Indexing and thread safety when using workers

[letmaik]

https://microsoft.github.io/CCF/main/architecture/threading.html#programming-model says a bit about the programming model when using the experimental worker_threads option.

When using an indexer then committed transactions are processed in the background and the state of the indexer is continuously updated.

With multiple worker threads, do indexers have to be made thread-safe or are indexers only being run between rpc calls to avoid this issue altogether?

[achamayou]

@letmaik the state that the indexers expose to historical queries does need to be made thread-safe.

[letmaik]

Do the built-in indexers expose state thread-safe?

[achamayou]

They do not, filed as #4038.

[achamayou]

Closed by #4075.