/*-
 * Copyright (c) 2011, 2012, 2013, 2014 Spectra Logic Corporation
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * Authors: Justin T. Gibbs     (Spectra Logic Corporation)
 */

/**
 * \file devdctl_consumer.h
 */
#ifndef _DEVDCTL_CONSUMER_H_
#define _DEVDCTL_CONSUMER_H_

/*============================ Namespace Control =============================*/
namespace DevdCtl
{

/*=========================== Forward Declarations ===========================*/
class Event;

/*============================ Class Declarations ============================*/
/*----------------------------- DevdCtl::Consumer ----------------------------*/

/**
 */
class Consumer
{
public:
        Consumer(Event::BuildMethod *defBuilder = NULL,
                 EventFactory::Record *regEntries = NULL,
                 size_t numEntries = 0);
        virtual ~Consumer();

        bool Connected() const;

        /**
         * Return file descriptor useful for client's wishing to poll(2)
         * for new events.
         */
        int GetPollFd();

        /**                                                          
         * Queue an event for deferred processing or replay.
         */ 
        bool SaveEvent(const Event &event);

        /**                                  
         * Reprocess any events saved via the SaveEvent() facility.   
         *
         * \param discardUnconsumed  If true, events that are not consumed
         *                           during replay are discarded.
         */                                                              
        void ReplayUnconsumedEvents(bool discardUnconsumed);

        /** Return an event, if one is available.  */
        Event *NextEvent();

        /**
         * Extract events and invoke each event's Process method.
         */
        void ProcessEvents();

        /** Discard all data pending in m_devdSockFD. */
        void FlushEvents();

        /**
         * Test for data pending in m_devdSockFD
         *
         * \return  True if data is pending.  Otherwise false.
         */
        bool EventsPending();

        /**
         * Open a connection to devd's unix domain socket.
         *
         * \return  True if the connection attempt is successful.  Otherwise
         *          false.
         */
        bool ConnectToDevd();

        /**
         * Close a connection (if any) to devd's unix domain socket.
         */
        void DisconnectFromDevd();

        EventFactory GetFactory();

protected:
        /**
         * \brief Reads the most recent record
         *
         * On error, "" is returned, and errno will be set by the OS
         *
         * \returns      A string containing the record
         */
        std::string ReadEvent();

        enum {
                /*
                 * The maximum event size supported by libdevdctl.
                 */
                MAX_EVENT_SIZE = 8192,
        };

        static const char  s_devdSockPath[];

        /**
         * File descriptor representing the unix domain socket
         * connection with devd.
         */
        int                m_devdSockFD;

        EventFactory       m_eventFactory;

        /** Queued events for replay. */
        EventList          m_unconsumedEvents;

        /**                                                             
         * Flag controlling whether events can be queued.  This boolean
         * is set during event replay to ensure that previosuly deferred
         * events are not requeued and thus retained forever.
         */
        bool               m_replayingEvents;
};

//- Consumer Const Public Inline Methods ---------------------------------------
inline bool
Consumer::Connected() const
{
        return (m_devdSockFD != -1);
}

//- Consumer Public Inline Methods ---------------------------------------------
inline int
Consumer::GetPollFd()
{
        return (m_devdSockFD);
}

inline EventFactory
Consumer::GetFactory()
{
        return (m_eventFactory);
}

} // namespace DevdCtl
#endif  /* _DEVDCTL_CONSUMER_H_ */