fix: Handle parent Ctrl-C in child process with setInterval

This fixes a bug (#118) which occured when there is a script
with active setInterval call and appmap-node runs this script
indirectly with a node process: npx appmap-node node interval.js.

package.json

@@ -21,13 +21,17 @@
     ".": {
       "require": {
         "default": "./dist/facade.js",
-        "types": ["./dist/facade.d.ts"] 
+        "types": [
+          "./dist/facade.d.ts"
+        ]
       },
       "import": {
         "default": "./dist/facade.js",
-        "types": ["./dist/facade.d.ts"] 
+        "types": [
+          "./dist/facade.d.ts"
+        ]
       }
-    } 
+    }
   },
   "repository": {
     "type": "git",
@@ -58,6 +62,7 @@
     "@types/mysql": "^2.15.24",
     "@types/node": "^20.5.0",
     "@types/pg": "^8.10.9",
+    "@types/ps-tree": "^1.1.6",
     "@types/sqlite3": "^3.1.11",
     "@types/tmp": "^0.2.3",
     "@typescript-eslint/eslint-plugin": "^6.4.0",
@@ -72,6 +77,7 @@
     "mongodb": "^6.3.0",
     "next": "^14.0.4",
     "prettier": "^3.0.2",
+    "ps-tree": "^1.2.0",
     "react": "^18",
     "react-dom": "^18",
     "semantic-release": "^22.0.5",

src/util/forwardSignals.ts

@@ -5,7 +5,12 @@ export default function forwardSignals(
   signals = DEFAULT_FORWARD,
 ) {
   const forward = proc.kill.bind(proc);
-  for (const signal of signals) process.on(signal, forward);
+  // Without setTimeout, child does not handle forwarded SIGINT
+  // caused by the parent receiving a Ctrl-C in certain cases.
+  // See: simple.test.ts "forwards SIGINT (ctrl-c) properly
+  // to the grandchild having active setInterval"
+  for (const signal of signals)
+    process.on(signal, (...args) => setTimeout(() => forward(...args), 100));
 }
 
 const DEFAULT_FORWARD: NodeJS.Signals[] = [

test/__snapshots__/simple.test.ts.snap

@@ -139,6 +139,74 @@ exports[`forwarding signals to the child 1`] = `
 }
 `;
 
+exports[`forwards SIGINT (ctrl-c) properly to the grandchild having active setInterval 1`] = `
+{
+  "classMap": [
+    {
+      "children": [
+        {
+          "children": [
+            {
+              "location": "interval.js:1",
+              "name": "f",
+              "static": true,
+              "type": "function",
+            },
+          ],
+          "name": "interval",
+          "type": "class",
+        },
+      ],
+      "name": "simple",
+      "type": "package",
+    },
+  ],
+  "events": [
+    {
+      "defined_class": "interval",
+      "event": "call",
+      "id": 1,
+      "lineno": 1,
+      "method_id": "f",
+      "parameters": [],
+      "path": "interval.js",
+      "static": true,
+      "thread_id": 0,
+    },
+    {
+      "elapsed": 31.337,
+      "event": "return",
+      "id": 2,
+      "parent_id": 1,
+      "return_value": {
+        "class": "Number",
+        "value": "1",
+      },
+      "thread_id": 0,
+    },
+  ],
+  "metadata": {
+    "app": "simple",
+    "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": "test process recording",
+    "recorder": {
+      "name": "process",
+      "type": "process",
+    },
+  },
+  "version": "1.12",
+}
+`;
+
 exports[`mapping a custom Error class with a message property 1`] = `
 {
   "classMap": [

test/helpers.ts

@@ -12,6 +12,10 @@ import fwdSlashPath from "../src/util/fwdSlashPath";
 
 const binPath = resolve(__dirname, "../bin/appmap-node.js");
 
+export function getAppMapBinPath() {
+  return binPath;
+}
+
 export function runAppmapNode(...args: string[]) {
   console.debug("Running %s %s", binPath, args.join(" "));
   const result = spawnSync(process.argv[0], [binPath, ...args], { cwd: target });

test/simple.test.ts

@@ -1,9 +1,12 @@
+import { spawn } from "node:child_process";
 import { cpSync, mkdirSync, readFileSync } from "node:fs";
 import { join } from "node:path";
 
 import tmp from "tmp";
+import psTree from "ps-tree";
 
 import {
+  getAppMapBinPath,
   integrationTest,
   readAppmap,
   readAppmaps,
@@ -43,6 +46,47 @@ integrationTestSkipOnWindows("forwarding signals to the child", async () => {
   expect(readAppmap()).toMatchSnapshot();
 });
 
