— Class: elephant:store-controller

Class precedence list: store-controller, standard-object, t

Slots:

• spec — initargs: :spec

  Data store initialization functions are expected to initialize :spec on the call to make-instance

• root

  This is an instance of the data store persistent btree. It should have an oid that is fixed in the code and does not change between sessions. Usually it this is something like 0, 1 or -1

• class-root

  This is another root for class indexing that is also a data store specific persistent btree instance with a unique oid that persists between sessions.

• instance-cache

  This is an instance cache and part of the metaclass protocol. Data stores should not override the default behavior.

• instance-cache-lock

  Protection for updates to the cache from multiple threads. Do not override.

• serializer-version

  Governs the default behavior regarding which serializer version the current elephant core is using. Data stores can override by creating a method on initialize-serializer.

• serialize

  Accessed by elephant::serialize to get the entry point to the default serializer or to a data store specific serializer

• deserialize

  Contains the entry point for the specific serializer to be called by elephant::deserialize

Superclass for the data store controller, the main interface to any book-keeping, references to db handles, the instance cache, btree table creation, counters, locks, the roots (for garbage collection,) et cetera. Behavior is shared between the superclass and subclasses. See slot documentation for details.

— Generic Function: elephant-data-store:open-controller sc &key recover recover-fatal thread &allow-other-keys

Opens the underlying environment and all the necessary database tables. Different data stores may use different keys so all methods should &allow-other-keys. There are three standard keywords: :recover, :recover-fatal and :thread. Recover means that recovery should be checked for or performed on startup. Recover fatal means a full rebuild from log files is requested. Thread merely indicates to the data store that it is a threaded application and any steps that need to be taken (for example transaction implementation) are taken. :thread is usually true.

— Generic Function: elephant-data-store:close-controller sc

Close the db handles and environment. Should be in a state where lisp could be shut down without causing an inconsistent state in the db. Also, the object could be used by open-controller to reopen the database

— Method: before elephant-data-store:close-controller (sc store-controller)

Ensure the classes don't have stale references to closed stores!

— Method: after elephant-data-store:close-controller (sc store-controller)

Delete connection spec so store-controller operations on cached controller information fail

— Generic Function: elephant-data-store:connection-is-indeed-open controller

Validate the controller and the db that it is connected to

— Generic Function: elephant-data-store:database-version sc

Data stores implement this to store the serializer version. The protocol requires that data stores report their database version. On new database creation, the database is written with the *elephant-code-version* so that is returned by database-version. If a legacy database does not have a version according to the method then it should return nil

— Method: around elephant-data-store:database-version sc

Default version assumption for unmarked databases is 0.6.0. It is possible to check for 0.5.0 databases, but it is not implemented now due to the low (none?) number of users still on 0.5.0

— Function: elephant-data-store:serialize-database-version-key bs

Given a buffer-stream, encode a key indicating the version using the constant +elephant-version+

— Function: elephant-data-store:serialize-database-version-value version bs

Serializes a list containing three integers to the buffer stream bs

— Function: elephant-data-store:deserialize-database-version-value bs

Deserializes the 3 integer list from buffer stream bs