feat: Code block recording

README.md

@@ -13,6 +13,24 @@ to your tool invocation:
     $ npx appmap-node yarn jest
     $ npx appmap-node npx ts-node foo.ts
 
+## Code Block Recording
+
+You can run appmap-node and use the exposed API to record snippets
+of interest.
+
+    $ npx appmap-node foo.js
+
+foo.js
+```JavaScript
+const { record } = require("appmap-node");
+
+const appmap = record(() => {
+  hello("world");
+});
+// You can consume the details of the appmap object
+console.log("# of events: ", appmap?.events.length);
+```
+
 ## Configuration
 
 You can create `appmap.yml` config file; if not found, a default one will be created:

src/Recording.ts

@@ -1,5 +1,5 @@
 import assert from "node:assert";
-import { renameSync, rmSync } from "node:fs";
+import { readFileSync, renameSync, rmSync } from "node:fs";
 import { join } from "node:path";
 import { inspect } from "node:util";
 
@@ -11,6 +11,7 @@ import { makeCallEvent, makeExceptionEvent, makeReturnEvent } from "./event";
 import { defaultMetadata } from "./metadata";
 import type { FunctionInfo } from "./registry";
 import compactObject from "./util/compactObject";
+import { shouldRecord } from "./recorderControl";
 
 export default class Recording {
   constructor(type: AppMap.RecorderType, recorder: string, ...names: string[]) {
@@ -172,6 +173,11 @@ export default class Recording {
   }
 
   private emit(event: unknown) {
+    // Check here if we should record instead of requiring each
+    // possible hook to check it.
+    // Checking this inside hooks too, will save CPU cycles only
+    // by preventing unnecessary event creation.
+    if (!shouldRecord()) return;
     assert(this.stream);
     this.stream.emit(event);
   }
@@ -206,6 +212,10 @@ export default class Recording {
   get running(): boolean {
     return !!this.stream;
   }
+
+  readAppMap(): AppMap.AppMap {
+    return JSON.parse(readFileSync(this.path, "utf8")) as AppMap.AppMap;
+  }
 }
 
 export const writtenAppMaps: string[] = [];

src/__tests__/recorder.test.ts

@@ -3,7 +3,7 @@ import type * as AppMap from "../AppMap";
 import Recording from "../Recording";
 import { resetObjectIds } from "../parameter";
 import * as recorder from "../recorder";
-import { pauseRecorder, resumeRecorder } from "../recorderPause";
+import { pauseRecorder, resumeRecorder } from "../recorderControl";
 import { getTime } from "../util/getTime";
 import { createTestFn } from "./helpers";
 

src/facade.ts

@@ -1 +1,51 @@
+import type * as AppMap from "./AppMap";
+import { exceptionMetadata } from "./metadata";
+
+import { recording, start } from "./recorder";
+import {
+  disableGlobalRecording,
+  startCodeBlockRecording,
+  stopCodeBlockRecording,
+} from "./recorderControl";
+import Recording from "./Recording";
+
+// Since _this_ module is loaded, we'll do code block recording only.
+recording.abandon();
+disableGlobalRecording();
+
+function isInstrumented() {
+  return "AppMapRecordHook" in global;
+}
+
+type NotPromise<T> = T extends Promise<unknown> ? never : T;
+
+export function record<T>(block: () => NotPromise<T>): AppMap.AppMap | undefined;
+export function record<T>(block: () => Promise<T>): Promise<AppMap.AppMap | undefined>;
+
+export function record(
+  block: () => unknown,
+): AppMap.AppMap | Promise<AppMap.AppMap | undefined> | undefined {
+  if (!isInstrumented())
+    throw Error("Code is not instrumented. Please run the project with appmap-node.");
+
+  start(new Recording("block", "block", new Date().toISOString()));
+  startCodeBlockRecording();
+  try {
+    const result = block();
+    if (result instanceof Promise) return result.then(() => finishRecording(), finishRecording);
+  } catch (exn) {
+    return finishRecording(exn);
+  }
+  return finishRecording();
+}
+
+function finishRecording(exn?: unknown): AppMap.AppMap | undefined {
+  stopCodeBlockRecording();
+  if (!recording.finish()) return;
+
+  const appmap = recording.readAppMap();
+  if (exn && appmap.metadata) appmap.metadata.exception = exceptionMetadata(exn);
+  return appmap;
+}
+
 export * as AppMap from "./AppMap";

src/parameter.ts

@@ -2,7 +2,7 @@ import { IncomingMessage, ServerResponse } from "node:http";
 import { format, inspect, isDeepStrictEqual } from "node:util";
 
 import type * as AppMap from "./AppMap";
-import { pauseRecorder, resumeRecorder } from "./recorderPause";
+import { pauseRecorder, resumeRecorder } from "./recorderControl";
 import compactObject from "./util/compactObject";
 
 export function parameter(value: unknown): AppMap.Parameter {

src/recorder.ts

@@ -6,7 +6,7 @@ import Recording, { writtenAppMaps } from "./Recording";
 import { makeExceptionEvent, makeReturnEvent } from "./event";
 import { info } from "./message";
 import { getClass, objectId } from "./parameter";
-import { recorderPaused } from "./recorderPause";
+import { shouldRecord } from "./recorderControl";
 import { FunctionInfo } from "./registry";
 import commonPathPrefix from "./util/commonPathPrefix";
 import { getTime } from "./util/getTime";
@@ -19,7 +19,7 @@ export function record<This, Return>(
   args: unknown[],
   funInfo: FunctionInfo,
 ): Return {
-  if (!recording.running || recorderPaused()) return fun.apply(this, args);
+  if (!recording.running || !shouldRecord()) return fun.apply(this, args);
 
