diff --git a/nomt/src/beatree/allocator/mod.rs b/nomt/src/beatree/allocator/mod.rs
index 4f92ad4a..8d07fbf8 100644
--- a/nomt/src/beatree/allocator/mod.rs
+++ b/nomt/src/beatree/allocator/mod.rs
@@ -2,7 +2,6 @@ use crate::{
     io::{IoCommand, IoHandle, IoKind},
     io::{Page, PAGE_SIZE},
 };
-use crossbeam_channel::TrySendError;
 
 use std::{
     fs::File,
diff --git a/nomt/src/beatree/branch/mod.rs b/nomt/src/beatree/branch/mod.rs
index 6bc9b9e3..bf953fd3 100644
--- a/nomt/src/beatree/branch/mod.rs
+++ b/nomt/src/beatree/branch/mod.rs
@@ -12,7 +12,7 @@ use std::{
 };
 
 pub use node::{
-    body_fullness, body_size, BranchNode, BranchNodeBuilder, BranchNodeView, BRANCH_NODE_BODY_SIZE,
+    body_size, BranchNode, BranchNodeBuilder, BranchNodeView, BRANCH_NODE_BODY_SIZE,
 };
 
 pub mod node;
diff --git a/nomt/src/beatree/branch/node.rs b/nomt/src/beatree/branch/node.rs
index 93b892f1..f8f9350f 100644
--- a/nomt/src/beatree/branch/node.rs
+++ b/nomt/src/beatree/branch/node.rs
@@ -58,10 +58,6 @@ impl BranchNode {
         slice[0..4].copy_from_slice(&pn.to_le_bytes());
     }
 
-    pub fn is_bbn(&self) -> bool {
-        self.view().is_bbn()
-    }
-
     pub fn n(&self) -> u16 {
         self.view().n()
     }
@@ -89,10 +85,6 @@ impl BranchNode {
         slice[7] = len;
     }
 
-    fn varbits(&self) -> &BitSlice<u8, Msb0> {
-        self.view().varbits()
-    }
-
     fn varbits_mut(&mut self) -> &mut BitSlice<u8, Msb0> {
         let body_end = body_size(
             self.prefix_len() as _,
@@ -152,10 +144,6 @@ impl<'a> BranchNodeView<'a> {
         u32::from_le_bytes(self.inner[0..4].try_into().unwrap())
     }
 
-    pub fn is_bbn(&self) -> bool {
-        self.bbn_pn() == 0
-    }
-
     pub fn n(&self) -> u16 {
         u16::from_le_bytes(self.inner[4..6].try_into().unwrap())
     }
@@ -200,10 +188,6 @@ pub fn body_size(prefix_len: usize, separator_len: usize, n: usize) -> usize {
     (prefix_len + (separator_len * n) + 7) / 8 + (4 * n)
 }
 
-pub fn body_fullness(prefix_len: usize, separator_len: usize, n: usize) -> f32 {
-    body_size(prefix_len, separator_len, n) as f32 / BRANCH_NODE_BODY_SIZE as f32
-}
-
 pub struct BranchNodeBuilder {
     branch: BranchNode,
     index: usize,
diff --git a/nomt/src/beatree/leaf/node.rs b/nomt/src/beatree/leaf/node.rs
index 8a9b2647..ea9d959a 100644
--- a/nomt/src/beatree/leaf/node.rs
+++ b/nomt/src/beatree/leaf/node.rs
@@ -37,12 +37,6 @@ pub struct LeafNode {
 }
 
 impl LeafNode {
-    pub fn zeroed() -> Self {
-        LeafNode {
-            inner: Box::new(Page::zeroed()),
-        }
-    }
-
     pub fn n(&self) -> usize {
         u16::from_le_bytes(self.inner[0..2].try_into().unwrap()) as usize
     }
diff --git a/nomt/src/beatree/ops/update/leaf.rs b/nomt/src/beatree/ops/update/leaf.rs
index 9a1b4a3c..5edd4d9d 100644
--- a/nomt/src/beatree/ops/update/leaf.rs
+++ b/nomt/src/beatree/ops/update/leaf.rs
@@ -1,5 +1,5 @@
 use bitvec::prelude::*;
-use std::{cmp::Ordering, io::Read};
+use std::cmp::Ordering;
 
