A basic LRU-type algorithm, except that it is adaptive and attempts to avoid evicting pages that have been used more frequently (even if less recently) than other pages. More...

#include "adaptiveLru.h"

Inheritance diagram for AdaptiveLru:

Public Types
enum	LruPagePriority { LPP_Highest = 0, LPP_High = 10, LPP_New = 20, LPP_Normal = 25, LPP_Intermediate = 30, LPP_Low = 40, LPP_TotalPriorities = 50 }

Public Member Functions
	AdaptiveLru (const std::string &name, size_t max_size)

void	begin_epoch ()
	Marks the end of the previous epoch and the beginning of the next one. More...

PN_stdfloat	calculate_exponential_moving_average (PN_stdfloat value, PN_stdfloat average) const

void	consider_evict ()
	Evicts a sequence of objects if the queue is full. More...

size_t	count_active_size () const
	Returns the total size of the pages that were enqueued since the last call to begin_epoch(). More...

void	do_access_page (AdaptiveLruPage *page)
	Marks a page accessed. More...

void	do_add_page (AdaptiveLruPage *page)
	Adds a new page the the LRU. More...

void	do_evict_to (size_t target_size, bool hard_evict)
	Evicts pages until the LRU is within the indicated size. More...

void	do_partial_lru_update (int num_updates)
	This only updates a number of pages up to the specified maximum_updates. More...

void	do_remove_page (AdaptiveLruPage *page)
	Removes a page from the LRU. More...

bool	do_validate ()
	Checks that the LRU is internally consistent. More...

void	evict_to (size_t target_size)
	Evicts a sequence of objects until the queue fits within the indicated target size, regardless of its normal max size. More...

size_t	get_max_size () const
	Returns the max size of all objects that are allowed to be active on the LRU. More...

int	get_max_updates_per_frame () const
	Returns the maximum number of pages the AdaptiveLru will update each frame. More...

size_t	get_total_size () const
	Returns the total size of all objects currently active on the LRU. More...

PN_stdfloat	get_weight () const
	Returns the weight value used to compute the exponential moving average. More...

void	output (std::ostream &out) const

void	set_max_size (size_t max_size)
	Changes the max size of all objects that are allowed to be active on the LRU. More...

void	set_max_updates_per_frame (int max_updates_per_frame)
	Specifies the maximum number of pages the AdaptiveLru will update each frame. More...

void	set_weight (PN_stdfloat weight)
	Specifies the weight value used to compute the exponential moving average. More...

void	update_page (AdaptiveLruPage *page)
	This updates the page's average utilization. More...

bool	validate ()
	Checks that the LRU is internally self-consistent. More...

void	write (std::ostream &out, int indent_level) const

Public Member Functions inherited from Namable
	Namable (const std::string &initial_name="")

void	clear_name ()
	Resets the Namable's name to empty. More...

const std::string &	get_name () const

bool	has_name () const
	Returns true if the Namable has a nonempty name set, false if the name is empty. More...

void	output (std::ostream &out) const
	Outputs the Namable. More...

void	set_name (const std::string &name)

Public Attributes
unsigned int	_current_frame_identifier

LightMutex	_lock

size_t	_max_size

int	_max_updates_per_frame

AdaptiveLruPageDynamicList	_page_array [LPP_TotalPriorities]

AdaptiveLruPageStaticList	_static_list

size_t	_total_size

PN_stdfloat	_weight

Public Attributes inherited from Namable
	get_name

	set_name

Friends
class	AdaptiveLruPage

Additional Inherited Members
Static Public Member Functions inherited from Namable
static TypeHandle	get_class_type ()

static void	init_type ()

Detailed Description

A basic LRU-type algorithm, except that it is adaptive and attempts to avoid evicting pages that have been used more frequently (even if less recently) than other pages.

The interface is designed to be identical to that for SimpleLru, so that it may be used as a drop-in replacement.

Definition at line 45 of file adaptiveLru.h.

Member Function Documentation

◆ begin_epoch()

void AdaptiveLru::begin_epoch ( )

Marks the end of the previous epoch and the beginning of the next one.

This will evict any objects that are pending eviction, and also update any internal bookkeeping.

Definition at line 225 of file adaptiveLru.cxx.

References do_evict_to(), do_partial_lru_update(), ClockObject::get_frame_count, and ClockObject::get_global_clock().

◆ consider_evict()

void AdaptiveLru::consider_evict ( )

inline

Evicts a sequence of objects if the queue is full.

Definition at line 52 of file adaptiveLru.I.

References do_evict_to().

◆ count_active_size()

size_t AdaptiveLru::count_active_size ( ) const

Returns the total size of the pages that were enqueued since the last call to begin_epoch().

Definition at line 204 of file adaptiveLru.cxx.

◆ do_access_page()

void AdaptiveLru::do_access_page ( AdaptiveLruPage * page )

Marks a page accessed.

Definition at line 312 of file adaptiveLru.cxx.

