class Poco::Pipe

Overview

This class implements an anonymous pipe. More…

#include <Pipe.h>

class Pipe
{
public:
    // typedefs

    typedef PipeImpl::Handle Handle;

    // enums

    enum CloseMode;

    // construction

    Pipe();
    Pipe(const Pipe& pipe);

    // methods

    Pipe&
    operator=(const Pipe& pipe);

    int
    writeBytes(
        const void* buffer,
        int length
        );

    int
    readBytes(
        void* buffer,
        int length
        );

    Handle
    readHandle() const;

    Handle
    writeHandle() const;

    void
    close(CloseMode mode = CLOSE_BOTH);
};

Detailed Documentation

This class implements an anonymous pipe.

Pipes are a common method of inter-process communication - on Unix, pipes are the oldest form of IPC.

A pipe is a half-duplex communication channel, which means that data only flows in one direction. Pipes have a read-end and a write-end. One process writes to the pipe and another process reads the data written by its peer. Read and write operations are always synchronous. A read will block until data is available and a write will block until the reader reads the data.

The sendBytes() and readBytes() methods of Pipe are usually used through a PipeOutputStream or PipeInputStream and are not called directly.

Pipe objects have value semantics; the actual work is delegated to a reference-counted PipeImpl object.

Typedefs

typedef PipeImpl::Handle Handle

The read/write handle or file descriptor.

Construction

Pipe()

Creates the Pipe.

Throws a CreateFileException if the pipe cannot be created.

Pipe(const Pipe& pipe)

Creates the Pipe using the PipeImpl from another one.

Methods

Pipe&
operator=(const Pipe& pipe)

Releases the Pipe ‘s PipeImpl and assigns another one.

int
writeBytes(
    const void* buffer,
    int length
    )

Sends the contents of the given buffer through the pipe.

Blocks until the receiver is ready to read the data.

Returns the number of bytes sent.

Throws a WriteFileException if the data cannot be written.

int
readBytes(
    void* buffer,
    int length
    )

Receives data from the pipe and stores it in buffer.

Up to length bytes are received. Blocks until data becomes available.

Returns the number of bytes received, or 0 if the pipe has been closed.

Throws a ReadFileException if nothing can be read.

Handle
readHandle() const

Returns the read handle or file descriptor for the Pipe.

For internal use only.

Handle
writeHandle() const

Returns the write handle or file descriptor for the Pipe.

For internal use only.

void
close(CloseMode mode = CLOSE_BOTH)

Depending on the argument, closes either the reading end, the writing end, or both ends of the Pipe.