MsgQueue.hpp

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/* INDI Server for protocol version 1.7.
 * Copyright (C) 2007 Elwood C. Downey <[email protected]>
                 2013 Jasem Mutlaq <[email protected]>
                 2022 Ludovic Pollet
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.
 
    This library 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
    Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/
#pragma once
 
#include "lilxml.h"
#include "Collectable.hpp"
#include "MsgChunckIterator.hpp"
#include "indicore/indidevapi.h"
 
#include <ev++.h>
#include <list>
#include <set>
 
class SerializedMsg;
class Msg;
 
class MsgQueue: public Collectable
{
        static constexpr unsigned maxFDPerMessage {16}; /* No more than 16 buffer attached to a message */
        static constexpr unsigned maxReadBufferLength {49152};
        static constexpr unsigned maxWriteBufferLength {49152};
 
        int rFd, wFd;
        LilXML * lp;         /* XML parsing context */
        ev::io   rio, wio;   /* Event loop io events */
        void ioCb(ev::io &watcher, int revents);
 
        // Update the status of FD read/write ability
        void updateIos();
 
        std::set<SerializedMsg*> readBlocker;     /* The message that block this queue */
 
        std::list<SerializedMsg*> msgq;           /* To send msg queue */
        std::list<int> incomingSharedBuffers; /* During reception, fds accumulate here */
 
        // Position in the head message
        MsgChunckIterator nsent;
 
        // Handle fifo or socket case
        size_t doRead(char * buff, size_t len);
        void readFromFd();
 
        /* write the next chunk of the current message in the queue to the given
         * client. pop message from queue when complete and free the message if we are
         * the last one to use it. shut down this client if trouble.
         */
        void writeToFd();
 
    protected:
        bool useSharedBuffer;
        int getRFd() const
        {
            return rFd;
        }
        int getWFd() const
        {
            return wFd;
        }
 
        /* print key attributes and values of the given xml to stderr. */
        void traceMsg(const std::string &log, XMLEle *root);
 
        /* Close the connection. (May be restarted later depending on driver logic) */
        virtual void close() = 0;
 
        /* Close the writing part of the connection. By default, shutdown the write part, but keep on reading. May delete this */
        virtual void closeWritePart();
 
        /* Handle a message. root will be freed by caller. fds of buffers will be closed, unless set to -1 */
        virtual void onMessage(XMLEle *root, std::list<int> &sharedBuffers) = 0;
 
        /* convert the string value of enableBLOB to our B_ state value.
         * no change if unrecognized
         */
        static void crackBLOB(const char *enableBLOB, BLOBHandling *bp);
 
        MsgQueue(bool useSharedBuffer);
    public:
        virtual ~MsgQueue();
 
        void pushMsg(Msg * msg);
 
        /* return storage size of all Msqs on the given q */
        unsigned long msgQSize() const;
 
        SerializedMsg * headMsg() const;
        void consumeHeadMsg();
 
        /* Remove all messages from queue */
        void clearMsgQueue();
 
        void messageMayHaveProgressed(const SerializedMsg * msg);
 
        void setFds(int rFd, int wFd);
 
        virtual bool acceptSharedBuffers() const
        {
            return useSharedBuffer;
        }
 
        virtual void log(const std::string &log) const;
};