Specialization of ConqurrentDeque::freeDeque and ObjectPool::release with Substitution failure is not an error (SFINAE)

build/CMakeLists.txt

@@ -4,7 +4,7 @@ project (CPP_UTILS_LIB)
 set(CMAKE_CXX_COMPILER "/usr/lib/colorgcc/bin/g++")
 
 set (CXX_FLAGS "-Wall -Wextra -pedantic -Weffc++ -Wshadow "
-               "-ggdb -fprofile-arcs -ftest-coverage")
+               "-ggdb -fprofile-arcs -ftest-coverage -std=c++0x")
 add_definitions( ${CXX_FLAGS} )
 
 include_directories (../include)

include/ConcurrentDeque.hpp

@@ -3,6 +3,7 @@
 
 #include <deque>
 #include <algorithm>
+#include <type_traits>
 
 #include "Mutex.hpp"
 #include "ConditionVariable.hpp"
@@ -15,11 +16,11 @@ class CancelledException {};
 
 
 template <typename T>
-class ConcurrentQueue
+class ConcurrentDeque
 {
 public:
 
-  ConcurrentQueue()
+  ConcurrentDeque()
     : m_queue()
     , m_cancelled(false)
     , m_mutex()
@@ -28,9 +29,10 @@ public:
     TRACE;
   }
 
-  ~ConcurrentQueue()
+  ~ConcurrentDeque()
   {
     TRACE;
+    freeDeque();
   }
 
 
@@ -81,29 +83,32 @@ public:
     return m_queue.empty();
   }
 
-
-  void cancel(T a)
+  void cancel()
   {
     TRACE;
     ScopedLock sl(m_mutex);
     m_cancelled = true;
     m_condVar.broadcast();
-
-    m_queue.clear();
+    freeDeque();
   }
 
-    void cancel(T *a)
+  template<class U = T>
+  typename std::enable_if< std::is_pointer<U>::value >::type
+  freeDeque()
   {
     TRACE;
-    ScopedLock sl(m_mutex);
-    m_cancelled = true;
-    m_condVar.broadcast();
-
-    typename std::deque<T*>::iterator it;
-    for ( it = m_queue.begin(); it != m_queue.end(); ++it ) {
-      LOG( Logger::INFO, std::string("Deleting: ").append(*it).c_str() );
+    typename std::deque<T>::iterator it;
+    for ( it = m_queue.begin(); it != m_queue.end(); ++it )
       delete *it;
+
+    m_queue.clear();
   }
+
+  template<class U = T>
+  typename std::enable_if< !(std::is_pointer<U>::value) >::type
+  freeDeque()
+  {
+    TRACE;
     m_queue.clear();
   }
 
@@ -116,8 +121,8 @@ public:
 private:
 
 
-  ConcurrentQueue& operator=( const ConcurrentQueue& );
-  ConcurrentQueue( const ConcurrentQueue& );
+  ConcurrentDeque& operator=( const ConcurrentDeque& );
+  ConcurrentDeque( const ConcurrentDeque& );
 
   std::deque<T> m_queue;
   bool m_cancelled;

include/MysqlConnectionPool.hpp

@@ -17,7 +17,6 @@ public:
 
   void create();
 
-  /// @note Shall this be a specialized ObjectPool::clear?
   void clear();
 
 private:

include/ObjectPool.hpp

@@ -1,7 +1,7 @@
 #ifndef OBJECT_POOL_HPP
 #define OBJECT_POOL_HPP
 
-#include "ConcurrentQueue.hpp"
+#include "ConcurrentDeque.hpp"
 #include "Logger.hpp"
 
 template <typename T>
@@ -36,11 +36,14 @@ public:
     return tmp;
   }
 
-  void release(T object)
+  template<class U = T>
+  typename std::enable_if< std::is_pointer<U>::value >::type
+  release(T object)
   {
     TRACE;
     if ( m_pool.cancelled() ) {
       m_numberOfUsedObjects--;
+      delete object;
       return;
     }
 
@@ -48,12 +51,13 @@ public:
     m_numberOfUsedObjects--;
   }
 
-  void release(T* object)
+  template<class U = T>
+  typename std::enable_if< !(std::is_pointer<U>::value) >::type
+  release(T object)
   {
     TRACE;
     if ( m_pool.cancelled() ) {
       m_numberOfUsedObjects--;
-      delete object;
       return;
     }
 
@@ -61,21 +65,16 @@ public:
     m_numberOfUsedObjects--;
   }
 
-  void clear(T a)
+  void clear()
   {
     TRACE;
-    m_pool.cancel(a);
+    m_pool.cancel();
   }
 
-  void clear(T* a)
-  {
-    TRACE;
-    m_pool.cancel(a);
-  }
 
 private:
 
-  ConcurrentQueue<T> m_pool;
+  ConcurrentDeque<T> m_pool;
   int m_numberOfUsedObjects;
 };
 

include/ThreadPool.hpp

@@ -3,7 +3,7 @@
 
 #include <vector>
 
-#include "ConcurrentQueue.hpp"
+#include "ConcurrentDeque.hpp"
 #include "Task.hpp"
 #include "Thread.hpp"
 #include "Mutex.hpp"
@@ -32,7 +32,7 @@ class ThreadPool
     ThreadPool& operator=( const ThreadPool& );
 
     std::vector<Thread*> m_threads;
-    ConcurrentQueue<Task*> m_tasks;
+    ConcurrentDeque<Task*> m_tasks;
 };
 
 

test/test_ObjectPool.hpp

@@ -34,11 +34,15 @@ public:
     op.add(a);
     op.add(b);
 
-    TS_ASSERT_EQUALS( op.acquire(), a );
-    TS_ASSERT_EQUALS( op.acquire(), b );
+    int *tmp_a = op.acquire();
+    int *tmp_b = op.acquire();
+
+    TS_ASSERT_EQUALS( *tmp_a, *a );
+    TS_ASSERT_EQUALS( *tmp_b, *b );
 
-    delete a;
-    delete b;
+    // release will delete them
+    op.release(tmp_a);
+    op.release(tmp_b);
   }
 
 
@@ -100,7 +104,7 @@ public:
     t1.join();
     t2.join();
 
-    delete a;
+    // no need to delete "a", dtor of the ConqurrentDeque takes care of it
   }