Add CompressibleBytesOutputStream for compression (#24927)

This is a follow-up to #23941. Currently there are a number of
complexities related to compression. The raw DeflaterOutputStream must
be closed prior to sending bytes to ensure that EOS bytes are written.
But the underlying ReleasableBytesStreamOutput cannot be closed until
the bytes are sent to ensure that the bytes are not reused.

Right now we have three different stream references hanging around in
TCPTransport to handle this complexity. This commit introduces
CompressibleBytesOutputStream to be one stream implemenation that will
behave properly with or without compression enabled.

core/src/main/java/org/elasticsearch/transport/CompressibleBytesOutputStream.java

@@ -0,0 +1,109 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.transport;
+
+import org.apache.lucene.util.IOUtils;
+import org.elasticsearch.common.bytes.BytesReference;
+import org.elasticsearch.common.compress.CompressorFactory;
+import org.elasticsearch.common.io.Streams;
+import org.elasticsearch.common.io.stream.BytesStream;
+import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.lease.Releasable;
+
+import java.io.IOException;
+import java.util.zip.DeflaterOutputStream;
+
+/**
+ * This class exists to provide a stream with optional compression. This is useful as using compression
+ * requires that the underlying {@link DeflaterOutputStream} be closed to write EOS bytes. However, the
+ * {@link BytesStream} should not be closed yet, as we have not used the bytes. This class handles these
+ * intricacies.
+ *
+ * {@link CompressibleBytesOutputStream#materializeBytes()} should be called when all the bytes have been
+ * written to this stream. If compression is enabled, the proper EOS bytes will be written at that point.
+ * The underlying {@link BytesReference} will be returned.
+ *
+ * {@link CompressibleBytesOutputStream#close()} should be called when the bytes are no longer needed and
+ * can be safely released.
+ */
+final class CompressibleBytesOutputStream extends StreamOutput implements Releasable {
+
+    private final StreamOutput stream;
+    private final BytesStream bytesStreamOutput;
+    private final boolean shouldCompress;
+
+    CompressibleBytesOutputStream(BytesStream bytesStreamOutput, boolean shouldCompress) throws IOException {
+        this.bytesStreamOutput = bytesStreamOutput;
+        this.shouldCompress = shouldCompress;
+        if (shouldCompress) {
+            this.stream = CompressorFactory.COMPRESSOR.streamOutput(Streams.flushOnCloseStream(bytesStreamOutput));
+        } else {
+            this.stream = bytesStreamOutput;
+        }
+    }
+
+    /**
+     * This method ensures that compression is complete and returns the underlying bytes.
+     *
+     * @return bytes underlying the stream
+     * @throws IOException if an exception occurs when writing or flushing
+     */
+    BytesReference materializeBytes() throws IOException {
+        // If we are using compression the stream needs to be closed to ensure that EOS marker bytes are written.
+        // The actual ReleasableBytesStreamOutput will not be closed yet as it is wrapped in flushOnCloseStream when
+        // passed to the deflater stream.
+        if (shouldCompress) {
+            stream.close();
+        }
+
+        return bytesStreamOutput.bytes();
+    }
+
+    @Override
+    public void writeByte(byte b) throws IOException {
+        stream.write(b);
+    }
+
+    @Override
+    public void writeBytes(byte[] b, int offset, int length) throws IOException {
+        stream.writeBytes(b, offset, length);
+    }
+
+    @Override
+    public void flush() throws IOException {
+        stream.flush();
+    }
+
+    @Override
+    public void close() {
+        if (stream == bytesStreamOutput) {
+            assert shouldCompress == false : "If the streams are the same we should not be compressing";
+            IOUtils.closeWhileHandlingException(stream);
+        } else {
+            assert shouldCompress : "If the streams are different we should be compressing";
+            IOUtils.closeWhileHandlingException(stream, bytesStreamOutput);
+        }
+    }
+
+    @Override
+    public void reset() throws IOException {
+        stream.reset();
+    }
+}

