package irmin-pack

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package irmin-pack
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Abstraction that governs the lifetime of the various files that are part of a pack store (except the branch store).

The file manager handles the files one by one and makes explicit all the interactions between them (except the index which is handled at a high level).

module Io : Io.S

Low level IO abstraction. A typical implementation is unix. This abstraction is meant to be dead simple. Not a lot of documentation is required.

module Control : Control_file.S with module Io = Io

Abstraction for irmin-pack's control file.

module Dict : Append_only_file.S with module Io = Io

Abstraction for irmin-pack's append only files (i.e. suffix and dict).

module Suffix : Append_only_file.S with module Io = Io

Abstraction for irmin-pack's append only files (i.e. suffix and dict).

module Index : sig ... end

An abstraction on top of the index library that exposes an API that better fits the irmin-pack use case.

type t
val control : t -> Control.t
val dict : t -> Dict.t
val suffix : t -> Suffix.t
val index : t -> Index.t
type create_error := [
  1. | Io.create_error
  2. | Io.write_error
  3. | Io.open_error
  4. | Io.mkdir_error
  5. | `Not_a_directory of string
  6. | `Index_failure of string
]
val create_rw : overwrite:bool -> Irmin.Backend.Conf.t -> (t, [> create_error ]) result

Note on SWMR consistency: It is undefined for a reader to attempt an opening before create_rw is over.

Note on crash consistency: Crashing during create_rw leaves the storage in an undefined state.

Note on errors: If create_rw returns an error, the storage is left in an undefined state and some file descriptors might not be closed.

type open_rw_error := [
  1. | `Corrupted_control_file
  2. | `Double_close
  3. | `File_exists of string
  4. | `Index_failure of string
  5. | `Invalid_argument
  6. | `Invalid_layout
  7. | `Io_misc of Control.Io.misc_error
  8. | `Migration_needed
  9. | `No_such_file_or_directory
  10. | `Not_a_directory of string
  11. | `Not_a_file
  12. | `Read_on_closed
  13. | `Read_out_of_bounds
  14. | `Ro_not_allowed
  15. | `Sys_error of string
  16. | `V3_store_from_the_future
  17. | `Write_on_closed
  18. | `Index_failure of string
  19. | `Unknown_major_pack_version of string
  20. | `Inconsistent_store
]
val open_rw : Irmin.Backend.Conf.t -> (t, [> open_rw_error ]) result

Note on SWMR consistency: It is undefined for a reader to attempt and opening during an open_rw.

Note on crash consistency: If open_rw crashes during open_rw_migrate_from_v1_v2, the storage is left in an undefined state. Otherwise the storage is unaffected.

Note on errors: If open_rw returns an error during open_rw_migrate_from_v1_v2, the storage is left in an undefined state. Otherwise the storage is unaffected. Anyhow, some file descriptors might not be closed.

type open_ro_error := [
  1. | `Corrupted_control_file
  2. | `File_exists of string
  3. | `Io_misc of Io.misc_error
  4. | `Migration_needed
  5. | `No_such_file_or_directory
  6. | `Not_a_file
  7. | `Read_on_closed
  8. | `V3_store_from_the_future
  9. | `Index_failure of string
  10. | `Unknown_major_pack_version of string
  11. | `Inconsistent_store
  12. | `Read_out_of_bounds
  13. | `Invalid_argument
  14. | `Inconsistent_store
]
val open_ro : Irmin.Backend.Conf.t -> (t, [> open_ro_error ]) result

Note on SWMR consistency: TODO: doc

Note on crash consistency: The storage is never mutated.

Note on errors: The storage is never mutated. Some file descriptors might not be closed.

type close_error := [
  1. | `Double_close
  2. | `Index_failure of string
  3. | `Io_misc of Io.misc_error
  4. | `Pending_flush
]
val close : t -> (unit, [> close_error ]) result

Close all the files.

This call fails if the append buffers are not in a flushed stated. This situation will most likely never occur because the append buffers will contain data only during the scope of a batch function.

After

type flush_error := [
  1. | `Index_failure of string
  2. | `Io_misc of Io.misc_error
  3. | `Ro_not_allowed
  4. | `Write_on_closed
]
val flush : t -> (unit, [> flush_error ]) result
type reload_error := [
  1. | `Corrupted_control_file
  2. | `Index_failure of string
  3. | `Invalid_argument
  4. | `Io_misc of Io.misc_error
  5. | `Read_on_closed
  6. | `Read_out_of_bounds
  7. | `Rw_not_allowed
  8. | `Unknown_major_pack_version of string
]
val reload : t -> (unit, [> reload_error ]) result
val register_dict_consumer : t -> after_reload:(unit -> (unit, Io.read_error) result) -> unit
val register_suffix_consumer : t -> after_flush:(unit -> unit) -> unit
type version_error := [
  1. | `Corrupted_control_file
  2. | `Corrupted_legacy_file
  3. | `Invalid_layout
  4. | `Io_misc of Io.misc_error
  5. | `No_such_file_or_directory
  6. | `Not_a_directory of string
  7. | `Unknown_major_pack_version of string
]
val version : root:string -> (Irmin_pack.Version.t, [> version_error ]) result

version ~root is the version of the files at root.

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