1 files changed, 57 insertions, 0 deletions
diff --git a/vendor/tracing-subscriber/src/sync.rs b/vendor/tracing-subscriber/src/sync.rs
new file mode 100644
index 000000000..ec42b834a
--- /dev/null
+++ b/vendor/tracing-subscriber/src/sync.rs
@@ -0,0 +1,57 @@
+//! Abstracts over sync primitive implementations.
+//!
+//! Optionally, we allow the Rust standard library's `RwLock` to be replaced
+//! with the `parking_lot` crate's implementation. This may provide improved
+//! performance in some cases. However, the `parking_lot` dependency is an
+//! opt-in feature flag. Because `parking_lot::RwLock` has a slightly different
+//! API than `std::sync::RwLock` (it does not support poisoning on panics), we
+//! wrap it with a type that provides the same method signatures. This allows us
+//! to transparently swap `parking_lot` in without changing code at the callsite.
+#[allow(unused_imports)] // may be used later;
+pub(crate) use std::sync::{LockResult, PoisonError, TryLockResult};
+
+#[cfg(not(feature = "parking_lot"))]
+pub(crate) use std::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard};
+
+#[cfg(feature = "parking_lot")]
+pub(crate) use self::parking_lot_impl::*;
+
+#[cfg(feature = "parking_lot")]
+mod parking_lot_impl {
+    pub(crate) use parking_lot::{RwLockReadGuard, RwLockWriteGuard};
+    use std::sync::{LockResult, TryLockError, TryLockResult};
+
+    #[derive(Debug)]
+    pub(crate) struct RwLock<T> {
+        inner: parking_lot::RwLock<T>,
+    }
+
+    impl<T> RwLock<T> {
+        pub(crate) fn new(val: T) -> Self {
+            Self {
+                inner: parking_lot::RwLock::new(val),
+            }
+        }
+
+        #[inline]
+        pub(crate) fn get_mut(&mut self) -> LockResult<&mut T> {
+            Ok(self.inner.get_mut())
+        }
+
+        #[inline]
+        pub(crate) fn read(&self) -> LockResult<RwLockReadGuard<'_, T>> {
+            Ok(self.inner.read())
+        }
+
+        #[inline]
+        #[allow(dead_code)] // may be used later;
+        pub(crate) fn try_read(&self) -> TryLockResult<RwLockReadGuard<'_, T>> {
+            self.inner.try_read().ok_or(TryLockError::WouldBlock)
+        }
+
+        #[inline]
+        pub(crate) fn write(&self) -> LockResult<RwLockWriteGuard<'_, T>> {
+            Ok(self.inner.write())
+        }
+    }
+}