85 lines
3.1 KiB
TypeScript
85 lines
3.1 KiB
TypeScript
/// SPDX-License-Identifier: GPL-3.0-or-later
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/// SPDX-FileCopyrightText: Copyright © 2021-2023 Tony Garnock-Jones <tonyg@leastfixedpoint.com>
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import { State } from '../gen/service';
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import { Actor, AnyValue, LocalAction, Turn } from './actor';
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import { Field } from './dataflow';
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type StateName = State['_variant'];
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export enum SupervisorRestartPolicy {
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ALWAYS,
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ON_ERROR_ONLY,
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}
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export type SupervisorConfiguration = {
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intensity: number,
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period: number, /* seconds */
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pauseTime: number, /* seconds */
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sleepTime: number, /* seconds */
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restartPolicy: SupervisorRestartPolicy,
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};
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export const DEFAULT_CONFIG: SupervisorConfiguration = {
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intensity: 1,
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period: 5,
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pauseTime: 0.2,
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sleepTime: 10,
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restartPolicy: SupervisorRestartPolicy.ON_ERROR_ONLY,
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};
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export class Supervisor {
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readonly config: SupervisorConfiguration;
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readonly nameFunction: () => AnyValue;
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readonly bootFunction: LocalAction;
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readonly restarts: number[] = []; /* timestamps */
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readonly state: Field<StateName> = Turn.active.field('started');
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supervisee: Actor | null = null;
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static always(nameFunction: () => AnyValue, bootFunction: LocalAction): Supervisor {
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return new Supervisor({ restartPolicy: SupervisorRestartPolicy.ALWAYS },
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nameFunction,
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bootFunction);
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}
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constructor(config: Partial<SupervisorConfiguration>,
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nameFunction: () => AnyValue,
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bootFunction: LocalAction)
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{
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this.config = Object.assign({}, DEFAULT_CONFIG, config);
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this.nameFunction = nameFunction;
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this.bootFunction = bootFunction;
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this.startSupervisee();
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}
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startSupervisee() {
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Turn.active.facet(() => {
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this.state.value = 'started';
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this.supervisee = Turn.active.spawnLink(this.bootFunction);
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if (this.supervisee) this.supervisee.name = this.nameFunction();
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Turn.activeFacet.onStop(() => {
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const exitReason = this.supervisee?.exitReason;
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if (!exitReason) {
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// Supervisor shutdown. Supervisee will exit soon.
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return;
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}
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if (exitReason.ok && (this.config.restartPolicy === SupervisorRestartPolicy.ON_ERROR_ONLY)) {
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this.state.value = 'complete';
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} else {
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this.state.value = exitReason.ok ? 'complete' : 'failed';
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const now = +(new Date());
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const oldestToKeep = now - this.config.period * 1000.0;
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this.restarts.push(now);
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while (this.restarts.length && (this.restarts[0] < oldestToKeep)) {
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this.restarts.shift();
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}
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const waitTime = (this.restarts.length > this.config.intensity)
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? this.config.sleepTime
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: this.config.pauseTime;
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Turn.active.after(waitTime * 1000.0, () => this.startSupervisee());
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}
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});
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});
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}
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}
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