source: xplcommon/src/xplcommon/BlockingStream.h@ 31:bbd688924703

// Copyright (c) 2013 by István Váradi

// This file is part of libxplcommon, a common utility library for
// development related to X-Plane

// 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 XPLCOMMON_BLOCKINGSTREAM_H
#define XPLCOMMON_BLOCKINGSTREAM_H
//------------------------------------------------------------------------------

#include "Failable.h"

#include "BufferedStream.h"

#include "Waiter.h"
#include "WaitableEvent.h"

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

namespace xplcommon {

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

/**
 * Wrapper for a buffered stream, which an event and provides
 * blocking, but interruptible read() and write() operations.
 *
 * The class is designed in a way, that it expects its constructed
 * instances to be called only from a single thread at a time, except
 * for the interrupt() function, which may be called from another
 * thread anytime.
 */
class BlockingStream : public Failable
{
private:
    /**
     * The buffered stream used.
     */
    BufferedStream& stream;

    /**
     * The waitable event.
     */
    WaitableEvent event;

    /**
     * Indicate if we are interrupted.
     */
    bool interrupted;

    /**
     * The offset in the buffer of the reading stream.
     */
    size_t readingOffset;

    /**
     * Indicate if the end-of-file has been reached while reading.
     */
    bool eof;

public:
    /**
     * Construct the blocking stream for the given buffered stream.
     *
     * The stream must have a waiter which is used for waiting.
     */
    BlockingStream(BufferedStream& stream);

    /**
     * Determine if the stream has neither failed nor been
     * interrupted.
     */
    operator bool() const;

    /**
     * Interrupt the stream. Pending or future read and write calls
     * will return indicating error. The isInterrupted() function can
     * be used to check if the stream was interrupted or not.
     */
    void interrupt();

    /**
     * Indicate if the stream is interrupted or not.
     */
    bool isInterrupted();

    /**
     * Read the given number of bytes into the given buffer.
     *
     * @return if the reading has succeeded
     */
    bool read(void* dest, size_t length);

    /**
     * Skip the given number of bytes.
     */
    bool skip(size_t length);

    /**
     * Write the given number of bytes from the given buffer. The data
     * may not be written to the underlying stream fully, so if you
     * want to make sure that it is sent, call flush() afterwards.
     *
     * @return true on success, false on error.
     */
    bool write(const void* src, size_t length);

    /**
     * Flush anything written so far into the buffer, but not to the
     * underlying stream.
     *
     * @return whether the operation has succeeded.
     */
    bool flush();

private:
    /**
     * Fill the buffer with data from the stream.
     */
    bool fill();

    /**
     * Check for the stream being interrupted.
     *
     * @return if the stream is interrupted, false otherwise
     */
    bool checkInterrupted();
};

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

inline BlockingStream::BlockingStream(BufferedStream& stream) :
    stream(stream),
    event(stream.getWaiter()),
    interrupted(false),
    readingOffset(0),
    eof(false)
{
}

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

inline BlockingStream::operator bool() const
{
    return !failed() && !interrupted && !eof;
}

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

inline void BlockingStream::interrupt()
{
    event.fire();
}

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

inline bool BlockingStream::isInterrupted()
{
    return interrupted;
}

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

} /* namespace xplcommon */

//------------------------------------------------------------------------------
#endif // XPLCOMMON_BLOCKINGSTREAM_H

// Local Variables:
// mode: C++
// c-basic-offset: 4
// indent-tabs-mode: nil
// End: