futures-task 0.3.34: futures_task

# This file is automatically @generated by Cargo.
# It is not intended for manual editing.
version = 4

[[package]]
name = "futures-task"
version = "0.3.34"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "cd417de3d1d015fc3bfd2b1ea46dfc7bab72ef86f1cc7cc9c78e728b34a6d1fd"

[[package]]
name = "sample-futures-task"
version = "1.0.0"
dependencies = [
 "futures-task",
]

[package]
name = "sample-futures-task"
version = "1.0.0"
edition = "2021"
publish = false

[dependencies]
futures-task = "=0.3.34"

[[bin]]
name = "contract"
path = "test/contract.rs"

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify futures_task in pkg:cargo/futures-task@0.3.34
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:cargo/futures-task@0.3.34
Demonstrate these symbols/APIs:
  - futures_task

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:8cb10ed0238ada29c64cf0cf897e315d7d9c5242183657084142cc899b9fb428","contract":["noop_waker and noop_waker_ref produce wakers that safely perform no-op on wake and wake_by_ref","ArcWake trait implementation converts into Waker via waker function and dispatches wake","waker_ref converts ArcWake reference into WakerRef and dispatches wake_by_ref"],"goal":"verify futures_task in pkg:cargo/futures-task@0.3.34","kind":"HOW","packages":["pkg:cargo/futures-task@0.3.34"],"schemaVersion":1,"symbols":["futures_task"]},"contractCommand":["cargo","run","--offline"],"environment":{"arch":"x64","distro":"alpine","ecosystem":"cargo","libc":"musl","os":"linux","packageManager":"cargo","schemaVersion":1},"license":"MIT-0","packages":["pkg:cargo/futures-task@0.3.34"],"schemaVersion":1,"subject":"pkg:cargo/futures-task@0.3.34","symbols":["futures_task"],"verifierAdapter":"cargo@1"}

{
  "schemaVersion": 1,
  "goal": "verify futures_task in pkg:cargo/futures-task@0.3.34",
  "kind": "HOW",
  "packages": [
    "pkg:cargo/futures-task@0.3.34"
  ],
  "symbols": [
    "futures_task"
  ]
}

//! Clean-room verification sample for futures-task.

pub use futures_task::*;

use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use futures_task::{noop_waker, noop_waker_ref, waker, waker_ref, ArcWake, Context};

struct CountingWaker {
    wake_count: AtomicUsize,
}

impl CountingWaker {
    fn new() -> Self {
        Self {
            wake_count: AtomicUsize::new(0),
        }
    }

    fn count(&self) -> usize {
        self.wake_count.load(Ordering::SeqCst)
    }
}

impl ArcWake for CountingWaker {
    fn wake(self: Arc<Self>) {
        self.wake_count.fetch_add(1, Ordering::SeqCst);
    }

    fn wake_by_ref(arc_self: &Arc<Self>) {
        arc_self.wake_count.fetch_add(1, Ordering::SeqCst);
    }
}

fn main() {
    // 1. noop_waker and noop_waker_ref produce wakers that safely perform no-op on wake and wake_by_ref
    let noop = noop_waker();
    noop.wake_by_ref();
    noop.wake();

    let noop_ref = noop_waker_ref();
    noop_ref.wake_by_ref();

    let cx = Context::from_waker(noop_ref);
    cx.waker().wake_by_ref();

    // 2. ArcWake trait implementation converts into Waker via waker function and dispatches wake
    let counter = Arc::new(CountingWaker::new());
    assert_eq!(counter.count(), 0);

    let waker_inst = waker(counter.clone());
    waker_inst.wake();
    assert_eq!(counter.count(), 1);

    // 3. waker_ref converts ArcWake reference into WakerRef and dispatches wake_by_ref
    {
        let w_ref = waker_ref(&counter);
        w_ref.wake_by_ref();
        assert_eq!(counter.count(), 2);

        let cx2 = Context::from_waker(&*w_ref);
        cx2.waker().wake_by_ref();
        assert_eq!(counter.count(), 3);
    }
    assert_eq!(counter.count(), 3);

    println!("All futures-task contract assertions passed.");
}