2 files changed, 12 insertions, 0 deletions
diff --git a/lib/pstore.rb b/lib/pstore.rb
index 2aa9864b5..cc90207aa 100644
--- a/lib/pstore.rb
+++ b/lib/pstore.rb
@@ -78,6 +78,16 @@ class PStore
     begin
       @transaction = true
       value = file = nil
+      lock = @filename + ".lock"
+      loop do
+	begin
+	  File::symlink("pstore::#$$", lock)
+	  break
+	rescue Errno::EEXIST
+	rescue
+	  sleep 1
+	end
+      end
       begin
 	File::open(@filename, "r") do |file|
 	  @table = Marshal.load(file)
@@ -112,6 +122,7 @@ class PStore
     ensure
       @table = nil
       @transaction = false
+      File::unlink(lock)
     end
     value
   end
diff --git a/lib/singleton.rb b/lib/singleton.rb
index 8167a01aa..4aea574e7 100644
--- a/lib/singleton.rb
+++ b/lib/singleton.rb
@@ -14,6 +14,7 @@ module Singleton
   def Singleton.append_features(klass)
     klass.private_class_method(:new)
     klass.instance_eval %{
+      @__instance__ = nil
       def instance
 	unless @__instance__
 	  @__instance__ = new