From 10a539ef002d1ec32552d22821232f57d59219a0 Mon Sep 17 00:00:00 2001
From: Cristian Carlesso <kentaromiura@gmail.com>
Date: Thu, 1 Dec 2016 12:54:11 +0000
Subject: [PATCH] Fixes race condition on yarn install mutex network (#2092)

* Fixes race condition on yarn install mutex network

* Better comment on  as per @bestander request
---
 src/cli/index.js | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/src/cli/index.js b/src/cli/index.js
index 209c07258c..91156b3d07 100644
--- a/src/cli/index.js
+++ b/src/cli/index.js
@@ -265,26 +265,28 @@ const runEventuallyWithNetwork = (mutexPort: ?string): Promise<void> => {
       port: +mutexPort || constants.SINGLE_INSTANCE_PORT,
     };
 
-    const clients = [];
-    const server = net.createServer((client: net$Socket) => {
-      clients.push(client);
-    });
+    const server = net.createServer();
 
     server.on('error', () => {
-      // another yarnn instance exists, let's connect to it to know when it dies.
+      // another Yarn instance exists, let's connect to it to know when it dies.
       reporter.warn(reporter.lang('waitingInstance'));
       const socket = net.createConnection(connectionOptions);
 
       socket
-        .on('data', () => {
-          // the server has informed us he's going to die soon™.
-          socket.unref(); // let it die
-          process.nextTick(() => {
-            ok(runEventuallyWithNetwork(mutexPort));
-          });
+        .on('connect', () => {
+          // Allow the program to exit if this is the only active server in the event system.
+          socket.unref();
+        })
+        .on('close', (hadError?: boolean) => {
+          // the `close` event gets always called after the `error` event
+          if (!hadError) {
+            process.nextTick(() => {
+              ok(runEventuallyWithNetwork(mutexPort));
+            });
+          }
         })
         .on('error', () => {
-          // No server to listen to ? :O let's retry to become the next server then.
+          // No server to listen to ? Let's retry to become the next server then.
           process.nextTick(() => {
             ok(runEventuallyWithNetwork(mutexPort));
           });
@@ -292,9 +294,6 @@ const runEventuallyWithNetwork = (mutexPort: ?string): Promise<void> => {
     });
 
     const onServerEnd = (): Promise<void> => {
-      clients.forEach((client) => {
-        client.write('closing. kthanx, bye.');
-      });
       server.close();
       return Promise.resolve();
     };