entity
and
collection
data.See: Description
Interface | Description |
---|---|
CollectionRegionAccessStrategy |
Contract for managing transactional and concurrent access to cached collection
data.
|
EntityRegionAccessStrategy |
Contract for managing transactional and concurrent access to cached entity
data.
|
NaturalIdRegionAccessStrategy |
Contract for managing transactional and concurrent access to cached naturalId
data.
|
RegionAccessStrategy |
Base access strategy for all regions.
|
SoftLock |
Marker object for use by synchronous concurrency strategies
|
Enum | Description |
---|---|
AccessType |
The types of access strategies available.
|
Exception | Description |
---|---|
UnknownAccessTypeException |
Indicates that an unknown AccessType external name was encountered
|
<p>
Defines contracts for transactional and concurrent access to cached
entity
and
collection
data. Transactions pass in a
timestamp indicating transaction start time which is then used to protect against concurrent access (exactly how
that occurs is based on the actual access-strategy impl used). Two different implementation patterns are provided
for:
<ul>
<li>
A transaction-aware cache implementation might be wrapped by a <i>synchronous</i> access strategy,
where updates to the cache are written to the cache inside the transaction.
</li>
<li>
A non-transaction-aware cache would be wrapped by an <i>asynchronous</i> access strategy, where items
are merely "soft locked" during the transaction and then updated during the "after transaction completion"
phase; the soft lock is not an actual lock on the database row - only upon the cached representation of the
item.
</li>
</ul>
The <i>asynchronous</i> access strategies are: read-only
,
read-write
and
nonstrict-read-write
. The only
<i>synchronous</i> access strategy is transactional
.
</p>
<p>
Note that, for an <i>asynchronous</i> cache, cache invalidation must be a two step process (lock→unlock or
lock→afterUpdate), since this is the only way to guarantee consistency with the database for a nontransactional
cache implementation. For a <i>synchronous</i> cache, cache invalidation is a single step process (evict or update).
Hence, these contracts (EntityRegionAccessStrategy
and
CollectionRegionAccessStrategy
) define a three step process to cater for both
models (see the individual contracts for details).
</p>
<p>
Note that query result caching does not go through an access strategy; those caches are managed directly against
the underlying QueryResultsRegion
.
</p>
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