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@lewiszlw
lewiszlw committed Feb 15, 2024
1 parent ac8c447 commit f079047
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Showing 5 changed files with 220 additions and 148 deletions.
81 changes: 41 additions & 40 deletions bustubx/src/buffer/buffer_pool.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ use crate::{BustubxError, BustubxResult};

use super::replacer::LRUKReplacer;

pub type FrameId = u32;
pub type FrameId = usize;

pub const TABLE_HEAP_BUFFER_POOL_SIZE: usize = 100;

Expand All @@ -32,7 +32,7 @@ impl BufferPoolManager {
pub fn new(num_pages: usize, disk_manager: Arc<DiskManager>) -> Self {
let mut free_list = VecDeque::with_capacity(num_pages);
for i in 0..num_pages {
free_list.push_back(i as FrameId);
free_list.push_back(i);
}
Self {
pool: vec![Arc::new(RwLock::new(Page::new(0))); num_pages],
Expand All @@ -58,7 +58,7 @@ impl BufferPoolManager {
} else {
// 无空闲frame，从缓冲池中替换一个页
if let Some(frame_id) = self.replacer.evict() {
let evicted_page = self.pool[frame_id as usize].clone();
let evicted_page = self.pool[frame_id].clone();
let evicted_page_id = evicted_page.read().unwrap().page_id;
// 如果页被修改过，则将其写回磁盘
let is_dirty = evicted_page.read().unwrap().is_dirty;
Expand All @@ -77,28 +77,28 @@ impl BufferPoolManager {
self.page_table.insert(new_page_id, frame_id);
let mut new_page = Page::new(new_page_id);
new_page.pin_count = 1;
self.pool[frame_id as usize] = Arc::new(RwLock::new(new_page));
self.pool[frame_id] = Arc::new(RwLock::new(new_page));

self.replacer.record_access(frame_id);
self.replacer.set_evictable(frame_id, false);
self.replacer.record_access(frame_id)?;
self.replacer.set_evictable(frame_id, false)?;

Ok(self.pool[frame_id as usize].clone())
Ok(self.pool[frame_id].clone())
}

pub fn fetch_page(&mut self, page_id: PageId) -> BustubxResult<Arc<RwLock<Page>>> {
if self.page_table.contains_key(&page_id) {
let frame_id = self.page_table[&page_id];
let page = self.pool[frame_id as usize].clone();
let page = self.pool[frame_id].clone();
page.write().unwrap().pin_count += 1;
self.replacer.set_evictable(frame_id, false);
self.replacer.set_evictable(frame_id, false)?;
return Ok(page);
} else {
// 分配一个frame
let frame_id = if !self.free_list.is_empty() {
self.free_list.pop_front().unwrap()
} else {
if let Some(frame_id) = self.replacer.evict() {
let evicted_page = self.pool[frame_id as usize].clone();
let evicted_page = self.pool[frame_id].clone();
let evicted_page_id = evicted_page.read().unwrap().page_id;
let is_dirty = evicted_page.read().unwrap().is_dirty;
if is_dirty {
Expand All @@ -115,48 +115,49 @@ impl BufferPoolManager {
let mut new_page = Page::new(page_id);
new_page.pin_count = 1;
new_page.data = self.disk_manager.read_page(page_id).unwrap();
self.pool[frame_id as usize] = Arc::new(RwLock::new(new_page));
self.pool[frame_id] = Arc::new(RwLock::new(new_page));

self.replacer.record_access(frame_id);
self.replacer.set_evictable(frame_id, false);
self.replacer.record_access(frame_id)?;
self.replacer.set_evictable(frame_id, false)?;

Ok(self.pool[frame_id as usize].clone())
Ok(self.pool[frame_id].clone())
}
}

pub fn write_page(&mut self, page_id: PageId, data: [u8; BUSTUBX_PAGE_SIZE]) {
if self.page_table.contains_key(&page_id) {
let frame_id = self.page_table[&page_id];
let page = self.pool[frame_id as usize].clone();
let page = self.pool[frame_id].clone();
page.write().unwrap().data = data;
page.write().unwrap().is_dirty = true;
}
}

// 从缓冲池中取消固定页
pub fn unpin_page(&mut self, page_id: PageId, is_dirty: bool) -> bool {
pub fn unpin_page(&mut self, page_id: PageId, is_dirty: bool) -> BustubxResult<bool> {
if self.page_table.contains_key(&page_id) {
let frame_id = self.page_table[&page_id];
let page = self.pool[frame_id as usize].clone();
let page = self.pool[frame_id].clone();
if page.read().unwrap().pin_count == 0 {
return false;
return Ok(false);
}
page.write().unwrap().pin_count -= 1;
page.write().unwrap().is_dirty |= is_dirty;
if page.read().unwrap().pin_count == 0 {
self.replacer.set_evictable(frame_id, true);
let pin_count = page.read().unwrap().pin_count;
if pin_count == 0 {
self.replacer.set_evictable(frame_id, true)?;
}
true
Ok(true)
} else {
false
Ok(false)
}
}

