improve: use the OnceLock api repalce the Once

bls-runtime/src/plog.rs

@@ -1,43 +1,36 @@
-use std::{fmt::Arguments, sync::Once};
+use std::{
+    fmt::Arguments, sync::OnceLock
+};
 
 use env_logger::Logger;
-use log::{Level, Log, MetadataBuilder, Record};
+use log::{
+    Level, Log, MetadataBuilder, Record
+};
 
-static mut ENV_LOGGER: Option<Logger> = None;
+static mut ENV_LOGGER: OnceLock<Logger> = OnceLock::new();
 
 /// The logger should only be set once in log crate by set_logger,
 /// if set the console as output, can't be set the file as output.
 /// Therefore, we need a logger where the console is set as output
 /// before initializing the env_log by the configure file.
-pub(crate) fn env_logger() -> Option<&'static mut Logger> {
-    static ONCE: Once = Once::new();
+pub(crate) fn env_logger() -> &'static Logger {
     unsafe {
-        ONCE.call_once(|| {
+        ENV_LOGGER.get_or_init(|| {
             // the log metadata
             let metadata = MetadataBuilder::new().build();
             let mut builder = env_logger::Builder::from_default_env();
             // set the console as output.
             builder.target(Default::default());
             let logger = builder.build();
             logger.enabled(&metadata);
-            ENV_LOGGER = Some(logger);
-        });
-        ENV_LOGGER.as_mut()
+            logger
+        })
     }
 }
 
 /// log info by level
 pub fn plog(level: Level, args: Arguments<'_>) {
     let record = Record::builder().args(args).level(level).build();
-    env_logger().map(|l| l.log(&record));
+    env_logger().log(&record)
 }
 
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_env_logger() {
-        assert_eq!(env_logger().is_some(), true);
-    }
-}