garydgregory commented on code in PR #703: URL: https://github.com/apache/httpcomponents-client/pull/703#discussion_r2265286350
########## httpclient5/src/main/java/org/apache/hc/client5/http/async/methods/DeflatingZstdEntityProducer.java: ########## @@ -0,0 +1,345 @@ +/* + * ==================================================================== + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF 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. + * ==================================================================== + * + * This software consists of voluntary contributions made by many + * individuals on behalf of the Apache Software Foundation. For more + * information on the Apache Software Foundation, please see + * <http://www.apache.org/>. + * + */ + +package org.apache.hc.client5.http.async.methods; + +import java.io.IOException; +import java.nio.ByteBuffer; +import java.util.ArrayDeque; +import java.util.Collections; +import java.util.Deque; +import java.util.Set; +import java.util.concurrent.atomic.AtomicBoolean; + +import com.github.luben.zstd.ZstdDirectBufferCompressingStream; + +import org.apache.hc.core5.http.Header; +import org.apache.hc.core5.http.nio.AsyncEntityProducer; +import org.apache.hc.core5.http.nio.DataStreamChannel; +import org.apache.hc.core5.util.Args; + +/** + * {@code AsyncEntityProducer} that compresses the bytes produced by a delegate entity + * into a single <a href="https://www.rfc-editor.org/rfc/rfc8878";>Zstandard</a> (zstd) frame + * on the fly. + * + * <p>This producer wraps a {@link org.apache.hc.core5.http.nio.AsyncEntityProducer} and + * performs streaming, ByteBuffer-to-ByteBuffer compression as the delegate writes to the + * provided {@link org.apache.hc.core5.http.nio.DataStreamChannel}. No {@code InputStream} + * is used in the client pipeline.</p> + * + * <p>Metadata reported by this producer:</p> + * <ul> + * <li>{@link #getContentEncoding()} returns {@code "zstd"}.</li> + * <li>{@link #getContentLength()} returns {@code -1} (unknown after compression).</li> + * <li>{@link #isChunked()} returns {@code true} (requests are typically sent chunked).</li> + * </ul> + * + * <h3>Usage</h3> + * <pre>{@code + * AsyncEntityProducer plain = new StringAsyncEntityProducer("payload", ContentType.TEXT_PLAIN); + * AsyncEntityProducer zstd = new DeflatingZstdEntityProducer(plain); + * + * SimpleHttpRequest req = SimpleRequestBuilder.post("http://localhost/echo";) + * .setHeader(HttpHeaders.CONTENT_ENCODING, "zstd") // inform the server + * .build(); + * + * client.execute( + * new BasicRequestProducer(req, zstd), + * new BasicResponseConsumer<>(new StringAsyncEntityConsumer()), + * null); + * }</pre> + * + * <h3>Behavior</h3> + * <ul> + * <li><b>Streaming & back-pressure:</b> compressed output is staged in direct + * {@link java.nio.ByteBuffer}s and written only when the channel accepts bytes. + * When {@code DataStreamChannel.write(...)} returns {@code 0}, the producer pauses and + * requests another output turn.</li> + * <li><b>Finalization:</b> after the delegate signals {@code endStream()}, this producer emits + * the zstd frame epilogue and then calls {@code DataStreamChannel.endStream()}.</li> + * <li><b>Repeatability:</b> repeatable only if the delegate is repeatable.</li> + * <li><b>Headers:</b> callers are responsible for sending {@code Content-Encoding: zstd} on + * the request if required by the server. Content length is not known in advance.</li> + * <li><b>Resources:</b> invoke {@link #releaseResources()} to free native compressor resources.</li> + * </ul> + * + * <h3>Constructors</h3> + * <ul> + * <li>{@code DeflatingZstdEntityProducer(delegate)} – uses a default compression level.</li> + * <li>{@code DeflatingZstdEntityProducer(delegate, level)} – explicitly sets the zstd level.</li> + * </ul> + * + * <h3>Thread-safety</h3> + * <p>Not thread-safe; one instance per message exchange.</p> + * + * <h3>Runtime dependency</h3> + * <p>Requires {@code com.github.luben:zstd-jni} on the classpath.</p> + * + * @see org.apache.hc.client5.http.async.methods.InflatingZstdDataConsumer + * @see org.apache.hc.core5.http.nio.support.BasicRequestProducer + * @see org.apache.hc.core5.http.nio.entity.StringAsyncEntityProducer + * @see org.apache.hc.client5.http.impl.async.ContentCompressionAsyncExec + * @since 5.6 + */ +public final class DeflatingZstdEntityProducer implements AsyncEntityProducer { + + private static final int IN_BUF = 64 * 1024; + private static final int OUT_BUF_DEFAULT = 128 * 1024; + + private final AsyncEntityProducer delegate; + + /** + * Direct staging for heap inputs. + */ + private final ByteBuffer inDirect = ByteBuffer.allocateDirect(IN_BUF); + + /** + * Pending compressed output buffers, ready to write (pos=0..limit). + */ + private final Deque<ByteBuffer> pending = new ArrayDeque<>(); + + /** + * Current output buffer owned by zstd; replaced when it overflows or flushes. + */ + private ByteBuffer outBuf; + + /** + * Zstd compressor stream. + */ + private final ZstdDirectBufferCompressingStream zstream; + + private volatile boolean upstreamEnded = false; Review Comment: Initializing to default values creates clutter IMO. -- This is an automated message from the Apache Git Service. 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