Watcher infrastructure (#1724)

* wip * Adding chokidar and types * specifiying build tasks * new structure, new types, executor and watchers * Adding log * Fully implemented watchers * adapt vscode launc * Add .babelrc.js to toplevel tsconfig project * Typo * Get schema path from .graphqlconfig * Use watcher binary * Add joi validation to watcher * Remove fb-watchman for now * Use correct ignore path * Fix dist folder * Allow setting watcher * Per default only spawn one process at a time * Support runOnInit * Rename RestartingExecutor to LongRunningExecutor * Use debounce instead of throttle * Remove console log * Debounce command execution * Simplify debounce * Watcher name change * Typos * Rename "watcher" root level config to "backend"
2026-09-12 13:01:11 +08:00 · 2018-07-03 12:21:58 -06:00
parent 9375f3ec23
commit 044e1c2863
16 changed files with 627 additions and 69 deletions
@@ -0,0 +1,88 @@
+import { ChildProcess } from "child_process";
+import spawn from "cross-spawn";
+import { Cancelable, debounce } from "lodash";
+import { Executor } from "./types";
+
+interface LongRunningExecutorOptions {
+  args?: ReadonlyArray<string>;
+
+  // Specify the period in which the process is restarted at max once.
+  debounce?: number;
+}
+
+export default class LongRunningExecutor implements Executor {
+  private cmd: string;
+  private args?: ReadonlyArray<string>;
+  private process: ChildProcess | null = null;
+  private isRunning: boolean = false;
+  private shouldRestart: boolean = false;
+  private restartDebounced: (() => void) & Cancelable;
+
+  constructor(cmd: string, opts: LongRunningExecutorOptions = {}) {
+    this.cmd = cmd;
+    this.args = opts.args;
+    this.restartDebounced = debounce(
+      () => this.restart(),
+      opts.debounce || 500
+    );
+  }
+
+  private spawnProcess() {
+    this.isRunning = true;
+    this.process = spawn(this.cmd, this.args as string[], {
+      stdio: "inherit",
+      // Have all child processes in their own group.
+      // See `process.kill` below.
+      detached: true,
+      shell: !this.args,
+    });
+
+    this.process!.on("exit", (code: number) => {
+      this.isRunning = false;
+
+      if (code !== 0 && code !== null) {
+        // tslint:disable-next-line: no-console
+        console.error(`Exit code returned ${code}`);
+        return;
+      }
+      if (this.shouldRestart) {
+        this.spawnProcess();
+      }
+    });
+  }
+
+  private restart(): void {
+    this.shouldRestart = true;
+    // Using the `-` will kill all child procceses in the group.
+    // See: https://azimi.me/2014/12/31/kill-child_process-node-js.html
+    process.kill(-this.process!.pid, "SIGTERM");
+  }
+
+  private kill(): void {
+    this.shouldRestart = false;
+    // Using the `-` will kill all child procceses in the group.
+    // See: https://azimi.me/2014/12/31/kill-child_process-node-js.html
+    process.kill(-this.process!.pid, "SIGTERM");
+  }
+
+  // This is called before watching starts.
+  public onInit(): void {
+    this.spawnProcess();
+  }
+
+  // This is called before exiting.
+  public onCleanup() {
+    this.restartDebounced.cancel();
+    if (this.isRunning) {
+      this.kill();
+    }
+  }
+
+  public execute(filePath: string) {
+    if (this.isRunning) {
+      this.restartDebounced();
+      return;
+    }
+    this.spawnProcess();
+  }
+}