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electron: fork backend in node process
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Simplify Electron's src-gen to always spawn the Theia backend in a
Node.js process, and make sure to patch the `process.versions.electron`
variable, for packages to correctly understand their environment
(Electron vs Node).

Patching is done via a THEIA_ELECTRON_VERSION environment variable that
the backend must pick up and apply to `process.versions.electron`.

Add a debug configuration for both electron-main process and backend
process.

Since Electron main process and backend process are now detached, I
added a THEIA_BACKEND_EXEC_ARGV environment variable in which you can
pass options to use when forking the backend. The format is a JSON
stringified array of strings.

Signed-off-by: Paul Maréchal <paul.marechal@ericsson.com>
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paul-marechal committed Mar 20, 2020
1 parent ae5591e commit 2f71ca7
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Showing 4 changed files with 95 additions and 56 deletions.
69 changes: 55 additions & 14 deletions .vscode/launch.json
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Original file line number Diff line number Diff line change
Expand Up @@ -19,30 +19,65 @@
{
"type": "node",
"request": "launch",
"name": "Launch Electron Backend",
"runtimeExecutable": "${workspaceRoot}/node_modules/.bin/electron",
"windows": {
"runtimeExecutable": "${workspaceRoot}/node_modules/.bin/electron.cmd"
},
"name": "Launch Electron Main Process",
"runtimeExecutable": "yarn",
"runtimeArgs": [
"electron",
"--inspect-brk=9228", // This config connects to port 9228.
"--remote-debugging-port=9222", // Allow attaching to browser-windows.
],
"cwd": "${workspaceRoot}/examples/electron",
"protocol": "inspector",
"port": 9228,
"args": [
".",
"--log-level=debug",
"--hostname=localhost",
"--no-cluster",
"--app-project-path=${workspaceRoot}/examples/electron",
"--remote-debugging-port=9222",
"--no-app-auto-install"
],
"env": {
"NODE_ENV": "development",
"THEIA_BACKEND_EXEC_ARGV": "[\"--inspect=9229\"]", // Pass debug flags to backend process.
"THEIA_WEBVIEW_EXTERNAL_ENDPOINT": "${env:THEIA_WEBVIEW_EXTERNAL_ENDPOINT}"
},
"sourceMaps": true,
"outFiles": [
"${workspaceRoot}/examples/electron/src-gen/frontend/electron-main.js",
"${workspaceRoot}/examples/electron/src-gen/backend/main.js",
"${workspaceRoot}/examples/electron/src-gen/backend/main.js"
],
"smartStep": true,
"internalConsoleOptions": "openOnSessionStart",
"outputCapture": "std"
},
{
"type": "node",
"request": "launch",
"name": "Launch Electron Node Backend",
"runtimeExecutable": "yarn",
"runtimeArgs": [
"electron",
"--remote-debugging-port=9222", // Allow attaching to browser-windows.
],
"cwd": "${workspaceRoot}/examples/electron",
"protocol": "inspector",
"port": 9229,
"args": [
".",
"--log-level=debug",
"--hostname=localhost",
"--no-cluster",
"--app-project-path=${workspaceRoot}/examples/electron",
"--no-app-auto-install"
],
"env": {
"NODE_ENV": "development",
"THEIA_BACKEND_EXEC_ARGV": "[\"--inspect-brk=9229\"]", // Pass debug flags to backend process.
"THEIA_WEBVIEW_EXTERNAL_ENDPOINT": "${env:THEIA_WEBVIEW_EXTERNAL_ENDPOINT}"
},
"sourceMaps": true,
"outFiles": [
"${workspaceRoot}/examples/electron/lib/**/*.js",
"${workspaceRoot}/packages/*/lib/**/*.js",
"${workspaceRoot}/dev-packages/*/lib/**/*.js"
Expand All @@ -51,6 +86,18 @@
"internalConsoleOptions": "openOnSessionStart",
"outputCapture": "std"
},
{
"type": "node",
"request": "attach",
"name": "Attach to Electron Node Backend",
"port": 9229
},
{
"type": "chrome",
"request": "attach",
"name": "Attach to Electron Frontend",
"port": 9222
},
{
"type": "node",
"request": "launch",
Expand Down Expand Up @@ -149,12 +196,6 @@
"url": "http://localhost:3000/",
"webRoot": "${workspaceRoot}"
},
{
"type": "chrome",
"request": "attach",
"name": "Attach to Electron Frontend",
"port": 9222
},
{
"name": "Launch VS Code Tests",
"type": "node",
Expand Down Expand Up @@ -184,7 +225,7 @@
{
"name": "Launch Electron Backend & Frontend",
"configurations": [
"Launch Electron Backend",
"Launch Electron Node Backend",
"Attach to Electron Frontend"
]
}
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6 changes: 6 additions & 0 deletions dev-packages/application-manager/src/generator/backend-generator.ts
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Expand Up @@ -27,6 +27,12 @@ export class BackendGenerator extends AbstractGenerator {
protected compileServer(backendModules: Map<string, string>): string {
return `// @ts-check
