Provided by: libcommoncpp2-doc_1.8.1-10_all 
NAME
ost::Buffer - The buffer class represents an IPC service that is built upon a buffer of
fixed capacity that can be used to transfer objects between one or more producer and
consumer threads.
SYNOPSIS
#include <buffer.h>
Inherits ost::Conditional.
Inherited by ost::FixedBuffer.
Public Member Functions
Buffer (size_t capacity)
Create a buffer object of known capacity.
virtual ~Buffer ()
In derived functions, may be used to free the actual memory used to hold buffered
data.
size_t getSize (void)
Return the capacity of the buffer as specified at creation.
size_t getUsed (void)
Return the current capacity in use for the buffer.
size_t wait (void *buf, timeout_t timeout=0)
Let one or more threads wait for an object to become available in the buffer.
size_t post (void *buf, timeout_t timeout=0)
Post an object into the buffer and enable a waiting thread to receive it.
size_t peek (void *buf)
Peek at the current content (first object) in the buffer.
virtual bool isValid (void)
New virtual to test if buffer is a valid object.
Static Public Attributes
static const size_t timeout
value to return when a timed operation returned with a timeout.
Protected Member Functions
virtual size_t onPeek (void *buf)=0
Invoke derived class buffer peeking method.
virtual size_t onWait (void *buf)=0
Invoke derived class object request from buffer.
virtual size_t onPost (void *buf)=0
Invoke derived class posting of object to buffer.
Related Functions
(Note that these are not member functions.)
size_t get (Buffer &b, void *o, timeout_t t=0)
size_t put (Buffer &b, void *o, timeout_t t=0)
size_t peek (Buffer &b, void *o)
Detailed Description
The buffer class represents an IPC service that is built upon a buffer of fixed capacity
that can be used to transfer objects between one or more producer and consumer threads.
Producer threads post objects into the buffer, and consumer threads wait for and receive
objects from the buffer. Semaphores are used to to block the buffer from overflowing and
indicate when there is data available, and mutexes are used to protect multiple consumers
and producer threads from stepping over each other.
The buffer class is an abstract class in that the actual data being buffered is not
directly specified within the buffer class itself. The buffer class should be used as a
base class for a class that actually impliments buffering and which may be aware of the
data types actually are being buffered. A template class could be created based on buffer
for this purpose. Another possibility is to create a class derived from both Thread and
Buffer which can be used to implement message passing threads.
Author
David Sugar dyfet@ostel.com
Producer/Consumer buffer for use between threads.
Constructor & Destructor Documentation
ost::Buffer::Buffer (size_t capacity)
Create a buffer object of known capacity.
Parameters
capacity is the integer capacity of the buffer.
virtual ost::Buffer::~Buffer () [virtual]
In derived functions, may be used to free the actual memory used to hold buffered data.
Member Function Documentation
size_t ost::Buffer::getSize (void) [inline]
Return the capacity of the buffer as specified at creation.
Returns
size of buffer.
size_t ost::Buffer::getUsed (void) [inline]
Return the current capacity in use for the buffer. Free space is technically getSize() -
getUsed().
Returns
integer used capacity of the buffer.
See also
getSize
virtual bool ost::Buffer::isValid (void) [virtual]
New virtual to test if buffer is a valid object.
Returns
true if object is valid.
Reimplemented in ost::FixedBuffer.
virtual size_t ost::Buffer::onPeek (void * buf) [protected], [pure virtual]
Invoke derived class buffer peeking method.
Returns
size of object found.
Parameters
buf pointer to copy contents of head of buffer to.
Implemented in ost::FixedBuffer.
virtual size_t ost::Buffer::onPost (void * buf) [protected], [pure virtual]
Invoke derived class posting of object to buffer.
Returns
size of object posted.
Parameters
buf pointer to object being posted to the buffer.
Implemented in ost::FixedBuffer.
virtual size_t ost::Buffer::onWait (void * buf) [protected], [pure virtual]
Invoke derived class object request from buffer.
Returns
size of object returned.
Parameters
buf pointer to hold object returned from the buffer.
Implemented in ost::FixedBuffer.
size_t ost::Buffer::peek (void * buf)
Peek at the current content (first object) in the buffer.
Returns
size of object in the buffer.
Parameters
buf pointer to store object found in the buffer.
Referenced by peek().
size_t ost::Buffer::post (void * buf, timeout_t timeout = 0)
Post an object into the buffer and enable a waiting thread to receive it.
Returns
size of object posted in bytes.
Parameters
buf pointer to object to store in the buffer.
timeout time to wait.
Referenced by put().
size_t ost::Buffer::wait (void * buf, timeout_t timeout = 0)
Let one or more threads wait for an object to become available in the buffer. The waiting
thread(s) will wait forever if no object is ever placed into the buffer.
Returns
size of object passed by buffer in bytes.
Parameters
buf pointer to store object retrieved from the buffer.
timeout time to wait.
Referenced by get().
Friends And Related Function Documentation
size_t get (Buffer & b, void * o, timeout_t t = 0) [related]
References wait().
size_t peek (Buffer & b, void * o) [related]
Examples
SampleSocketPort.cpp.
References peek().
size_t put (Buffer & b, void * o, timeout_t t = 0) [related]
References post().
Member Data Documentation
const size_t ost::Buffer::timeout [static]
value to return when a timed operation returned with a timeout.
Author
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