Enum BackpressureLevel 

pub enum BackpressureLevel {
    Normal = 0,
    Warn = 1,
    Throttle = 2,
    Critical = 3,
    Emergency = 4,
    Shutdown = 5,
}

Backpressure level based on memory/queue pressure.

Six-tier cascade for graceful degradation:

• Normal (< 70%): Accept all operations
• Warn (70-80%): Evict aggressively, emit warnings
• Throttle (80-90%): Rate limit writes (HTTP 429)
• Critical (90-95%): Reject writes, reads only (HTTP 503)
• Emergency (95-98%): Read-only mode, prepare shutdown
• Shutdown (> 98%): Graceful shutdown initiated

Variants

Normal = 0

Warn = 1

Throttle = 2

Critical = 3

Emergency = 4

Shutdown = 5

Implementations

impl BackpressureLevel

pub fn from_pressure(pressure: f64) -> Self

Calculate backpressure level from pressure ratio (0.0 → 1.0)

pub fn should_accept_writes(&self) -> bool

Check if writes should be accepted at this level

pub fn should_accept_reads(&self) -> bool

Check if reads should be accepted at this level

pub fn eviction_multiplier(&self) -> f64

Get eviction multiplier (higher pressure = more aggressive)

pub fn http_status_code(&self) -> Option<u16>

Suggested HTTP status code for this level

pub fn retry_after_secs(&self) -> Option<u64>

Suggested Retry-After header value (seconds)

pub fn description(&self) -> &'static str

Trait Implementations

impl Clone for BackpressureLevel

fn clone(&self) -> BackpressureLevel

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BackpressureLevel

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

Formats the value using the given formatter.

impl Display for BackpressureLevel

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

Formats the value using the given formatter.

impl Ord for BackpressureLevel

fn cmp(&self, other: &BackpressureLevel) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for BackpressureLevel

fn eq(&self, other: &BackpressureLevel) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for BackpressureLevel

fn partial_cmp(&self, other: &BackpressureLevel) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for BackpressureLevel

impl Eq for BackpressureLevel

impl StructuralPartialEq for BackpressureLevel