nopool (#244)

* nopool

* cleanup

Author: bitfaster

BitFaster.Caching/Lfu/ConcurrentLfu.cs

@@ -12,10 +12,6 @@
 using BitFaster.Caching.Lru;
 using BitFaster.Caching.Scheduler;
 
-#if !NETSTANDARD2_0
-using System.Buffers;
-#endif
-
 #if DEBUG
 using System.Linq;
 using System.Text;
@@ -56,9 +52,7 @@ public sealed class ConcurrentLfu<K, V> : ICache<K, V>, IAsyncCache<K, V>, IBoun
 
         private readonly IScheduler scheduler;
 
-#if NETSTANDARD2_0
         private readonly LfuNode<K, V>[] drainBuffer;
-#endif
 
         /// <summary>
         /// Initializes a new instance of the ConcurrentLfu class with the specified capacity.
@@ -97,9 +91,7 @@ public ConcurrentLfu(int concurrencyLevel, int capacity, IScheduler scheduler, I
 
             this.scheduler = scheduler;
 
-#if NETSTANDARD2_0
             this.drainBuffer = new LfuNode<K, V>[this.readBuffer.Capacity];
-#endif
         }
 
         ///<inheritdoc/>
@@ -435,26 +427,25 @@ private void DrainBuffers()
         private bool Maintenance(LfuNode<K, V> droppedWrite = null)
         {
             this.drainStatus.Set(DrainStatus.ProcessingToIdle);
-            var localDrainBuffer = RentDrainBuffer();
 
             // extract to a buffer before doing book keeping work, ~2x faster
-            int readCount = readBuffer.DrainTo(localDrainBuffer);
+            int readCount = readBuffer.DrainTo(this.drainBuffer);
 
             for (int i = 0; i < readCount; i++)
             {
-                this.cmSketch.Increment(localDrainBuffer[i].Key);
+                this.cmSketch.Increment(this.drainBuffer[i].Key);
             }
 
             for (int i = 0; i < readCount; i++)
             {
-                OnAccess(localDrainBuffer[i]);
+                OnAccess(this.drainBuffer[i]);
             }
 
-            int writeCount = this.writeBuffer.DrainTo(new ArraySegment<LfuNode<K, V>>(localDrainBuffer));
+            int writeCount = this.writeBuffer.DrainTo(new ArraySegment<LfuNode<K, V>>(this.drainBuffer));
 
             for (int i = 0; i < writeCount; i++)
             {
-                OnWrite(localDrainBuffer[i]);
+                OnWrite(this.drainBuffer[i]);
             }
 
             // we are done only when both buffers are empty
@@ -466,8 +457,6 @@ private bool Maintenance(LfuNode<K, V> droppedWrite = null)
                 done = true;
             }
 
-            ReturnDrainBuffer(localDrainBuffer);
-
             EvictEntries();
             this.capacity.OptimizePartitioning(this.metrics, this.cmSketch.ResetSampleSize);
             ReFitProtected();
@@ -687,22 +676,6 @@ private void ReFitProtected()
             }
         }
 
-        private LfuNode<K, V>[] RentDrainBuffer()
-        {
-#if !NETSTANDARD2_0
-            return ArrayPool<LfuNode<K, V>>.Shared.Rent(this.readBuffer.Capacity);
-#else
-            return drainBuffer;
-#endif
-        }
-
-        private void ReturnDrainBuffer(LfuNode<K, V>[] localDrainBuffer)
-        {
-#if !NETSTANDARD2_0
-            ArrayPool<LfuNode<K, V>>.Shared.Return(localDrainBuffer);
-#endif
-        }
-
         [DebuggerDisplay("{Format(),nq}")]
         private class DrainStatus
         {