v0.44.1

What changed

OpenOptions and lock_timeout_ms for Database::open_with_options

New opt-in knob for cross-process lock acquisition. Default 0 keeps the historical fail-fast behavior; pass OpenOptions { lock_timeout_ms: 5_000 } for SQLite-style busy_timeout semantics with 1ms, then 10ms, then 50ms backoff against a hard deadline. Lets multiple writers commit cleanly against the same database instead of the second opener seeing locked by another process.

create* constructors now refuse to clobber an existing database

Database::create, create_encrypted, create_with_key, create_with_credentials, and create_encrypted_with_credentials now return MongrelError::InvalidArgument("database already exists at <path>; use Database::open() to open it, or remove the directory first") when the on-disk CATALOG file is present. Previously these would silently overwrite a populated directory, destroying the catalog and any encryption keys. Use Database::open* to open an existing database.

Lock retry respects error class

The cross-process lock retry loop now only treats WouldBlock as retryable. Other I/O errors (PermissionDenied, NotFound, etc.) bubble up immediately instead of being treated as "locked, try again" and looping or hiding the real problem.

Tests

• New crates/mongreldb-core/tests/cross_process_lock.rs: 5 tests covering fail-fast, retry-until-acquired, retry-with-no-timeout, retry-after-engine-holder-releases, and a 4-writer subprocess harness that commits 100 rows cleanly with the new lock_timeout_ms knob.
• New database_basic.rs cases for the reject_existing_database guard across plain, encrypted, and encrypted + credentialed paths.
• Writer subprocess PK fixed from idx to writer_id * rows + idx so parallel writers no longer collide on the primary key.

Misc

• OpenOptions now derives Default (was a hand-rolled impl Default).
• fail_fast_default_rejects_concurrent_open timing slack bumped 500ms to 2s to stop CI flake on slow machines.

Full Changelog: v0.44.0...v0.44.1