+integrationTestSkipOnWindows(
+  "forwards SIGINT (ctrl-c) properly to the grandchild having active setInterval",
+  async () => {
+    // This test tests a fix (see: forwardSignals.ts) for a bug which occured
+    // when there is a script with active setInterval call and appmap-node
+    // runs this script indirectly with a node process: appmap-node node interval.js.
+    // We run the commands similarly as reported in:
+    // https://github.com/getappmap/appmap-node/issues/118
+    const child = spawn("npx", [getAppMapBinPath(), "node", "interval.js"], {
+      cwd: resolveTarget(),
+      shell: true,
+    });
+
+    await new Promise<void>(
+      (r) =>
+        child.stdout?.on("data", (chunk: Buffer) => chunk.toString().includes("heartbeat") && r()),
+    );
+
+    child.kill("SIGINT");
+
+    // child.kill does not kill all grandchildren, we have to
+    // send the kill signal to all of them. Otherwise Jest will
+    // not finish and we are not able to get the SIGINT in
+    // appmap-node process.
+    // https://krasimirtsonev.com/blog/article/Nodejs-managing-child-processes-starting-stopping-exec-spawn#killing-stopping-the-command
+    psTree(child.pid!, function (err, children) {
+      children.forEach((child) => process.kill(parseInt(child.PID), "SIGINT"));
+    });
+
+    await new Promise<void>((r) => {
+      const handler = (): void => {
+        child.removeListener("exit", handler);
+        r();
+      };
+      child.once("exit", handler);
+    });
+
+    expect(readAppmap()).toMatchSnapshot();
+  },
+);
+
 integrationTest("mapping generator functions", () => {
   expect(runAppmapNode("generator.js").status).toBe(0);
   expect(readAppmap()).toMatchSnapshot();

test/simple/interval.js

@@ -0,0 +1,9 @@
+function f() {
+  return 1;
+}
+
+f();
+
+setInterval(() => {
+  console.log("heartbeat");
+}, 1000);

yarn.lock

@@ -2226,6 +2226,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@types/ps-tree@npm:^1.1.6":
+  version: 1.1.6
+  resolution: "@types/ps-tree@npm:1.1.6"
+  checksum: bf5b7bb9bd11b8762a8302b93c335728ecb19c85a74c640a3888d476368a03733f11612b9a87b1ad9ea56f95720db23a824c78113b16024dc59264b7f9008df5
+  languageName: node
+  linkType: hard
+
 "@types/react@npm:^18":
   version: 18.2.45
   resolution: "@types/react@npm:18.2.45"
@@ -2744,6 +2751,7 @@ __metadata:
     "@types/mysql": ^2.15.24
     "@types/node": ^20.5.0
     "@types/pg": ^8.10.9
+    "@types/ps-tree": ^1.1.6
     "@types/sqlite3": ^3.1.11
     "@types/tmp": ^0.2.3
     "@typescript-eslint/eslint-plugin": ^6.4.0
@@ -2763,6 +2771,7 @@ __metadata:
     mongodb: ^6.3.0
     next: ^14.0.4
     prettier: ^3.0.2
+    ps-tree: ^1.2.0
     react: ^18
     react-dom: ^18
     semantic-release: ^22.0.5
@@ -3990,6 +3999,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"duplexer@npm:~0.1.1":
+  version: 0.1.2
+  resolution: "duplexer@npm:0.1.2"
+  checksum: 62ba61a830c56801db28ff6305c7d289b6dc9f859054e8c982abd8ee0b0a14d2e9a8e7d086ffee12e868d43e2bbe8a964be55ddbd8c8957714c87373c7a4f9b0
+  languageName: node
+  linkType: hard
+
 "eastasianwidth@npm:^0.2.0":
   version: 0.2.0
   resolution: "eastasianwidth@npm:0.2.0"
@@ -4361,6 +4377,21 @@ __metadata:
   languageName: node
   linkType: hard
 
