Increase the num segments of the waiters hash table from 16 to 64

This will reduce the chance of issue #34 occurring.

src/future/value_initializer.rs

@@ -7,6 +7,8 @@ use std::{
 };
 use triomphe::Arc as TrioArc;
 
+const WAITER_MAP_NUM_SEGMENTS: usize = 64;
+
 type ErrorObject = Arc<dyn Any + Send + Sync + 'static>;
 
 pub(crate) enum InitResult<V, E> {
@@ -102,7 +104,10 @@ where
 {
     pub(crate) fn with_hasher(hasher: S) -> Self {
         Self {
-            waiters: crate::cht::SegmentedHashMap::with_num_segments_and_hasher(16, hasher),
+            waiters: crate::cht::SegmentedHashMap::with_num_segments_and_hasher(
+                WAITER_MAP_NUM_SEGMENTS,
+                hasher,
+            ),
         }
     }
 

src/sync/base_cache.rs

@@ -564,9 +564,9 @@ where
         let initial_capacity = initial_capacity
             .map(|cap| cap + WRITE_LOG_SIZE * 4)
             .unwrap_or_default();
-        let num_segments = 64;
+        const NUM_SEGMENTS: usize = 64;
         let cache = crate::cht::SegmentedHashMap::with_num_segments_capacity_and_hasher(
-            num_segments,
+            NUM_SEGMENTS,
             initial_capacity,
             build_hasher.clone(),
         );

src/sync/value_initializer.rs

@@ -6,6 +6,8 @@ use std::{
 };
 use triomphe::Arc as TrioArc;
 
+const WAITER_MAP_NUM_SEGMENTS: usize = 64;
+
 type ErrorObject = Arc<dyn Any + Send + Sync + 'static>;
 type WaiterValue<V> = Option<Result<V, ErrorObject>>;
 type Waiter<V> = TrioArc<RwLock<WaiterValue<V>>>;
@@ -32,7 +34,10 @@ where
 {
     pub(crate) fn with_hasher(hasher: S) -> Self {
         Self {
-            waiters: crate::cht::SegmentedHashMap::with_num_segments_and_hasher(16, hasher),
+            waiters: crate::cht::SegmentedHashMap::with_num_segments_and_hasher(
+                WAITER_MAP_NUM_SEGMENTS,
+                hasher,
+            ),
         }
     }