core/src/main/java/org/elasticsearch/transport/TcpTransport.java

@@ -41,7 +41,6 @@ import org.elasticsearch.common.component.Lifecycle;
 import org.elasticsearch.common.compress.Compressor;
 import org.elasticsearch.common.compress.CompressorFactory;
 import org.elasticsearch.common.compress.NotCompressedException;
-import org.elasticsearch.common.io.Streams;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.io.stream.NamedWriteableAwareStreamInput;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
@@ -1031,16 +1030,18 @@ public abstract class TcpTransport<Channel> extends AbstractLifecycleComponent i
         if (compress) {
             options = TransportRequestOptions.builder(options).withCompress(true).build();
         }
+
+        // only compress if asked and the request is not bytes. Otherwise only
+        // the header part is compressed, and the "body" can't be extracted as compressed
+        final boolean compressMessage = options.compress() && canCompress(request);
+
         status = TransportStatus.setRequest(status);
         ReleasableBytesStreamOutput bStream = new ReleasableBytesStreamOutput(bigArrays);
+        final CompressibleBytesOutputStream stream = new CompressibleBytesOutputStream(bStream, compressMessage);
         boolean addedReleaseListener = false;
-        StreamOutput stream = Streams.flushOnCloseStream(bStream);
         try {
-            // only compress if asked, and, the request is not bytes, since then only
+            if (compressMessage) {
-            // the header part is compressed, and the "body" can't be extracted as compressed
-            if (options.compress() && canCompress(request)) {
                 status = TransportStatus.setCompress(status);
-                stream = CompressorFactory.COMPRESSOR.streamOutput(stream);
             }
 
             // we pick the smallest of the 2, to support both backward and forward compatibility
@@ -1051,18 +1052,16 @@ public abstract class TcpTransport<Channel> extends AbstractLifecycleComponent i
             stream.setVersion(version);
             threadPool.getThreadContext().writeTo(stream);
             stream.writeString(action);
-            BytesReference message = buildMessage(requestId, status, node.getVersion(), request, stream, bStream);
+            BytesReference message = buildMessage(requestId, status, node.getVersion(), request, stream);
             final TransportRequestOptions finalOptions = options;
-            final StreamOutput finalStream = stream;
             // this might be called in a different thread
-            SendListener onRequestSent = new SendListener(
+            SendListener onRequestSent = new SendListener(stream,
-                () -> IOUtils.closeWhileHandlingException(finalStream, bStream),
                 () -> transportServiceAdapter.onRequestSent(node, requestId, action, request, finalOptions));
             internalSendMessage(targetChannel, message, onRequestSent);
             addedReleaseListener = true;
         } finally {
             if (!addedReleaseListener) {
-                IOUtils.close(stream, bStream);
+                IOUtils.close(stream);
             }
         }
     }
@@ -1125,27 +1124,25 @@ public abstract class TcpTransport<Channel> extends AbstractLifecycleComponent i
         }
         status = TransportStatus.setResponse(status); // TODO share some code with sendRequest
         ReleasableBytesStreamOutput bStream = new ReleasableBytesStreamOutput(bigArrays);
+        CompressibleBytesOutputStream stream = new CompressibleBytesOutputStream(bStream, options.compress());
         boolean addedReleaseListener = false;
-        StreamOutput stream = Streams.flushOnCloseStream(bStream);
         try {
             if (options.compress()) {
                 status = TransportStatus.setCompress(status);
-                stream = CompressorFactory.COMPRESSOR.streamOutput(stream);
             }
             threadPool.getThreadContext().writeTo(stream);
             stream.setVersion(nodeVersion);
-            BytesReference reference = buildMessage(requestId, status, nodeVersion, response, stream, bStream);
+            BytesReference reference = buildMessage(requestId, status, nodeVersion, response, stream);
 
             final TransportResponseOptions finalOptions = options;
-            final StreamOutput finalStream = stream;
             // this might be called in a different thread
-            SendListener listener = new SendListener(() -> IOUtils.closeWhileHandlingException(finalStream, bStream),
+            SendListener listener = new SendListener(stream,
                 () -> transportServiceAdapter.onResponseSent(requestId, action, response, finalOptions));
             internalSendMessage(channel, reference, listener);
             addedReleaseListener = true;
         } finally {
             if (!addedReleaseListener) {
-                IOUtils.close(stream, bStream);
+                IOUtils.close(stream);
             }
         }
     }
@@ -1173,8 +1170,8 @@ public abstract class TcpTransport<Channel> extends AbstractLifecycleComponent i
     /**
      * Serializes the given message into a bytes representation
      */
-    private BytesReference buildMessage(long requestId, byte status, Version nodeVersion, TransportMessage message, StreamOutput stream,
+    private BytesReference buildMessage(long requestId, byte status, Version nodeVersion, TransportMessage message,
-                                        ReleasableBytesStreamOutput writtenBytes) throws IOException {
+                                        CompressibleBytesOutputStream stream) throws IOException {
         final BytesReference zeroCopyBuffer;
         if (message instanceof BytesTransportRequest) { // what a shitty optimization - we should use a direct send method instead
             BytesTransportRequest bRequest = (BytesTransportRequest) message;
@@ -1185,12 +1182,12 @@ public abstract class TcpTransport<Channel> extends AbstractLifecycleComponent i
             message.writeTo(stream);
             zeroCopyBuffer = BytesArray.EMPTY;
         }
-        // we have to close the stream here - flush is not enough since we might be compressing the content
+        // we have to call materializeBytes() here before accessing the bytes. A CompressibleBytesOutputStream
-        // and if we do that the close method will write some marker bytes (EOS marker) and otherwise
+        // might be implementing compression. And materializeBytes() ensures that some marker bytes (EOS marker)
-        // we barf on the decompressing end when we read past EOF on purpose in the #validateRequest method.
+        // are written. Otherwise we barf on the decompressing end when we read past EOF on purpose in the
-        // this might be a problem in deflate after all but it's important to close it for now.
+        // #validateRequest method. this might be a problem in deflate after all but it's important to write
-        stream.close();
+        // the marker bytes.
-        final BytesReference messageBody = writtenBytes.bytes();
+        final BytesReference messageBody = stream.materializeBytes();
         final BytesReference header = buildHeader(requestId, status, stream.getVersion(), messageBody.length() + zeroCopyBuffer.length());
         return new CompositeBytesReference(header, messageBody, zeroCopyBuffer);
     }

