MultiDataIO Class Reference

This DataIO holds a list of one or more other DataIO objects, and passes any calls made to all the sub-DataIOs. More...

#include <MultiDataIO.h>

Inheritance diagram for MultiDataIO:

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

 MultiDataIO ()
 Default Constructor.
virtual ~MultiDataIO ()
 Virtual destructor, to keep C++ honest.
virtual int32 Read (void *buffer, uint32 size)
 Implemented to read data from the first held DataIO only.
virtual int32 Write (const void *buffer, uint32 size)
 Calls Write() on all our held sub-DataIOs have Seek() called on them instead, to simulate a read without actually having to read their data.
virtual status_t Seek (int64 offset, int whence)
 Seek to a given position in the I/O stream.
virtual int64 GetPosition () const
 Should return the current position, in bytes, of the stream from its start position, or -1 if the current position is not known.
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 void FlushOutput ()
 Flushes the output buffer, if possible.
virtual void Shutdown ()
 Closes the connection.
virtual const SocketRefGetSelectSocket () const
 If this DataIO is usable with select(), this method should return the SocketRef object containing the file descriptor to select on for this DataIO.
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.
const Queue< DataIORef > & GetChildDataIOs () const
 Returns a read-only reference to our list of child DataIO objects.
Queue< DataIORef > & GetChildDataIOs ()
 Returns a read/write reference to our list of child DataIO objects.
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

This DataIO holds a list of one or more other DataIO objects, and passes any calls made to all the sub-DataIOs.

If an error occurs on any of the sub-objects, the call will error out. This class can be useful when implementing RAID-like behavior.

Definition at line 15 of file MultiDataIO.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.


Constructor & Destructor Documentation

MultiDataIO::MultiDataIO (  )  [inline]

Default Constructor.

Be sure to add some child DataIOs to our Queue of DataIOs (as returned by GetChildDataIOs()) so that this object will do something useful!

Definition at line 21 of file MultiDataIO.h.


Member Function Documentation

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

Implemented to read data from the first held DataIO only.

The other DataIOs will have Seek() called on them instead, to simulate a read without actually having to read their data (since we only have one memory-buffer to place it in anyway).

Implements DataIO.

virtual status_t MultiDataIO::Seek ( int64  offset,
int  whence 
) [inline, virtual]

Seek to a given position in the I/O stream.

May not be supported by a DataIO subclass, in which case B_ERROR will always be returned.

Parameters:
offset Byte offset to seek to or by (depending on the next arg)
whence Set this to IO_SEEK_SET if you want the offset to be relative to the start of the stream; or to IO_SEEK_CUR if it should be relative to the current stream position, or IO_SEEK_END if it should be relative to the end of the stream.
Returns:
B_NO_ERROR on success, or B_ERROR on failure or if unsupported.

Implements DataIO.

Definition at line 38 of file MultiDataIO.h.

virtual uint64 MultiDataIO::GetOutputStallLimit (  )  const [inline, virtual]

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 from DataIO.

Definition at line 40 of file MultiDataIO.h.

References DataIO::GetOutputStallLimit().

virtual void MultiDataIO::FlushOutput (  )  [virtual]

Flushes the output buffer, if possible.

For some implementations, this is a no-op. For others (e.g. TCPSocketDataIO) this can be called to reduced latency of outgoing data blocks.

Implements DataIO.

virtual void MultiDataIO::Shutdown (  )  [inline, virtual]

Closes the connection.

After calling this method, the DataIO object should not be used any more.

Implements DataIO.

Definition at line 44 of file MultiDataIO.h.

virtual const SocketRef& MultiDataIO::GetSelectSocket (  )  const [inline, virtual]

If this DataIO is usable with select(), this method should return the SocketRef object containing the file descriptor to select on for this DataIO.

If this DataIO isn't usable with select(), then this method should return GetNullSocket().

Note that the only thing you are allowed to do with the returned file descriptor is pass it to select(). For all other operations, use the appropriate methods in the DataIO interface. If you attempt to do any other I/O operations on this file descriptor directly, the results are non-portable and undefined and will probably break your program.

Implements DataIO.

Definition at line 46 of file MultiDataIO.h.

References DataIO::GetSelectSocket().

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

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 from DataIO.

Definition at line 48 of file MultiDataIO.h.

References DataIO::GetReadByteTimeStamp().

virtual bool MultiDataIO::HasBufferedOutput (  )  const [virtual]

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 from DataIO.

virtual void MultiDataIO::WriteBufferedOutput (  )  [virtual]

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 from DataIO.

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 17:48:14 2008 for MUSCLE by  doxygen 1.5.1