lws-adapt.h File Reference

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Functions
LWS_VISIBLE LWS_EXTERN struct lws_adapt *	lws_adapt_create (int num_levels, uint32_t ewma_halflife_short_us, uint32_t ewma_halflife_long_us)
LWS_VISIBLE LWS_EXTERN void	lws_adapt_destroy (struct lws_adapt **padapt)
LWS_VISIBLE LWS_EXTERN void	lws_adapt_report (struct lws_adapt *adapt, int success, lws_usec_t us)
LWS_VISIBLE LWS_EXTERN void	lws_adapt_report_val (struct lws_adapt *adapt, uint64_t val, lws_usec_t us)
LWS_VISIBLE LWS_EXTERN int	lws_adapt_get_level (struct lws_adapt *adapt)
LWS_VISIBLE LWS_EXTERN uint64_t	lws_adapt_get_val (struct lws_adapt *adapt, int level, int is_short)

Function Documentation

lws_adapt_create()

LWS_VISIBLE LWS_EXTERN struct lws_adapt * lws_adapt_create	(	int	num_levels,
		uint32_t	ewma_halflife_short_us,
		uint32_t	ewma_halflife_long_us )

lws_adapt_create() - Create an adaptive performance tracking context

Parameters

num_levels	The number of discrete capability levels (0=Best, num_levels-1=Safest)
ewma_halflife_short_us	Half-life decay for short-term reaction (e.g. 5 seconds)
ewma_halflife_long_us	Half-life decay for long-term recovery (e.g. 60 seconds)

Returns an opaque tracking object. Level 0 is considered the highest quality but most-demanding state. Level N is the safest fallback.

References LWS_EXTERN, and LWS_VISIBLE.

lws_adapt_destroy()

LWS_VISIBLE LWS_EXTERN void lws_adapt_destroy

(

struct lws_adapt **

padapt

)

lws_adapt_destroy() - Destroy the adaptation tracking context

Parameters

padapt

Pointer to the adapt context pointer.

References LWS_EXTERN, and LWS_VISIBLE.

lws_adapt_report()

LWS_VISIBLE LWS_EXTERN void lws_adapt_report	(	struct lws_adapt *	adapt,
		int	success,
		lws_usec_t	us )

lws_adapt_report() - Report success or failure of the current capability cycle

Parameters

adapt	The adaptation context
success	0 if the system failed to meet constraints (lag, frame drop), 1 if it met them
us	Current timestamp in microseconds (e.g. from lws_now_usecs())

Records a data point. The underlying EWMAs will decay older points based on the elapsed time since the previous report.

References LWS_EXTERN, and LWS_VISIBLE.

lws_adapt_report_val()

LWS_VISIBLE LWS_EXTERN void lws_adapt_report_val	(	struct lws_adapt *	adapt,
		uint64_t	val,
		lws_usec_t	us )

lws_adapt_report_val() - Report an arbitrary value tracker for the current capability cycle

Parameters

adapt	The adaptation context
val	The arbitrary value to track via EWMA (e.g., ping duration)
us	Current timestamp in microseconds (e.g. from lws_now_usecs())

Records a data point tracking an arbitrary value.

References LWS_EXTERN, and LWS_VISIBLE.

lws_adapt_get_level()

LWS_VISIBLE LWS_EXTERN int lws_adapt_get_level

(

struct lws_adapt *

adapt

)

lws_adapt_get_level() - Query the recommended capability tier

Parameters

adapt

The adaptation context

Returns the currently recommended level integer (0 ... num_levels-1). If the short-term EWMA falls below a drop threshold, it immediately degrades the recommended internal level. If both the short-term and long-term EWMAs for the lower level are highly stable and the exponential backoff from any previous failure has expired, it recommends an upgrade.

References LWS_EXTERN, and LWS_VISIBLE.

lws_adapt_get_val()

LWS_VISIBLE LWS_EXTERN uint64_t lws_adapt_get_val	(	struct lws_adapt *	adapt,
		int	level,
		int	is_short )

lws_adapt_get_val() - Query the EWMA value for a given level

Parameters

adapt	The adaptation context
level	The level to query
is_short	1 to query the short term EWMA, 0 for the long term EWMA

Returns the currently tracked EWMA value for a specific level.