router.h

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///
/// \file       router.h
///             Support classes for the pluggable socket routing system.
///

/*
    Copyright (C) 2005-2012, Net Direct Inc. (http://www.netdirect.ca/)

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

    See the GNU General Public License in the COPYING file at the
    root directory of this project for more details.
*/

#ifndef __BARRY_ROUTER_H__
#define __BARRY_ROUTER_H__

#include "dll.h"
#include <stdint.h>
#include <map>
#include <tr1/memory>
#include <stdexcept>
#include <pthread.h>
#include "dataqueue.h"
#include "error.h"
#include "usbwrap.h"

namespace Barry {

class DataHandle;

class BXEXPORT SocketRoutingQueue
{
        friend class DataHandle;

public:
        // Interface class for socket data callbacks
        // See RegisterInterest() for more information.
        class BXEXPORT SocketDataHandler
        {
        public:
                // Called when data is received on the socket
                // for which interest has been registered.
                //
                // The lifetime of the data parameter is only valid
                // for the duration of this method call.
                virtual void DataReceived(Data& data) = 0;

                // Called when an error has occured on the socket
                // for which interest has been registered.
                //
                // The lifetime of the error parameter is only valid
                // for the lifetime of this method call.
                virtual void Error(Barry::Error &error);

                virtual ~SocketDataHandler();
        };

        typedef std::tr1::shared_ptr<SocketDataHandler> SocketDataHandlerPtr;

        // Simple wrapper template class for SocketDataHandler which provides a basic data recieved callback
        template<typename T> class SimpleSocketDataHandler : public SocketDataHandler
        {
                void (*m_callback)(T&, Data*);
                T& m_context;
        public:
                SimpleSocketDataHandler<T>(T& context, void (*callback)(T& context, Data* data))
                        : m_callback(callback)
                        , m_context(context)
                {}
                virtual void DataReceived(Data& data)
                {
                        m_callback(m_context, &data);
                }
        };

        struct QueueEntry
        {
                SocketDataHandlerPtr m_handler;
                DataQueue m_queue;

                QueueEntry(SocketDataHandlerPtr h)
                        : m_handler(h)
                        {}
        };
        typedef std::tr1::shared_ptr<QueueEntry>        QueueEntryPtr;
        typedef uint16_t                                SocketId;
        typedef std::map<SocketId, QueueEntryPtr>       SocketQueueMap;

private:
        Usb::Device * volatile m_dev;
        volatile int m_writeEp, m_readEp;

        volatile bool m_interest; // true if at least one socket has an interest.
                                // used to optimize the reading

        mutable pthread_mutex_t m_mutex;// controls access to local data, but not
                                // DataQueues, as they have their own
                                // locking per queue

        pthread_mutex_t m_readwaitMutex;
        pthread_cond_t m_readwaitCond;
        bool m_seen_usb_error;
        SocketDataHandlerPtr m_usb_error_dev_callback;

        DataQueue m_free;
        DataQueue m_default;
        SocketQueueMap m_socketQueues;

        int m_timeout;

        // thread state
        pthread_t m_usb_read_thread;
        volatile bool m_continue_reading;// set to true when the thread is created,
                                // then set to false in the destructor
                                // to signal the end of the thread
                                // and handle the join

protected:
        // Provides a method of returning a buffer to the free queue
        // after processing.  The DataHandle class calls this automatically
        // from its destructor.
        void ReturnBuffer(Data *buf);

        // Helper function to add a buffer to a socket queue
        // Returns false if no queue is available for that socket
        // Also empties the DataHandle on success.
        bool QueuePacket(SocketId socket, DataHandle &buf);
        bool QueuePacket(DataQueue &queue, DataHandle &buf);
        bool RouteOrQueuePacket(SocketId socket, DataHandle &buf);

        // Thread function for the simple read behaviour... thread is
        // created in the SpinoffSimpleReadThread() member below.
        static void *SimpleReadThread(void *userptr);

        void DumpSocketQueue(SocketId socket, const DataQueue &dq);

public:
        SocketRoutingQueue(int prealloc_buffer_count = 4,
                int default_read_timeout = USBWRAP_DEFAULT_TIMEOUT);
        ~SocketRoutingQueue();

        //
        // data access
        //
        int GetWriteEp() const { return m_writeEp; }
        int GetReadEp() const { return m_readEp; }


