Switch page cache to approximate LRU

This resolves an edge case where values stored near the beginning of the database file could become uncacheable. It also simplifies the caching code
cberner · Oct 11, 2024 · 3d184aa · 3d184aa
1 parent db458e9
commit 3d184aa
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Showing 9 changed files with 164 additions and 254 deletions.
diff --git a/src/multimap_table.rs b/src/multimap_table.rs
@@ -4,8 +4,8 @@ use crate::sealed::Sealed;
 use crate::table::{ReadableTableMetadata, TableStats};
 use crate::tree_store::{
     btree_stats, AllPageNumbersBtreeIter, BranchAccessor, BranchMutator, Btree, BtreeHeader,
-    BtreeMut, BtreeRangeIter, BtreeStats, CachePriority, Checksum, LeafAccessor, LeafMutator, Page,
-    PageHint, PageNumber, PagePath, RawBtree, RawLeafBuilder, TransactionalMemory, UntypedBtree,
+    BtreeMut, BtreeRangeIter, BtreeStats, Checksum, LeafAccessor, LeafMutator, Page, PageHint,
+    PageNumber, PagePath, RawBtree, RawLeafBuilder, TransactionalMemory, UntypedBtree,
     UntypedBtreeMut, BRANCH, DEFERRED, LEAF, MAX_PAIR_LENGTH, MAX_VALUE_LENGTH,
 };
 use crate::types::{Key, TypeName, Value};
@@ -1057,7 +1057,7 @@ impl<'txn, K: Key + 'static, V: Key + 'static> MultimapTable<'txn, K, V> {
                             .insert(key.borrow(), &DynamicCollection::new(&inline_data))?;
                     } else {
                         // convert into a subtree
-                        let mut page = self.mem.allocate(leaf_data.len(), CachePriority::Low)?;
+                        let mut page = self.mem.allocate(leaf_data.len())?;
                         page.memory_mut()[..leaf_data.len()].copy_from_slice(leaf_data);
                         let page_number = page.get_page_number();
                         drop(page);

diff --git a/src/transactions.rs b/src/transactions.rs
@@ -5,9 +5,9 @@ use crate::sealed::Sealed;
 use crate::table::ReadOnlyUntypedTable;
 use crate::transaction_tracker::{SavepointId, TransactionId, TransactionTracker};
 use crate::tree_store::{
-    Btree, BtreeHeader, BtreeMut, CachePriority, FreedPageList, FreedTableKey,
-    InternalTableDefinition, Page, PageHint, PageNumber, SerializedSavepoint, TableTree,
-    TableTreeMut, TableType, TransactionalMemory, MAX_PAIR_LENGTH, MAX_VALUE_LENGTH,
+    Btree, BtreeHeader, BtreeMut, FreedPageList, FreedTableKey, InternalTableDefinition, Page,
+    PageHint, PageNumber, SerializedSavepoint, TableTree, TableTreeMut, TableType,
+    TransactionalMemory, MAX_PAIR_LENGTH, MAX_VALUE_LENGTH,
 };
 use crate::types::{Key, Value};
 use crate::{
@@ -1177,10 +1177,7 @@ impl WriteTransaction {
                 continue;
             }
             let old_page = self.mem.get_page(path.page_number())?;
-            let mut new_page = self.mem.allocate_lowest(
-                old_page.memory().len(),
-                CachePriority::default_btree(old_page.memory()),
-            )?;
+            let mut new_page = self.mem.allocate_lowest(old_page.memory().len())?;
             let new_page_number = new_page.get_page_number();
             // We have to copy at least the page type into the new page.
             // Otherwise its cache priority will be calculated incorrectly
@@ -1194,10 +1191,7 @@ impl WriteTransaction {
                         continue;
                     }
                     let old_parent = self.mem.get_page(*parent)?;
-                    let mut new_page = self.mem.allocate_lowest(
-                        old_parent.memory().len(),
-                        CachePriority::default_btree(old_parent.memory()),
-                    )?;
+                    let mut new_page = self.mem.allocate_lowest(old_parent.memory().len())?;
                     let new_page_number = new_page.get_page_number();
                     // We have to copy at least the page type into the new page.
                     // Otherwise its cache priority will be calculated incorrectly