Referenced by AdaptiveLruPage::enqueue_lru().

◆ do_add_page()

void AdaptiveLru::do_add_page ( AdaptiveLruPage * page )

Adds a new page the the LRU.

Definition at line 286 of file adaptiveLru.cxx.

◆ do_evict_to()

void AdaptiveLru::do_evict_to	(	size_t	target_size,
		bool	hard_evict
	)

Evicts pages until the LRU is within the indicated size.

Assumes the lock is already held. If hard_evict is false, does not evict "active" pages that were added within this epoch.

Definition at line 340 of file adaptiveLru.cxx.

Referenced by begin_epoch(), consider_evict(), evict_to(), and set_max_size().

◆ do_partial_lru_update()

void AdaptiveLru::do_partial_lru_update ( int num_updates )

This only updates a number of pages up to the specified maximum_updates.

Assumes the lock is held.

Definition at line 76 of file adaptiveLru.cxx.

Referenced by begin_epoch().

◆ do_remove_page()

void AdaptiveLru::do_remove_page ( AdaptiveLruPage * page )

Removes a page from the LRU.

Definition at line 299 of file adaptiveLru.cxx.

Referenced by AdaptiveLruPage::enqueue_lru().

◆ do_validate()

bool AdaptiveLru::do_validate ( )

Checks that the LRU is internally consistent.

Assume the lock is already held.

Definition at line 392 of file adaptiveLru.cxx.

Referenced by validate().

◆ evict_to()

void AdaptiveLru::evict_to ( size_t target_size )

inline

Evicts a sequence of objects until the queue fits within the indicated target size, regardless of its normal max size.

Definition at line 64 of file adaptiveLru.I.

References do_evict_to().

◆ get_max_size()

size_t AdaptiveLru::get_max_size ( ) const

inline

Returns the max size of all objects that are allowed to be active on the LRU.

Definition at line 28 of file adaptiveLru.I.

Referenced by PreparedGraphicsObjects::get_graphics_memory_limit(), and PreparedGraphicsObjects::set_graphics_memory_limit().

◆ get_max_updates_per_frame()

int AdaptiveLru::get_max_updates_per_frame ( ) const

inline

Returns the maximum number of pages the AdaptiveLru will update each frame.

Definition at line 111 of file adaptiveLru.I.

◆ get_total_size()

size_t AdaptiveLru::get_total_size ( ) const

inline

Returns the total size of all objects currently active on the LRU.

Definition at line 18 of file adaptiveLru.I.

◆ get_weight()

PN_stdfloat AdaptiveLru::get_weight ( ) const

inline

Returns the weight value used to compute the exponential moving average.

Definition at line 93 of file adaptiveLru.I.

◆ set_max_size()

void AdaptiveLru::set_max_size ( size_t max_size )

inline

Changes the max size of all objects that are allowed to be active on the LRU.

If the size is (size_t)-1, there is no limit.

Definition at line 40 of file adaptiveLru.I.

References do_evict_to().

Referenced by PreparedGraphicsObjects::set_graphics_memory_limit().

◆ set_max_updates_per_frame()

void AdaptiveLru::set_max_updates_per_frame ( int max_updates_per_frame )

inline

Specifies the maximum number of pages the AdaptiveLru will update each frame.

This is a performance optimization: keeping this number low limits the impact of the AdaptiveLru's adaptive algorithm.

Definition at line 103 of file adaptiveLru.I.

◆ set_weight()

void AdaptiveLru::set_weight ( PN_stdfloat weight )

inline

Specifies the weight value used to compute the exponential moving average.

Definition at line 85 of file adaptiveLru.I.

◆ update_page()

void AdaptiveLru::update_page ( AdaptiveLruPage * page )

This updates the page's average utilization.

Priority LPP_New is considered to be average usage of 1.0 (which means the page is used once per frame on average). Priorities < LPP_New are for pages used more than once per frame and Priorities > LPP_New are for pages used less than once per frame.

Assumes the lock is held.

Definition at line 111 of file adaptiveLru.cxx.

◆ validate()

bool AdaptiveLru::validate ( )

inline

Checks that the LRU is internally self-consistent.

Returns true if successful, false if there is some problem.

Definition at line 76 of file adaptiveLru.I.

References do_validate().

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

panda/src/gobj/adaptiveLru.h
panda/src/gobj/adaptiveLru.cxx
panda/src/gobj/adaptiveLru.I

Public Types

Public Member Functions

Public Attributes

Friends

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ begin_epoch()

◆ consider_evict()

◆ count_active_size()

◆ do_access_page()

◆ do_add_page()

◆ do_evict_to()

◆ do_partial_lru_update()

◆ do_remove_page()

◆ do_validate()

◆ evict_to()

◆ get_max_size()

◆ get_max_updates_per_frame()

◆ get_total_size()

◆ get_weight()

◆ set_max_size()

◆ set_max_updates_per_frame()

◆ set_weight()

◆ update_page()

◆ validate()