http/writer.h

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/**
 * \file
 * Write ready responses to an output stream.
 *
 * \author  Georg Hopp
 *
 * \copyright
 * Copyright © 2012  Georg Hopp
 *
 * 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 3 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 for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef __HTTP_WRITER_H__
#define __HTTP_WRITER_H__

#include <sys/types.h>

#include "class.h"
#include "http/message.h"
#include "queue.h"
#include "stream.h"

#include "commons.h"


/*
 * the buffer that will be written back to an http client.
 * If we have open 1024 paralell connection this will result
 * in a memory usage of 128MB. Right now, we don't allow more
 * than this amount of paralell connections.
 * 
 * This one and the parser buffer are the hugest memory pools
 * we need. The parser buffer is of the same size.
 *
 * Right now only the ringbuffer is reused for each connection
 * resulting in some memory movement between some temporary
 * space and the circular buffer.
 *
 * This behavioru should be kept in place for low memory machines
 * running this code.
 *
 * Anyway, I will build a version which uses two ringbuffers for
 * each connection, Resulting in a 256KB memory used for each
 * connection. Which in turn means 256MB for 1024 paralell connections.
 *
 * And as I will also implement a cbuf pool, this memory will not be
 * freed before application end.
 */

/*
 * This is the multiplier for the size of the initial write buffer.
 * It is used to store the
 * string representation of the message, as well as the first part of
 * the body if the headers exceed the size a multiple of this will
 * be reserved...very unlikely, but not impossible.
 * If no the whole body fits within this buffer only part of it will
 * be copied in there. The rest will be send in following send calls.
 */
#define WRITER_BUF_CHUNK    1024 * 10 // our default buffer chunk for
                                      // headers is 10k. This will result
                                      // in at least 20m for 2000 concurrent
                                      // connections.

typedef enum e_HttpWriterState {
    HTTP_WRITER_GET=0,
    HTTP_WRITER_WRITE,
    HTTP_WRITER_DONE
} HttpWriterState;

CLASS(HttpWriter) {
    char        * buffer;

    Queue         queue;
    HttpMessage   current;

    size_t        nbuffer; // size of buffer
    size_t        nheader; // size headers in buf
    size_t        nbody;   // sizeof body in buffer
    size_t        written; // already written bytes

    HttpWriterState state;
};

ssize_t httpWriterWrite(void *, Stream);

#endif // __HTTP_WRITER_H__

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