   const call = recording.functionCall(
     funInfo,

src/recorderControl.ts

@@ -0,0 +1,18 @@
+// Not put into recorder.ts to prevent circular dependency
+let _recorderPaused = false;
+export const pauseRecorder = () => (_recorderPaused = true);
+export const resumeRecorder = () => (_recorderPaused = false);
+export const recorderPaused = () => _recorderPaused;
+
+let _globalRecordingDisabled = false;
+export const disableGlobalRecording = () => (_globalRecordingDisabled = true);
+export const enableGlobalRecording = () => (_globalRecordingDisabled = false);
+export const globalRecordingDisabled = () => _globalRecordingDisabled;
+
+let _codeBlockRecordingActive = false;
+export const startCodeBlockRecording = () => (_codeBlockRecordingActive = true);
+export const stopCodeBlockRecording = () => (_codeBlockRecordingActive = false);
+export const codeBlockRecordingActive = () => _codeBlockRecordingActive;
+
+export const shouldRecord = () =>
+  !recorderPaused() && (!globalRecordingDisabled() || codeBlockRecordingActive());

test/__snapshots__/codeBlock.test.ts.snap

@@ -0,0 +1,140 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`mapping code block recording 1`] = `
+{
+  "./tmp/appmap/block/<timestamp 0>.appmap.json": {
+    "classMap": [
+      {
+        "children": [
+          {
+            "children": [
+              {
+                "location": "index.js:5",
+                "name": "hello",
+                "static": true,
+                "type": "function",
+              },
+            ],
+            "name": "index",
+            "type": "class",
+          },
+        ],
+        "name": "codeBlock",
+        "type": "package",
+      },
+    ],
+    "events": [
+      {
+        "defined_class": "index",
+        "event": "call",
+        "id": 1,
+        "lineno": 5,
+        "method_id": "hello",
+        "parameters": [
+          {
+            "class": "String",
+            "name": "message",
+            "value": "'world'",
+          },
+        ],
+        "path": "index.js",
+        "static": true,
+        "thread_id": 0,
+      },
+      {
+        "elapsed": 31.337,
+        "event": "return",
+        "id": 2,
+        "parent_id": 1,
+        "thread_id": 0,
+      },
+    ],
+    "metadata": {
+      "app": "codeBlock",
+      "client": {
+        "name": "appmap-node",
+        "url": "https://github.com/getappmap/appmap-node",
+        "version": "test node-appmap version",
+      },
+      "language": {
+        "engine": "Node.js",
+        "name": "javascript",
+        "version": "test node version",
+      },
+      "name": "<timestamp 0>",
+      "recorder": {
+        "name": "block",
+        "type": "block",
+      },
+    },
+    "version": "1.12",
+  },
+  "./tmp/appmap/block/<timestamp 1>.appmap.json": {
+    "classMap": [
+      {
+        "children": [
+          {
+            "children": [
+              {
+                "location": "index.js:5",
+                "name": "hello",
+                "static": true,
+                "type": "function",
+              },
+            ],
+            "name": "index",
+            "type": "class",
+          },
+        ],
+        "name": "codeBlock",
+        "type": "package",
+      },
+    ],
+    "events": [
+      {
+        "defined_class": "index",
+        "event": "call",
+        "id": 1,
+        "lineno": 5,
+        "method_id": "hello",
+        "parameters": [
+          {
+            "class": "String",
+            "name": "message",
+            "value": "'world async'",
+          },
+        ],
+        "path": "index.js",
+        "static": true,
+        "thread_id": 0,
+      },
+      {
+        "elapsed": 31.337,
+        "event": "return",
+        "id": 2,
+        "parent_id": 1,
+        "thread_id": 0,
+      },
+    ],
+    "metadata": {
+      "app": "codeBlock",
+      "client": {
+        "name": "appmap-node",
+        "url": "https://github.com/getappmap/appmap-node",
+        "version": "test node-appmap version",
+      },
+      "language": {
+        "engine": "Node.js",
+        "name": "javascript",
+        "version": "test node version",
+      },
+      "name": "<timestamp 1>",
+      "recorder": {
+        "name": "block",
+        "type": "block",
+      },
+    },
+    "version": "1.12",
+  },
+}
+`;

test/codeBlock.test.ts

@@ -0,0 +1,16 @@
+import { spawnSync } from "node:child_process";
+
+import { integrationTest, readAppmaps, resolveTarget, runAppmapNode } from "./helpers";
+
+integrationTest("mapping code block recording", () => {
+  expect(runAppmapNode("index.js").status).toBe(0);
+  expect(readAppmaps()).toMatchSnapshot();
+});
+
+integrationTest("throws when not run with appmap-node", () => {
+  const testDir = resolveTarget();
+  const result = spawnSync(process.argv[0], ["index.js"], { cwd: testDir });
+  expect(result.stderr?.toString()).toContain(
+    "Code is not instrumented. Please run the project with appmap-node.",
+  );
+});

test/codeBlock/appmap.yml

@@ -0,0 +1,2 @@
+name: codeBlock
+appmap_dir: tmp/appmap

test/codeBlock/index.js

@@ -0,0 +1,31 @@
+/* eslint-disable @typescript-eslint/no-var-requires */
+const assert = require("node:assert");
+const { record } = require("../../dist/facade");
+
+function hello(message) {
+  console.log("hello", message);
+}
+
+async function main() {
+  hello("darkness my old friend");
+
+  const appmap1 = record(() => {
+    hello("world");
+  });
+
+  hello("123");
+
+  assert(appmap1.events.filter((e) => e.event == "call").length == 1);
+
+  const appmap2 = await record(async () => {
+    hello("world async");
+  });
+
+  hello("x");
+  hello("y");
+  hello("z");
+
+  assert(appmap2.events.filter((e) => e.event == "call").length == 1);
+}
+
+main();