优化和收尾

chusql-storage/tests/btree_test.rs

@@ -153,3 +153,63 @@ fn order_too_large_for_page_errors() {
     let dir = tempfile::tempdir().unwrap();
     assert!(DiskBTree::open(dir.path().join("t.idx"), 512, 300, DEFAULT_POOL_SIZE).is_err());
 }
+
+/// 删掉键之后查不到，别人不受影响
+#[test]
+fn delete_removes_only_that_key() {
+    let dir = tempfile::tempdir().unwrap();
+    let mut t = DiskBTree::open(
+        dir.path().join("t.idx"),
+        DEFAULT_PAGE_SIZE,
+        DEFAULT_BTREE_ORDER,
+        DEFAULT_POOL_SIZE,
+    )
+    .unwrap();
+    for i in 0..200 {
+        t.insert(i, i as u64 + 1).unwrap();
+    }
+
+    assert!(t.delete(50).unwrap(), "删一个存在的键应该返回 true");
+    assert_eq!(t.get(50).unwrap(), None);
+    assert_eq!(t.get(49).unwrap(), Some(50));
+    assert_eq!(t.get(51).unwrap(), Some(52));
+
+    // 再删一次：它已经不在了
+    assert!(!t.delete(50).unwrap());
+
+    // 遍历里也不能再有它
+    let all = t.iter_all().unwrap();
+    assert_eq!(all.len(), 199);
+    assert!(all.iter().all(|(k, _)| *k != 50));
+}
+
+/// 删过之后树还能继续插（惰性删除会留下稀疏节点，但不能影响正确性）
+#[test]
+fn insert_after_delete_still_works() {
+    let dir = tempfile::tempdir().unwrap();
+    let mut t = DiskBTree::open(
+        dir.path().join("t.idx"),
+        DEFAULT_PAGE_SIZE,
+        DEFAULT_BTREE_ORDER,
+        DEFAULT_POOL_SIZE,
+    )
+    .unwrap();
+    for i in 0..300 {
+        t.insert(i, i as u64).unwrap();
+    }
+    // 把偶数键全删掉
+    for i in (0..300).step_by(2) {
+        assert!(t.delete(i).unwrap());
+    }
+    // 再插一批新的
+    for i in 1000..1100 {
+        t.insert(i, i as u64).unwrap();
+    }
+    for i in 0..300 {
+        let want = if i % 2 == 0 { None } else { Some(i as u64) };
+        assert_eq!(t.get(i).unwrap(), want, "key {}", i);
+    }
+    for i in 1000..1100 {
+        assert_eq!(t.get(i).unwrap(), Some(i as u64));
+    }
+}