Crate active_standby

A concurrency primitive for high concurrency reads with a single writer.

While Readers will need to acquire a reader lock, they are guaranteed to never compete with the writer, meaning readers never face lock contention. This is achieved at the cost of:

1. Memory - Internally we hold 2 copies of the underlying type the user is using. This allows us to have the active table, which is used by readers and the standby_table which is used by the writer.
2. Writer thread CPU usage - The writer must apply all updates twice. Lock contention for the writer should be less than with a plain RwLock due to Readers using the active_table.

The usage is meant to be similar to a RwLock. Some of the inspiration came from the left_right crate, so feel free to check that out. We don't implement aliasing, so each table is a true deepcopy of the other. We also don't optimize for startup.

Minimizing lock contention also makes batching a more effective strategy for Reader performance. Now you can grab a ReadGuard, and handle multiple requests without worrying aboutstarving the writer since it will be able to work on the standby table. This means multiple requests can be handled without having to relock the active_table.

Creation is done through the Writer, which can then spawn Readers (Readers are clonable).

Modules

collections
primitives