NullDataIO Class Reference

Data I/O equivalent to /dev/null. More...

#include <NullDataIO.h>

Inheritance diagram for NullDataIO:

Inheritance graph
[legend]
List of all members.

Public Types

enum  { IO_SEEK_SET = 0, IO_SEEK_CUR, IO_SEEK_END, NUM_IO_SEEKS }
 Values to pass in to DataIO::Seek()'s second parameter. More...

Public Member Functions

 NullDataIO ()
 Default Constructor.
virtual ~NullDataIO ()
 Virtual Destructor, to keep C++ honest.
virtual int32 Read (void *buffer, uint32 size)
 No-op method, always returns zero (except if Shutdown() was called).
virtual int32 Write (const void *buffer, uint32 size)
 No-op method, always returns (size) (except if Shutdown() was called).
virtual status_t Seek (int64, int)
 This method always returns B_ERROR.
virtual int64 GetPosition () const
 This method always return -1.
virtual void FlushOutput ()
 No-op method.
virtual void Shutdown ()
 Disable us!
virtual const SocketRefGetSelectSocket () const
 Can't select on this one, sorry.
virtual uint64 GetOutputStallLimit () const
 Returns the max number of microseconds to allow for an output stall, before presuming that the I/O is hosed.
virtual status_t GetReadByteTimeStamp (int32 whichByte, uint64 &retStamp) const
 Optional interface for returning information on when a given byte returned by the previous Read() call was received.
virtual bool HasBufferedOutput () const
 Optional: If your DataIO subclass is holding buffered data that it wants to output as soon as possible but hasn't been able to yet, then override this method to return true, and that will cause FlushBufferedOutput() to be called ASAP.
virtual void WriteBufferedOutput ()
 Optional: If this DataIO is holding any buffered output data, this method should be implemented to Write() as much of that data as possible.
uint32 WriteFully (const void *buffer, uint32 size)
 Convenience method: Calls Write() in a loop until the entire buffer is written, or until an error occurs.
uint32 ReadFully (void *buffer, uint32 size)
 Convenience method: Calls Read() in a loop until the entire buffer is written, or until an error occurs.
virtual int64 GetLength ()
 Convenience method: Determines the length of this DataIO stream by Seek()'ing to the end of the stream, recording the current seek position, and then Seek()'ing back to the previous position in the stream.
void IncrementRefCount () const
 Increments the counter and returns true iff the new value is zero.
bool DecrementRefCount () const
 Decrements the counter and returns true iff the new value is zero.
void SetManager (AbstractObjectManager *manager)
 Sets the recycle-pointer for this object.
AbstractObjectManagerGetManager () const
 Returns this object's current recyler pointer.
uint32 GetRefCount () const
 Returns this object's current reference count.

Detailed Description

Data I/O equivalent to /dev/null.

Definition at line 13 of file NullDataIO.h.


Member Enumeration Documentation

anonymous enum [inherited]

Values to pass in to DataIO::Seek()'s second parameter.

Enumerator:
IO_SEEK_SET  Tells Seek that its value specifies bytes-after-beginning-of-stream.
IO_SEEK_CUR  Tells Seek that its value specifies bytes-after-current-stream-position.
IO_SEEK_END  Tells Seek that its value specifies bytes-after-end-of-stream (you'll usually specify a non-positive seek value with this).
NUM_IO_SEEKS  A guard value.

Definition at line 15 of file DataIO.h.


Member Function Documentation

virtual int32 NullDataIO::Read ( void *  buffer,
uint32  size 
) [inline, virtual]

No-op method, always returns zero (except if Shutdown() was called).

Parameters:
buffer Points to a buffer to read bytes into (ignored).
size Number of bytes in the buffer (ignored).
Returns:
zero.

Implements DataIO.

Definition at line 28 of file NullDataIO.h.

virtual int32 NullDataIO::Write ( const void *  buffer,
uint32  size 
) [inline, virtual]

No-op method, always returns (size) (except if Shutdown() was called).

Parameters:
buffer Points to a buffer to write bytes from (ignored).
size Number of bytes in the buffer (ignored).
Returns:
(size).

Implements DataIO.

Definition at line 36 of file NullDataIO.h.

virtual void NullDataIO::FlushOutput (  )  [inline, virtual]

No-op method.

This method doesn't do anything at all.

Implements DataIO.

Definition at line 52 of file NullDataIO.h.

virtual uint64 DataIO::GetOutputStallLimit (  )  const [inline, virtual, inherited]

Returns the max number of microseconds to allow for an output stall, before presuming that the I/O is hosed.

Default implementation returns MUSCLE_TIME_NEVER, aka no limit.

Reimplemented in FailoverDataIO, MultiDataIO, PacketizedDataIO, TCPSocketDataIO, and XorDataIO.

Definition at line 72 of file DataIO.h.