core/src/test/java/org/elasticsearch/transport/CompressibleBytesOutputStreamTests.java

@@ -0,0 +1,116 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.transport;
+
+import org.elasticsearch.common.bytes.BytesReference;
+import org.elasticsearch.common.compress.CompressorFactory;
+import org.elasticsearch.common.io.stream.BytesStream;
+import org.elasticsearch.common.io.stream.BytesStreamOutput;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.test.ESTestCase;
+
+import java.io.EOFException;
+import java.io.IOException;
+
+public class CompressibleBytesOutputStreamTests extends ESTestCase {
+
+    public void testStreamWithoutCompression() throws IOException {
+        BytesStream bStream = new ZeroOutOnCloseStream();
+        CompressibleBytesOutputStream stream = new CompressibleBytesOutputStream(bStream, false);
+
+        byte[] expectedBytes = randomBytes(randomInt(30));
+        stream.write(expectedBytes);
+
+        BytesReference bytesRef = stream.materializeBytes();
+
+        assertFalse(CompressorFactory.COMPRESSOR.isCompressed(bytesRef));
+
+        StreamInput streamInput = bytesRef.streamInput();
+        byte[] actualBytes = new byte[expectedBytes.length];
+        streamInput.readBytes(actualBytes, 0, expectedBytes.length);
+
+        assertEquals(-1, streamInput.read());
+        assertArrayEquals(expectedBytes, actualBytes);
+        stream.close();
+
+        // The bytes should be zeroed out on close
+        for (byte b : bytesRef.toBytesRef().bytes) {
+            assertEquals((byte) 0, b);
+        }
+    }
+
+    public void testStreamWithCompression() throws IOException {
+        BytesStream bStream = new ZeroOutOnCloseStream();
+        CompressibleBytesOutputStream stream = new CompressibleBytesOutputStream(bStream, true);
+
+        byte[] expectedBytes = randomBytes(randomInt(30));
+        stream.write(expectedBytes);
+
+        BytesReference bytesRef = stream.materializeBytes();
+
+        assertTrue(CompressorFactory.COMPRESSOR.isCompressed(bytesRef));
+
+        StreamInput streamInput = CompressorFactory.COMPRESSOR.streamInput(bytesRef.streamInput());
+        byte[] actualBytes = new byte[expectedBytes.length];
+        streamInput.readBytes(actualBytes, 0, expectedBytes.length);
+
+        assertEquals(-1, streamInput.read());
+        assertArrayEquals(expectedBytes, actualBytes);
+        stream.close();
+
+        // The bytes should be zeroed out on close
+        for (byte b : bytesRef.toBytesRef().bytes) {
+            assertEquals((byte) 0, b);
+        }
+    }
+
+    public void testCompressionWithCallingMaterializeFails() throws IOException {
+        BytesStream bStream = new ZeroOutOnCloseStream();
+        CompressibleBytesOutputStream stream = new CompressibleBytesOutputStream(bStream, true);
+
+        byte[] expectedBytes = randomBytes(randomInt(30));
+        stream.write(expectedBytes);
+
+
+        StreamInput streamInput = CompressorFactory.COMPRESSOR.streamInput(bStream.bytes().streamInput());
+        byte[] actualBytes = new byte[expectedBytes.length];
+        EOFException e = expectThrows(EOFException.class, () -> streamInput.readBytes(actualBytes, 0, expectedBytes.length));
+        assertEquals("Unexpected end of ZLIB input stream", e.getMessage());
+
+        stream.close();
+    }
+
+    private static byte[] randomBytes(int length) {
+        byte[] bytes = new byte[length];
+        for (int i = 0; i < bytes.length; ++i) {
+            bytes[i] = randomByte();
+        }
+        return bytes;
+    }
+
+    private static class ZeroOutOnCloseStream extends BytesStreamOutput {
+
+        @Override
+        public void close() {
+            int size = (int) bytes.size();
+            bytes.set(0, new byte[size], 0, size);
+        }
+    }
+}