Static tantivy::directory::META_LOCK

pub static META_LOCK: Lazy<Lock>

The meta lock file is here to protect the segment files being opened by IndexReader::reload() from being garbage collected. It makes it possible for another process to safely consume our index in-writing. Ideally, we may have prefered RWLock semantics here, but it is difficult to achieve on Windows.

Opening segment readers is a very fast process.