Merge pull request #631 from zeromq/gc-fixes

Author: aminya

.vscode/extensions.json

@@ -5,6 +5,7 @@
     "llvm-vs-code-extensions.vscode-clangd",
     "xadillax.gyp",
     "dbaeumer.vscode-eslint",
-    "esbenp.prettier-vscode"
+    "esbenp.prettier-vscode",
+    "vadimcn.vscode-lldb"
   ]
 }

.vscode/launch.json

@@ -0,0 +1,46 @@
+{
+    "configurations": [
+        {
+            "name": "JS-Attach",
+            "type": "node",
+            "request": "attach",
+            "port": 9229,
+            "continueOnAttach": true,
+            "autoAttachChildProcesses": true,
+            "resolveSourceMapLocations": [
+                "!**/node_modules/**",
+                "!**/.vscode/extensions/hbenl.vscode-mocha-test-adapter-*/**"
+            ],
+            "skipFiles": [
+                "<node_internals>/**"
+            ],
+        },
+        {
+            "type": "lldb",
+            "request": "launch",
+            "name": "Native-Launch",
+            "preLaunchTask": "clean_build_debug",
+            "program": "node",
+            "suppressMultipleSessionWarning": true,
+            "sourceLanguages": [
+                "cpp"
+            ],
+            "args": [
+                "--inspect-brk=9229",
+                "--expose-gc",
+                "-r",
+                "ts-node/register",
+                "${workspaceFolder}/test/debug.ts"
+            ],
+        }
+    ],
+    "compounds": [
+        {
+            "name": "Node-Launch",
+            "configurations": [
+                "Native-Launch",
+                "JS-Attach",
+            ]
+        }
+    ]
+}

.vscode/settings.json

@@ -1,4 +1,8 @@
 {
   "mochaExplorer.parallel": true,
-  "mochaExplorer.globImplementation": "vscode"
+  "mochaExplorer.globImplementation": "vscode",
+  "mochaExplorer.nodeArgv": [
+    "--expose-gc"
+  ],
+  "mochaExplorer.debuggerConfig": "JS-Attach"
 }

.vscode/tasks.json

@@ -0,0 +1,10 @@
+{
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "clean_build_debug",
+            "type": "shell",
+            "command": "pnpm clean.release && pnpm build.debug",
+        }
+    ]
+}

CONTRIBUTING.md

@@ -38,13 +38,3 @@ tool similar to Cmake. GYP was originally created to generate native IDE project
 files (Visual Studio, Xcode) for building Chromium.
 
 The `.gyp` file is structured as a Python dictionary.
-
-## Weak-napi
-
-https://www.npmjs.com/package/weak-napi On certain rarer occasions, you run into
-the need to be notified when a JavaScript object is going to be garbage
-collected. This feature is exposed to V8's C++ API, but not to JavaScript.
-
-That's where weak-napi comes in! This module exports the JS engine's GC tracking
-functionality to JavaScript. This allows you to create weak references, and
-optionally attach a callback function to any arbitrary JS object.

package.json

@@ -84,6 +84,7 @@
   "scripts": {
     "install": "(shx test -f ./script/build.js || run-s build.js) && cross-env npm_config_build_from_source=true aminya-node-gyp-build",
     "clean": "shx rm -rf ./build ./lib/ ./prebuilds ./script/*.js ./script/*.js.map ./script/*.d.ts ./script/*.tsbuildinfo",
+    "clean.release": "shx rm -rf ./build/Release",
     "clean.temp": "shx rm -rf ./tmp && shx mkdir -p ./tmp",
     "build.library": "tsc -p ./src/tsconfig.json",
     "build.script": "tsc -p ./script/tsconfig.json && tsc -p ./script/tsconfig.esm.json",
@@ -95,10 +96,9 @@
     "build.native.debug": "node-gyp configure --debug && node-gyp configure --debug -- -f compile_commands_json && cross-env CMAKE_BUILD_TYPE=Debug node-gyp build --debug",
     "build": "run-s build.js build.native",
     "build.debug": "run-s build.js build.native.debug",
-    "test.deps": "cd test && pnpm install && cd ..",
-    "test": "run-s clean.temp test.deps build && mocha",
-    "test.skip_gc_tests": "run-s clean.temp test.deps build.debug && cross-env SKIP_GC_TESTS=true mocha",
-    "test.electron.main": "run-s clean.temp test.deps build && electron-mocha",
+    "test": "run-s clean.temp build && mocha",
+    "test.skip_gc_tests": "run-s clean.temp build.debug && cross-env SKIP_GC_TESTS=true mocha",
+    "test.electron.main": "run-s clean.temp build && electron-mocha",
     "format": "prettier --write .",
     "test.electron.renderer": "run-s build && electron-mocha --renderer",
     "lint.clang-format": "clang-format -i -style=file ./src/*.cc ./src/*.h ./src/util/*.h",

test/debug.ts

@@ -0,0 +1,26 @@
+import * as zmq from "../src"
+
+import {getGcOrSkipTest} from "./unit/helpers"
+
+async function main() {
+  const gc = getGcOrSkipTest()
+
+  let weakRef: undefined | WeakRef<zmq.Context>
+  const task = async () => {
+    const context: zmq.Context | undefined = new zmq.Context()
+    const dealer = new zmq.Dealer({context, linger: 0})
+    weakRef = new WeakRef(context)
+
+    // dealer.close()
+  }
+
+  await task()
+  await gc()
+
+  console.log(weakRef?.deref())
+}
+
+main().catch(err => {
+  console.error(err)
+  process.exit(1)
+})

test/package.json

@@ -1,4 +1,6 @@
 {
   "extends": "../tsconfig.json",
-  "include": ["**/*.ts"]
+  "include": [
+    "**/*.ts"
+  ]
 }

test/pnpm-lock.yaml

@@ -235,3 +235,43 @@ export async function captureEventsUntil(
 
   return events
 }
+
+// REAL typings for global.gc per
+// https://github.com/nodejs/node/blob/v20.0.0/deps/v8/src/extensions/gc-extension.cc
+interface GCFunction {
+  (options: {
+    execution?: "sync"
+    flavor?: "regular" | "last-resort"
+    type?: "major-snapshot" | "major" | "minor"
+    filename?: string
+  }): void
+  (options: {
+    execution?: "async"
+    flavor?: "regular" | "last-resort"
+    type?: "major-snapshot" | "major" | "minor"
+    filename?: string
+  }): Promise<void>
+  (options: {
+    execution?: "async" | "sync"
+    flavor?: "regular" | "last-resort"
+    type?: "major-snapshot" | "major" | "minor"
+    filename?: string
+  }): void | Promise<void>
+}
+
+export function getGcOrSkipTest(test?: Mocha.Context) {
+  if (process.env.SKIP_GC_TESTS === "true") {
+    test?.skip()
+  }
+
+  const gc = global.gc as undefined | GCFunction
+  if (typeof gc !== "function") {
+    throw new Error(
+      "Garbage collection is not exposed. It may be enabled by the node --expose-gc flag or v8-expose-gc flag in Mocha. To skip GC tests, set the environment variable `SKIP_GC_TESTS`",
+    )
+  }
+  // https://github.com/nodejs/node/blob/v20.0.0/deps/v8/src/extensions/gc-extension.h
+  // per docs, we we're using use case 2 (Test that certain objects indeed are reclaimed)
+  const asyncMajorGc = () => gc({type: "major", execution: "async"})
+  return asyncMajorGc
+}