PQueueChannel Class Reference

#include <qchannel.h>

Inheritance diagram for PQueueChannel:
PChannel PObject

List of all members.

Public Member Functions

Construction

 PQueueChannel (PINDEX queueSize=0)
 ~PQueueChannel ()
Overrides from class PChannel

virtual PBoolean Read (void *buf, PINDEX len)
virtual PBoolean Write (const void *buf, PINDEX len)
virtual PBoolean Close ()
Queue manipulation functions

virtual PBoolean Open (PINDEX queueSize)
PINDEX GetSize () const
 Get the queue size.
PINDEX GetLength () const
 Get the current queue length.

Protected Attributes

PMutex mutex
BYTE * queueBuffer
PINDEX queueSize
PINDEX queueLength
PINDEX enqueuePos
PINDEX dequeuePos
PSyncPoint unempty
PSyncPoint unfull

Detailed Description

Class for implementing a serial queue channel in memory. This implements a simple memory based First In First Out queue. Data written to an instance of the class may be read from the same instance at some later time.

The queue will block the read for the Read Timeout if the queue is empty. Similarly a write will be clocked for Write Timeout if the queue is full.

If there is any data to be read then it returns immediately with those bytes, so you must check the GetLastReadCount() to determine the actual number of bytes read and not rely on the count being passed into the read function.


Constructor & Destructor Documentation

PQueueChannel::PQueueChannel ( PINDEX  queueSize = 0  ) 

Create a new queue channel with the specified maximum size.

Parameters:
queueSize Queue size
PQueueChannel::~PQueueChannel (  ) 

Delete queue and release memory used.


Member Function Documentation

virtual PBoolean PQueueChannel::Close (  )  [virtual]

Close the file channel.

Returns:
PTrue if close was OK.

Reimplemented from PChannel.

PINDEX PQueueChannel::GetLength (  )  const [inline]

Get the current queue length.

References queueLength.

PINDEX PQueueChannel::GetSize (  )  const [inline]

Get the queue size.

virtual PBoolean PQueueChannel::Open ( PINDEX  queueSize  )  [virtual]

Open a queue, allocating the queueSize bytes.

Parameters:
queueSize Queue size
virtual PBoolean PQueueChannel::Read ( void *  buf,
PINDEX  len 
) [virtual]

Low level read from the file channel. The read timeout is ignored for file I/O. The GetLastReadCount() function returns the actual number of bytes read.

The GetErrorCode() function should be consulted after Read() returns PFalse to determine what caused the failure.

Returns:
PTrue indicates that at least one character was read from the channel. PFalse means no bytes were read due to timeout or some other I/O error.
Parameters:
buf Pointer to a block of memory to receive the read bytes.
len Maximum number of bytes to read into the buffer.

Reimplemented from PChannel.

virtual PBoolean PQueueChannel::Write ( const void *  buf,
PINDEX  len 
) [virtual]

Low level write to the file channel. The write timeout is ignored for file I/O. The GetLastWriteCount() function returns the actual number of bytes written.

The GetErrorCode() function should be consulted after Write() returns PFalse to determine what caused the failure.

Returns:
PTrue if at least len bytes were written to the channel.
Parameters:
buf Pointer to a block of memory to write.
len Number of bytes to write.

Reimplemented from PChannel.


Member Data Documentation

PINDEX PQueueChannel::dequeuePos [protected]
PINDEX PQueueChannel::enqueuePos [protected]
BYTE* PQueueChannel::queueBuffer [protected]
PINDEX PQueueChannel::queueLength [protected]

Referenced by GetLength().

PINDEX PQueueChannel::queueSize [protected]

The documentation for this class was generated from the following file:
Generated on Fri May 28 07:32:34 2010 for PTLib by  doxygen 1.6.3