1 files changed, 13 insertions, 5 deletions
diff --git a/prelude.rb b/prelude.rb
index 1d084dfd8f..40fca6ab36 100644
--- a/prelude.rb
+++ b/prelude.rb
@@ -1,7 +1,9 @@
-
-# Mutex
-
 class Mutex
+  # call-seq:
+  #    mutex.synchronize { ... }
+  #
+  # Obtains a lock, runs the block, and releases the lock when the
+  # block completes.  See the example under Mutex.
   def synchronize
     self.lock
     begin
@@ -12,10 +14,16 @@ class Mutex
   end
 end
 
-# Thread
-
 class Thread
+  # :nodoc:
   MUTEX_FOR_THREAD_EXCLUSIVE = Mutex.new
+
+  # call-seq:
+  #    Thread.exclusive { block }   => obj
+  #  
+  # Wraps a block in Thread.critical, restoring the original value
+  # upon exit from the critical section, and returns the value of the
+  # block.
   def self.exclusive
     MUTEX_FOR_THREAD_EXCLUSIVE.synchronize{
       yield