[hibernate-dev] [HSEARCH] Dynamic Sharding and directory template

[Emmanuel Bernard]

I am currently working on a solution for dynamically adding new shards
to Hibernate Search (for example one per tenant with a list growing).

https://hibernate.atlassian.net/browse/HSEARCH-472

Things are going well but there is an interesting problem related to a
subsequent feature

https://hibernate.atlassian.net/browse/HSEARCH-1295

In short, EntityIndexBinders create additional IndexManagers when a not
yet created shard id requested. The IndexManager is uniquely identified
by its indexName.

In the old sharding approach, the index name was turned into indexName.n
(n being the shard number) and this new indexName.n is passed along to
DirectoryProviders etc

To implement HSEARCH-1295 properly, you need the DirectoryProvider to
have access to the original index name and the shard identifier as
independent dataset.

We can hack around the model and pass the original indexName and shard
identifier in specific Properties entries. That's backward compatible.

An alternative is to replace String indexName in all thee contracts with
a proper IndexName object pointing to the original indexName and to the
shard idenfitier. That one breaks a bunch of SPI and in particular
DirectoryProvider.

Thoughts?

Emmanuel