seal (#225)

* seal

* comments

Author: bitfaster

BitFaster.Caching/Buffers/MpmcBoundedBuffer.cs

@@ -1,9 +1,6 @@
 using System;
-using System.Collections.Generic;
 using System.Diagnostics;
-using System.Drawing;
 using System.Runtime.InteropServices;
-using System.Text;
 using System.Threading;
 
 namespace BitFaster.Caching.Buffers
@@ -16,7 +13,7 @@ namespace BitFaster.Caching.Buffers
     /// Based on the Segment internal class from ConcurrentQueue
     /// https://github.com/dotnet/runtime/blob/main/src/libraries/System.Private.CoreLib/src/System/Collections/Concurrent/ConcurrentQueueSegment.cs
     /// </remarks>
-    public class MpmcBoundedBuffer<T>
+    public sealed class MpmcBoundedBuffer<T>
     {
         private Slot[] slots;
         private readonly int slotsMask;

BitFaster.Caching/Buffers/MpscBoundedBuffer.cs

@@ -1,9 +1,6 @@
 using System;
-using System.Collections.Generic;
 using System.Diagnostics;
-using System.Text;
 using System.Threading;
-using System.Threading.Tasks;
 
 namespace BitFaster.Caching.Buffers
 {
@@ -16,7 +13,7 @@ namespace BitFaster.Caching.Buffers
     /// https://github.com/ben-manes/caffeine/blob/master/caffeine/src/main/java/com/github/benmanes/caffeine/cache/BoundedBuffer.java
     /// </remarks>
     [DebuggerDisplay("Count = {Count}/{Capacity}")]
-    public class MpscBoundedBuffer<T> where T : class
+    public sealed class MpscBoundedBuffer<T> where T : class
     {
         private T[] buffer;
         private readonly int mask;

BitFaster.Caching/Buffers/StripedMpmcBuffer.cs

@@ -1,13 +1,8 @@
 using System;
-using System.Collections.Generic;
-using System.Collections.Specialized;
-using System.Runtime.InteropServices;
+
 #if !NETSTANDARD2_0
 using System.Runtime.Intrinsics.X86;
 #endif
-using System.Text;
-using System.Threading;
-using BitFaster.Caching.Lfu;
 
 namespace BitFaster.Caching.Buffers
 {
@@ -17,7 +12,7 @@ namespace BitFaster.Caching.Buffers
     /// rehashed to select a different buffer to retry up to 3 times. Using this approach
     /// writes scale linearly with number of concurrent threads.
     /// </summary>
-    public class StripedMpmcBuffer<T>
+    public sealed class StripedMpmcBuffer<T>
     {
         const int MaxAttempts = 3;
 

BitFaster.Caching/Buffers/StripedMpscBuffer.cs

@@ -1,9 +1,6 @@
 using System;
-using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
-using System.Text;
-using System.Threading;
 
 #if !NETSTANDARD2_0
 using System.Runtime.Intrinsics.X86;
@@ -18,7 +15,7 @@ namespace BitFaster.Caching.Buffers
     /// writes scale linearly with number of concurrent threads.
     /// </summary>
     [DebuggerDisplay("Count = {Count}/{Capacity}")]
-    public class StripedMpscBuffer<T> where T : class
+    public sealed class StripedMpscBuffer<T> where T : class
     {
         const int MaxAttempts = 3;
 

BitFaster.Caching/Lfu/CmSketch.cs

@@ -1,31 +1,18 @@
-/*
- * Copyright 2015 Ben Manes. All Rights Reserved.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-using System;
+using System;
 using System.Collections.Generic;
-using System.Text;
 
 namespace BitFaster.Caching.Lfu
 {
-    // https://en.wikipedia.org/wiki/Count%E2%80%93min_sketch#:~:text=In%20computing%2C%20the%20count%E2%80%93min,some%20events%20due%20to%20collisions.
-    // Parallel count min: https://www.atlantis-press.com/proceedings/mmebc-16/25859036
-    // SIMD: https://thlujy.github.io/papers/Lujianyuan-tpds-ufbf.pdf
-    // https://github.com/ben-manes/caffeine/blob/master/caffeine/src/main/java/com/github/benmanes/caffeine/cache/FrequencySketch.java
-    // https://github.com/ben-manes/caffeine/blob/master/caffeine/src/test/java/com/github/benmanes/caffeine/cache/FrequencySketchTest.java
-    public class CmSketch<T>
+    /// <summary>
+    /// A probabilistic data structure used to estimate the frequency of a given value. Periodic aging reduces the
+    /// accumulated count across all values over time, such that a historic popular value will decay to zero frequency
+    /// over time if it is not accessed.
+    /// </summary>
+    /// <remarks>
+    /// This is a direct C# translation of FrequencySketch in the Caffeine library by ben.manes@gmail.com (Ben Manes).
+    /// http://www.apache.org/licenses/LICENSE-2.0
+    /// </remarks>
+    public sealed class CmSketch<T>
     {
         // A mixture of seeds from FNV-1a, CityHash, and Murmur3
         private static ulong[] Seed = { 0xc3a5c85c97cb3127L, 0xb492b66fbe98f273L, 0x9ae16a3b2f90404fL, 0xcbf29ce484222325L};

BitFaster.Caching/Lfu/LfuCapacityPartition.cs

@@ -1,12 +1,10 @@
 using System;
-using System.Collections.Generic;
 using System.Diagnostics;
-using System.Text;
 
 namespace BitFaster.Caching.Lfu
 {
     [DebuggerDisplay("{Capacity} ({Window}/{Protected}/{Probation})")]
-    public class LfuCapacityPartition
+    public sealed class LfuCapacityPartition
     {
         private readonly int max;
 

BitFaster.Caching/Lfu/LfuNodeList.cs

@@ -10,7 +10,7 @@ namespace BitFaster.Caching.Lfu
     /// Adapted from the .NET linked list code, but with arg checking only applied in debug builds. 
     /// </summary>
     [DebuggerDisplay("Count = {Count}")]
-    internal class LfuNodeList<K, V> : IEnumerable<LfuNode<K, V>>
+    internal sealed class LfuNodeList<K, V> : IEnumerable<LfuNode<K, V>>
     {
         internal LfuNode<K, V> head;
         private int count;

BitFaster.Caching/Scheduler/ForegroundScheduler.cs

@@ -1,14 +1,11 @@
 using System;
-using System.Collections.Generic;
-using System.Text;
-using System.Threading.Tasks;
 
 namespace BitFaster.Caching.Scheduler
 {
     /// <summary>
     /// Represents a scheduler that runs tasks synchronously.
     /// </summary>
-    public class ForegroundScheduler : IScheduler
+    public sealed class ForegroundScheduler : IScheduler
     {
         private long count;
 

BitFaster.Caching/Scheduler/NullScheduler.cs

@@ -8,7 +8,7 @@ namespace BitFaster.Caching.Scheduler
     /// <summary>
     /// Represents a scheduler that does no scheduling. Scheduled Tasks will not be run.
     /// </summary>
-    public class NullScheduler : IScheduler
+    public sealed class NullScheduler : IScheduler
     {
         private long count;
 

BitFaster.Caching/Scheduler/ThreadPoolScheduler.cs

@@ -9,7 +9,7 @@ namespace BitFaster.Caching.Scheduler
     /// <summary>
     /// Represents a scheduler that handles queuing tasks to execute in the ThreadPool.
     /// </summary>
-    public class ThreadPoolScheduler : IScheduler
+    public sealed class ThreadPoolScheduler : IScheduler
     {
         private long count;
         private Optional<Exception> lastException = Optional<Exception>.None();