Sync - Crystal 1.20.2

# module Sync

##
Overview

Synchronization primitives to build concurrent-safe and parallel-safe data structures, so we can embrace concurrency and parallelism with more serenity.

Communication through a `Channel` should be preferred whenever possible, but sometimes we need to protect critical sections manually, for example to build higher level constructs, or to protect a mutable global constant:

- `Sync::Mutex` to protect critical sections using mutual exclusion.
- `Sync::RWLock` to protect critical sections using shared access and mutual exclusion.
- `Sync::ConditionVariable` to synchronize critical sections together.
- `Sync::Exclusive(T)` to protect a value `T` using mutual exclusion.
- `Sync::Shared(T)` to protect a value `T` using a mix of shared access and mutual exclusion.

##
Defined in:

sync/condition_variable.cr
sync/cv.cr
sync/errors.cr
sync/exclusive.cr
sync/lockable.cr
sync/mu.cr
sync/mutex.cr
sync/rw_lock.cr
sync/shared.cr
sync/sync.cr
sync/type.cr
sync/waiter.cr