plucky (3) KiokuDB::Backend.3pm.gz

NAME

       KiokuDB::Backend - Backend interface role

VERSION

       version 0.57

SYNOPSIS

           package KiokuDB::Backend::Foo;
           use Moose;

           # load the core api and additional interfaces based on backend capabilities
           with qw(
               KiokuDB::Backend

               KiokuDB::Backend::Role::TXN
               KiokuDB::Backend::Role::Clear
               KiokuDB::Backend::Role::Scan
               KiokuDB::Backend::Role::UnicodeSafe
               KiokuDB::Backend::Role::BinarySafe
           );

           sub insert { ... }

           sub get { ... }

           sub delete { ... }

           sub exists { ... }

           # use the backend like this:

           my $dir = KiokuDB->new(
               backend => KiokuDB::Backend::Foo->new( );
           );

DESCRIPTION

       KiokuDB is designed to be fairly backend agnostic.

       This role defines the minimal API for writing new backends.

TRANSACTIONS

       This role is supplemented by KiokuDB::Backend::Role::TXN, a role for first class transaction support that
       issues rollbacks using the KiokuDB::Entry objects.

QUERYING

       This role is supplemented by KiokuDB::Backend::Role::Query, a role for backend specific queries.

       KiokuDB::Backend::Role::Query::Simple provides a universal query api for backends that can perform
       property based lookup.

       KiokuDB::Backend::Role::Query::GIN is a role for using Search::GIN based indexing/querying with backends
       that do not natively support querying.

REQUIRED METHODS

       get @ids
           Retrieve the KiokuDB::Entry objects associated with the @ids.

           If any other error is encountered, this method should die.

           The backend may store private data in "backend_data", to be used in a subsequent update.

           Returns a list of KiokuDB::Entry, with the order corresponding to @ids.  If an entry does not exist
           then "undef" should be returned in place of it. The backend may abort retrieval on the first non
           existent entry.

       insert @entries
           Insert entries to the store.

           If the backend is transactional this operation should be atomic with respect to the inserted/updated
           data.

           The backend is required to store the data in the fields "data", "class" using the key in "id".

           Entries which have an entry in "prev" denote updates (either objects that have been previously
           stored, or objects that were looked up). The previous entry may be used to compare state for issuing
           a partial update, and will contain the value of "backend_data" for any other state tracking.

           "object" is a weak reference to the object this entry is representing, and may be used for high level
           indexing. Do not use this field for storage.

           If this backend implements some form of garbage collection, "root" denotes that the objects is part
           of the root set.

           After all entries have been successfully written, "backend_data" should be set if necessary just as
           in "get".

           Has no return value.

           If "insert" does not die the write is assumed to be successful.

       delete @ids_or_entries
           Delete the specified IDs or entries.

           If the user provided objects then entries will be passed in. Any associated state the entries may
           have (e.g. a revision) should be used in order to enforce atomicity with respect to the time when the
           objects were loaded.

           After all entries have been successfully deleted, "deleted" should be set. The entry passed in is the
           same one as was loaded by "get" or last written by "insert", so it is already up to date in the live
           objects.

           Has no return value.

           If "delete" does not die the write is assumed to be successful.

       exists @ids
           Check for existence of the specified IDs, without retrieving their data.

           Returns a list of true or false values.

METHODS

       These methods are provided by the KiokuDB::Backend role, and may be overridden.

       new_from_dsn
           Parses the second half of the DSN using "parse_dsn_params" and instantiates a new object using
           "new_from_dsn".

           See KiokuDB::Util.

       new_from_dsn_params @args
           Takes DSN parameters and converts them to arguments suitable for "new"

       parse_dsn_params $str
           The string is split on ";" to produce arguments. Arguments in the form "foo=bar" are split on "="
           into a key/value pair, and other arguments are treated as a boolean key and returned as "$arg => 1".

ADDITIONAL INTERFACES

       Your backend may include more roles, based on its capabilities.

       KiokuDB::Backend::Serialize
       KiokuDB::Backend::Serialize::Delegate
           For the actual serialization of entries, there are a number of serialization roles.

       KiokuDB::Backend::Role::Clear
           API for clearing all entries.

       KiokuDB::Backend::Role::Scan
           API for enumerating entries.

       KiokuDB::Backend::Role::BinarySafe
       KiokuDB::Backend::Role::UnicodeSafe
           If your serialization is able to store arbitrary binary data and/or unicode strings, these
           informational roles should be included.

       KiokuDB::Backend::Role::TXN
           If your storage supports nested transactions ("txn_begin", "txn_commit" etc) this role provides the
           api to expose that functionality to the high level KiokuDB api.

       KiokuDB::Backend::Role::Query
       KiokuDB::Backend::Role::Query::GIN
           If your backend supports querying of some sort, these are the roles to include.

           The querying API uses backend specific lookups to fetch entries, which KiokuDB will then relink into
           result objects.

SHARED BACKENDS

       A backend may be shared by several KiokuDB instances, each with its own distinct live object set. The
       backend may choose to share cached entry data, as that is not mutated by KiokuDB::Linker, but not the
       KiokuDB::Entry instances themselves.

AUTHOR

       Yuval Kogman <nothingmuch@woobling.org>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2014 by Yuval Kogman, Infinity Interactive.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
       programming language system itself.