 use crate::beatree::{
     allocator::PageNumber,
diff --git a/nomt/src/bitbox/meta_map.rs b/nomt/src/bitbox/meta_map.rs
index 7ead27d3..3990051e 100644
--- a/nomt/src/bitbox/meta_map.rs
+++ b/nomt/src/bitbox/meta_map.rs
@@ -23,6 +23,7 @@ impl MetaMap {
         }
     }
 
+    #[allow(unused)]
     pub fn full_count(&self) -> usize {
         self.bitvec
             .iter()
@@ -38,11 +39,6 @@ impl MetaMap {
         self.bitvec[bucket] = full_entry(hash);
     }
 
-    pub fn set_empty(&mut self, bucket: usize) {
-        self.bitvec[bucket] = EMPTY;
-    }
-
-    #[allow(unused)]
     pub fn set_tombstone(&mut self, bucket: usize) {
         self.bitvec[bucket] = TOMBSTONE;
     }
diff --git a/nomt/src/bitbox/wal/mod.rs b/nomt/src/bitbox/wal/mod.rs
index 9c55ed0b..69f97f28 100644
--- a/nomt/src/bitbox/wal/mod.rs
+++ b/nomt/src/bitbox/wal/mod.rs
@@ -2,7 +2,6 @@ use std::{
     fs::File,
     io::{Read, Write},
     os::fd::AsRawFd,
-    path::PathBuf,
 };
 
 mod batch;
diff --git a/nomt/src/io/mod.rs b/nomt/src/io/mod.rs
index 48d47269..5bfc7334 100644
--- a/nomt/src/io/mod.rs
+++ b/nomt/src/io/mod.rs
@@ -173,9 +173,4 @@ impl IoHandle {
     pub fn try_recv(&self) -> Result<CompleteIo, TryRecvError> {
         self.completion_receiver.try_recv()
     }
-
-    /// Get the underlying completion receiver for raw access.
-    pub fn receiver(&self) -> &Receiver<CompleteIo> {
-        &self.completion_receiver
-    }
 }
diff --git a/nomt/src/page_cache.rs b/nomt/src/page_cache.rs
index ccd21429..4dd2ad2d 100644
--- a/nomt/src/page_cache.rs
+++ b/nomt/src/page_cache.rs
@@ -7,7 +7,7 @@ use crate::{
     Options,
 };
 use bitvec::prelude::*;
-use fxhash::{FxBuildHasher, FxHashMap};
+use fxhash::FxBuildHasher;
 use lru::LruCache;
 use nomt_core::{
     page::DEPTH,
@@ -15,7 +15,7 @@ use nomt_core::{
     trie::{LeafData, Node},
     trie_pos::{ChildNodeIndices, TriePosition},
 };
-use parking_lot::{Condvar, Mutex, RwLock};
+use parking_lot::{Mutex, RwLock};
 use std::{fmt, num::NonZeroUsize, sync::Arc};
 
 // Total number of nodes stored in one Page. It depends on the `DEPTH`
diff --git a/nomt/src/store/mod.rs b/nomt/src/store/mod.rs
index c893f679..94a0186d 100644
--- a/nomt/src/store/mod.rs
+++ b/nomt/src/store/mod.rs
@@ -8,7 +8,7 @@ use crate::{
 use meta::Meta;
 use nomt_core::{
     page_id::PageId,
-    trie::{KeyPath, Node, TERMINATOR},
+    trie::KeyPath,
 };
 use parking_lot::Mutex;
 use std::{
@@ -43,6 +43,8 @@ struct Shared {
     ln_fd: File,
     bbn_fd: File,
     ht_fd: File,
+    // keep alive.
+    #[allow(unused)]
     wal_fd: File,
 }