        // These functions connect the router to an external Usb::Device
        // object.  Normally this is handled automatically by the
        // Controller class, but are public here in case they are needed.
        //
        // If DoRead encounters an error, it sets a flag and stops
        // reading.  To recover, you should handle the Error() call in
        // the callback, fix the USB device, and then call
        // ClearUsbError() to clear the flag.
        //
        void SetUsbDevice(Usb::Device *dev, int writeEp, int readEp,
                SocketDataHandlerPtr callback = SocketDataHandlerPtr());
        void ClearUsbDevice();
        bool UsbDeviceReady();
        Usb::Device* GetUsbDevice() { return m_dev; }
        void ClearUsbError();


        // This class starts out with no buffers, and will grow one buffer
        // at a time if needed.  Call this to allocate count buffers
        // all at once and place them on the free queue.
        void AllocateBuffers(int count);

        // Returns the data for the next unregistered socket.
        // Blocks until timeout or data is available.
        // Returns false (or null pointer) on timeout and no data.
        // With the return version of the function, there is no
        // copying performed.
        //
        // Timeout is in milliseconds.  Default timeout set by constructor
        // is used if set to -1.
        bool DefaultRead(Data &receive, int timeout = -1);
        DataHandle DefaultRead(int timeout = -1);

        // Register an interest in data from a certain socket.  To read
        // from that socket, use the SocketRead() function from then on.
        // Any non-registered socket goes in the default queue
        // and must be read by DefaultRead()
        // If not null, handler is called when new data is read.  It will
        // be called in the same thread instance that DoRead() is called from.
        // Handler is passed the DataQueue Data object, and so no
        // copying is done.  Once the handler returns, the data is
        // considered processed and not added to the interested queue,
        // but instead returned to m_free.
        void RegisterInterest(SocketId socket, SocketDataHandlerPtr handler);

        // Unregisters interest in data from the given socket, and discards
        // any existing data in its interest queue.  Any new incoming data
        // for this socket will be placed in the default queue.
        void UnregisterInterest(SocketId socket);

        // Reads data from the interested socket cache.  Can only read
        // from sockets that have been previously registered.
        // Blocks until timeout or data is available.
        // Returns false (or null pointer) on timeout and no data.
        // With the return version of the function, there is no
        // copying performed.
        //
        // Timeout is in milliseconds.  Default timeout set by constructor
        // is used if set to -1.
        bool SocketRead(SocketId socket, Data &receive, int timeout = -1);
        DataHandle SocketRead(SocketId socket, int timeout = -1);

        // Returns true if data is available for that socket.
        bool IsAvailable(SocketId socket) const;

        // Called by the application's "read thread" to read the next usb
        // packet and route it to the correct queue.  Returns after every
        // read, even if a handler is associated with a queue.
        // Note: this function is safe to call before SetUsbDevice() is
        // called... it just doesn't do anything if there is no usb
        // device to work with.
        //
        // Timeout is in milliseconds.  Default is default USB timeout.
        void DoRead(int timeout = -1);

        // Utility function to make it easier for the user to create the
        // USB pure-read thread.  If the user wants anything more complicated
        // in this background thread, he can implement it himself and call
        // the above DoRead() in a loop.  If only the basics are needed,
        // then this makes it easy.
        // Throws Barry::ErrnoError on thread creation error.
        void SpinoffSimpleReadThread();
};


//
// DataHandle
//
/// std::auto_ptr like class that handles pointers to Data, but instead of
/// freeing them completely, the Data objects are turned to the
/// SocketRoutingQueue from whence they came.
///
class BXEXPORT DataHandle
{
private:
        SocketRoutingQueue &m_queue;
        mutable Data *m_data;

protected:
        void clear()
        {
                if( m_data ) {
                        m_queue.ReturnBuffer(m_data);
                        m_data = 0;
                }
        }

public:
        DataHandle(SocketRoutingQueue &q, Data *data)
                : m_queue(q)
                , m_data(data)
        {
        }

        DataHandle(const DataHandle &other)
                : m_queue(other.m_queue)
                , m_data(other.m_data)
        {
                // we now own the pointer
                other.m_data = 0;
        }

        ~DataHandle()
        {
                clear();
        }

        Data* get()
        {
                return m_data;
        }

        Data* release() // no longer owns the pointer, and does not free it
        {
                Data *ret = m_data;
                m_data = 0;
                return ret;
        }

        // frees current pointer, and takes ownership of new one
        void reset(Data *next = 0)
        {
                clear();
                m_data = next;
        }

        Data* operator->()
        {
                return m_data;
        }

        const Data* operator->() const
        {
                return m_data;
        }

        DataHandle& operator=(const DataHandle &other)
        {
                if( &m_queue != &other.m_queue )
                        throw std::logic_error("Trying to copy DataHandles of different queues!");

                // remove our current data
                clear();

                // accept the new
                m_data = other.m_data;

                // we now own it
                other.m_data = 0;

                return *this;
        }

};


} // namespace Barry

#endif