QpackEncoder.encode should take buffer to encode into instead of allocating.

Signed-off-by: Lachlan Roberts <lachlan@webtide.com>

jetty-http3/http3-qpack/src/main/java/org/eclipse/jetty/http3/qpack/QpackEncoder.java

@@ -36,8 +36,6 @@ import org.eclipse.jetty.http3.qpack.internal.parser.EncoderInstructionParser;
 import org.eclipse.jetty.http3.qpack.internal.table.DynamicTable;
 import org.eclipse.jetty.http3.qpack.internal.table.Entry;
 import org.eclipse.jetty.http3.qpack.internal.util.NBitIntegerEncoder;
-import org.eclipse.jetty.io.ByteBufferPool;
-import org.eclipse.jetty.io.NullByteBufferPool;
 import org.eclipse.jetty.util.BufferUtil;
 import org.eclipse.jetty.util.component.Dumpable;
 import org.slf4j.Logger;
@@ -83,27 +81,19 @@ public class QpackEncoder implements Dumpable
         void onInstruction(Instruction instruction) throws QpackException;
     }
 
-    private final ByteBufferPool _bufferPool;
     private final Handler _handler;
     private final QpackContext _context;
     private final int _maxBlockedStreams;
     private final Map<Integer, StreamInfo> _streamInfoMap = new HashMap<>();
     private final EncoderInstructionParser _parser;
-    private int _knownInsertCount;
+    private int _knownInsertCount = 0;
     private int _blockedStreams = 0;
 
     public QpackEncoder(Handler handler, int maxBlockedStreams)
-    {
-        this(handler, maxBlockedStreams, new NullByteBufferPool());
-    }
-
-    public QpackEncoder(Handler handler, int maxBlockedStreams, ByteBufferPool bufferPool)
     {
         _handler = handler;
-        _bufferPool = bufferPool;
         _context = new QpackContext();
         _maxBlockedStreams = maxBlockedStreams;
-        _knownInsertCount = 0;
         _parser = new EncoderInstructionParser(new EncoderAdapter());
     }
 
@@ -115,7 +105,6 @@ public class QpackEncoder implements Dumpable
     /**
      * Set the capacity of the DynamicTable and send a instruction to set the capacity on the remote Decoder.
      * @param capacity the new capacity.
-     * @throws QpackException
      */
     public void setCapacity(int capacity) throws QpackException
     {
@@ -180,7 +169,7 @@ public class QpackEncoder implements Dumpable
         }
     }
 
-    public ByteBuffer encode(int streamId, MetaData metadata) throws QpackException
+    public void encode(ByteBuffer buffer, int streamId, MetaData metadata) throws QpackException
     {
         // Verify that we can encode without errors.
         if (metadata.getFields() != null)
@@ -234,16 +223,7 @@ public class QpackEncoder implements Dumpable
             deltaBase = signBit ? requiredInsertCount - base - 1 : base - requiredInsertCount;
         }
 
-        // Calculate the size required. TODO: it may be more efficient to just use a buffer of MAX_HEADER_SIZE?
+        // Encode all the entries into the buffer.
-        int spaceRequired = 0;
-        spaceRequired += 1 + NBitIntegerEncoder.octectsNeeded(8, encodedInsertCount);
-        spaceRequired += 1 + NBitIntegerEncoder.octectsNeeded(7, deltaBase);
-        for (EncodableEntry encodableEntry : encodableEntries)
-        {
-            spaceRequired += encodableEntry.getRequiredSize(base);
-        }
-
-        ByteBuffer buffer = _bufferPool.acquire(spaceRequired, false);
         int pos = BufferUtil.flipToFill(buffer);
 
         // Encode the Field Section Prefix into the ByteBuffer.
@@ -258,7 +238,6 @@ public class QpackEncoder implements Dumpable
         }
 
         BufferUtil.flipToFlush(buffer, pos);
-        return buffer;
     }
 
     private EncodableEntry encode(StreamInfo streamInfo, HttpField field) throws QpackException

jetty-http3/http3-qpack/src/test/java/org/eclipse/jetty/http3/qpack/EncodeDecodeTest.java

@@ -77,7 +77,8 @@ public class EncodeDecodeTest
         int streamId = 0;
         HttpFields httpFields = HttpFields.build().add(":path", "/index.html");
 
-        ByteBuffer buffer = _encoder.encode(streamId, new MetaData(HttpVersion.HTTP_3, httpFields));
+        ByteBuffer buffer = BufferUtil.allocate(1024);
+        _encoder.encode(buffer, streamId, new MetaData(HttpVersion.HTTP_3, httpFields));
         assertNull(_encoderHandler.getInstruction());
         assertThat(BufferUtil.toHexString(buffer), QpackTestUtil.equalsHex("0000 510b 2f69 6e64 6578 2e68 746d 6c"));
         assertTrue(_encoderHandler.isEmpty());
@@ -107,7 +108,7 @@ public class EncodeDecodeTest
         httpFields = HttpFields.build()
             .add(":authority", "www.example.com")
             .add(":path", "/sample/path");
-        buffer = _encoder.encode(streamId, new MetaData(HttpVersion.HTTP_3, httpFields));
+        _encoder.encode(buffer, streamId, new MetaData(HttpVersion.HTTP_3, httpFields));
 
         instruction = _encoderHandler.getInstruction();
         assertThat(instruction, instanceOf(IndexedNameEntryInstruction.class));

jetty-http3/http3-qpack/src/test/java/org/eclipse/jetty/http3/qpack/EvictionTest.java

@@ -20,6 +20,7 @@ import org.eclipse.jetty.http.HttpField;
 import org.eclipse.jetty.http.HttpFields;
 import org.eclipse.jetty.http.HttpVersion;
 import org.eclipse.jetty.http.MetaData;
+import org.eclipse.jetty.util.BufferUtil;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -58,12 +59,14 @@ public class EvictionTest
     public void test() throws Exception
     {
         _encoder.setCapacity(1024);
+        ByteBuffer encodedFields = BufferUtil.allocate(1024);
 
         for (int i = 0; i < 10000; i++)
         {
             HttpFields httpFields = newRandomFields(5);
             int streamId = getPositiveInt(10);
-            ByteBuffer encodedFields = _encoder.encode(streamId, new MetaData(HttpVersion.HTTP_3, httpFields));
+
+            _encoder.encode(encodedFields, streamId, new MetaData(HttpVersion.HTTP_3, httpFields));
             _decoder.decode(streamId, encodedFields);
             MetaData result = _decoderHandler.getMetaData();
 
@@ -77,6 +80,7 @@ public class EvictionTest
 //            System.err.println();
 
             assertTrue(result.getFields().isEqualTo(httpFields));
+            BufferUtil.clear(encodedFields);
         }
     }