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rust: Replace once_cell with std::sync primitives #273

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Merged
emeryberger merged 1 commit into from
Mar 3, 2026
Merged

rust: Replace once_cell with std::sync primitives #273

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1 change: 0 additions & 1 deletion rust/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,6 @@ Rust support for the `coz` Causal Profiler: https://github.com/plasma-umass/coz

[dependencies]
libc = "0.2"
once_cell = "1.1"

[profile.release]
debug = 1
14 changes: 7 additions & 7 deletions rust/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,10 +11,10 @@
//! [coz-readme]: https://github.com/plasma-umass/coz/blob/master/README.md
//! [rust-readme]: https://github.com/alexcrichton/coz-rs/blob/master/README.md

use once_cell::sync::OnceCell;
use std::ffi::{CStr, CString};
use std::mem;
use std::sync::atomic::{AtomicUsize, Ordering::Relaxed};
use std::sync::{LazyLock, OnceLock};

/// Equivalent of the `COZ_PROGRESS` and `COZ_PROGRESS_NAMED` macros
///
Expand Down Expand Up @@ -103,7 +103,7 @@ macro_rules! scope {
/// `end!()`, but if necessary you can also create one of these manually in your
/// own application for your own macros.
pub struct Counter {
slot: OnceCell<Option<&'static coz_counter_t>>,
slot: OnceLock<Option<&'static coz_counter_t>>,
ty: libc::c_int,
name: &'static str,
}
Expand Down Expand Up @@ -138,7 +138,7 @@ impl Counter {

const fn new(ty: libc::c_int, name: &'static str) -> Counter {
Counter {
slot: OnceCell::new(),
slot: OnceLock::new(),
ty,
name,
}
Expand Down Expand Up @@ -211,8 +211,7 @@ type AddDelaysFn = unsafe extern "C" fn();

#[cfg(target_os = "linux")]
fn coz_get_counter(ty: libc::c_int, name: &CStr) -> Option<*mut coz_counter_t> {
static GET_COUNTER: OnceCell<Option<GetCounterFn>> = OnceCell::new();
let func = GET_COUNTER.get_or_init(|| {
static GET_COUNTER: LazyLock<Option<GetCounterFn>> = LazyLock::new(|| {
let name = CStr::from_bytes_with_nul(b"_coz_get_counter\0").unwrap();
// SAFETY: We are calling an external function that does exist in Linux.
// No specific invariants that we must uphold have been defined.
Expand All @@ -226,6 +225,7 @@ fn coz_get_counter(ty: libc::c_int, name: &CStr) -> Option<*mut coz_counter_t> {
Some(unsafe { mem::transmute(func) })
}
});
let func = &*GET_COUNTER;

// SAFETY: We are calling an external function which exists as it is not None
// No specific invariants that we must uphold have been defined.
Expand All @@ -239,8 +239,7 @@ fn coz_get_counter(ty: libc::c_int, name: &CStr) -> Option<*mut coz_counter_t> {
/// the profiler cannot detect progress points and will report 0 experiments.
#[cfg(target_os = "linux")]
fn coz_add_delays() {
static ADD_DELAYS: OnceCell<Option<AddDelaysFn>> = OnceCell::new();
let func = ADD_DELAYS.get_or_init(|| {
static ADD_DELAYS: LazyLock<Option<AddDelaysFn>> = LazyLock::new(|| {
let name = CStr::from_bytes_with_nul(b"_coz_add_delays\0").unwrap();
let func = unsafe { libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr()) };
if func.is_null() {
Expand All @@ -249,6 +248,7 @@ fn coz_add_delays() {
Some(unsafe { mem::transmute(func) })
}
});
let func = &*ADD_DELAYS;

if let Some(f) = func {
// SAFETY: _coz_add_delays is a void->void function with no invariants.
Expand Down