RWTPCValBufferBasePrioritized< Type, PriorityDecorator > Class Template Reference

Base class that provides producer-consumer synchronization semantics for exchanging prioritized values between cooperating threads. More...

#include <rw/itc/RWTPCValBufferBasePrioritized.h>

Inheritance diagram for RWTPCValBufferBasePrioritized< Type, PriorityDecorator >:

Public Member Functions
virtual	~RWTPCValBufferBasePrioritized (void)
bool	tryWrite (long priority, const Type &value)
void	write (long priority, const Type &value)
RWWaitStatus	write (long priority, const Type &value, unsigned long milliseconds)
Public Member Functions inherited from RWTPCValBufferBaseDecorated< Type, PriorityDecorator >
virtual	~RWTPCValBufferBaseDecorated (void)
RWWaitStatus	peek (Type &result, unsigned long milliseconds)
Type	peek (void)
RWWaitStatus	read (Type &result, unsigned long milliseconds)
Type	read (void)
bool	tryPeek (Type &result)
bool	tryRead (Type &result)
bool	tryWrite (const Type &value)
void	write (const Type &value)
RWWaitStatus	write (const Type &value, unsigned long milliseconds)

Additional Inherited Members
Protected Types inherited from RWTMonitor< RWMutexLock >
typedef RWTLockGuard< RWTMonitor< RWMutexLock > >	LockGuard
typedef RWTTryLockGuard< RWTMonitor< RWMutexLock > >	TryLockGuard
typedef RWTUnlockGuard< RWTMonitor< RWMutexLock > >	UnlockGuard
Protected Member Functions inherited from RWTPCValBufferBase< PriorityDecorator >
virtual	~RWTPCValBufferBase (void)
RWWaitStatus	peek (PriorityDecorator &result, unsigned long milliseconds)
PriorityDecorator	peek (void)
RWWaitStatus	read (PriorityDecorator &result, unsigned long milliseconds)
PriorityDecorator	read (void)
bool	tryPeek (PriorityDecorator &result)
bool	tryRead (PriorityDecorator &result)
bool	tryWrite (const PriorityDecorator &value)
void	write (const PriorityDecorator &value)
RWWaitStatus	write (const PriorityDecorator &value, unsigned long milliseconds)
virtual	~RWPCBufferBase (void)
bool	canRead (void) const
bool	canWrite (void) const
void	close (void)
size_t	entries (void) const
void	flush (void)
size_t	getCapacity (void) const
RWTFunctor< void()>	getCloseCallback (void) const
RWTFunctor< void()>	getEmptyCallback (void) const
RWTFunctor< void()>	getFullCallback (void) const
RWTFunctor< void()>	getOpenCallback (void) const
bool	isOpen (void) const
void	open (void)
size_t	setCapacity (size_t maxCapacity)
void	setCloseCallback (const RWTFunctor< void()> &onCloseCallback)
void	setEmptyCallback (const RWTFunctor< void()> &onEmptyCallback)
void	setFullCallback (const RWTFunctor< void()> &onFullCallback)
void	setOpenCallback (const RWTFunctor< void()> &onOpenCallback)
Protected Member Functions inherited from RWTMonitor< RWMutexLock >
	RWTMonitor (const RWTMonitor< RWMutexLock > &second)
	RWTMonitor (RWStaticCtor)
	RWTMonitor (void)
	~RWTMonitor (void)
void	acquire (void)
bool	isAcquired (void) const
RWTMonitor< RWMutexLock > &	monitor (void) const
RWMutexLock &	mutex (void)
RWTMonitor< RWMutexLock > &	operator= (const RWTMonitor< RWMutexLock > &)
void	release (void)
bool	tryAcquire (void)

Detailed Description

template<class Type, class PriorityDecorator>
class RWTPCValBufferBasePrioritized< Type, PriorityDecorator >

RWTPCValBufferBasePrioritized is the base class for the family of classes that provides producer-consumer synchronization semantics for exchanging prioritized values between cooperating threads.

In the producer-consumer synchronization model, reader threads (consumers) are blocked while a buffer is empty, and writer threads (producers) are blocked while a buffer is full. A buffer is considered full when the number of unread entries equals or exceeds some user-specified maximum capacity.

The write operations provided by this class and its subclasses bind additional data items to each value prior to storing that value in an internal buffer. One of these additional data items, or decorations, is a priority value that is used during write operations to determine a value's insertion point within the buffer, such that the set of unread values will be retrieved in priority order when eventually read from the buffer. The template parameter PriorityDecorator identifies the class that is used to encapsulate both the data value, priority value, and any other decorations as a single object for storage in the internal buffer. The decorator classes used by subclasses to instantiate this class are intended for the Threads Module's internal use, and are not documented as part of the public interface.

Constructor & Destructor Documentation

~RWTPCValBufferBasePrioritized()

template<class Type , class PriorityDecorator >

virtual RWTPCValBufferBasePrioritized< Type, PriorityDecorator >::~RWTPCValBufferBasePrioritized ( void )

virtual

Virtual destructor.

Member Function Documentation

tryWrite()

template<class Type , class PriorityDecorator >

bool RWTPCValBufferBasePrioritized< Type, PriorityDecorator >::tryWrite	(	long	priority,
		const Type &	value )

Inserts a value with the specified priority into the buffer at a position determined by the implementation supplied in derived classes, but only if the value may be written immediately; in other words, only if there is sufficient free capacity.

