Switch to newer thread::LocalKey convenience methods by coolreader18 · Pull Request #6123 · RustPython/RustPython

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Walkthrough

Introduces scoped TLS and scopeguard dependencies. Refactors multiple thread-local RefCell access patterns to with_borrow/with_borrow_mut helpers. Converts VM current-thread storage to scoped TLS, revising VM entry/access control flow. Adjusts sys/thread context accessors and cleanup logic. Minor iterator-based update in Levenshtein buffer initialization.

Changes

Cohort / File(s)	Summary
Dependencies `Cargo.toml`, `vm/Cargo.toml`	Added dependencies: scoped-tls and scopeguard; wired vm crate to workspace versions.
Thread-local borrow refactors `common/src/str.rs`, `stdlib/src/contextvars.rs`, `vm/src/stdlib/sys.rs`, `vm/src/stdlib/thread.rs`, `wasm/lib/src/vm_class.rs`	Replaced RefCell borrow patterns with with_borrow/with_borrow_mut helpers; streamlined reads/writes; adjusted cleanup in thread sentinel handling; minor iterator initialization optimization in Levenshtein buffer.
VM TLS mechanism `vm/src/vm/thread.rs`	Migrated VM_CURRENT from manual RefCell TLS to scoped_tls::scoped_thread_local; updated enter/access helpers to use scoped set/with and scopeguard for stack unwind.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  participant Caller
  participant VM as VirtualMachine
  participant TLS as VM_CURRENT (scoped TLS)
  participant Stack as VM_STACK

  rect rgb(240,248,255)
    note over Caller,VM: enter_vm(vm, f)
    Caller->>VM: enter_vm(vm, f)
    VM->>Stack: push(vm)
    VM->>TLS: set(vm) {scoped}
    activate TLS
    TLS-->>VM: run f()
    VM->>VM: scopeguard defer Stack.pop()
    deactivate TLS
    VM-->>Caller: result
  end

  rect rgb(255,250,240)
    note over Caller,TLS: with_current_vm(f)
    Caller->>TLS: with(f) (requires is_set)
    TLS-->>Caller: f(&VM)
  end

sequenceDiagram
  autonumber
  participant Py as Python code
  participant CV as ContextVar
  participant Ctxs as CONTEXTS (TLS)
  participant Ctx as PyContext

  rect rgb(245,255,250)
    note over Py,Ctxs: current(vm)
    Py->>Ctxs: with_borrow_mut
    alt last exists
      Ctxs-->>Py: &last
    else create
      Ctxs->>Ctx: new default
      Ctxs->>Ctxs: push(Ctx)
      Ctxs-->>Py: &first
    end
  end

  rect rgb(250,245,255)
    note over Py,CV: CV.get(default)
    Py->>Ctxs: with_borrow
    Ctxs-->>Py: last context ref
    Py->>CV: check cache or lookup vars
    CV-->>Py: value or default
  end

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Possibly related PRs

Wtf8-compatible fixes #5985 — Also modifies common/src/str.rs Levenshtein logic (byte-slice change) touching the same buffer init area.

Suggested reviewers

youknowone

Poem

I nuzzle the stack where VMs now dwell,
Scoped threads whisper, “all is well.”
Contexts hop neatly, borrow-light,
Guards stand watch through unwind night.
With paws on hooks and buffers anew—
I thump: refactors done, carrots due! 🥕🐇

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