/**
* Helper method to unset the specified ShardedEntity from the ShardedEntityContextHolder
*
* @param entity the ShardedEntity to unset from the ShardedEntityContextHolder
* @throws PersistenceException in case the shard hint of specified ShardedEntity does not match
* with the value of the entity held by ShardedEntityContextHolder
*/
private void unsetShardedEntityContextHolder(ShardedEntity entity) throws PersistenceException {
// unset the ShardedEntity from the ShardedEntityContextHolder if the type is
// ShardedPersistentEntity. Cleans up the context that was
// populated earlier using the ShardedEntityContextHolder#setShardedPersistentEntity() call
ShardedEntity contextEntity = ShardedEntityContextHolder.getShardedEntity();
if (contextEntity != null
&& !contextEntity.getShardHint().equals(((ShardedEntity) entity).getShardHint())) {
throw new PersistenceException(
"Shard hints do not match for the specified ShardedEntity instance and the one held in the context"
+ " Mismatched values are : "
+ contextEntity.getShardHint()
+ ","
+ ((ShardedEntity) entity).getShardHint());
}
ShardedEntityContextHolder.clearShardedEntity();
}
/**
* Helper method to set the first of specified Criteria instances into the
* ShardedEntityContextHolder if it is of type ShardedEntity. Throws an exception if
* shardedentities are mixed with non-sharded ones in the same call. Also checks to see if all the
* ShardedEntity instances belong to the same shard i.e. {@link ShardedEntity#getShardHint()}
* returns the same value. Throws a PersistenceException otherwise. This defensive check is done
* to avoid indeterministic transaction boundary behavior when shards are mapped to multiple
* database instances. when shards are mapped to multiple database instances.
*
* @param criteria the ShardedEntity instances, the first of which is to be set into the
* ShardedEntityContextHolder if it is of type ShardedEntity
* @throws PersistenceException in case the shard hints of specified ShardedEntity instances do
* not match
*/
private void checkAndPopulateShardedEntityContextHolder(Criteria[] criteria)
throws PersistenceException {
if (criteria.length != 0) {
// check to see if sharded and non-sharded entities are part of the same call
ShardedEntity shardedEntity = null;
Criteria nonShardedEntity = null;
for (Criteria entity : criteria) {
if (ShardedEntity.class.isAssignableFrom(entity.getClass())) {
shardedEntity = (ShardedEntity) entity;
} else {
nonShardedEntity = entity;
}
}
if (shardedEntity != null && nonShardedEntity != null) {
throw new PersistenceException(
"Attempt to use sharded and non-sharded criteria in the same call. "
+ "Mixed types are : "
+ shardedEntity.getClass().getName()
+ ","
+ nonShardedEntity.getClass().getName());
}
Criteria firstEntity = criteria[0];
String shardHint =
(ShardedEntity.class.isAssignableFrom(firstEntity.getClass()))
? ((ShardedEntity) firstEntity).getShardHint()
: ShardedEntity.DEFAULT_SHARD;
for (Criteria entity : criteria) {
if (ShardedEntity.class.isAssignableFrom(entity.getClass())) {
if (!((ShardedEntity) entity).getShardHint().equals(shardHint)) {
throw new PersistenceException(
"Shard hints do not match for the specified Criteria i.e. ShardedEntity instances."
+ " Mismatched values are : "
+ shardHint
+ ","
+ ((ShardedEntity) entity).getShardHint());
}
}
// Set the PersistentEntity into the ShardedEntityContextHolder if the type is
// ShardedPersistentEntity. Will be used in Datasource resolution
if (ShardedEntity.class.isAssignableFrom(firstEntity.getClass())) {
ShardedEntityContextHolder.setShardedEntity((ShardedEntity) firstEntity);
}
}
}
}