Enum CachePolicy 

pub enum CachePolicy {
    Auto,
    Refresh,
    ReadOnly,
    Only,
    Off,
}

How an open may use the snapshot cache.

One explicit axis rather than a pair of booleans, because “did this answer touch the filesystem” and “did it leave a trace” are the two questions a caller actually has, and a boolean pair can express combinations that have no meaning.

Variants

Auto

Read the snapshot, revalidate it, and write it back when the scan is complete.

A root has one cache path, and its snapshot carries the scan scope that wrote it. A read under another scope normally treats that snapshot as absent and scans cold. The lawful exception is a controls-off request with the same entry identity: it projects a controls-on snapshot into the requested blind scope and never replaces the stronger image with that projection.

Every default request observes .gitignore control state – the one-shot fdu <dir> and prepare_report, fdu --watch <dir>, and a default open – so they share one scope: an open or a watch starts warm from a one-shot report’s snapshot, and a report that reads the snapshot, as content analysis does, starts warm from theirs. A request that turns ScanConfig::read_controls off is a second scope, but every route can start from a default snapshot by discarding its control tier while loading. A summary-only report that turned observation off saves nothing and replaces nothing.

Refresh

Ignore any snapshot, scan cold, and rewrite it. The benchmark control.

ReadOnly

Read and revalidate, but never write. A warm answer that leaves no trace.

Only

Answer from the snapshot alone, without touching the tree.

Fails when no usable snapshot exists: there is no data to answer with, and silently falling back to a scan would make the fast path unpredictable.

Off

Ignore the snapshot entirely and leave nothing behind.

Implementations

impl CachePolicy

pub fn writes(self) -> bool

Whether this policy may write a snapshot back.

Public because a caller deciding whether to prepare a cache directory, or to warn that a run will leave nothing behind, is asking about the policy it was handed – and the alternative is matching on the variants, which is the same knowledge copied into every caller.

Trait Implementations

impl Clone for CachePolicy

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for CachePolicy

impl Debug for CachePolicy

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

Formats the value using the given formatter.

impl Default for CachePolicy

fn default() -> Self

Returns the “default value” for a type.

impl Eq for CachePolicy

impl PartialEq for CachePolicy

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for CachePolicy