khepri
khepri v0.6.0

khepri_payload (khepri v0.6.0)

Khepri payloads.

Payloads are the structure used to attach something to a tree node in the store. Khepri supports the following payloads:
  • No payload at all (no_payload()
  • Data payload used to store any Erlang term (data())
  • Stored procedure payload used to store functions (sproc())
Usually, there is no need to explicitly use this module as the type of payload will be autodetected, thanks to the wrap/1 function already called internally.

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Types

data/0

Internal structure to wrap any Erlang term before it can be stored in a tree node.

no_payload/0
Internal value used to mark that a tree node has no payload attached.
payload/0

All types of payload stored in the nodes of the tree structure.

sproc/0
Internal structure to wrap an anonymous function before it can be stored in a tree node and later executed.

Functions

data(Term)
Returns the same term wrapped into an internal structure ready to be stored in the tree.

See also: data().

none()
Returns the internal value used to mark that a tree node has no payload attached.

See also: no_payload().

sproc(Fun)
Returns the same function wrapped into an internal structure ready to be stored in the tree.

See also: sproc().

wrap(Payload)

Automatically detects the payload type and ensures it is wrapped in one of the internal types.

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data/0

-type data() :: #p_data{}.

Internal structure to wrap any Erlang term before it can be stored in a tree node.

The only constraint is the conversion to an Erlang binary must be supported by this term.
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no_payload/0

-type no_payload() :: '$__NO_PAYLOAD__'.
Internal value used to mark that a tree node has no payload attached.
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payload/0

-type payload() :: no_payload() | data() | sproc().

All types of payload stored in the nodes of the tree structure.

Beside the absence of payload, the only type of payload supported is data.
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sproc/0

-type sproc() :: #p_sproc{}.
Internal structure to wrap an anonymous function before it can be stored in a tree node and later executed.

Link to this section Functions

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data(Term)

-spec data(Term) -> Payload when Term :: khepri:data(), Payload :: data().
Returns the same term wrapped into an internal structure ready to be stored in the tree.

See also: data().

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none()

-spec none() -> no_payload().
Returns the internal value used to mark that a tree node has no payload attached.

See also: no_payload().

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sproc(Fun)

-spec sproc(Fun) -> Payload when Fun :: khepri_fun:standalone_fun() | fun(), Payload :: sproc().
Returns the same function wrapped into an internal structure ready to be stored in the tree.

See also: sproc().

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wrap(Payload)

-spec wrap(Payload) -> WrappedPayload
        when Payload :: payload() | khepri:data() | fun(), WrappedPayload :: payload().

Automatically detects the payload type and ensures it is wrapped in one of the internal types.

The internal types make sure we avoid any collision between any user-provided terms and internal structures.