Fixes #8810 - ArrayRetainableByteBufferPool inefficiently calculates bucket indices (#8882)

Added constructor that uses IntUnaryOperator to avoid boxing.
Deprecated constructor that uses Function<Integer, Integer>.

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>

jetty-io/src/main/java/org/eclipse/jetty/io/ArrayRetainableByteBufferPool.java

@@ -19,6 +19,7 @@ import java.util.Arrays;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.function.Consumer;
 import java.util.function.Function;
+import java.util.function.IntUnaryOperator;
 
 import org.eclipse.jetty.util.BufferUtil;
 import org.eclipse.jetty.util.NanoTime;
@@ -54,7 +55,7 @@ public class ArrayRetainableByteBufferPool implements RetainableByteBufferPool,
     private final long _maxDirectMemory;
     private final AtomicLong _currentHeapMemory = new AtomicLong();
     private final AtomicLong _currentDirectMemory = new AtomicLong();
-    private final Function<Integer, Integer> _bucketIndexFor;
+    private final IntUnaryOperator _bucketIndexFor;
 
     /**
      * Creates a new ArrayRetainableByteBufferPool with a default configuration.
@@ -91,7 +92,7 @@ public class ArrayRetainableByteBufferPool implements RetainableByteBufferPool,
      */
     public ArrayRetainableByteBufferPool(int minCapacity, int factor, int maxCapacity, int maxBucketSize, long maxHeapMemory, long maxDirectMemory)
     {
-        this(minCapacity, factor, maxCapacity, maxBucketSize, maxHeapMemory, maxDirectMemory, null, null);
+        this(minCapacity, factor, maxCapacity, maxBucketSize, null, null, maxHeapMemory, maxDirectMemory);
     }
 
     /**
@@ -105,9 +106,29 @@ public class ArrayRetainableByteBufferPool implements RetainableByteBufferPool,
      * @param maxDirectMemory the max direct memory in bytes, -1 for unlimited memory or 0 to use default heuristic
      * @param bucketIndexFor a {@link Function} that takes a capacity and returns a bucket index
      * @param bucketCapacity a {@link Function} that takes a bucket index and returns a capacity
+     * @deprecated use {@link #ArrayRetainableByteBufferPool(int, int, int, int, IntUnaryOperator, IntUnaryOperator, long, long)}
+     * instead
      */
+    @Deprecated
     protected ArrayRetainableByteBufferPool(int minCapacity, int factor, int maxCapacity, int maxBucketSize, long maxHeapMemory, long maxDirectMemory,
                                             Function<Integer, Integer> bucketIndexFor, Function<Integer, Integer> bucketCapacity)
+    {
+        this(minCapacity, factor, maxCapacity, maxBucketSize, bucketIndexFor::apply, bucketCapacity::apply, maxHeapMemory, maxDirectMemory);
+    }
+
+    /**
+     * Creates a new ArrayRetainableByteBufferPool with the given configuration.
+     *
+     * @param minCapacity the minimum ByteBuffer capacity
+     * @param factor the capacity factor
+     * @param maxCapacity the maximum ByteBuffer capacity
+     * @param maxBucketSize the maximum number of ByteBuffers for each bucket
+     * @param bucketIndexFor a {@link IntUnaryOperator} that takes a capacity and returns a bucket index
+     * @param bucketCapacity a {@link IntUnaryOperator} that takes a bucket index and returns a capacity
+     * @param maxHeapMemory the max heap memory in bytes, -1 for unlimited memory or 0 to use default heuristic
+     * @param maxDirectMemory the max direct memory in bytes, -1 for unlimited memory or 0 to use default heuristic
+     */
+    protected ArrayRetainableByteBufferPool(int minCapacity, int factor, int maxCapacity, int maxBucketSize, IntUnaryOperator bucketIndexFor, IntUnaryOperator bucketCapacity, long maxHeapMemory, long maxDirectMemory)
     {
         if (minCapacity <= 0)
             minCapacity = 0;
@@ -123,12 +144,12 @@ public class ArrayRetainableByteBufferPool implements RetainableByteBufferPool,
         if (bucketCapacity == null)
             bucketCapacity = i -> (i + 1) * f;
 
-        int length = bucketIndexFor.apply(maxCapacity) + 1;
+        int length = bucketIndexFor.applyAsInt(maxCapacity) + 1;
         RetainedBucket[] directArray = new RetainedBucket[length];
         RetainedBucket[] indirectArray = new RetainedBucket[length];
         for (int i = 0; i < directArray.length; i++)
         {
-            int capacity = Math.min(bucketCapacity.apply(i), maxCapacity);
+            int capacity = Math.min(bucketCapacity.applyAsInt(i), maxCapacity);
             directArray[i] = new RetainedBucket(capacity, maxBucketSize);
             indirectArray[i] = new RetainedBucket(capacity, maxBucketSize);
         }
@@ -225,7 +246,7 @@ public class ArrayRetainableByteBufferPool implements RetainableByteBufferPool,
     {
         if (capacity < _minCapacity)
             return null;
-        int idx = _bucketIndexFor.apply(capacity);
+        int idx = _bucketIndexFor.applyAsInt(capacity);
         RetainedBucket[] buckets = direct ? _direct : _indirect;
         if (idx >= buckets.length)
             return null;

jetty-io/src/main/java/org/eclipse/jetty/io/LogarithmicArrayByteBufferPool.java

@@ -152,10 +152,11 @@ public class LogarithmicArrayByteBufferPool extends ArrayByteBufferPool
                 -1,
                 maxCapacity,
                 maxBucketSize,
-                maxHeapMemory,
-                maxDirectMemory,
                 c -> 32 - Integer.numberOfLeadingZeros(c - 1),
-                i -> 1 << i);
+                i -> 1 << i,
+                maxHeapMemory,
+                maxDirectMemory
+            );
         }
     }
 }

jetty-io/src/test/java/org/eclipse/jetty/io/ArrayRetainableByteBufferPoolTest.java

@@ -377,10 +377,11 @@ public class ArrayRetainableByteBufferPoolTest
                 -1,
                 maxCapacity,
                 maxBucketSize,
-                maxHeapMemory,
-                maxDirectMemory,
                 c -> 32 - Integer.numberOfLeadingZeros(c - 1),
-                i -> 1 << i);
+                i -> 1 << i,
+                maxHeapMemory,
+                maxDirectMemory
+            );
         }
     }