Crate thread_local_macro

Provides a thread_local!() macro, a helper to instantiate lazily-initialized thread-local storage (TLS) variables.

The primary difference between using this crate’s thread_local!() macro and directly using the #[thread_local] attribute is that static items tagged with the #[thread_local] attribute will never be dropped, just like all other statics.

However, static items defined in a thread_local!() macro block will be destructed (e.g., dropped, destroyed) when that task exits.

Rust std-based implementation notes

The code in this crate is adapted from this version of the thread_local!() macro from the Rust standard library. The main design has been left unchanged, but we have removed most of the configuration blocks for complex platform-specific or OS-specific behavior. Because Theseus supports the #[thread_local] attribute, we can directly use the TLS “fast path”, which the Rust standard library refers to as the “FastLocalInnerKey”.

Unsafety

We could probably could remove most of the unsafe code from this implementation, because we don’t have to account for the various raw platform-specific interfaces or using raw libc types like the original Rust std implementation does. However, I have chosen to leave the code as close as possible to the original Rust std implementation in order to make updates as easy as possible, for if and when the Rust std version changes and we wish to track/merge in those changes.

Macros

• thread_local
  Declare a new thread local storage key of type LocalKey.

Structs

• AccessError
  An error returned by LocalKey::try_with.
• LocalKey
  A thread-local storage key which owns its contents.