package irmin

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  1. Read-write stores
package irmin
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Read-write stores.

Read-write stores

Read-write stores read-only stores where it is also possible to update and remove elements, with atomically guarantees.

include RO

Read-only stores

type t

The type for read-only backend stores.

type key

The type for keys.

type value

The type for raw values.

val mem : t -> key -> bool Lwt.t

mem t k is true iff k is present in t.

val find : t -> key -> value option Lwt.t

find t k is Some v if k is associated to v in t and None is k is not present in t.

val set : t -> key -> value -> unit Lwt.t

set t k v replaces the contents of k by v in t. If k is not already defined in t, create a fresh binding. Raise Invalid_argument if k is the empty path.

val test_and_set : t -> key -> test:value option -> set:value option -> bool Lwt.t

test_and_set t key ~test ~set sets key to set only if the current value of key is test and in that case returns true. If the current value of key is different, it returns false. None means that the value does not have to exist or is removed.

Note: The operation is guaranteed to be atomic.

val remove : t -> key -> unit Lwt.t

remove t k remove the key k in t.

val list : t -> key list Lwt.t

list t it the list of keys in t. RW stores are typically smaller than AO stores, so scanning these is usually cheap.

type watch

The type of watch handlers.

val watch : t -> ?init:(key * value) list -> (key -> value diff -> unit Lwt.t) -> watch Lwt.t

watch t ?init f adds f to the list of t's watch handlers and returns the watch handler to be used with unwatch. init is the optional initial values. It is more efficient to use watch_key to watch only a single given key.

val watch_key : t -> key -> ?init:value -> (value diff -> unit Lwt.t) -> watch Lwt.t

watch_key t k ?init f adds f to the list of t's watch handlers for the key k and returns the watch handler to be used with unwatch. init is the optional initial value of the key.

val unwatch : t -> watch -> unit Lwt.t

unwatch t w removes w from t's watch handlers.