Changes to process, added fork

chapter03/src/process_exec.js

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+/* @flow */
+
+const child_process = require("child_process");
+const { promisify } = require("util");
+
+child_process.exec = promisify(child_process.exec);
+
+async function getDirectory(path: ?string) {
+    try {
+        const cmd = "ls -ld -1 *.js";
+
+        let stdout;
+        if (typeof path === "undefined") {
+            ({ stdout } = await child_process.exec(cmd));
+        } else {
+            // $FlowFixMe: Flow doesn't understand "promisify()"
+            ({ stdout } = await child_process.exec(cmd, { cwd: path }));
+        }
+
+        console.log("OUT", path || "");
+        console.log(stdout);
+    } catch (e) {
+        console.log("ERR", e.stderr);
+    }
+}
+
+getDirectory();
+/*
+OUT
+-rw-r--r-- 1 fkereki users 3336 Apr 10 13:12 dbaccess.js
+-rw-r--r-- 1 fkereki users  319 Apr 10 13:12 doroundmath.js
+-rw-r--r-- 1 fkereki users  890 Apr 10 13:12 flowcomments.js
+-rw-r--r-- 1 fkereki users  293 Apr 10 13:12 miniserver.js
+-rw-r--r-- 1 fkereki users  751 Apr 10 13:12 process_exec.js
+-rw-r--r-- 1 fkereki users 1311 Apr 10 13:12 promisify.js
+-rw-r--r-- 1 fkereki users  828 Apr 10 13:12 roundmath.js
+*/
+
+getDirectory("/home/fkereki/MODERNJS/chapter03/flow-typed/npm");
+/*
+OUT /home/fkereki/MODERNJS/chapter03/flow-typed/npm
+-rw-r--r-- 1 fkereki users  4791 Apr  9 12:52 axios_v0.18.x.js
+-rw-r--r-- 1 fkereki users  3006 Mar 28 14:51 babel-cli_vx.x.x.js
+-rw-r--r-- 1 fkereki users  3904 Apr  9 12:52 babel-eslint_vx.x.x.js
+-rw-r--r-- 1 fkereki users  2760 Apr  9 12:52 babel-preset-env_vx.x.x.js
+-rw-r--r-- 1 fkereki users   888 Apr  9 12:52 babel-preset-flow_vx.x.x.js
+-rw-r--r-- 1 fkereki users   518 Apr  9 12:52 eslint-config-recommended_vx.x.x.js
+-rw-r--r-- 1 fkereki users 14995 Apr  9 12:52 eslint-plugin-flowtype_vx.x.x.js
+-rw-r--r-- 1 fkereki users 73344 Apr  9 12:52 eslint_vx.x.x.js
+-rw-r--r-- 1 fkereki users  1889 Mar 28 14:51 fetch_vx.x.x.js
+-rw-r--r-- 1 fkereki users   188 Apr  9 12:52 flow-bin_v0.x.x.js
+-rw-r--r-- 1 fkereki users 13290 Apr  9 12:52 flow-coverage-report_vx.x.x.js
+-rw-r--r-- 1 fkereki users  1091 Apr  9 12:52 flow-remove-types_vx.x.x.js
+-rw-r--r-- 1 fkereki users  5763 Apr  9 12:52 flow-typed_vx.x.x.js
+-rw-r--r-- 1 fkereki users  1009 Apr  9 12:52 mariasql_vx.x.x.js
+-rw-r--r-- 1 fkereki users     0 Mar 28 14:51 moment_v2.3.x.js
+-rw-r--r-- 1 fkereki users  5880 Apr  9 12:52 nodemon_vx.x.x.js
+-rw-r--r-- 1 fkereki users  4786 Apr  9 12:52 prettier_v1.x.x.js
+*/

chapter03/src/process_fork.js

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+/* @flow */
+
+const path = require("path");
+const { fork } = require("child_process");
+
+console.log(path.resolve("out/process_dir.js"));
+
+const child = fork(path.resolve("out/process_fork_dir.js"));
+
+const filePath = "/home/fkereki";
+
+child.send({ path: filePath });
+
+child.on("message", data => {
+    console.log(String(data));
+});

chapter03/src/process_fork_dir.js

@@ -0,0 +1,14 @@
+const fs = require("fs");
+
+process.on("message", obj => {
+    console.log("GOT!", obj);
+
+    // Received a path to process
+    fs
+        .readdirSync(obj.path)
+        .sort((a, b) => a.toLowerCase().localeCompare(b.toLowerCase()))
+        .filter(file => !file.startsWith("."))
+        .forEach(file => {
+            process.send(file);
+        });
+});

chapter03/src/process_spawn.js

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+/* @flow */
+
+const path = require("path");
+const { spawn } = require("child_process");
+const child = spawn("node", [path.resolve("out/process_spawn_dir.js")]);
+
+const filePath = "/home/fkereki";
+
+child.stdin.write(filePath);
+
+child.stdout.on("data", data => {
+    console.log(String(data));
+});
+
+child.stdout.on("end", () => {
+    child.kill();
+});

chapter03/src/process_spawn_dir.js

@@ -0,0 +1,16 @@
+const fs = require("fs");
+
+process.stdin.resume();
+
+process.stdin.on("data", path => {
+    // Received a path to process
+    fs
+        .readdirSync(path)
+        .sort((a, b) => a.toLowerCase().localeCompare(b.toLowerCase()))
+        .filter(file => !file.startsWith("."))
+        .forEach(file => {
+            process.stdout.write(file + "\n");
+        });
+
+    process.stdout.end();
+});