From c457d3bf2851d70c87ce27aa316333b19f5bbed4 Mon Sep 17 00:00:00 2001
From: Sam Saffron <sam.saffron@gmail.com>
Date: Wed, 4 Mar 2020 16:48:06 +1100
Subject: [PATCH] FIX: under concurrent usage booting rails could cause plugin
 corruption

Previously on boot we were always removing and adding the same pre-generated
files and symlinks.

This change attempts to avoid writing any automatically generated content if
it is exactly what it should be on disk.

This corrects issues where running a rails console can temporarily corrupt
internal state in production.
---
 lib/plugin/instance.rb | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/lib/plugin/instance.rb b/lib/plugin/instance.rb
index b810a9dd78..837de08957 100644
--- a/lib/plugin/instance.rb
+++ b/lib/plugin/instance.rb
@@ -543,9 +543,17 @@ class Plugin::Instance
 
       Discourse::Utils.execute_command('mkdir', '-p', target)
       target << name.gsub(/\s/, "_")
-      # TODO a cleaner way of registering and unregistering
-      Discourse::Utils.execute_command('rm', '-f', target)
-      Discourse::Utils.execute_command('ln', '-s', public_data, target)
+
+      symlink_is_correct = false
+      begin
+        symlink_is_correct = File.exists?(target) && File.readlink(target) == public_data
+      rescue Errno::EINVAL, Errno::ENOENT
+      end
+
+      if !symlink_is_correct
+        Discourse::Utils.execute_command('rm', '-f', target)
+        Discourse::Utils.execute_command('ln', '-s', public_data, target)
+      end
     end
 
     ensure_directory(Plugin::Instance.js_path)
@@ -558,12 +566,22 @@ class Plugin::Instance
       contents << (is_dir ? "depend_on('#{f}')" : "require_asset('#{f}')")
     end
 
-    File.delete(js_file_path) if js_asset_exists?
-
     if contents.present?
       contents.insert(0, "<%")
       contents << "%>"
-      write_asset(js_file_path, contents.join("\n"))
+
+      contents = contents.join("\n")
+
+      if File.exists?(js_file_path)
+        current_contents = File.read(js_file_path)
+        if current_contents != contents
+          File.write(js_file_path, conten)
+        end
+      else
+        write_asset(js_file_path, contents)
+      end
+    else
+      File.delete(js_file_path) if js_asset_exists?
     end
   end