fair.h File Reference

Helps with determining if resources can be fairly allocated given current conditions. More...

#include "qev.h"

Go to the source code of this file.

Typedefs
typedef struct qev_fair	qev_fair_t
	Don't even try modifying this.

Functions
qev_fair_t *	qev_fair_new (const gchar *name, const guint total, const gsize pressure, const gsize min)
	Create a new limited pool that needs allocating. More...
void	qev_fair_free (qev_fair_t *fair)
	Free the fairness pool. More...
gboolean	qev_fair_use (qev_fair_t *fair, const gsize in_use, const gsize wants)
	Determines if the given number of resources may be used. More...
gboolean	qev_fair_used (qev_fair_t *fair, const gsize in_use, const gsize added)
	Like qev_fair_use, except this one just tells the fair pool that the number of resources has already been allocated. More...
void	qev_fair_return (qev_fair_t *fair, const gsize giving)
	Return used resources to the pool. More...
gsize	qev_fair_get_usage (qev_fair_t *fair)
	Get how much of the shared resource is currently in use.
void	qev_fair_set_total (qev_fair_t *fair, const gsize total)
	Set the total number of things the pool may allocate. More...
void	qev_fair_set_pressure (qev_fair_t *fair, const gsize pressure)
	Change the pressure of the pool. More...
void	qev_fair_set_min (qev_fair_t *fair, const gsize min)
	Change the min allocation for the pool. More...

Detailed Description

Helps with determining if resources can be fairly allocated given current conditions.

Typically, this is used for allocating limited resources to clients.

Author

Andrew Stone andre.nosp@m.w@cl.nosp@m.ovar..nosp@m.com

Copyright

2012-2014 Clear Channel Inc.

Function Documentation

void qev_fair_free

(

qev_fair_t *

fair

)

Free the fairness pool.

Parameters

fair	The pool to free

qev_fair_t* qev_fair_new	(	const gchar *	name,
		const guint	total,
		const gsize	pressure,
		const gsize	min
	)

Create a new limited pool that needs allocating.

Note

Because pools use stats, they must be setup completely before the server is run.

Parameters

name	The name of this pool. A stat will be created with this name that reports the status of this pool.
total	The total number of resources that this pool may distribute
pressure	At what percent of total pressure should be applied to bring resource usage back down
min	The smallest amount of resources that a single client has access to, regardless of memory pressure. If the number of allocated resources is greater than total, then this will be ignored.

Returns

The fairness allocation pool.

void qev_fair_return	(	qev_fair_t *	fair,
		const gsize	giving
	)

Return used resources to the pool.

Parameters

fair	The fair pool to return resources to
giving	The number of resources that are being given up

void qev_fair_set_min	(	qev_fair_t *	fair,
		const gsize	min
	)

Change the min allocation for the pool.

Parameters

fair	The pool to update
min	The new min value (will be constrained to be less than total)

void qev_fair_set_pressure	(	qev_fair_t *	fair,
		const gsize	pressure
	)

Change the pressure of the pool.

Parameters

fair	The pool to update
pressure	The new pressure for the pool (0-100)

void qev_fair_set_total	(	qev_fair_t *	fair,
		const gsize	total
	)

Set the total number of things the pool may allocate.

Parameters

fair	The pool to update
total	The new total resource count for the pool

gboolean qev_fair_use	(	qev_fair_t *	fair,
		const gsize	in_use,
		const gsize	wants
	)

Determines if the given number of resources may be used.

Note

This only gives a fuzzy yes/no. It's possible for this to give out more than the number of available resources as no locks are used. In reality, it will only really give out a slightly-higher number of resources.

Parameters

fair	The fair pool to allocate from
in_use	How many resources this user has already used from the pool
wants	How many additional resources the user wants.

Returns

If the user may, in fact, allocate the request resources.

gboolean qev_fair_used	(	qev_fair_t *	fair,
		const gsize	in_use,
		const gsize	added
	)

Like qev_fair_use, except this one just tells the fair pool that the number of resources has already been allocated.

Like qev_fair_use, this will return if the number of resources now in use is too many.

Parameters

fair	The fair pool to allocate from
in_use	How many resources this user has already used from the pool
added	How many additional resources the user took

Returns

If the user is now using too many of the resource.