Issue #6974 - allow empty buffers to be pooled

Signed-off-by: Lachlan Roberts <lachlan@webtide.com>
jetty · Nov 29, 2021 · aa09b8b · aa09b8b
1 parent 377d0d1
commit aa09b8b
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Showing 3 changed files with 12 additions and 11 deletions.
diff --git a/jetty-io/src/main/java/org/eclipse/jetty/io/ArrayByteBufferPool.java b/jetty-io/src/main/java/org/eclipse/jetty/io/ArrayByteBufferPool.java
@@ -104,13 +104,13 @@ public ArrayByteBufferPool(int minCapacity, int factor, int maxCapacity, int max
         _minCapacity = minCapacity;
 
         // Initialize all buckets in constructor and never modify the array again.
-        int length = bucketFor(maxCapacity);
+        int length = bucketFor(maxCapacity) + 1;
         _direct = new ByteBufferPool.Bucket[length];
         _indirect = new ByteBufferPool.Bucket[length];
         for (int i = 0; i < length; i++)
         {
-            _direct[i] = newBucket(i + 1, true);
-            _indirect[i] = newBucket(i + 1, false);
+            _direct[i] = newBucket(i, true);
+            _indirect[i] = newBucket(i, false);
         }
     }
 
@@ -197,7 +197,7 @@ protected void releaseMemory(boolean direct)
 
     protected int bucketFor(int capacity)
     {
-        return Math.max((int)Math.ceil((double)capacity / getCapacityFactor()), 1);
+        return (int)Math.ceil((double)capacity / getCapacityFactor());
     }
 
     protected int capacityFor(int bucket)
@@ -209,11 +209,11 @@ private ByteBufferPool.Bucket bucketFor(int capacity, boolean direct)
     {
         if (capacity < _minCapacity)
             return null;
-        int index = bucketFor(capacity) - 1;
-        if (index >= _direct.length)
+        int bucket = bucketFor(capacity);
+        if (bucket >= _direct.length)
             return null;
         Bucket[] buckets = bucketsFor(direct);
-        return buckets[index];
+        return buckets[bucket];
     }
 
     @ManagedAttribute("The number of pooled direct ByteBuffers")

diff --git a/jetty-io/src/main/java/org/eclipse/jetty/io/MappedByteBufferPool.java b/jetty-io/src/main/java/org/eclipse/jetty/io/MappedByteBufferPool.java
@@ -185,7 +185,7 @@ protected void releaseMemory(boolean direct)
 
     protected int bucketFor(int capacity)
     {
-        return Math.max((int)Math.ceil((double)capacity / getCapacityFactor()), 1);
+        return (int)Math.ceil((double)capacity / getCapacityFactor());
     }
 
     protected int capacityFor(int bucket)

diff --git a/jetty-io/src/test/java/org/eclipse/jetty/io/MappedByteBufferPoolTest.java b/jetty-io/src/test/java/org/eclipse/jetty/io/MappedByteBufferPoolTest.java
@@ -27,6 +27,7 @@
 import static org.hamcrest.Matchers.lessThan;
 import static org.hamcrest.Matchers.lessThanOrEqualTo;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -158,7 +159,7 @@ public void testMaxMemory()
         // Now the oldest buffer should be gone and we have: 1+2x2+3=8
         long memory = bufferPool.getMemory(true);
         assertThat(memory, lessThan((long)maxMemory));
-        assertTrue(buckets.get(4).isEmpty());
+        assertNull(buckets.get(4));
 
         // Create and release a large buffer.
         // Max memory is exceeded and buckets 3 and 1 are cleared.
@@ -167,7 +168,7 @@ public void testMaxMemory()
         bufferPool.release(buffer);
         memory = bufferPool.getMemory(true);
         assertThat(memory, lessThanOrEqualTo((long)maxMemory));
-        assertTrue(buckets.get(1).isEmpty());
-        assertTrue(buckets.get(3).isEmpty());
+        assertNull(buckets.get(1));
+        assertNull(buckets.get(3));
     }
 }