Enum RetentionPolicy 

pub enum RetentionPolicy {
    KeepAll,
    KeepLatest(usize),
    TimeBased(Duration),
}

Checkpoint 保留策略 — 决定保留多少个。

Variants

KeepAll

保留所有 Checkpoint（默认，与 v0.4 行为一致）

KeepLatest(usize)

仅保留最新的 N 个

TimeBased(Duration)

保留指定时间范围内的 Checkpoint

Implementations

impl RetentionPolicy

pub fn prune_keep(&self) -> Option<usize>

根据策略计算需要保留的数量。

• KeepAll → None（不修剪）
• KeepLatest(n) → Some(n)
• TimeBased → None（需要存储层按时间判断，暂不支援自动修剪）

Trait Implementations

impl Clone for RetentionPolicy

fn clone(&self) -> RetentionPolicy

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for RetentionPolicy

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

Formats the value using the given formatter.

impl Default for RetentionPolicy

fn default() -> RetentionPolicy

Returns the “default value” for a type.

impl Eq for RetentionPolicy

impl PartialEq for RetentionPolicy

fn eq(&self, other: &RetentionPolicy) -> 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 StructuralPartialEq for RetentionPolicy