source: vscpl/src/hu/varadiistvan/scpl/io/_posix/BufferedStream.h

// Copyright (c) 2013 by István Váradi

// This file is part of VSCPL, a simple cross-platform utility library

// 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.
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.

// 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 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL, 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 DAMAGE.

// The views and conclusions contained in the software and documentation are those
// of the authors and should not be interpreted as representing official policies,
// either expressed or implied, of the FreeBSD Project.

#ifndef HU_VARADIISTVAN_SCPL_IO_POSIX_BUFFEREDSTREAM_H
#define HU_VARADIISTVAN_SCPL_IO_POSIX_BUFFEREDSTREAM_H
//------------------------------------------------------------------------------

#include "Waitable.h"

#include <cstdlib>

//------------------------------------------------------------------------------

namespace hu { namespace varadiistvan { namespace scpl { namespace io {

//------------------------------------------------------------------------------

class ReadingBuffer;
class WritingBuffer;

//------------------------------------------------------------------------------

/**
 * A waitable that has a read and/or a write buffer associated with
 * it.
 */
class BufferedStream : public Waitable
{
public:
    /**
     * The default buffer capacity.
     */
    static const size_t DEFAULT_CAPACITY = 4096;

private:
    /**
     * The reading buffer. It may be 0, if no reading buffer is
     * associated with this waitable.
     */
    ReadingBuffer* readingBuffer;

    /**
     * The writing buffer. It may be 0, if no writing buffer is
     * associated with this waitable.
     */
    WritingBuffer* writingBuffer;

protected:
    /**
     * Construct the buffered waitable with the given capacities of
     * the reading and writing buffers. If any of the capacities is 0,
     * the corresponding buffer will not be created.
     */
    BufferedStream(Waiter* waiter = 0, int fd = -1,
                     size_t readingCapacity = DEFAULT_CAPACITY,
                     size_t writingCapacity = DEFAULT_CAPACITY,
                     short events = 0);

public:
    /**
     * Destroy the buffered waitable.
     */
    virtual ~BufferedStream();

    /**
     * Get the reference of the reading buffer. Note, that it can be a
     * 0 reference, if the waitable has no reading buffer.
     */
    ReadingBuffer& getReadingBuffer();

    /**
     * Get the reference of the writing buffer. Note, that it can be a
     * 0 reference, if the waitable has no writing buffer.
     */
    WritingBuffer& getWritingBuffer();

protected:
    /**
     * Read using the file descriptor at most the given number of
     * bytes into the given buffer.
     *
     * This default implementation uses the read(2) function for
     * reading.
     *
     * @return the number of bytes read (0 in case of end-of-file or
     * when the connection is closed), -1 on error. In case of error,
     * the error code will be set up.
     */
    virtual ssize_t read(void* dest, size_t length);

    /**
     * Write using the file descriptor the given number of bytes from
     * the given buffer.
     *
     * This default implementation uses the write(2) function for
     * writing.
     *
     * @return the number of bytes written, or -1 on error. In case of error,
     * the error code will be set up.
     */
    virtual ssize_t write(const void* src, size_t length);

    /**
     * Check if the waitable is ready.
     */
    virtual bool isReady();

    /**
     * Handle any events on the file descriptor.
     */
    virtual void handleEvents(short events);

    friend class ReadingBuffer;
    friend class WritingBuffer;
};

//------------------------------------------------------------------------------
// Inline definitions
//------------------------------------------------------------------------------

inline ReadingBuffer& BufferedStream::getReadingBuffer()
{
    return *readingBuffer;
}

//------------------------------------------------------------------------------

inline WritingBuffer& BufferedStream::getWritingBuffer()
{
    return *writingBuffer;
}

//------------------------------------------------------------------------------

} /* namespace hu::varadiistvan::scpl::io */ } /* namespace hu::varadiistvan::scpl */ } /* namespace hu::varadiistvan */ } /* namespace hu */

//------------------------------------------------------------------------------
#endif // HU_VARADIISTVAN_SCPL_IO_POSIX_BUFFEREDSTREAM_H

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