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+// -*- C++ -*-
+
+//=============================================================================
+/**
+ * @file LF_Event.h
+ *
+ * $Id$
+ *
+ * @author Carlos O'Ryan <coryan@uci.edu>
+ */
+//=============================================================================
+
+#ifndef TAO_LF_EVENT_H
+#define TAO_LF_EVENT_H
+
+#include /**/ "ace/pre.h"
+
+#include /**/ "tao/TAO_Export.h"
+
+#if !defined (ACE_LACKS_PRAGMA_ONCE)
+# pragma once
+#endif /* ACE_LACKS_PRAGMA_ONCE */
+
+#include /**/ "tao/Versioned_Namespace.h"
+
+TAO_BEGIN_VERSIONED_NAMESPACE_DECL
+
+class TAO_LF_Follower;
+class TAO_Leader_Follower;
+
+/**
+ * @class TAO_LF_Event
+ *
+ * @brief Use the Leader/Follower loop to wait for one specific event.
+ *
+ * The Leader/Follower event loop is used to wait for incoming
+ * responses, as well as to wait for all the data to be flushed.
+ * This class encapsulates this event loop. It uses Template Method to
+ * parametrize the 'waited for' predicate (i.e. reply received or
+ * message sent or connection establishment etc.)
+ *
+ * @todo Implementing the Leader/Followers loop in this class, as
+ * well as the callbacks to communicate that an event has completed
+ * leads to excessive coupling. A better design would use a separate
+ * class to signal the events, that would allow us to remove the
+ * Leader/Followers logic from the ORB. However, that requires other
+ * major changes and it somewhat complicates the design.
+ *
+ */
+class TAO_Export TAO_LF_Event
+{
+public:
+
+ friend class TAO_Leader_Follower;
+
+ /// Constructor
+ TAO_LF_Event (void);
+
+ /// Destructor
+ virtual ~TAO_LF_Event (void);
+
+ /// Bind a follower
+ /**
+ * An event can be waited on by at most one follower thread, this
+ * method is used to bind the waiting thread to the event, in order
+ * to let the event signal any important state changes.
+ *
+ * This is virtual to allow the LF_Multi_Event derived type share
+ * the follower with all the subordinate LF_CH_Events.
+ *
+ * @return -1 if the LF_Event is already bound, 0 otherwise
+ */
+ virtual int bind (TAO_LF_Follower *follower);
+
+ /// Unbind the follower
+ virtual int unbind (TAO_LF_Follower *follower);
+
+ //@{
+ /** @name State management
+ *
+ * A Leader/Followers event goes through several states during its
+ * lifetime. We use an enum to represent those states and state
+ * changes are validated according to the rules defined in the
+ * concrete classes. We treat the states as finite states in a
+ * FSM. The possible sequence of states through which the FSM
+ * migrates is defined in the concrete classes.
+ */
+ enum {
+ /// The event is created, and is in initial state
+ LFS_IDLE = 0,
+ /// The event is active
+ LFS_ACTIVE,
+ /// The event is waiting for connection completion.
+ LFS_CONNECTION_WAIT,
+ /// The event has completed successfully
+ LFS_SUCCESS,
+ /// A failure has been detected while the event was active
+ LFS_FAILURE,
+ /// The event has timed out
+ LFS_TIMEOUT,
+ /// The connection was closed.
+ LFS_CONNECTION_CLOSED
+ };
+
+ /**
+ * Virtual methods for this class hierarchy..
+ */
+ /// Accessor to change the state. The state isnt changed unless
+ /// certain conditions are satisfied.
+ void state_changed (int new_state, TAO_Leader_Follower &lf);
+
+ /// Return 1 if the condition was satisfied successfully, 0 if it
+ /// has not
+ virtual int successful (void) const = 0 ;
+
+ /// Return 1 if an error was detected while waiting for the
+ /// event
+ virtual int error_detected (void) const = 0;
+
+ /// Check if we should keep waiting.
+ int keep_waiting (void);
+ //@}
+
+ /// Reset the state, irrespective of the previous states
+ void reset_state (int new_state);
+
+ static const char *state_name (int st);
+
+protected:
+
+ /// Validate the state change
+ virtual void state_changed_i (int new_state) = 0;
+
+ /// Check whether we have reached the final state..
+ virtual int is_state_final (void) = 0;
+
+private:
+
+ /// Set the state irrespective of anything.
+ virtual void set_state (int new_state);
+
+protected:
+ /// The current state
+ int state_;
+
+ /// The bounded follower
+ TAO_LF_Follower *follower_;
+};
+
+TAO_END_VERSIONED_NAMESPACE_DECL
+
+#if defined (__ACE_INLINE__)
+# include "tao/LF_Event.inl"
+#endif /* __ACE_INLINE__ */
+
+#include /**/ "ace/post.h"
+
+#endif /* TAO_LF_EVENT_H */