Database.Muesli.Backend.File

Binary seekable file backend that uses Prelude functions.

Only one process at a time can safely use the files, but file locking is not yet implemented.

Documentation

data FileHandle

newtype wrapper around Handle, so that we can accomodate other instances.

Instances

Eq FileHandle

Show FileHandle

DataHandle FileHandle

DbHandle FileHandle

data FileLogState

Implements a stateful binary log file backend.

It uses a FileHandle for both the log and data files.

Constructors

FileLogState

Fields

flogHandle :: FileHandle

The Handle for the log file

flogPos :: DocAddress

Current valid position in the (quasi)append-only log file. Located at address 0 of the log file, it is the last write performd as part of a batch logAppend operation, which makes it atomic.

flogSize :: DocSize

Current size of the log file. logAppend first checks the file size and increases it with minimum 4KB if necessary, then writes the records, and then updates the flogPos.

Instances

Show FileLogState

LogState FileLogState

type LogHandleOf FileLogState = FileHandle

type DataHandleOf FileLogState = FileHandle