Struct SourceFingerprint 

pub struct SourceFingerprint {
    pub mtime_ns: u64,
    pub ctime_ns: u64,
    pub file_size: u64,
}

File metadata used to decide whether a source-derived cache entry is fresh.

This is intentionally metadata-only. Callers that need content validation can combine it with their existing content hash, while cheap caches can use the same freshness shape without inventing their own (mtime, size) tuple.

Fields

mtime_ns: u64

Source file modification time as nanoseconds since the Unix epoch.

A value of 0 means the timestamp could not be read. Fast metadata-only cache hits should treat that as unknown and miss conservatively.

ctime_ns: u64

Source file inode change time (ctime) as nanoseconds since the Unix epoch, or 0 when the platform does not expose it.

mtime alone is writer-controlled: an editor, a git checkout, a codemod, or touch -r can restore it byte-for-byte after rewriting a file. When the replacement happens to keep the same length the (mtime, size) pair is unchanged and a metadata-only cache hit serves stale analysis for genuinely different content. ctime moves on every inode write and cannot be restored through the normal filesystem API, so pairing it with mtime makes the metadata-only fast path trustworthy.

Only Unix reports it (stat.st_ctime). Windows keeps 0, which costs the metadata-only fast path (the caller falls through to the read plus content-hash comparison and still hits) until someone wires up FILE_BASIC_INFO.ChangeTime.

file_size: u64

Source file size in bytes.

Implementations

impl SourceFingerprint

pub const fn new(mtime_ns: u64, file_size: u64) -> Self

Build a fingerprint from explicit metadata parts, with no known ctime.

A fingerprint built this way is never trustworthy without content.

pub const fn with_ctime(mtime_ns: u64, ctime_ns: u64, file_size: u64) -> Self

Build a fingerprint from explicit metadata parts, including ctime.

pub fn from_metadata(metadata: &Metadata) -> Self

Build a fingerprint from filesystem metadata.

pub const fn has_known_mtime(self) -> bool

Returns true when the modification time is known.

pub const fn is_trustworthy_without_content(self) -> bool

Returns true when this fingerprint may stand in for the file’s content.

Requires both timestamps: mtime detects the ordinary edit, ctime detects the same-size edit whose mtime was restored. A caller that gets false must fall through to reading the file and comparing content hashes.

Trait Implementations

impl Clone for SourceFingerprint

fn clone(&self) -> SourceFingerprint

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for SourceFingerprint

impl Debug for SourceFingerprint

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for SourceFingerprint

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for SourceFingerprint

impl Hash for SourceFingerprint

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for SourceFingerprint

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for SourceFingerprint

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for SourceFingerprint