start-os/sdk/package/lib/mainFn/Daemon.ts

import * as T from "../../../base/lib/types"
import { asError } from "../../../base/lib/util/asError"
import { Drop } from "../util"
import { ExecSpawnable, SubContainer } from "../util/SubContainer"
import { CommandController } from "./CommandController"

const TIMEOUT_INCREMENT_MS = 1000
const MAX_TIMEOUT_MS = 30000
/**
 * This is a wrapper around CommandController that has a state of off, where the command shouldn't be running
 * and the others state of running, where it will keep a living running command
 */

export class Daemon<Manifest extends T.SDKManifest> extends Drop {
  private commandController: CommandController<Manifest> | null = null
  private shouldBeRunning = false
  protected exitedSuccess = false
  protected constructor(
    private startCommand: () => Promise<CommandController<Manifest>>,
    readonly oneshot: boolean = false,
    protected onExitSuccessFns: (() => void)[] = [],
  ) {
    super()
  }
  get subContainerHandle(): undefined | ExecSpawnable {
    return this.commandController?.subContainerHandle
  }
  static of<Manifest extends T.SDKManifest>() {
    return async (
      effects: T.Effects,
      subcontainer: SubContainer<Manifest>,
      command: T.CommandType,
      options: {
        runAsInit?: boolean
        env?:
          | {
              [variable: string]: string
            }
          | undefined
        cwd?: string | undefined
        user?: string | undefined
        onStdout?: (chunk: Buffer | string | any) => void
        onStderr?: (chunk: Buffer | string | any) => void
        sigtermTimeout?: number
      },
    ) => {
      const startCommand = () =>
        CommandController.of<Manifest>()(
          effects,
          subcontainer,
          command,
          options,
        )
      return new Daemon(startCommand)
    }
  }
  async start() {
    if (this.commandController) {
      return
    }
    this.shouldBeRunning = true
    this.exitedSuccess = false
    let timeoutCounter = 0
    ;(async () => {
      while (this.shouldBeRunning) {
        if (this.commandController)
          await this.commandController
            .term({ keepSubcontainer: true })
            .catch((err) => console.error(err))
        this.commandController = await this.startCommand()
        if (
          this.oneshot &&
          (await this.commandController.wait({ keepSubcontainer: true }).then(
            (_) => true,
            (err) => {
              console.error(err)
              return false
            },
          ))
        ) {
          for (const fn of this.onExitSuccessFns) {
            try {
              fn()
            } catch (e) {
              console.error("EXIT_SUCCESS handler", e)
            }
          }
          this.onExitSuccessFns = []
          this.exitedSuccess = true
          break
        }
        await new Promise((resolve) => setTimeout(resolve, timeoutCounter))
        timeoutCounter += TIMEOUT_INCREMENT_MS
        timeoutCounter = Math.min(MAX_TIMEOUT_MS, timeoutCounter)
      }
    })().catch((err) => {
      console.error(asError(err))
    })
  }
  async term(termOptions?: {
    signal?: NodeJS.Signals | undefined
    timeout?: number | undefined
  }) {
    return this.stop(termOptions)
  }
  async stop(termOptions?: {
    signal?: NodeJS.Signals | undefined
    timeout?: number | undefined
  }) {
    this.shouldBeRunning = false
    await this.commandController
      ?.term({ ...termOptions })
      .catch((e) => console.error(asError(e)))
    this.commandController = null
  }
  onDrop(): void {
    this.stop().catch((e) => console.error(asError(e)))
  }
}