Write ahead logging for rust applications. Write ahead logging is a crucial component for applications requiring data persistence and durability. Many times it is inefficient to flush and sync new data (or modifications to existing data) to on-disk data-structures, like an index. Write-ahead-logging facilitates by ingesting write operations by appending and syncing it to disk and allows applications to pre-process a batch of write-operations and write them to on-disk structures in the most efficient manner.

Goals

• [x] Serialize write operations to an append only journal file.
• [x] Generate monotonically increasing sequence-number and return the same to the application.
• [x] Configurable limit for journal file, beyond which log files are rotate.
• [x] Configurable fsync, for persistence guarantee.
• [x] Iterate over all entries persisted in the log file in monotonically increasing seqno order.
• [x] Range over a subset of entries, specified with start-seqno and end-seqno.
• [x] Wal type is parameterized over a state type S. This is helpful for using Wal type to be used with consensus protocol like Raft.
• [x] Concurrent readers and writers into single log instance.

Concurrency

A single log-instance can be cloned and shared among multiple threads for concurrent writing and reading. All write operations are serialized. While read operations and write-operation are mutually exclusive, concurrent reads are allowed.

Contribution

• Simple workflow. Fork, modify and raise a pull request.
• Before making a PR,
  • Run cargo build to make sure 0 warnings and 0 errors.
  • Run cargo test to make sure all test cases are passing.
  • Run cargo bench to make sure all benchmark cases are passing.
  • Run cargo +nightly clippy --all-targets --all-features to fix clippy issues.
  • Install and run cargo spellcheck to remove common spelling mistakes.
• Developer certificate of origin is preferred.