mypy.fscache

Interface for accessing the file system with automatic caching.

The idea is to cache the results of any file system state reads during a single transaction. This has two main benefits:

• This avoids redundant syscalls, as we won't perform the same OS operations multiple times.
• This makes it easier to reason about concurrent FS updates, as different operations targeting the same paths can't report different state during a transaction.

Note that this only deals with reading state, not writing.

Properties maintained by the API:

• The contents of the file are always from the same or later time compared to the reported mtime of the file, even if mtime is queried after reading a file.
• Repeating an operation produces the same result as the first one during a transaction.
• Call flush() to start a new transaction (flush the caches).

The API is a bit limited. It's easy to add new cached operations, however. You should perform all file system reads through the API to actually take advantage of the benefits.