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code-server/src/node/wrapper.ts
2021-09-30 19:14:17 -04:00

371 lines
10 KiB
TypeScript

import { field, Logger, logger } from "@coder/logger"
import * as cp from "child_process"
import * as path from "path"
import * as rfs from "rotating-file-stream"
import { Emitter } from "../common/emitter"
import { DefaultedArgs } from "./cli"
import { paths } from "./util"
const timeoutInterval = 10000 // 10s, matches VS Code's timeouts.
/**
* Listen to a single message from a process. Reject if the process errors,
* exits, or times out.
*
* `fn` is a function that determines whether the message is the one we're
* waiting for.
*/
export function onMessage<M, T extends M>(
proc: cp.ChildProcess | NodeJS.Process,
fn: (message: M) => message is T,
customLogger?: Logger,
): Promise<T> {
return new Promise((resolve, reject) => {
const cleanup = () => {
proc.off("error", onError)
proc.off("exit", onExit)
proc.off("message", onMessage)
clearTimeout(timeout)
}
const timeout = setTimeout(() => {
cleanup()
reject(new Error("timed out"))
}, timeoutInterval)
const onError = (error: Error) => {
cleanup()
reject(error)
}
const onExit = (code: number) => {
cleanup()
reject(new Error(`exited unexpectedly with code ${code}`))
}
const onMessage = (message: M) => {
;(customLogger || logger).trace("got message", field("message", message))
if (fn(message)) {
cleanup()
resolve(message)
}
}
proc.on("message", onMessage)
// NodeJS.Process doesn't have `error` but binding anyway shouldn't break
// anything. It does have `exit` but the types aren't working.
;(proc as cp.ChildProcess).on("error", onError)
;(proc as cp.ChildProcess).on("exit", onExit)
})
}
interface ParentHandshakeMessage {
type: "handshake"
args: DefaultedArgs
}
interface ChildHandshakeMessage {
type: "handshake"
}
interface RelaunchMessage {
type: "relaunch"
version: string
}
type ChildMessage = RelaunchMessage | ChildHandshakeMessage
type ParentMessage = ParentHandshakeMessage
class ProcessError extends Error {
public constructor(message: string, public readonly code: number | undefined) {
super(message)
this.name = this.constructor.name
Error.captureStackTrace(this, this.constructor)
}
}
/**
* Wrapper around a process that tries to gracefully exit when a process exits
* and provides a way to prevent `process.exit`.
*/
abstract class Process {
/**
* Emit this to trigger a graceful exit.
*/
protected readonly _onDispose = new Emitter<NodeJS.Signals | undefined>()
/**
* Emitted when the process is about to be disposed.
*/
public readonly onDispose = this._onDispose.event
/**
* Uniquely named logger for the process.
*/
public abstract logger: Logger
public constructor() {
process.on("SIGINT", () => this._onDispose.emit("SIGINT"))
process.on("SIGTERM", () => this._onDispose.emit("SIGTERM"))
process.on("exit", () => this._onDispose.emit(undefined))
this.onDispose((signal, wait) => {
// Remove listeners to avoid possibly triggering disposal again.
process.removeAllListeners()
// Try waiting for other handlers to run first then exit.
this.logger.debug("disposing", field("code", signal))
wait.then(() => this.exit(0))
setTimeout(() => this.exit(0), 5000)
})
}
/**
* Ensure control over when the process exits.
*/
public preventExit(): void {
;(process.exit as any) = (code?: number) => {
this.logger.warn(`process.exit() was prevented: ${code || "unknown code"}.`)
}
}
private readonly processExit: (code?: number) => never = process.exit
/**
* Will always exit even if normal exit is being prevented.
*/
public exit(error?: number | ProcessError): never {
if (error && typeof error !== "number") {
this.processExit(typeof error.code === "number" ? error.code : 1)
} else {
this.processExit(error)
}
}
}
/**
* Child process that will clean up after itself if the parent goes away and can
* perform a handshake with the parent and ask it to relaunch.
*/
class ChildProcess extends Process {
public logger = logger.named(`child:${process.pid}`)
public constructor(private readonly parentPid: number) {
super()
// Kill the inner process if the parent dies. This is for the case where the
// parent process is forcefully terminated and cannot clean up.
setInterval(() => {
try {
// process.kill throws an exception if the process doesn't exist.
process.kill(this.parentPid, 0)
} catch (_) {
// Consider this an error since it should have been able to clean up
// the child process unless it was forcefully killed.
this.logger.error(`parent process ${parentPid} died`)
this._onDispose.emit(undefined)
}
}, 5000)
}
/**
* Initiate the handshake and wait for a response from the parent.
*/
public async handshake(): Promise<DefaultedArgs> {
this.send({ type: "handshake" })
const message = await onMessage<ParentMessage, ParentHandshakeMessage>(
process,
(message): message is ParentHandshakeMessage => {
return message.type === "handshake"
},
this.logger,
)
return message.args
}
/**
* Notify the parent process that it should relaunch the child.
