From d8c9bffe5b4d643db84fd23219c00cc93e8a9e52 Mon Sep 17 00:00:00 2001
From: arkpar <arkady.paronyan@gmail.com>
Date: Fri, 5 Jan 2024 12:30:30 +0100
Subject: [PATCH] Fix loom

---
 src/file.rs  | 12 ++++++++++--
 src/table.rs | 14 +++++++-------
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/src/file.rs b/src/file.rs
index bba9af8f..6bb7a18d 100644
--- a/src/file.rs
+++ b/src/file.rs
@@ -8,7 +8,6 @@ use crate::{
 	parking_lot::RwLock,
 	table::TableId,
 };
-use parking_lot::RwLockReadGuard;
 use std::sync::atomic::{AtomicU64, Ordering};
 
 #[cfg(target_os = "linux")]
@@ -125,6 +124,7 @@ impl TableFile {
 		Ok(())
 	}
 
+	#[cfg(not(feature = "loom"))]
 	pub fn slice_at(&self, offset: u64, len: usize) -> MappedBytesGuard {
 		let offset = offset as usize;
 		let map = self.map.read();
@@ -134,6 +134,14 @@ impl TableFile {
 		})
 	}
 
+	#[cfg(feature = "loom")]
+	pub fn slice_at(&self, offset: u64, len: usize) -> MappedBytesGuard {
+		let offset = offset as usize;
+		let map = self.map.read();
+		let (map, _) = map.as_ref().unwrap();
+		MappedBytesGuard::new(map[offset..offset + len].to_vec())
+	}
+
 	pub fn write_at(&self, buf: &[u8], offset: u64) -> Result<()> {
 		let map = self.map.read();
 		let (map, _) = map.as_ref().unwrap();
@@ -204,7 +212,7 @@ pub struct MappedBytesGuard<'a> {
 
 #[cfg(feature = "loom")]
 impl<'a> MappedBytesGuard<'a> {
-	fn new(data: Vec<u8>) -> Self {
+	pub fn new(data: Vec<u8>) -> Self {
 		Self { _phantom: std::marker::PhantomData, data }
 	}
 }
diff --git a/src/table.rs b/src/table.rs
index 7d7e7433..dae909de 100644
--- a/src/table.rs
+++ b/src/table.rs
@@ -382,12 +382,12 @@ impl<B: AsRef<[u8]> + AsMut<[u8]>> std::ops::IndexMut<std::ops::Range<usize>> fo
 	}
 }
 
-enum LockedSlice<'a> {
-	FromOverlay(&'a [u8]),
-	FromFile(parking_lot::MappedRwLockReadGuard<'a, [u8]>),
+enum LockedSlice<O: std::ops::Deref<Target = [u8]>, F: std::ops::Deref<Target = [u8]>> {
+	FromOverlay(O),
+	FromFile(F),
 }
 
-impl<'a> LockedSlice<'a> {
+impl<O: std::ops::Deref<Target = [u8]>, F: std::ops::Deref<Target = [u8]>> LockedSlice<O, F> {
 	fn as_slice(&self) -> &[u8] {
 		match self {
 			LockedSlice::FromOverlay(slice) => &*slice,
@@ -472,7 +472,7 @@ impl ValueTable {
 		let entry_size = self.entry_size as usize;
 		loop {
 			let vbuf = log.value_ref(self.id, index);
-			let buf: LockedSlice = if let Some(buf) = vbuf.as_deref() {
+			let buf: LockedSlice<_, _> = if let Some(buf) = vbuf.as_deref() {
 				log::trace!(
 					target: "parity-db",
 					"{}: Found in overlay {}",
@@ -487,8 +487,8 @@ impl ValueTable {
 					self.id,
 					index,
 				);
-				let buf = self.file.slice_at(index * self.entry_size as u64, entry_size);
-				LockedSlice::FromFile(buf)
+				let vbuf = self.file.slice_at(index * self.entry_size as u64, entry_size);
+				LockedSlice::FromFile(vbuf)
 			};
 			let mut buf = EntryRef::new(buf.as_slice());