Library

Module

Module type

Parameter

Class

Class type

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Library

Module

Module type

Parameter

Class

Class type

Library

Module

Module type

Parameter

Class

Class type

Consider a filesystem device as a key/value read-only store.

`include Mirage_kv_lwt.RO with type t = FS.t`

The type for errors.

`type key = Mirage_kv.Key.t`

The type for keys.

```
val exists :
t ->
key ->
([ `Value | `Dictionary ] option, error) Pervasives.result io
```

`exists t k`

is `Some `Value`

if `k`

is bound to a value in `t`

, `Some `Dictionary`

if `k`

is a prefix of a valid key in `t`

and `None`

if no key with that prefix exists in `t`

.

`exists`

answers two questions: does the key exist and is it referring to a value or a dictionary.

An error occurs when the underlying storage layer fails.

`get t k`

is the value bound to `k`

in `t`

.

The result is `Error (`Value_expected k)`

if `k`

refers to a dictionary in `t`

.

```
val list :
t ->
key ->
((string * [ `Value | `Dictionary ]) list, error) Pervasives.result io
```

`list t k`

is the list of entries and their types in the dictionary referenced by `k`

in `t`

.

The result is `Error (`Dictionary_expected k)`

if `k`

refers to a value in `t`

.

`val last_modified : t -> key -> (int * int64, error) Pervasives.result io`

`last_modified t k`

is the last time the value bound to `k`

in `t`

has been modified.

The modification time `(d, ps)`

is a span for the signed POSIX picosecond span `d`

* 86_400e12 + `ps`

. `d`

is a signed number of POSIX days and `ps`

a number of picoseconds in the range [`0`

;`86_399_999_999_999_999L`

].

When the value bound to `k`

is a dictionary, the modification time is the latest modification of all entries in that dictionary. This behaviour is only one level deep and not recursive.

`val digest : t -> key -> (string, error) Pervasives.result io`

`digest t k`

is the unique digest of the value bound to `k`

in `t`

.

When the value bound to `k`

is a dictionary, the digest is a unique and deterministic digest of its entries.

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