*/
public relaunch(version: string): void {
this.send({ type: "relaunch", version })
}
/**
* Send a message to the parent.
*/
private send(message: ChildMessage): void {
if (!process.send) {
throw new Error("not spawned with IPC")
}
process.send(message)
}
}
/**
* Parent process wrapper that spawns the child process and performs a handshake
* with it. Will relaunch the child if it receives a SIGUSR1 or is asked to by
* the child. If the child otherwise exits the parent will also exit.
*/
export class ParentProcess extends Process {
public logger = logger.named(`parent:${process.pid}`)
private child?: cp.ChildProcess
private started?: Promise<void>
private readonly logStdoutStream: rfs.RotatingFileStream
private readonly logStderrStream: rfs.RotatingFileStream
protected readonly _onChildMessage = new Emitter<ChildMessage>()
protected readonly onChildMessage = this._onChildMessage.event
private args?: DefaultedArgs
public constructor(private currentVersion: string) {
super()
process.on("SIGUSR1", async () => {
this.logger.info("Received SIGUSR1; hotswapping")
this.relaunch()
})
const opts = {
size: "10M",
maxFiles: 10,
}
this.logStdoutStream = rfs.createStream(path.join(paths.data, "coder-logs", "code-server-stdout.log"), opts)
this.logStderrStream = rfs.createStream(path.join(paths.data, "coder-logs", "code-server-stderr.log"), opts)
this.onDispose(() => this.disposeChild())
this.onChildMessage((message) => {
switch (message.type) {
case "relaunch":
this.logger.info(`Relaunching: ${this.currentVersion} -> ${message.version}`)
this.currentVersion = message.version
this.relaunch()
break
default:
this.logger.error(`Unrecognized message ${message}`)
break
}
})
}
private async disposeChild(): Promise<void> {
this.started = undefined
if (this.child) {
const child = this.child
child.removeAllListeners()
child.kill()
// Wait for the child to exit otherwise its output will be lost which can
// be especially problematic if you're trying to debug why cleanup failed.
await new Promise((r) => child!.on("exit", r))
}
}
private async relaunch(): Promise<void> {
this.disposeChild()
try {
this.started = this._start()
await this.started
} catch (error: any) {
this.logger.error(error.message)
this.exit(typeof error.code === "number" ? error.code : 1)
}
}
public start(args: DefaultedArgs): Promise<void> {
// Store for relaunches.
this.args = args
if (!this.started) {
this.started = this._start()
}
return this.started
}
private async _start(): Promise<void> {
const child = this.spawn()
this.child = child
// Log both to stdout and to the log directory.
if (child.stdout) {
child.stdout.pipe(this.logStdoutStream)
child.stdout.pipe(process.stdout)
}
if (child.stderr) {
child.stderr.pipe(this.logStderrStream)
child.stderr.pipe(process.stderr)
}
this.logger.debug(`spawned inner process ${child.pid}`)
await this.handshake(child)
child.once("exit", (code) => {
this.logger.debug(`inner process ${child.pid} exited unexpectedly`)
this.exit(code || 0)
})
}
private spawn(): cp.ChildProcess {
// Use spawn (instead of fork) to use the new binary in case it was updated.
return cp.spawn(process.argv[0], process.argv.slice(1), {
env: {
...process.env,
CODE_SERVER_PARENT_PID: process.pid.toString(),
NODE_OPTIONS: `--max-old-space-size=2048 ${process.env.NODE_OPTIONS || ""}`,
},
stdio: ["inherit", "inherit", "inherit", "ipc"],
})
}
/**
* Wait for a handshake from the child then reply.
*/
private async handshake(child: cp.ChildProcess): Promise<void> {
if (!this.args) {
throw new Error("started without args")
}
await onMessage<ChildMessage, ChildHandshakeMessage>(
child,
(message): message is ChildHandshakeMessage => {
return message.type === "handshake"
},
this.logger,
)
this.send(child, { type: "handshake", args: this.args })
}
/**
* Send a message to the child.
*/
private send(child: cp.ChildProcess, message: ParentMessage): void {
child.send(message)
}
}
/**
* Process wrapper.
*/
export const wrapper =
typeof process.env.CODE_SERVER_PARENT_PID !== "undefined"
? new ChildProcess(parseInt(process.env.CODE_SERVER_PARENT_PID))
: new ParentProcess(require("../../package.json").version)
export function isChild(proc: ChildProcess | ParentProcess): proc is ChildProcess {
return proc instanceof ChildProcess
}
// It's possible that the pipe has closed (for example if you run code-server
// --version | head -1). Assume that means we're done.
if (!process.stdout.isTTY) {
process.stdout.on("error", () => wrapper.exit())
}
// Don't let uncaught exceptions crash the process.
process.on("uncaughtException", (error) => {
wrapper.logger.error(`Uncaught exception: ${error.message}`)
if (typeof error.stack !== "undefined") {
wrapper.logger.error(error.stack)
}
})