From 9d1368b0ea380a9446b4697af668d1685464b6c7 Mon Sep 17 00:00:00 2001
From: Chuyan Zhang <me@zcy.moe>
Date: Sun, 26 Nov 2023 02:33:01 -0800
Subject: more code idk what they are im so tired ohno

---
 src/memory/cached_block.rs | 53 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 14 deletions(-)

(limited to 'src/memory/cached_block.rs')

diff --git a/src/memory/cached_block.rs b/src/memory/cached_block.rs
index 783e987..002a75b 100644
--- a/src/memory/cached_block.rs
+++ b/src/memory/cached_block.rs
@@ -75,7 +75,7 @@ impl<T: Block> BlockCache<T> {
         if !self.cache.contains(&index) {
             self.load_block(index);
         }
-        self.cache.get(&index).map(convert::<T,U>)
+        self.cache.get(&index).map(convert::<T, U>)
     }
 
     /// 从 LRU cache 里获取一个 block 的可变引用, 如果没有在 cache 中会加载.
@@ -90,6 +90,24 @@ impl<T: Block> BlockCache<T> {
         })
     }
 
+    /// 向 LRU cache 中插入一个全新初始化的 block
+    /// 这个 block 全 0, 而且是 dirty 的, 即使被挤出去也会触发一次落盘
+    pub(crate) fn init_block(&mut self, index: usize) {
+        let allocated_block = CachedBlock {
+            block: T::default(),
+            index,
+            dirty: true,
+        };
+        if let Some((old_index, old_block)) = self.cache.push(index, allocated_block) {
+            if old_block.dirty {
+                let old_block_ptr = &old_block.block as *const T as *mut u8;
+                let old_block_buffer =
+                    unsafe { std::slice::from_raw_parts(old_block_ptr, BLOCK_SIZE) };
+                self.device.write(old_index, old_block_buffer);
+            }
+        }
+    }
+
     /// 从 LRU cache 中读取一个 block 的引用, *不会* 影响 LRU cache 的结构, 如果没有在 cache 中不会加载.
     pub(crate) fn peek_block<U: Block>(&self, index: usize) -> Option<&CachedBlock<U>> {
         self.cache.peek(&index).map(convert::<T, U>)
@@ -117,26 +135,33 @@ impl<T: Block> BlockCache<T> {
 }
 
 impl AyaFS {
-    pub(crate) fn load_block(&mut self, index: usize) -> bool {
-        if !self.data_bitmap.query(index) {
-            self.cached_blocks.pop(&index);
-            // deallocate 时只更新 bitmap 没有动 cache, lazy 地驱逐 cache 中的无效 entry.
-            return false;
-        }
-        self.cached_blocks.load_block(index)
+    pub(crate) fn init_block(&mut self, index: usize) {
+        self.cached_blocks.init_block(index);
     }
 
     pub(crate) fn get_block<T: Block>(&mut self, index: usize) -> Option<&CachedBlock<T>> {
-        self.data_bitmap
-            .query(index)
-            .then(|| self.cached_blocks.get_block::<T>(index).unwrap())
+        if self.data_bitmap.query(index) {
+            Some(self.cached_blocks.get_block::<T>(index).unwrap())
+        } else {
+            self.cached_blocks.pop(&index);
+            None
+        }
+        // self.data_bitmap
+        //     .query(index)
+        //     .then(|| self.cached_blocks.get_block::<T>(index).unwrap())
         // 返回 None 当且仅当 data_bitmap 中这个 block 为 invalid
     }
 
     pub(crate) fn get_block_mut<T: Block>(&mut self, index: usize) -> Option<&mut CachedBlock<T>> {
-        self.data_bitmap
-            .query(index)
-            .then(|| self.cached_blocks.get_block_mut::<T>(index).unwrap())
+        if self.data_bitmap.query(index) {
+            Some(self.cached_blocks.get_block_mut::<T>(index).unwrap())
+        } else {
+            self.cached_blocks.pop(&index);
+            None
+        }
+        // self.data_bitmap
+        //     .query(index)
+        //     .then(|| self.cached_blocks.get_block_mut::<T>(index).unwrap())
         // 返回 None 当且仅当 data_bitmap 中这个 block 为 invalid
     }
 
-- 
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