Referenced by MultiDataIO::GetOutputStallLimit(), and FailoverDataIO::GetOutputStallLimit().

virtual status_t DataIO::GetReadByteTimeStamp ( int32  whichByte,
uint64 &  retStamp 
) const [inline, virtual, inherited]

Optional interface for returning information on when a given byte returned by the previous Read() call was received.

Not implemented by default, and not implemented by any of the standard MUSCLE DataIO subclasses. (Used by an LCS dataIO class that needs precision timing)

Parameters:
whichByte Index of the byte in the previously returned read-buffer that you are interested in.
retStamp On success, this value is set to the timestamp of the byte.
Returns:
B_NO_ERROR if a timestamp was written into (retStamp), otherwise B_ERROR. Default implementation always returns B_ERROR.

Reimplemented in FailoverDataIO, MultiDataIO, and XorDataIO.

Definition at line 114 of file DataIO.h.

Referenced by MultiDataIO::GetReadByteTimeStamp(), and FailoverDataIO::GetReadByteTimeStamp().

virtual bool DataIO::HasBufferedOutput (  )  const [inline, virtual, inherited]

Optional: If your DataIO subclass is holding buffered data that it wants to output as soon as possible but hasn't been able to yet, then override this method to return true, and that will cause FlushBufferedOutput() to be called ASAP.

Default implementation always returns false.

Reimplemented in FailoverDataIO, MultiDataIO, PacketizedDataIO, and XorDataIO.

Definition at line 123 of file DataIO.h.

Referenced by FailoverDataIO::HasBufferedOutput().

virtual void DataIO::WriteBufferedOutput (  )  [inline, virtual, inherited]

Optional: If this DataIO is holding any buffered output data, this method should be implemented to Write() as much of that data as possible.

Default implementation is a no-op.

Reimplemented in FailoverDataIO, MultiDataIO, PacketizedDataIO, and XorDataIO.

Definition at line 130 of file DataIO.h.

Referenced by FailoverDataIO::WriteBufferedOutput().

uint32 DataIO::WriteFully ( const void *  buffer,
uint32  size 
) [inherited]

Convenience method: Calls Write() in a loop until the entire buffer is written, or until an error occurs.

This method should only be used in conjunction with blocking I/O; it will not work reliably with non-blocking I/O.

Parameters:
buffer Pointer to the first byte of the buffer to write data from.
size Number of bytes to write
Returns:
The number of bytes that were actually written. On success, This will be equal to (size). On failure, it will be a smaller value.

uint32 DataIO::ReadFully ( void *  buffer,
uint32  size 
) [inherited]

Convenience method: Calls Read() in a loop until the entire buffer is written, or until an error occurs.

This method should only be used in conjunction with blocking I/O; it will not work reliably with non-blocking I/O.

Parameters:
buffer Pointer to the first byte of the buffer to place the read data into.
size Number of bytes to read
Returns:
The number of bytes that were actually read. On success, This will be equal to (size). On failure, it will be a smaller value.

virtual int64 DataIO::GetLength (  )  [virtual, inherited]

Convenience method: Determines the length of this DataIO stream by Seek()'ing to the end of the stream, recording the current seek position, and then Seek()'ing back to the previous position in the stream.

Of course this only works with DataIOs that support seeking and have a fixed length.

Returns:
The total length of this DataIO in bytes, or -1 on error.

Reimplemented in PacketizedDataIO.

void RefCountable::IncrementRefCount (  )  const [inline, inherited]

Increments the counter and returns true iff the new value is zero.

Thread safe.

Definition at line 32 of file RefCount.h.

References AtomicCounter::AtomicIncrement().

bool RefCountable::DecrementRefCount (  )  const [inline, inherited]

Decrements the counter and returns true iff the new value is zero.

Thread safe.

Definition at line 35 of file RefCount.h.

References AtomicCounter::AtomicDecrement().

void RefCountable::SetManager ( AbstractObjectManager manager  )  [inline, inherited]

Sets the recycle-pointer for this object.

If set to non-NULL, this pointer is used by the ObjectPool class to recycle this object when it is no longer in use, so as to avoid the overhead of having to delete it and re-create it later on. The RefCountable class itself does nothing with this pointer. Default value is NULL.

Parameters:
manager Pointer to the new manager object to use, or NULL to use no manager.

Definition at line 44 of file RefCount.h.

uint32 RefCountable::GetRefCount (  )  const [inline, inherited]

Returns this object's current reference count.

Note that the value returned by this method is volatile in multithreaded environments, so it may already be wrong by the time it is returned. Be careful!

Definition at line 54 of file RefCount.h.

References AtomicCounter::GetCount().


The documentation for this class was generated from the following file:
Generated on Thu Jun 5 17:48:16 2008 for MUSCLE by  doxygen 1.5.1