// 将缓冲池中指定页写回磁盘
pub fn flush_page(&mut self, page_id: PageId) -> BustubxResult<bool> {
if self.page_table.contains_key(&page_id) {
let frame_id = self.page_table[&page_id];
let page = self.pool[frame_id as usize].clone();
let page = self.pool[frame_id].clone();
self.disk_manager
.write_page(page_id, &page.read().unwrap().data)?;
page.write().unwrap().is_dirty = false;
Expand All @@ -176,15 +177,15 @@ impl BufferPoolManager {
}

// 删除缓冲池中的页
pub fn delete_page(&mut self, page_id: PageId) -> bool {
pub fn delete_page(&mut self, page_id: PageId) -> BustubxResult<bool> {
if !self.page_table.contains_key(&page_id) {
return true;
return Ok(true);
}
let frame_id = self.page_table[&page_id];
let page = self.pool[frame_id as usize].clone();
let page = self.pool[frame_id].clone();
if page.read().unwrap().pin_count > 0 {
// 页被固定，无法删除
return false;
return Ok(false);
}

// 从缓冲池中删除
Expand All @@ -194,8 +195,8 @@ impl BufferPoolManager {
self.replacer.remove(frame_id);

// 从磁盘上删除
self.disk_manager.deallocate_page(page_id).unwrap();
return true;
self.disk_manager.deallocate_page(page_id)?;
Ok(true)
}
}

Expand Down Expand Up @@ -231,7 +232,7 @@ mod tests {
let page = buffer_pool_manager.new_page();
assert!(page.is_err());

buffer_pool_manager.unpin_page(0, false);
buffer_pool_manager.unpin_page(0, false).unwrap();
let page = buffer_pool_manager.new_page().unwrap();
assert_eq!(page.read().unwrap().page_id, 3);

Expand All @@ -252,7 +253,7 @@ mod tests {
let page = buffer_pool_manager.new_page();
assert!(page.is_err());

buffer_pool_manager.unpin_page(0, true);
buffer_pool_manager.unpin_page(0, true).unwrap();
let page = buffer_pool_manager.new_page().unwrap();
assert_eq!(page.read().unwrap().page_id, 3);

Expand All @@ -268,19 +269,19 @@ mod tests {
let mut buffer_pool_manager = BufferPoolManager::new(3, Arc::new(disk_manager));

let page = buffer_pool_manager.new_page().unwrap();
buffer_pool_manager.unpin_page(0, true);
buffer_pool_manager.unpin_page(0, true).unwrap();
let page = buffer_pool_manager.new_page().unwrap();
buffer_pool_manager.unpin_page(1, false);
buffer_pool_manager.unpin_page(1, false).unwrap();
let page = buffer_pool_manager.new_page().unwrap();
buffer_pool_manager.unpin_page(2, false);
buffer_pool_manager.unpin_page(2, false).unwrap();

let page = buffer_pool_manager.fetch_page(0).unwrap();
assert_eq!(page.read().unwrap().page_id, 0);
buffer_pool_manager.unpin_page(0, false);
buffer_pool_manager.unpin_page(0, false).unwrap();

let page = buffer_pool_manager.fetch_page(1).unwrap();
assert_eq!(page.read().unwrap().page_id, 1);
buffer_pool_manager.unpin_page(1, false);
buffer_pool_manager.unpin_page(1, false).unwrap();
assert_eq!(buffer_pool_manager.replacer.size(), 3);

let _ = remove_file(db_path);
Expand All @@ -295,13 +296,13 @@ mod tests {
let mut buffer_pool_manager = BufferPoolManager::new(3, Arc::new(disk_manager));

let page_id = buffer_pool_manager.new_page().unwrap();
buffer_pool_manager.unpin_page(0, true);
buffer_pool_manager.unpin_page(0, true).unwrap();
let page_id = buffer_pool_manager.new_page().unwrap();
buffer_pool_manager.unpin_page(1, true);
buffer_pool_manager.unpin_page(1, true).unwrap();
let page_id = buffer_pool_manager.new_page().unwrap();
buffer_pool_manager.unpin_page(2, false);
buffer_pool_manager.unpin_page(2, false).unwrap();

let res = buffer_pool_manager.delete_page(0);
let res = buffer_pool_manager.delete_page(0).unwrap();
assert!(res);
assert_eq!(buffer_pool_manager.pool.len(), 3);
assert_eq!(buffer_pool_manager.free_list.len(), 1);
Expand Down
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