If the buffer is open and has sufficient capacity to hold another value, this function inserts the value, and returns a value of true to indicate that the write succeeded. If the buffer is open and full, this function immediately returns a value of false to indicate that the write was unsuccessful. If the buffer is closed, this function immediately returns by throwing an RWTHRClosedException.

Calling this function on an full buffer may result in the invocation of the on-full callback functor, if a valid one has been registered. The on-full callback functor is guaranteed to execute only within a writer thread. Calling this function on a full buffer results in the invocation of an on-full callback functor under either of these scenarios:

• The calling thread is waiting on an full buffer when an on-full callback is registered.
• The calling thread is the first to attempt writing to a full buffer in which an on-full callback was previously registered.

Repeated attempts to write to a full buffer does not result in repeated invocations of the callback functor. Once the full buffer is read from, however, it resets the callback trigger. If the buffer again becomes full, the first thread to attempt to write to it causes another invocation of the on-full callback.

While this function guarantees not to block the caller if the buffer is full, it cannot prevent the on-full callback functor, if executed, from indirectly blocking the caller.

This function takes two parameters. The parameter value is a const reference to an instance of the type used to instantiate this template class. The parameter priority is a long that is used to determine the insertion point of the value within the buffer. A value with a greater priority value is positioned to be read before a value of lower priority. Values of equal priority are positioned as determined by the implementation supplied in derived classes.

write() [1/2]

template<class Type , class PriorityDecorator >

void RWTPCValBufferBasePrioritized< Type, PriorityDecorator >::write	(	long	priority,
		const Type &	value )

Inserts a value with the specified priority into the buffer at a position determined by the implementation supplied in derived classes.

If the buffer is open and has sufficient capacity to hold another value, this function inserts the value. If the buffer is open and full, this function blocks the calling thread until the buffer is no longer full (because another thread or threads have read values or have changed the maximum capacity), or until the buffer is closed.

If the buffer is closed while the calling thread is blocked and waiting within this function for room to write, the calling thread is unblocked and the function returns by throwing an RWTHRClosedException.

If the buffer is already closed when this function is called, it immediately returns by throwing an RWTHRClosedException.

Calling this function on an full buffer may result in the invocation of the on-full callback functor, if a valid one has been registered. The on-full callback functor is guaranteed to execute only within a writer thread. Calling this function on a full buffer results in the invocation of an on-full callback functor under either of these scenarios:

• The calling thread is waiting on an full buffer when an on-full callback is registered.
• The calling thread is the first to attempt writing to a full buffer in which an on-full callback was previously registered.

Repeated attempts to write to a full buffer does not result in repeated invocations of the callback functor. Once the full buffer is read from, however, it resets the callback trigger. If the buffer again becomes full, the first thread to attempt to write to it causes another invocation of the on-full callback.

This function takes two parameters. The parameter value is a const reference to an instance of the type used to instantiate this template class. The parameter priority is a long that is used to determine the insertion point of the value within the buffer. A value with a greater priority value is positioned to be read before a value of lower priority. Values of equal priority are positioned as determined by the implementation supplied in derived classes.

write() [2/2]

template<class Type , class PriorityDecorator >

RWWaitStatus RWTPCValBufferBasePrioritized< Type, PriorityDecorator >::write	(	long	priority,
		const Type &	value,
		unsigned long	milliseconds )

Inserts a value with the specified priority into the buffer at a position determined by the implementation supplied in derived classes.

If the buffer is open and has sufficient capacity to hold another value, this function inserts the value and returns RW_THR_COMPLETED to indicate that the write succeeded. If the buffer is open and full, this function blocks the calling thread until the buffer is no longer full (because another thread or threads have read values or have changed the maximum capacity), or until the buffer is closed, or until the specified amount of time passes. If sufficient space does not become available within the specified amount of time, the function returns a value of RW_THR_TIMEOUT.

If the buffer is closed while the calling thread is blocked and waiting within this function for room to write, the calling thread is unblocked and the function returns by throwing an RWTHRClosedException.

If the buffer is already closed when this function is called, the function immediately returns by throwing an RWTHRClosedException.

Calling this function on an full buffer may result in the invocation of the on-full callback functor, if a valid one has been registered. The on-full callback functor is guaranteed to execute only within a writer thread. Calling this function on a full buffer results in the invocation of an on-full callback functor under either of these scenarios:

• The calling thread is waiting on an full buffer when an on-full callback is registered.
• The calling thread is the first to attempt writing to a full buffer in which an on-full callback was previously registered.

Repeated attempts to write to a full buffer does not result in repeated invocations of the callback functor. Once the full buffer is read from, however, it resets the callback trigger. If the buffer again becomes full, the first thread to attempt to write to it causes another invocation of the on-full callback.

While this function guarantees to wait, if necessary, for a period time equal to or greater than the specified number of milliseconds, it cannot guarantee that the thread is actually scheduled for execution at the end of the time-out period. It cannot prevent the on-full callback functor from indirectly blocking the caller for an indefinite period of time.

This function takes three parameters:

• The parameter priority is a long that is used to determine the insertion point of the value within the buffer. A value with a greater priority value is positioned to be read before a value of lower priority. Values of equal priority are positioned to be read as determined by the implementation supplied in derived classes.
• The parameter value is a const reference to an instance of the type used to instantiate this template class.
• The parameter milliseconds is an unsigned long value that specifies the maximum number of milliseconds to wait for the operation to complete.