+"event-stream@npm:=3.3.4":
+  version: 3.3.4
+  resolution: "event-stream@npm:3.3.4"
+  dependencies:
+    duplexer: ~0.1.1
+    from: ~0
+    map-stream: ~0.1.0
+    pause-stream: 0.0.11
+    split: 0.3
+    stream-combiner: ~0.0.4
+    through: ~2.3.1
+  checksum: 80b467820b6daf824d9fb4345d2daf115a056e5c104463f2e98534e92d196a27f2df5ea2aa085624db26f4c45698905499e881d13bc7c01f7a13eac85be72a22
+  languageName: node
+  linkType: hard
+
 "event-target-shim@npm:^5.0.0":
   version: 5.0.1
   resolution: "event-target-shim@npm:5.0.1"
@@ -4718,6 +4749,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"from@npm:~0":
+  version: 0.1.7
+  resolution: "from@npm:0.1.7"
+  checksum: b85125b7890489656eb2e4f208f7654a93ec26e3aefaf3bbbcc0d496fc1941e4405834fcc9fe7333192aa2187905510ace70417bbf9ac6f6f4784a731d986939
+  languageName: node
+  linkType: hard
+
 "fs-extra@npm:^11.0.0":
   version: 11.1.1
   resolution: "fs-extra@npm:11.1.1"
@@ -6763,6 +6801,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"map-stream@npm:~0.1.0":
+  version: 0.1.0
+  resolution: "map-stream@npm:0.1.0"
+  checksum: 38abbe4eb883888031e6b2fc0630bc583c99396be16b8ace5794b937b682a8a081f03e8b15bfd4914d1bc88318f0e9ac73ba3512ae65955cd449f63256ddb31d
+  languageName: node
+  linkType: hard
+
 "marked-terminal@npm:^6.0.0":
   version: 6.0.0
   resolution: "marked-terminal@npm:6.0.0"
@@ -8112,6 +8157,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"pause-stream@npm:0.0.11":
+  version: 0.0.11
+  resolution: "pause-stream@npm:0.0.11"
+  dependencies:
+    through: ~2.3
+  checksum: 3c4a14052a638b92e0c96eb00c0d7977df7f79ea28395250c525d197f1fc02d34ce1165d5362e2e6ebbb251524b94a76f3f0d4abc39ab8b016d97449fe15583c
+  languageName: node
+  linkType: hard
+
 "pg-cloudflare@npm:^1.1.1":
   version: 1.1.1
   resolution: "pg-cloudflare@npm:1.1.1"
@@ -8522,6 +8576,17 @@ __metadata:
   languageName: node
   linkType: hard
 
+"ps-tree@npm:^1.2.0":
+  version: 1.2.0
+  resolution: "ps-tree@npm:1.2.0"
+  dependencies:
+    event-stream: =3.3.4
+  bin:
+    ps-tree: ./bin/ps-tree.js
+  checksum: e635dd00f53d30d31696cf5f95b3a8dbdf9b1aeb36d4391578ce8e8cd22949b7c5536c73b0dc18c78615ea3ddd4be96101166be59ca2e3e3cb1e2f79ba3c7f98
+  languageName: node
+  linkType: hard
+
 "punycode@npm:^2.1.0":
   version: 2.3.0
   resolution: "punycode@npm:2.3.0"
@@ -9337,6 +9402,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"split@npm:0.3":
+  version: 0.3.3
+  resolution: "split@npm:0.3.3"
+  dependencies:
+    through: 2
+  checksum: 2e076634c9637cfdc54ab4387b6a243b8c33b360874a25adf6f327a5647f07cb3bf1c755d515248eb3afee4e382278d01f62c62d87263c118f28065b86f74f02
+  languageName: node
+  linkType: hard
+
 "sprintf-js@npm:^1.1.3":
   version: 1.1.3
   resolution: "sprintf-js@npm:1.1.3"
@@ -9444,6 +9518,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"stream-combiner@npm:~0.0.4":
+  version: 0.0.4
+  resolution: "stream-combiner@npm:0.0.4"
+  dependencies:
+    duplexer: ~0.1.1
+  checksum: 844b622cfe8b9de45a6007404f613b60aaf85200ab9862299066204242f89a7c8033b1c356c998aa6cfc630f6cd9eba119ec1c6dc1f93e245982be4a847aee7d
+  languageName: node
+  linkType: hard
+
 "streamsearch@npm:^1.1.0":
   version: 1.1.0
   resolution: "streamsearch@npm:1.1.0"
@@ -9715,7 +9798,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"through@npm:>=2.2.7 <3":
+"through@npm:2, through@npm:>=2.2.7 <3, through@npm:~2.3, through@npm:~2.3.1":
   version: 2.3.8
   resolution: "through@npm:2.3.8"
   checksum: a38c3e059853c494af95d50c072b83f8b676a9ba2818dcc5b108ef252230735c54e0185437618596c790bbba8fcdaef5b290405981ffa09dce67b1f1bf190cbd