diff --git a/src/tree_store/btree_base.rs b/src/tree_store/btree_base.rs
@@ -1,6 +1,4 @@
-use crate::tree_store::page_store::{
-    xxh3_checksum, CachePriority, Page, PageImpl, PageMut, TransactionalMemory,
-};
+use crate::tree_store::page_store::{xxh3_checksum, Page, PageImpl, PageMut, TransactionalMemory};
 use crate::tree_store::PageNumber;
 use crate::types::{Key, MutInPlaceValue, Value};
 use crate::{Result, StorageError};
@@ -555,7 +553,7 @@ impl<'a, 'b> LeafBuilder<'a, 'b> {
 
         let required_size =
             self.required_bytes(division, first_split_key_bytes + first_split_value_bytes);
-        let mut page1 = self.mem.allocate(required_size, CachePriority::Low)?;
+        let mut page1 = self.mem.allocate(required_size)?;
         let mut builder = RawLeafBuilder::new(
             page1.memory_mut(),
             division,
@@ -574,7 +572,7 @@ impl<'a, 'b> LeafBuilder<'a, 'b> {
                 - first_split_key_bytes
                 - first_split_value_bytes,
         );
-        let mut page2 = self.mem.allocate(required_size, CachePriority::Low)?;
+        let mut page2 = self.mem.allocate(required_size)?;
         let mut builder = RawLeafBuilder::new(
             page2.memory_mut(),
             self.pairs.len() - division,
@@ -595,7 +593,7 @@ impl<'a, 'b> LeafBuilder<'a, 'b> {
             self.pairs.len(),
             self.total_key_bytes + self.total_value_bytes,
         );
-        let mut page = self.mem.allocate(required_size, CachePriority::Low)?;
+        let mut page = self.mem.allocate(required_size)?;
         let mut builder = RawLeafBuilder::new(
             page.memory_mut(),
             self.pairs.len(),
@@ -1306,7 +1304,7 @@ impl<'a, 'b> BranchBuilder<'a, 'b> {
             self.total_key_bytes,
             self.fixed_key_size,
         );
-        let mut page = self.mem.allocate(size, CachePriority::High)?;
+        let mut page = self.mem.allocate(size)?;
         let mut builder = RawBranchBuilder::new(&mut page, self.keys.len(), self.fixed_key_size);
         builder.write_first_page(self.children[0].0, self.children[0].1);
         for i in 1..self.children.len() {
@@ -1337,7 +1335,7 @@ impl<'a, 'b> BranchBuilder<'a, 'b> {
 
         let size =
             RawBranchBuilder::required_bytes(division, first_split_key_len, self.fixed_key_size);
-        let mut page1 = self.mem.allocate(size, CachePriority::High)?;
+        let mut page1 = self.mem.allocate(size)?;
         let mut builder = RawBranchBuilder::new(&mut page1, division, self.fixed_key_size);
         builder.write_first_page(self.children[0].0, self.children[0].1);
         for i in 0..division {
@@ -1356,7 +1354,7 @@ impl<'a, 'b> BranchBuilder<'a, 'b> {
             second_split_key_len,
             self.fixed_key_size,
         );
-        let mut page2 = self.mem.allocate(size, CachePriority::High)?;
+        let mut page2 = self.mem.allocate(size)?;
         let mut builder = RawBranchBuilder::new(
             &mut page2,
             self.keys.len() - division - 1,

diff --git a/src/tree_store/mod.rs b/src/tree_store/mod.rs
@@ -17,8 +17,8 @@ pub(crate) use btree_base::{
 pub(crate) use btree_iters::{AllPageNumbersBtreeIter, BtreeExtractIf, BtreeRangeIter};
 pub use page_store::{file_backend, InMemoryBackend, Savepoint};
 pub(crate) use page_store::{
-    CachePriority, Page, PageHint, PageNumber, SerializedSavepoint, TransactionalMemory,
-    FILE_FORMAT_VERSION2, MAX_PAIR_LENGTH, MAX_VALUE_LENGTH, PAGE_SIZE,
+    Page, PageHint, PageNumber, SerializedSavepoint, TransactionalMemory, FILE_FORMAT_VERSION2,
+    MAX_PAIR_LENGTH, MAX_VALUE_LENGTH, PAGE_SIZE,
 };
 pub(crate) use table_tree::{FreedPageList, FreedTableKey, TableTree, TableTreeMut};
 pub(crate) use table_tree_base::{InternalTableDefinition, TableType};