refactor: move PerfLogger from core to @docusaurus/logger (#10480)

packages/docusaurus-logger/src/perfLogger.ts

@@ -0,0 +1,96 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+import {AsyncLocalStorage} from 'async_hooks';
+import logger from './logger';
+
+// For now this is a private env variable we use internally
+// But we'll want to expose this feature officially some day
+const PerfDebuggingEnabled: boolean = !!process.env.DOCUSAURUS_PERF_LOGGER;
+
+const Thresholds = {
+  min: 5,
+  yellow: 100,
+  red: 1000,
+};
+
+const PerfPrefix = logger.yellow(`[PERF] `);
+
+// This is what enables to "see the parent stack" for each log
+// Parent1 > Parent2 > Parent3 > child trace
+const ParentPrefix = new AsyncLocalStorage<string>();
+function applyParentPrefix(label: string) {
+  const parentPrefix = ParentPrefix.getStore();
+  return parentPrefix ? `${parentPrefix} > ${label}` : label;
+}
+
+type PerfLoggerAPI = {
+  start: (label: string) => void;
+  end: (label: string) => void;
+  log: (message: string) => void;
+  async: <Result>(
+    label: string,
+    asyncFn: () => Result | Promise<Result>,
+  ) => Promise<Result>;
+};
+
+function createPerfLogger(): PerfLoggerAPI {
+  if (!PerfDebuggingEnabled) {
+    const noop = () => {};
+    return {
+      start: noop,
+      end: noop,
+      log: noop,
+      async: async (_label, asyncFn) => asyncFn(),
+    };
+  }
+
+  const formatDuration = (duration: number): string => {
+    if (duration > Thresholds.red) {
+      return logger.red(`${(duration / 1000).toFixed(2)} seconds!`);
+    } else if (duration > Thresholds.yellow) {
+      return logger.yellow(`${duration.toFixed(2)} ms`);
+    } else {
+      return logger.green(`${duration.toFixed(2)} ms`);
+    }
+  };
+
+  const logDuration = (label: string, duration: number) => {
+    if (duration < Thresholds.min) {
+      return;
+    }
+    console.log(`${PerfPrefix + label} - ${formatDuration(duration)}`);
+  };
+
+  const start: PerfLoggerAPI['start'] = (label) => performance.mark(label);
+
+  const end: PerfLoggerAPI['end'] = (label) => {
+    const {duration} = performance.measure(label);
+    performance.clearMarks(label);
+    logDuration(applyParentPrefix(label), duration);
+  };
+
+  const log: PerfLoggerAPI['log'] = (label: string) =>
+    console.log(PerfPrefix + applyParentPrefix(label));
+
+  const async: PerfLoggerAPI['async'] = async (label, asyncFn) => {
+    const finalLabel = applyParentPrefix(label);
+    const before = performance.now();
+    const result = await ParentPrefix.run(finalLabel, () => asyncFn());
+    const duration = performance.now() - before;
+    logDuration(finalLabel, duration);
+    return result;
+  };
+
+  return {
+    start,
+    end,
+    log,
+    async,
+  };
+}
+
+export const PerfLogger: PerfLoggerAPI = createPerfLogger();