(merged partially from r42927)

* lib/rubygems/core_ext/kernel_require.rb: Backport a fix for concurrent
  requires. [ruby-core:58918] [Backport #9224]
  see also https://github.com/rubygems/rubygems/pull/833


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@45100 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 24 insertions, 4 deletions

diff --git a/lib/rubygems/core_ext/kernel_require.rb b/lib/rubygems/core_ext/kernel_require.rb
index 4cd120b120..a591d386a9 100755
--- a/lib/rubygems/core_ext/kernel_require.rb
+++ b/lib/rubygems/core_ext/kernel_require.rb
@@ -50,7 +50,12 @@ module Kernel
     # normal require handle loading a gem from the rescue below.
 
     if Gem::Specification.unresolved_deps.empty? then
-      return gem_original_require(path)
+      begin
+        RUBYGEMS_ACTIVATION_MONITOR.exit
+        return gem_original_require(path)
+      ensure
+        RUBYGEMS_ACTIVATION_MONITOR.enter
+      end
     end
 
     # If +path+ is for a gem that has already been loaded, don't
@@ -63,7 +68,12 @@ module Kernel
       s.activated? and s.contains_requirable_file? path
     }
 
-    return gem_original_require(path) if spec
+    begin
+      RUBYGEMS_ACTIVATION_MONITOR.exit
+      return gem_original_require(path)
+    ensure
+      RUBYGEMS_ACTIVATION_MONITOR.enter
+    end if spec
 
     # Attempt to find +path+ in any unresolved gems...
 
@@ -111,11 +121,21 @@ module Kernel
       valid.activate
     end
 
-    gem_original_require path
+    begin
+      RUBYGEMS_ACTIVATION_MONITOR.exit
+      return gem_original_require(path)
+    ensure
+      RUBYGEMS_ACTIVATION_MONITOR.enter
+    end
   rescue LoadError => load_error
     if load_error.message.start_with?("Could not find") or
         (load_error.message.end_with?(path) and Gem.try_activate(path)) then
-      return gem_original_require(path)
+      begin
+        RUBYGEMS_ACTIVATION_MONITOR.exit
+        return gem_original_require(path)
+      ensure
+        RUBYGEMS_ACTIVATION_MONITOR.enter
+      end
     end
 
     raise load_error