82 lines
3.0 KiB
Rust
82 lines
3.0 KiB
Rust
//! Checks for uses of Mutex where an atomic value could be used
|
|
//!
|
|
//! This lint is **warn** by default
|
|
|
|
use rustc::lint::{LintPass, LintArray, LateLintPass, LateContext};
|
|
use rustc_front::hir::Expr;
|
|
|
|
use syntax::ast;
|
|
use rustc::middle::ty;
|
|
use rustc::middle::subst::ParamSpace;
|
|
|
|
use utils::{span_lint, MUTEX_PATH, match_type};
|
|
|
|
/// **What it does:** It `Warn`s on usages of `Mutex<X>` where an atomic will do
|
|
///
|
|
/// **Why is this bad?** Using a Mutex just to make access to a plain bool or reference sequential is shooting flies with cannons. `std::atomic::AtomicBool` and `std::atomic::AtomicPtr` are leaner and faster.
|
|
///
|
|
/// **Known problems:** This lint cannot detect if the Mutex is actually used for waiting before a critical section.
|
|
///
|
|
/// **Example:** `let x = Mutex::new(&y);`
|
|
declare_lint! {
|
|
pub MUTEX_ATOMIC,
|
|
Warn,
|
|
"using a Mutex where an atomic value could be used instead"
|
|
}
|
|
|
|
/// **What it does:** It `Warn`s on usages of `Mutex<X>` where `X` is an integral type.
|
|
///
|
|
/// **Why is this bad?** Using a Mutex just to make access to a plain integer sequential is shooting flies with cannons. `std::atomic::usize` is leaner and faster.
|
|
///
|
|
/// **Known problems:** This lint cannot detect if the Mutex is actually used for waiting before a critical section.
|
|
///
|
|
/// **Example:** `let x = Mutex::new(0usize);`
|
|
declare_lint! {
|
|
pub MUTEX_INTEGER,
|
|
Allow,
|
|
"using a Mutex for an integer type"
|
|
}
|
|
|
|
impl LintPass for MutexAtomic {
|
|
fn get_lints(&self) -> LintArray {
|
|
lint_array!(MUTEX_ATOMIC, MUTEX_INTEGER)
|
|
}
|
|
}
|
|
|
|
pub struct MutexAtomic;
|
|
|
|
impl LateLintPass for MutexAtomic {
|
|
fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
|
|
let ty = cx.tcx.expr_ty(expr);
|
|
if let ty::TyStruct(_, subst) = ty.sty {
|
|
if match_type(cx, ty, &MUTEX_PATH) {
|
|
let mutex_param = &subst.types.get(ParamSpace::TypeSpace, 0).sty;
|
|
if let Some(atomic_name) = get_atomic_name(mutex_param) {
|
|
let msg = format!("Consider using an {} instead of a \
|
|
Mutex here. If you just want the \
|
|
locking behaviour and not the internal \
|
|
type, consider using Mutex<()>.",
|
|
atomic_name);
|
|
match *mutex_param {
|
|
ty::TyUint(t) if t != ast::TyUs =>
|
|
span_lint(cx, MUTEX_INTEGER, expr.span, &msg),
|
|
ty::TyInt(t) if t != ast::TyIs =>
|
|
span_lint(cx, MUTEX_INTEGER, expr.span, &msg),
|
|
_ => span_lint(cx, MUTEX_ATOMIC, expr.span, &msg)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn get_atomic_name(ty: &ty::TypeVariants) -> Option<(&'static str)> {
|
|
match *ty {
|
|
ty::TyBool => Some("AtomicBool"),
|
|
ty::TyUint(_) => Some("AtomicUsize"),
|
|
ty::TyInt(_) => Some("AtomicIsize"),
|
|
ty::TyRawPtr(_) => Some("AtomicPtr"),
|
|
_ => None
|
|
}
|
|
}
|