ScheduledQueue Class Reference

ScheduledQueue is a queue with multiple priorities, where each priority is a FIFO list. More...

#include <ScheduledQueue.hxx>

Classes
struct	Band
	This structure contains information about one priority band. More...

Public Member Functions
	ScheduledQueue (unsigned num_bands, const Fixed16 *strides)
	Constructor.
	~ScheduledQueue ()
	Destructor.
Result	next ()
	Get an item from the queue.
Result	next_locked ()
	Get an item from the queue.
OSMutex *	lock ()
	The caller must acquire this lock before using any of the _locked() functions.
void	insert (QMember *item, unsigned prio)
	Adds an entry to the queue.
void	insert_locked (QMember *item, unsigned prio)
	Adds an entry to the queue.
size_t	pending (unsigned prio)
	Get the number of pending items in the queue.
size_t	pending () const
	Get the number of pending items in the queue (all bands total)
bool	empty () const
unsigned	num_prio () const

Private Attributes
OSMutex	lock_
	Protects insert and next operations.
unsigned	numBands_
	How many priority bands we have.
unsigned	numPending_ {0}
	How many queue entries are pending.
Band *	bands_
	The actual priority bands.

Detailed Description

ScheduledQueue is a queue with multiple priorities, where each priority is a FIFO list.

The different priorities are polled according to a weighted stride scheduler instead of in strict numerical priority order.

Definition at line 47 of file ScheduledQueue.hxx.

Constructor & Destructor Documentation

ScheduledQueue()

ScheduledQueue::ScheduledQueue ( unsigned  num_bands, const Fixed16 *  strides  )

inline

Constructor.

Parameters

num_bands	now many priority bands should there be.
strides	is an array of the size num_bands. It contains the stride coefficients (they should all be numbers <= 1. A value of 1 degrades to strict priority order). This array is not used anymore after the constructor returns. A stride of 0.2 means that 20% of all tokens at this level will be allocated to this band, and 80% of the tokens are passed down to lower priorities (bands with higher index).

Definition at line 58 of file ScheduledQueue.hxx.

~ScheduledQueue()

ScheduledQueue::~ScheduledQueue ( )

inline

Destructor.

Definition at line 70 of file ScheduledQueue.hxx.

Member Function Documentation

empty()

bool ScheduledQueue::empty ( ) const

inline

Returns

true if the queue is empty (on all priority bands).

Definition at line 185 of file ScheduledQueue.hxx.

insert()

void ScheduledQueue::insert ( QMember *  item, unsigned  prio  )

inline

Adds an entry to the queue.

It will be added to the end of the given priority band.

Parameters

item	the entry to be added to the queue.
prio	which priority band to add to. 0 = highest priority. Must be within 0 and numBands_ - 1.

Definition at line 150 of file ScheduledQueue.hxx.

insert_locked()

void ScheduledQueue::insert_locked ( QMember *  item, unsigned  prio  )

inline

Adds an entry to the queue.

It will be added to the end of the given priority band. The caller must hold lock().

Parameters

item	the entry to be added to the queue.
prio	which priority band to add to. 0 = highest priority. Must be within 0 and numBands_ - 1.

Definition at line 161 of file ScheduledQueue.hxx.

lock()

OSMutex * ScheduledQueue::lock ( )

inline

The caller must acquire this lock before using any of the _locked() functions.

If the caller needs to do many operations in quick succession, it might be faster to do them under a single lock, i.e. acquire lock() first, then call xxx_locked() repeatedly, then unlock.

Returns

the lock to use for the _locked() functions.

Definition at line 140 of file ScheduledQueue.hxx.

next()

Result ScheduledQueue::next ( )

inline

Get an item from the queue.

The returned item will be according to the priority scheduler.

Returns

the member and the priority from which it came.

Definition at line 78 of file ScheduledQueue.hxx.

next_locked()

Result ScheduledQueue::next_locked ( )

inline

Get an item from the queue.

The returned item will be according to the priority scheduler. The caller must acquire the lock() first.

Returns

the member and the priority from which it came.

Definition at line 87 of file ScheduledQueue.hxx.

num_prio()

unsigned ScheduledQueue::num_prio ( ) const

inline

Returns

the number of available priority bands.

Definition at line 191 of file ScheduledQueue.hxx.

pending() [1/2]

size_t ScheduledQueue::pending ( ) const

inline

Get the number of pending items in the queue (all bands total)

Returns

number of pending items

Definition at line 179 of file ScheduledQueue.hxx.

pending() [2/2]

size_t ScheduledQueue::pending ( unsigned  prio )

inline

Get the number of pending items in the queue.

Parameters

prio	in the list to operate on

Returns

number of pending items in that priority band in the queue

Definition at line 171 of file ScheduledQueue.hxx.

Member Data Documentation

bands_

Band* ScheduledQueue::bands_

private

The actual priority bands.

Definition at line 220 of file ScheduledQueue.hxx.

lock_

OSMutex ScheduledQueue::lock_

private

Protects insert and next operations.

Definition at line 211 of file ScheduledQueue.hxx.

numBands_

unsigned ScheduledQueue::numBands_

private

How many priority bands we have.

Definition at line 214 of file ScheduledQueue.hxx.

numPending_

unsigned ScheduledQueue::numPending_ {0}

private

How many queue entries are pending.

Definition at line 217 of file ScheduledQueue.hxx.

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The documentation for this class was generated from the following file:

• ScheduledQueue.hxx