ClickHouse/base/poco/Foundation/include/Poco/FIFOBufferStream.h

//
// FIFOBufferStream.h
//
// Library: Foundation
// Package: Streams
// Module:  FIFOBufferStream
//
// Definition of the FIFOBufferStream class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_FIFOBufferStream_INCLUDED
#define Foundation_FIFOBufferStream_INCLUDED


#include <istream>
#include <ostream>
#include "Poco/BufferedBidirectionalStreamBuf.h"
#include "Poco/FIFOBuffer.h"
#include "Poco/Foundation.h"


namespace Poco
{


class Foundation_API FIFOBufferStreamBuf : public BufferedBidirectionalStreamBuf
/// This is the streambuf class used for reading from and writing to a FIFOBuffer.
/// FIFOBuffer is enabled for empty/non-empty/full state transitions notifications.
{
public:
    FIFOBufferStreamBuf();
    /// Creates a FIFOBufferStreamBuf.

    explicit FIFOBufferStreamBuf(FIFOBuffer & fifoBuffer);
    /// Creates a FIFOBufferStreamBuf and assigns the given buffer to it.

    FIFOBufferStreamBuf(char * pBuffer, std::size_t length);
    /// Creates a FIFOBufferStreamBuf and assigns the given buffer to it.

    FIFOBufferStreamBuf(const char * pBuffer, std::size_t length);
    /// Creates a FIFOBufferStreamBuf and assigns the given buffer to it.

    explicit FIFOBufferStreamBuf(std::size_t length);
    /// Creates a FIFOBufferStreamBuf of the given length.

    ~FIFOBufferStreamBuf();
    /// Destroys the FIFOBufferStreamBuf.

    FIFOBuffer & fifoBuffer();
    /// Returns the underlying FIFO buffer reference.

protected:
    int readFromDevice(char * buffer, std::streamsize length);
    int writeToDevice(const char * buffer, std::streamsize length);

private:
    enum
    {
        STREAM_BUFFER_SIZE = 1024
    };

    FIFOBuffer * _pFIFOBuffer;
    FIFOBuffer & _fifoBuffer;
};


class Foundation_API FIFOIOS : public virtual std::ios
/// The base class for FIFOBufferInputStream and
/// FIFOBufferStream.
///
/// This class is needed to ensure the correct initialization
/// order of the stream buffer and base classes.
{
public:
    explicit FIFOIOS(FIFOBuffer & buffer);
    /// Creates a FIFOIOS and assigns the given buffer to it.

    FIFOIOS(char * pBuffer, std::size_t length);
    /// Creates a FIFOIOS and assigns the given buffer to it.

    FIFOIOS(const char * pBuffer, std::size_t length);
    /// Creates a FIFOIOS and assigns the given buffer to it.

    explicit FIFOIOS(std::size_t length);
    /// Creates a FIFOIOS of the given length.

    ~FIFOIOS();
    /// Destroys the FIFOIOS.
    ///
    /// Flushes the buffer.

    FIFOBufferStreamBuf * rdbuf();
    /// Returns a pointer to the internal FIFOBufferStreamBuf.

    void close();
    /// Flushes the stream.

protected:
    FIFOBufferStreamBuf _buf;
};


class Foundation_API FIFOBufferStream : public FIFOIOS, public std::iostream
/// An output stream for writing to a FIFO.
{
public:
    Poco::BasicEvent<bool> & readable;
    Poco::BasicEvent<bool> & writable;

    explicit FIFOBufferStream(FIFOBuffer & buffer);
    /// Creates the FIFOBufferStream with supplied buffer as initial value.

    FIFOBufferStream(char * pBuffer, std::size_t length);
    /// Creates a FIFOBufferStream and assigns the given buffer to it.

    FIFOBufferStream(const char * pBuffer, std::size_t length);
    /// Creates a FIFOBufferStream and assigns the given buffer to it.

    explicit FIFOBufferStream(std::size_t length);
    /// Creates a FIFOBufferStream of the given length.

    ~FIFOBufferStream();
    /// Destroys the FIFOBufferStream.
    ///
    /// Flushes the buffer.

private:
    FIFOBufferStream();
    FIFOBufferStream(const FIFOBufferStream & other);
    FIFOBufferStream & operator=(const FIFOBufferStream & other);
};


///
/// inlines
///


inline FIFOBuffer & FIFOBufferStreamBuf::fifoBuffer()
{
    return _fifoBuffer;
}


} // namespace Poco


#endif // Foundation_FIFOBufferStream_INCLUDED