Example for multithreaded usage

[lquenti]

Hi,

could you add an example for multithreaded use? Especially because of this in the README:

MVCC support for concurrent readers & writer, without blocking

This confuses me with the definition of the struct:

pub struct Database {
    mem: Arc<TransactionalMemory>,
    transaction_tracker: Arc<TransactionTracker>,
}

Having an Arc and "concurrent readers" reads to me like I can just clone it to other threads/routes, but it does not implement clone!

• Is it thread safe?
• Do I have to use an Arc<Mutex<Database>> or is Arc<Database> enough?
• Is it okay when I just do Database::open on the same file twice?

[geniot]

Hi, I just looked at the benchmark test, perhaps it can help you further: https://github.com/cberner/redb/blob/master/benches/lmdb_benchmark.rs#L224

[cberner]

This file is a good example of concurrent writing: https://github.com/cberner/redb/blob/master/benches%2Fmultithreaded_insert_benchmark.rs

You can't open a database file twice, but concurrent access to the Database and Transaction objects should be safe. As long as it compiles it should be correct 😊