Initial attempt at ConditionVariable implementation.

lib/process_shared/condition_variable.rb

@@ -1,14 +1,16 @@
 require 'process_shared/semaphore'
 
 module ProcessShared
-  # TODO: implement this
   class ConditionVariable
     def initialize
-      @sem = Semaphore.new
+      @internal = Semaphore.new(1)
+      @waiting = SharedMemory.new(:int)
+      @waiting.write_int(0)
+      @sem = Semaphore.new(0)
     end
 
     def broadcast
-      @sem.post
+      waiting.times { @sem.post }
     end
 
     def signal
@@ -18,10 +20,38 @@ module ProcessShared
     def wait(mutex, timeout = nil)
       mutex.unlock
       begin
-        @sem.wait
+        inc_waiting
+        if timeout
+          begin
+            @sem.try_wait(timeout)
+          rescue Errno::EAGAIN, Errno::ETIMEDOUT
+            # success!
+          end
+        else
+          @sem.wait
+        end
+        dec_waiting
       ensure
         mutex.lock
       end
     end
+
+    private
+
+    def waiting
+      @internal.synchronize do
+        @waiting.read_int
+      end
+    end
+
+    def inc_waiting(val = 1)
+      @internal.synchronize do
+        @waiting.write_int(@waiting.read_int + val)
+      end
+    end
+
+    def dec_waiting
+      inc_waiting(-1)
+    end
   end
 end