Fix issue jetty#5499

this PR let the ByteAccumulator recyclable. after invoke ByteAccumulator.transferTo method
we can invoke ByteAccumulator.recycle method to reuse byte[] via ByteAccumulator.newByteArray method

Signed-off-by: Baoyi Chen <chen.bao.yi@qq.com>

jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/ByteAccumulator.java

@@ -54,6 +54,11 @@ public int getLength()
         return length;
     }
 
+    int getMaxSize() 
+    {
+        return maxSize;
+    }
+
     ByteBuffer newByteBuffer(int size)
     {
         ByteBuffer buf;

jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/CompressExtension.java

@@ -48,9 +48,9 @@ public abstract class CompressExtension extends AbstractExtension
     private static final Logger LOG = Log.getLogger(CompressExtension.class);
 
     /**
-     * thread local accumulator
+     * Accumulator
      */
-    protected ThreadLocal<ByteAccumulator> accumulator = ThreadLocal.withInitial(() -> newByteAccumulator());
+    protected ByteAccumulator accumulator;
 
     /**
      * Never drop tail bytes 0000FFFF, from any frame type
@@ -181,7 +181,11 @@ protected void forwardIncoming(Frame frame, ByteAccumulator accumulator)
     protected ByteAccumulator newByteAccumulator()
     {
         int maxSize = Math.max(getPolicy().getMaxTextMessageSize(), getPolicy().getMaxBinaryMessageSize());
-        return new ByteAccumulator(maxSize);
+        if (accumulator == null || accumulator.getMaxSize() != maxSize)
+        {
+            accumulator = new ByteAccumulator(maxSize);
+        }
+        return accumulator;
     }
 
     protected void decompress(ByteAccumulator accumulator, ByteBuffer buf) throws DataFormatException

jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/DeflateFrameExtension.java

@@ -63,7 +63,7 @@ public void incomingFrame(Frame frame)
 
         try
         {
-            ByteAccumulator accumulator = this.accumulator.get();
+            accumulator = newByteAccumulator();
             decompress(accumulator, frame.getPayload());
             decompress(accumulator, TAIL_BYTES_BUF.slice());
             forwardIncoming(frame, accumulator);

jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/PerMessageDeflateExtension.java

@@ -78,10 +78,9 @@ public void incomingFrame(Frame frame)
             throw new ProtocolException("Invalid RSV1 set on permessage-deflate CONTINUATION frame");
         }
 
-        ByteAccumulator accumulator = this.accumulator.get();
-
         try
         {
+            accumulator = newByteAccumulator();
             ByteBuffer payload = frame.getPayload();
             decompress(accumulator, payload);
             if (frame.isFin())