From 075f568f61c4b73180f12ed6caace3eb4c746dc1 Mon Sep 17 00:00:00 2001
From: Luke Barnard <luke@matrix.org>
Date: Fri, 2 Mar 2018 15:30:06 +0000
Subject: [PATCH] Fix crash; fs event received /w langauge file empty

It was common, at least for me, to experience a crash produced
when running the `matrix-react-sdk/scripts/gen-i18n.js` script
because when writing en_EN.json (via the script or otherwise)
choikdar would receive an event and cause the file to be read,
but the file would be empty when clearly it wasn't.

This would happen even when doing an atomic write in gen-i18n.

The fix adds a debounce as a workaround.
---
 scripts/copy-res.js | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/scripts/copy-res.js b/scripts/copy-res.js
index 305ea05ead..84b1d1b259 100755
--- a/scripts/copy-res.js
+++ b/scripts/copy-res.js
@@ -134,8 +134,19 @@ function next(i, err) {
             const reactSdkFile = 'node_modules/matrix-react-sdk/src/i18n/strings/' + source + '.json';
             const riotWebFile = 'src/i18n/strings/' + source + '.json';
 
-            const translations = {};
-            const makeLang = () => { genLangFile(source, dest) };
+            // XXX: Use a debounce because for some reason if we read the language
+            // file immediately after the FS event is received, the file contents
+            // appears empty. Possibly https://github.com/nodejs/node/issues/6112
+            let makeLangDebouncer;
+            const makeLang = () => {
+                if (makeLangDebouncer) {
+                    clearTimeout(makeLangDebouncer);
+                }
+                makeLangDebouncer = setTimeout(() => {
+                    genLangFile(source, dest);
+                }, 500);
+            };
+
             [reactSdkFile, riotWebFile].forEach(function(f) {
                 chokidar.watch(f)
                     .on('add', makeLang)
@@ -170,13 +181,13 @@ function genLangFile(lang, dest) {
                     JSON.parse(fs.readFileSync(f).toString())
                 );
             } catch (e) {
-                console.error("Failed: "+f, e);
+                console.error("Failed: " + f, e);
                 throw e;
             }
         }
     });
 
-    translations = weblateToCounterpart(translations)
+    translations = weblateToCounterpart(translations);
 
     fs.writeFileSync(dest + lang + '.json', JSON.stringify(translations, null, 4));
     if (verbose) {