Struct AdaptiveCachePolicy 

pub struct AdaptiveCachePolicy { /* private fields */ }

Read-only policy object that reads ResourceGuard::pressure() and produces cache directives. Does not own any cache — it only tells other code what to do.

Use AdaptiveCachePolicy::new_with_guard when sharing a ResourceGuard with a builder or other subsystem (recommended). Use AdaptiveCachePolicy::new when the cache policy needs its own independent ceiling.

Implementations

impl AdaptiveCachePolicy

pub fn new(ceiling_fraction: f64) -> Self

Creates a new policy with the given ceiling fraction of system memory.

For example, 0.6 means use 60 % of system memory as the ceiling. Internally delegates to ResourceGuard::auto(ceiling_fraction).

pub fn new_with_guard(guard: ResourceGuard, ceiling_bytes: usize) -> Self

Creates a policy sharing an existing ResourceGuard.

This is the recommended constructor for daemons: one guard governs both the builder’s safety checks AND the cache’s pressure readings, so they never disagree about how much memory is available.

ceiling_bytes must match the guard’s internal ceiling (i.e., the value passed to ResourceGuard::new or computed by auto).

pub fn guard(&self) -> &ResourceGuard

Returns a reference to the underlying ResourceGuard.

pub fn directive(&self) -> CacheDirective

Returns a CacheDirective reflecting the current memory pressure.

⚠ BLOCKING: This call internally invokes ResourceGuard::pressure() which reads /proc/stat twice with a 100 ms sleep between reads on Linux (via raw_entropy() / delta_iowait_ratio()). Do not call this in an async context without spawn_blocking.

Zone mapping

Zone	Pressure	evict_fraction	allow_new_entries	allow_mmap_pin
Green	0–40	0.0	true	true
Yellow	41–70	0.1	true	true
Orange	71–90	0.5	false	false
Red	91–100	1.0	false	false

pub fn pressure(&self) -> u8

Convenience wrapper for ResourceGuard::pressure().

⚠ BLOCKING: See directive for blocking details.

pub fn rss_bytes(&self) -> usize

Returns the current RSS in bytes.

pub fn ceiling_bytes(&self) -> usize

Returns the memory ceiling in bytes that this policy is configured with.

Trait Implementations

impl Debug for AdaptiveCachePolicy

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.