✨ Added new job manager package

- Minimal working version of a job manager
- Uses fastq for handling the queue
- Exposes 2 methods: addJob and shutdown

ghost/job-manager/.eslintrc.js

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+module.exports = {
+    plugins: ['ghost'],
+    extends: [
+        'plugin:ghost/node'
+    ]
+};

ghost/job-manager/LICENSE

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+MIT License
+
+Copyright (c) 2013-2020 Ghost Foundation
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

ghost/job-manager/README.md

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+# Job Manager
+
+## Install
+
+`npm install @tryghost/job-manager --save`
+
+or
+
+`yarn add @tryghost/job-manager`
+
+
+## Usage
+
+
+## Develop
+
+This is a mono repository, managed with [lerna](https://lernajs.io/).
+
+Follow the instructions for the top-level repo.
+1. `git clone` this repo & `cd` into it as usual
+2. Run `yarn` to install top-level dependencies.
+
+
+## Run
+
+- `yarn dev`
+
+
+## Test
+
+- `yarn lint` run just eslint
+- `yarn test` run lint and tests
+
+
+
+
+# Copyright & License 
+
+Copyright (c) 2020 Ghost Foundation - Released under the [MIT license](LICENSE).

ghost/job-manager/index.js

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+module.exports = require('./lib/job-manager');

ghost/job-manager/lib/job-manager.js

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+const fastq = require('fastq');
+const pWaitFor = require('p-wait-for');
+
+const worker = async (task, callback) => {
+    try {
+        let result = await task();
+        callback(null, result);
+    } catch (error) {
+        callback(error);
+    }
+};
+
+const handler = (error, result) => {
+    if (error) {
+        throw error;
+    }
+    // Can potentially standardise the result here
+    return result;
+};
+
+class JobManager {
+    constructor(logging) {
+        this.queue = fastq(this, worker, 1);
+        this.logging = logging;
+    }
+
+    addJob(job, data) {
+        this.queue.push(async () => {
+            await job(data);
+        }, handler);
+    }
+
+    async shutdown(options) {
+        if (this.queue.idle()) {
+            return;
+        }
+
+        this.logging.warn('Waiting for busy job queue');
+
+        await pWaitFor(() => this.queue.idle() === true, options);
+
+        this.logging.warn('Job queue finished');
+    }
+}
+
+module.exports = JobManager;

ghost/job-manager/package.json

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+{
+  "name": "@tryghost/job-manager",
+  "version": "0.0.0",
+  "repository": "https://github.com/TryGhost/Ghost-Utils/tree/master/packages/job-manager",
+  "author": "Ghost Foundation",
+  "license": "MIT",
+  "main": "index.js",
+  "scripts": {
+    "dev": "echo \"Implement me!\"",
+    "test": "NODE_ENV=testing mocha './test/**/*.test.js'",
+    "lint": "eslint . --ext .js --cache",
+    "posttest": "yarn lint"
+  },
+  "files": [
+    "index.js",
+    "lib"
+  ],
+  "publishConfig": {
+    "access": "public"
+  },
+  "devDependencies": {
+    "mocha": "8.1.1",
+    "should": "13.2.3",
+    "sinon": "9.0.2"
+  },
+  "dependencies": {
+    "fastq": "1.8.0",
+    "p-wait-for": "3.1.0"
+  }
+}

ghost/job-manager/test/.eslintrc.js

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+module.exports = {
+    plugins: ['ghost'],
+    extends: [
+        'plugin:ghost/test'
+    ]
+};

ghost/job-manager/test/hello.test.js

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+// Switch these lines once there are useful utils
+// const testUtils = require('./utils');
+require('./utils');
+
+describe('Hello world', function () {
+    it('Runs a test', function () {
+        // TODO: Write me!
+        'hello'.should.eql('hello');
+    });
+});

ghost/job-manager/test/utils/assertions.js

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+/**
+ * Custom Should Assertions
+ *
+ * Add any custom assertions to this file.
+ */
+
+// Example Assertion
+// should.Assertion.add('ExampleAssertion', function () {
+//     this.params = {operator: 'to be a valid Example Assertion'};
+//     this.obj.should.be.an.Object;
+// });

ghost/job-manager/test/utils/index.js

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+/**
+ * Test Utilities
+ *
+ * Shared utils for writing tests
+ */
+
+// Require overrides - these add globals for tests
+require('./overrides');
+
+// Require assertions - adds custom should assertions
+require('./assertions');

ghost/job-manager/test/utils/overrides.js

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+// This file is required before any test is run
+
+// Taken from the should wiki, this is how to make should global
+// Should is a global in our eslint test config
+global.should = require('should').noConflict();
+should.extend();
+
+// Sinon is a simple case
+// Sinon is a global in our eslint test config
+global.sinon = require('sinon');