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+// -*- C++ -*-
+
+//=============================================================================
+/**
+ * @file CSD_TP_Task.h
+ *
+ * $Id$
+ *
+ * @author Tim Bradley <bradley_t@ociweb.com>
+ */
+//=============================================================================
+
+#ifndef TAO_CSD_TP_TASK_H
+#define TAO_CSD_TP_TASK_H
+
+#include /**/ "ace/pre.h"
+
+#include "tao/CSD_ThreadPool/CSD_TP_Export.h"
+
+#include "tao/CSD_ThreadPool/CSD_TP_Queue.h"
+#include "tao/PortableServer/PortableServer.h"
+#include "tao/Condition.h"
+
+#if !defined (ACE_LACKS_PRAGMA_ONCE)
+# pragma once
+#endif /* ACE_LACKS_PRAGMA_ONCE */
+
+#include "ace/Task.h"
+#include "ace/Synch.h"
+#include "ace/Containers_T.h"
+#include "ace/Vector_T.h"
+
+TAO_BEGIN_VERSIONED_NAMESPACE_DECL
+
+namespace TAO
+{
+ namespace CSD
+ {
+ /// Typedef for the number of threads.
+ typedef unsigned long Thread_Counter;
+
+ /**
+ * @class TP_Task
+ *
+ * @brief Active Object managing a queue of request objects.
+ *
+ * There are two types of "users" of a TP_Task object:
+ *
+ * 1) The TP_Strategy object that "owns" this task object.
+ * 2) The worker threads that "run" this task object as an
+ * "active object".
+ *
+ * The TP_Strategy object that "owns" this task object dictates
+ * when the worker threads are activated and when they are shutdown. It
+ * also injects requests into this task's queue via calls to the
+ * add_request() method. It is also the TP_Strategy object that
+ * dictates the number of worker threads to be activated via a call to
+ * the set_num_threads() method.
+ *
+ * The active object pattern is implemented via the use of the
+ * the ACE_Task_Base base class, and each worker thread will
+ * invoke this task's svc() method, and when the svc() returns, the
+ * worker thread will invoke this task's close() method (with the
+ * flag argument equal to 0).
+ *
+ * @note I just wanted to document an idea... When the pool consists
+ * of only one worker thread, we could care less about checking
+ * if target servant objects are busy or not. The simple fact
+ * that only one thread will be dispatching all requests means
+ * that servant objects will never be busy when the thread
+ * tests to see if a request is "ready_for_dispatch()". I'm
+ * just wondering if this knowledge can be applied to the
+ * implementation such that the "pool with one worker thread" case
+ * performs more efficiently. This is STP vs SSTP.
+ *
+ */
+ class TAO_CSD_TP_Export TP_Task : public ACE_Task_Base
+ {
+ public:
+
+ /// Default Constructor.
+ TP_Task();
+
+ /// Virtual Destructor.
+ virtual ~TP_Task();
+
+ /// Put a request object on to the request queue.
+ /// Returns true if successful, false otherwise (it has been "rejected").
+ bool add_request(TP_Request* request);
+
+ /// Activate the worker threads
+ virtual int open(void* num_threads_ptr = 0);
+
+ /// The "mainline" executed by each worker thread.
+ virtual int svc();
+
+ /// Multi-purpose: argument value is used to differentiate purpose.
+ ///
+ /// 0) Invoked by each worker thread after its invocation of the
+ /// svc() method has completed (ie, returned).
+ /// 1) Invoked by the strategy object to shutdown all worker threads.
+ virtual int close(u_long flag = 0);
+
+ /// Cancel all requests that are targeted for the provided servant.
+ void cancel_servant (PortableServer::Servant servant);
+
+ private:
+
+ typedef TAO_SYNCH_MUTEX LockType;
+ typedef ACE_Guard<LockType> GuardType;
+ typedef TAO_Condition<LockType> ConditionType;
+
+
+ /// Lock to protect the "state" (all of the data members) of this object.
+ LockType lock_;
+
+ /// Condition used to signal worker threads that they may be able to
+ /// find a request in the queue_ that needs to be dispatched to a
+ /// servant that is currently "not busy".
+ /// This condition will be signal()'ed each time a new request is
+ /// added to the queue_, and also when a servant has become "not busy".
+ ConditionType work_available_;
+
+ /// This condition will be signal()'ed each time the num_threads_
+ /// data member has its value changed. This is used to keep the
+ /// close(1) invocation (ie, a shutdown request) blocked until all
+ /// of the worker threads have stopped running.
+ ConditionType active_workers_;
+
+ /// Flag used to indicate when this task will (or will not) accept
+ /// requests via the the add_request() method.
+ bool accepting_requests_;
+
+ /// Flag used to initiate a shutdown request to all worker threads.
+ bool shutdown_initiated_;
+
+ /// Complete shutdown needed to be deferred because the thread calling
+ /// close(1) was also one of the ThreadPool threads
+ bool deferred_shutdown_initiated_;
+
+ /// Flag used to avoid multiple open() calls.
+ bool opened_;
+
+ /// The number of currently active worker threads.
+ Thread_Counter num_threads_;
+
+ /// The queue of pending servant requests (a.k.a. the "request queue").
+ TP_Queue queue_;
+
+ typedef ACE_Vector <ACE_thread_t> Thread_Ids;
+
+ /// The list of ids for the threads launched by this task.
+ Thread_Ids activated_threads_;
+
+ enum { MAX_THREADPOOL_TASK_WORKER_THREADS = 50 };
+ };
+
+ }
+}
+
+TAO_END_VERSIONED_NAMESPACE_DECL
+
+#if defined (__ACE_INLINE__)
+# include "tao/CSD_ThreadPool/CSD_TP_Task.inl"
+#endif /* __ACE_INLINE__ */
+
+#include /**/ "ace/post.h"
+
+#endif /* TAO_CSD_TP_TASK_H */