of actions) { |
| this.dispatch(action); |
| } |
| } |
| |
| // This is called by the frontend logic which now owns and handle the |
| // source-of-truth state, to give us an update on the newer state updates. |
| patchState(patches: Patch[]): void { |
| this._state = applyPatches(assertExists(this._state), patches); |
| this.runControllers(); |
| } |
| |
| private runControllers() { |
| if (this._runningControllers) throw new Error('Re-entrant call detected'); |
| |
| // Run controllers locally until all state machines reach quiescence. |
| let runAgain = true; |
| for (let iter = 0; runAgain; iter++) { |
| if (iter > 100) throw new Error('Controllers are stuck in a livelock'); |
| this._runningControllers = true; |
| try { |
| runAgain = assertExists(this._rootController).invoke(); |
| } finally { |
| this._runningControllers = false; |
| } |
| } |
| } |
| |
| get state(): State { |
| return assertExists(this._state); |
| } |
| |
| resetForTesting() { |
| this._state = undefined; |
| this._rootController = undefined; |
| } |
| } |
| |
| export const globals = new Globals(); |