package irmin-pack
Install
Dune Dependency
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doc/irmin-pack.unix/Irmin_pack_unix/Dict/Make/argument-1-Fm/Io/index.html
Module Fm.Io
Low level IO abstraction. A typical implementation is unix. This abstraction is meant to be dead simple. Not a lot of documentation is required.
It is not resistant to race condictions. There should not be concurrent modifications of the files.
These functions are essentially invoking the underlying functions from Unix
directly; there is no buffering for example.
Errors
An abstract error type that contains the IO-backend specific errors. (e.g. Unix.error
)
val misc_error_t : misc_error Irmin.Type.t
type mkdir_error = [
| `Io_misc of misc_error
| `File_exists of string
| `No_such_file_or_directory
| `Invalid_parent_directory
]
Safe Functions
None of the functions in this section raise exceptions. They may however perform effects that are always continued.
Life Cycle
val create : path:string -> overwrite:bool -> (t, [> create_error ]) result
val open_ : path:string -> readonly:bool -> (t, [> open_error ]) result
val close : t -> (unit, [> close_error ]) result
Write Functions
val write_string :
t ->
off:Optint.Int63.t ->
string ->
(unit, [> write_error ]) result
write_string t ~off s
writes s
at offset
in t
.
val fsync : t -> (unit, [> write_error ]) result
fsync t
persists to the file system the effects of previous create
or write.
val move_file :
src:string ->
dst:string ->
(unit, [> `Sys_error of string ]) result
val copy_file :
src:string ->
dst:string ->
(unit, [> `Sys_error of string ]) result
val mkdir : string -> (unit, [> mkdir_error ]) result
val unlink : string -> (unit, [> `Sys_error of string ]) result
Read Functions
val read_to_string :
t ->
off:Optint.Int63.t ->
len:int ->
(string, [> read_error ]) result
read_to_string t ~off ~len
are the len
bytes of t
at off
.
val read_all_to_string :
t ->
(string, [> `Io_misc of misc_error | `Closed ]) result
read_to_string t
is the contents full contents of the file.
The individual pages are not guaranteed to be read atomically.
val read_size : t -> (Optint.Int63.t, [> read_error ]) result
read_size t
is the number of bytes of the file handled by t
.
This function is expensive in the unix implementation because it performs syscalls.
val size_of_path :
string ->
(Optint.Int63.t,
[> `Io_misc of misc_error | `No_such_file_or_directory | `Not_a_file ])
result
MISC.
val readonly : t -> bool
val path : t -> string
Unsafe Functions
These functions are equivalents to exising safe ones, but using exceptions instead of the result monad for performances reasons.
val read_exn : t -> off:Optint.Int63.t -> len:int -> bytes -> unit
read_exn t ~off ~len b
reads the len
bytes of t
at off
to b
.
Raises Errors.Pack_error
and Errors.RO_not_allowed
.
Also raises backend-specific exceptions (e.g. Unix.Unix_error
for the unix backend).
val write_exn : t -> off:Optint.Int63.t -> len:int -> string -> unit
write_exn t ~off ~len b
writes the first len
bytes pf b
to t
at offset off
.
Raises Errors.Pack_error
and Errors.RO_not_allowed
.
Also raises backend-specific exceptions (e.g. Unix.Unix_error
for the unix backend).
val raise_misc_error : misc_error -> 'a
val catch_misc_error : (unit -> 'a) -> ('a, [> `Io_misc of misc_error ]) result