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Relax atomic orderings #520

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Relax atomic orderings #520

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21a6ef4
Relax atomic orderings
Cassy343 Jun 10, 2022
78bb15d
Format
Cassy343 Jun 10, 2022
2e69066
Fix potential reordering issue
Cassy343 Jun 10, 2022
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29 changes: 13 additions & 16 deletions src/lib.rs
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Expand Up @@ -406,7 +406,7 @@ const UNINITIALIZED: usize = 0;
const INITIALIZING: usize = 1;
const INITIALIZED: usize = 2;

static MAX_LOG_LEVEL_FILTER: AtomicUsize = AtomicUsize::new(0);
static MAX_LOG_LEVEL_FILTER: AtomicUsize = AtomicUsize::new(LevelFilter::Off as usize);

static LOG_LEVEL_NAMES: [&str; 6] = ["OFF", "ERROR", "WARN", "INFO", "DEBUG", "TRACE"];

Expand Down Expand Up @@ -1346,24 +1346,21 @@ fn set_logger_inner<F>(make_logger: F) -> Result<(), SetLoggerError>
where
F: FnOnce() -> &'static dyn Log,
{
let old_state = match STATE.compare_exchange(
match STATE.compare_exchange(
UNINITIALIZED,
INITIALIZING,
Ordering::SeqCst,
Ordering::SeqCst,
Ordering::Acquire,
Ordering::Relaxed,
) {
Ok(s) | Err(s) => s,
};
match old_state {
UNINITIALIZED => {
Ok(UNINITIALIZED) => {
unsafe {
LOGGER = make_logger();
}
STATE.store(INITIALIZED, Ordering::SeqCst);
STATE.store(INITIALIZED, Ordering::Release);
Ok(())
}
INITIALIZING => {
while STATE.load(Ordering::SeqCst) == INITIALIZING {
Err(INITIALIZING) => {
while STATE.load(Ordering::Relaxed) == INITIALIZING {
// TODO: replace with `hint::spin_loop` once MSRV is 1.49.0.
#[allow(deprecated)]
std::sync::atomic::spin_loop_hint();
Expand Down Expand Up @@ -1394,10 +1391,10 @@ where
///
/// [`set_logger`]: fn.set_logger.html
pub unsafe fn set_logger_racy(logger: &'static dyn Log) -> Result<(), SetLoggerError> {
match STATE.load(Ordering::SeqCst) {
match STATE.load(Ordering::Acquire) {
UNINITIALIZED => {
LOGGER = logger;
STATE.store(INITIALIZED, Ordering::SeqCst);
STATE.store(INITIALIZED, Ordering::Release);
Ok(())
}
INITIALIZING => {
Expand Down Expand Up @@ -1446,11 +1443,11 @@ impl error::Error for ParseLevelError {}
///
/// If a logger has not been set, a no-op implementation is returned.
pub fn logger() -> &'static dyn Log {
if STATE.load(Ordering::SeqCst) != INITIALIZED {
if STATE.load(Ordering::Acquire) == INITIALIZED {
unsafe { LOGGER }
} else {
static NOP: NopLogger = NopLogger;
&NOP
} else {
unsafe { LOGGER }
}
}

Expand Down