added Barrier

lib/Basics/Barrier.cpp

@@ -0,0 +1,105 @@
+////////////////////////////////////////////////////////////////////////////////
+/// @brief barrier for synchronization
+///
+/// @file
+///
+/// DISCLAIMER
+///
+/// Copyright 2014 ArangoDB GmbH, Cologne, Germany
+/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     http://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+///
+/// Copyright holder is ArangoDB GmbH, Cologne, Germany
+///
+/// @author Jan Steemann
+/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
+/// @author Copyright 2013-2013, triAGENS GmbH, Cologne, Germany
+////////////////////////////////////////////////////////////////////////////////
+
+#include "Barrier.h"
+#include "Basics/ConditionLocker.h"
+
+using namespace triagens::basics;
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                                           Barrier
+// -----------------------------------------------------------------------------
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                        constructors / destructors
+// -----------------------------------------------------------------------------
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief create a barrier for the specified number of waiters
+////////////////////////////////////////////////////////////////////////////////
+
+Barrier::Barrier (size_t size)
+  : _condition(),
+    _missing(size) {
+ 
+  TRI_ASSERT(size > 0);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief destroy the barrier. this will call synchronize() to ensure all tasks
+/// are joined
+////////////////////////////////////////////////////////////////////////////////
+
+Barrier::~Barrier () {
+  synchronize();
+}
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                                  public functions
+// -----------------------------------------------------------------------------
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief join a single task. reduces the number of waiting tasks and wakes
+/// up the barrier's synchronize() routine
+////////////////////////////////////////////////////////////////////////////////
+
+void Barrier::join () {
+  {
+    CONDITION_LOCKER(guard, _condition);
+    TRI_ASSERT(_missing > 0);
+    --_missing;
+  }
+
+  _condition.signal();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief wait for all tasks to join
+////////////////////////////////////////////////////////////////////////////////
+
+void Barrier::synchronize () {
+  while (true) {
+    CONDITION_LOCKER(guard, _condition);
+
+    if (_missing == 0) {
+      break;
+    }
+
+    guard.wait(100000);
+  }
+}
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                                       END-OF-FILE
+// -----------------------------------------------------------------------------
+
+// Local Variables:
+// mode: outline-minor
+// outline-regexp: "/// @brief\\|/// {@inheritDoc}\\|/// @page\\|// --SECTION--\\|/// @\\}"
+// End:

lib/Basics/Barrier.h

@@ -0,0 +1,148 @@
+////////////////////////////////////////////////////////////////////////////////
+/// @brief barrier for synchronization
+///
+/// @file
+///
+/// DISCLAIMER
+///
+/// Copyright 2014 ArangoDB GmbH, Cologne, Germany
+/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     http://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+///
+/// Copyright holder is ArangoDB GmbH, Cologne, Germany
+///
+/// @author Jan Steemann
+/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
+/// @author Copyright 2013-2013, triAGENS GmbH, Cologne, Germany
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef ARANGODB_BASICS_BARRIER_H
+#define ARANGODB_BASICS_BARRIER_H 1
+
+#include "Basics/Common.h"
+#include "Basics/ConditionVariable.h"
+
+namespace triagens {
+  namespace basics {
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                                           Barrier
+// -----------------------------------------------------------------------------
+
+    class Barrier {
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                        constructors / destructors
+// -----------------------------------------------------------------------------
+
+      public:
+
+        Barrier (Barrier const&) = delete;
+        Barrier& operator= (Barrier const&) = delete;
+
+        Barrier (size_t);
+
+        ~Barrier ();
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                                  public functions
+// -----------------------------------------------------------------------------
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief join a single task. reduces the number of waiting tasks and wakes
+/// up the barrier's synchronize() routine
+////////////////////////////////////////////////////////////////////////////////
+
+        void join ();
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief wait for all tasks to join
+////////////////////////////////////////////////////////////////////////////////
+
+        void synchronize ();
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                                 private variables
+// -----------------------------------------------------------------------------
+
+      private:
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief condition variable
+////////////////////////////////////////////////////////////////////////////////
+
+        triagens::basics::ConditionVariable _condition;
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief number of non-joined tasks
+////////////////////////////////////////////////////////////////////////////////
+
+        size_t _missing;
+    }; 
+    
+// -----------------------------------------------------------------------------
+// --SECTION--                                                       BarrierTask
+// -----------------------------------------------------------------------------
+    
+    class BarrierTask {
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                        constructors / destructors
+// -----------------------------------------------------------------------------
+
+      public:
+        
+        BarrierTask () = delete; 
+        BarrierTask (BarrierTask const&) = delete;
+        BarrierTask& operator= (BarrierTask const&) = delete;
+
+        explicit BarrierTask (Barrier* barrier) 
+          : _barrier(barrier) {
+        }
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief destructor. joins the underlying barrier
+////////////////////////////////////////////////////////////////////////////////
+
+        ~BarrierTask () {
+          _barrier->join();
+        }
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                                 private variables
+// -----------------------------------------------------------------------------
+
+      private:
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief the underlying barrier
+////////////////////////////////////////////////////////////////////////////////
+
+        Barrier* _barrier;
+
+    };
+
+  }   // namespace triagens::basics
+}   // namespace triagens
+
+#endif
+
+// -----------------------------------------------------------------------------
+// --SECTION--                                                       END-OF-FILE
+// -----------------------------------------------------------------------------
+
+// Local Variables:
+// mode: outline-minor
+// outline-regexp: "/// @brief\\|/// {@inheritDoc}\\|/// @page\\|// --SECTION--\\|/// @\\}"
+// End:

lib/CMakeLists.txt

@@ -48,6 +48,7 @@ add_library(
     Basics/application-exit.cpp
     Basics/associative-multi.cpp
     Basics/associative.cpp
+    Basics/Barrier.cpp
     Basics/ConditionLocker.cpp
     Basics/ConditionVariable.cpp
     Basics/conversions.cpp

lib/Makefile.files

@@ -15,6 +15,7 @@ lib_libarango_a_SOURCES = \
 	lib/Basics/application-exit.cpp \
 	lib/Basics/associative-multi.cpp \
 	lib/Basics/associative.cpp \
+	lib/Basics/Barrier.cpp \
 	lib/Basics/ConditionLocker.cpp \
 	lib/Basics/ConditionVariable.cpp \
 	lib/Basics/conversions.cpp \