require('reflect-metadata');
// Patch electron version if missing, see https://github.com/eclipse-theia/theia/pull/7361#pullrequestreview-377065146
if (typeof process.versions.electron === 'undefined' && typeof process.env.THEIA_ELECTRON_VERSION === 'string') {
process.versions.electron = process.env.THEIA_ELECTRON_VERSION;
}
const path = require('path');
const express = require('express');
const { Container } = require('inversify');
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65 changes: 32 additions & 33 deletions dev-packages/application-manager/src/generator/frontend-generator.ts
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Expand Up @@ -325,43 +325,42 @@ app.on('ready', () => {
// https://github.com/eclipse-theia/theia/issues/3297#issuecomment-439172274
process.env.THEIA_APP_PROJECT_PATH = resolve(__dirname, '..', '..');
// Set the electron version for both the dev and the production mode. (https://github.com/eclipse-theia/theia/issues/3254)
// Otherwise, the forked backend processes will not know that they're serving the electron frontend.
const { versions } = process;
// @ts-ignore
if (versions && typeof versions.electron !== 'undefined') {
// @ts-ignore
process.env.THEIA_ELECTRON_VERSION = versions.electron;
// Used for debugging:
// The backend runs in a separate process, we may want to pass options to it.
const theiaNodeBackendExecArgv = [...process.execArgv];
if (typeof process.env.THEIA_BACKEND_EXEC_ARGV === 'string') {
const parsedExecArgv = JSON.parse(process.env.THEIA_BACKEND_EXEC_ARGV);
if (!Array.isArray(parsedExecArgv)) {
throw new TypeError('process.env.THEIA_BACKEND_EXEC_ARGV should be a serialized JSON array.');
}
theiaNodeBackendExecArgv.push(...parsedExecArgv);
delete process.env.THEIA_BACKEND_EXEC_ARGV;
}
const mainPath = join(__dirname, '..', 'backend', 'main');
// We need to distinguish between bundled application and development mode when starting the clusters.
// See: https://github.com/electron/electron/issues/6337#issuecomment-230183287
if (devMode) {
process.env[ElectronSecurityToken] = JSON.stringify(electronSecurityToken);
require(mainPath).then(address => {
loadMainWindow(address.port);
}).catch((error) => {
console.error(error);
app.exit(1);
});
} else {
const cp = fork(mainPath, [], { env: Object.assign({
const theiaNodeBackend = fork(mainPath, [], {
execArgv: theiaNodeBackendExecArgv,
env: Object.assign({
[ElectronSecurityToken]: JSON.stringify(electronSecurityToken),
}, process.env) });
cp.on('message', (address) => {
loadMainWindow(address.port);
});
cp.on('error', (error) => {
console.error(error);
app.exit(1);
});
app.on('quit', () => {
// If we forked the process for the clusters, we need to manually terminate it.
// See: https://github.com/eclipse-theia/theia/issues/835
process.kill(cp.pid);
});
}
/**
* Set the electron version for both the dev and the production mode. (https://github.com/eclipse-theia/theia/issues/3254)
* Otherwise, the forked backend processes will not know that they're serving the electron frontend.
* The forked backend should patch its \`process.versions.electron\` with this value if it is missing.
*/
THEIA_ELECTRON_VERSION: process.versions.electron,
}, process.env)
});
theiaNodeBackend.on('message', (address) => {
loadMainWindow(address.port);
});
theiaNodeBackend.on('error', (error) => {
console.error(error);
app.exit(1);
});
app.on('quit', () => {
// Avoid process leak, see: https://github.com/eclipse-theia/theia/issues/835
process.kill(theiaNodeBackend.pid);
});
});
`;
}
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11 changes: 2 additions & 9 deletions dev-packages/application-package/src/environment.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -21,20 +21,13 @@ const isElectron: () => boolean = require('is-electron');
*/
class ElectronEnv {

/**
* Environment variable that can be accessed on the `process` to check if running in electron or not.
*/
readonly THEIA_ELECTRON_VERSION = 'THEIA_ELECTRON_VERSION';

/**
* `true` if running in electron. Otherwise, `false`.
*
* Can be called from both the `main` and the render process. Also works for forked cluster workers.
* Can be called from both the `main` and the render process.
*/
is(): boolean {
// When forking a new process from the cluster, we can rely neither on `process.versions` nor `process.argv`.
// Se we look into the `process.env` as well. `is-electron` does not do it for us.
return isElectron() || typeof process !== 'undefined' && typeof process.env === 'object' && !!process.env.THEIA_ELECTRON_VERSION;
return isElectron();
}

/**
Expand Down

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