Struct FileTimes 

pub struct FileTimes<'a> {
    pub source_modified_us: &'a dyn Fn(&str) -> Option<u64>,
    pub doctree_exists: &'a dyn Fn(&str) -> bool,
    pub dependency_modified_us: &'a dyn Fn(&Path) -> Option<u64>,
}

What BuildEnvironment::get_outdated_files needs to know about the filesystem, as the three questions it actually asks — so the computation itself stays pure and the caller decides what “the source of docname” and “the doctree of docname” mean.

Times are microseconds since the Unix epoch, the unit all_docs stores (Sphinx’s _last_modified_time). None means “cannot be stated” — the file is gone, or unstat-able — which is Sphinx’s except OSError: return True: the document is outdated.

Fields

source_modified_us: &'a dyn Fn(&str) -> Option<u64>

Modification time of the document’s own source file.

doctree_exists: &'a dyn Fn(&str) -> bool

Whether the document’s persisted doctree is on disk. Sphinx stats doctreedir/<docname>.doctree; a doctree that exists but can no longer be read is caught later, when the read phase tries to load it, and re-read then.

dependency_modified_us: &'a dyn Fn(&Path) -> Option<u64>

Modification time of one of a document’s dependencies entries.