garydgregory commented on code in PR #580: URL: https://github.com/apache/httpcomponents-client/pull/580#discussion_r1768632771
########## httpclient5/src/main/java/org/apache/hc/client5/http/entity/CompressorFactory.java: ########## @@ -0,0 +1,294 @@ +/* + * ==================================================================== + * 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.entity; + +import java.io.InputStream; +import java.io.OutputStream; +import java.util.Collections; +import java.util.HashMap; +import java.util.Locale; +import java.util.Map; +import java.util.Set; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.atomic.AtomicReference; +import java.util.stream.Collectors; + +import org.apache.commons.compress.compressors.CompressorStreamFactory; +import org.apache.commons.compress.compressors.deflate.DeflateCompressorInputStream; +import org.apache.commons.compress.compressors.deflate.DeflateParameters; +import org.apache.hc.core5.http.HttpEntity; +import org.apache.hc.core5.util.Args; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * A factory class for managing compression and decompression of HTTP entities using different compression formats. + * <p> + * This factory uses a cache to optimize access to available input and output stream providers for compression formats. + * It also allows the use of aliases (e.g., "gzip" and "x-gzip") and automatically formats the compression names + * to ensure consistency. + * </p> + * + * <p> + * Supported compression formats include gzip, deflate, and other available formats provided by the + * {@link CompressorStreamFactory}. + * </p> + * + * <p> + * This class is thread-safe and uses {@link AtomicReference} to cache the available input and output stream providers. + * </p> + */ +public class CompressorFactory { + + private static final Logger LOG = LoggerFactory.getLogger(CompressorFactory.class); + /** + * Singleton instance of the factory. + */ + public static final CompressorFactory INSTANCE = new CompressorFactory(); + + private final CompressorStreamFactory compressorStreamFactory = new CompressorStreamFactory(); + private final AtomicReference<Set<String>> inputProvidersCache = new AtomicReference<>(); + private final AtomicReference<Set<String>> outputProvidersCache = new AtomicReference<>(); + private final Map<String, String> formattedNameCache = new ConcurrentHashMap<>(); + + private static final Map<String, String> COMPRESSION_ALIASES; + static { + final Map<String, String> aliases = new HashMap<>(); + aliases.put("gzip", "gz"); + aliases.put("x-gzip", "gz"); + aliases.put("compress", "z"); + COMPRESSION_ALIASES = Collections.unmodifiableMap(aliases); + } + + /** + * Returns a set of available input stream compression providers. + * + * @return a set of available input stream compression providers in lowercase. + */ + public Set<String> getAvailableInputProviders() { + return getAvailableProviders(inputProvidersCache, false); + } + + /** + * Returns a set of available output stream compression providers. + * + * @return a set of available output stream compression providers in lowercase. + */ + public Set<String> getAvailableOutputProviders() { + return getAvailableProviders(outputProvidersCache, true); + } + + /** + * Returns the formatted name of the provided compression format. + * <p> + * If the provided name matches an alias (e.g., "gzip" or "x-gzip"), the method will return the standard name. + * </p> + * + * @param name the compression format name. + * @return the formatted name, or the original name if no alias is found. + * @throws IllegalArgumentException if the name is null or empty. + */ + public String getFormattedName(final String name) { + if (name == null || name.isEmpty()) { + LOG.warn("Compression name is null or empty"); + return null; + } + final String lowerCaseName = name.toLowerCase(Locale.ROOT); + return formattedNameCache.computeIfAbsent(lowerCaseName, key -> COMPRESSION_ALIASES.getOrDefault(key, key)); + } + + + /** + * Creates an input stream for the specified compression format and decompresses the provided input stream. + * <p> + * This method uses the specified compression name to decompress the input stream and supports the "nowrap" option + * for deflate streams. + * </p> + * + * @param name the compression format. + * @param inputStream the input stream to decompress. + * @param nowrap if true, disables the zlib header and trailer for deflate streams. + * @return the decompressed input stream, or the original input stream if the format is not supported. + */ + public InputStream getCompressorInputStream(final String name, final InputStream inputStream, final boolean nowrap) { + Args.notNull(inputStream, "InputStream"); + Args.notNull(name, "name"); + + final String formattedName = getFormattedName(name); + return isSupported(formattedName, false) + ? createCompressorInputStream(formattedName, inputStream, nowrap) + : inputStream; + } + + /** + * Creates an output stream for the specified compression format and compresses the provided output stream. + * + * @param name the compression format. + * @param outputStream the output stream to compress. + * @return the compressed output stream, or the original output stream if the format is not supported. + */ + public OutputStream getCompressorOutputStream(final String name, final OutputStream outputStream) { + final String formattedName = getFormattedName(name); + return isSupported(formattedName, true) + ? createCompressorOutputStream(formattedName, outputStream) + : outputStream; + } + + /** + * Compresses the provided HTTP entity using the specified compression format. + * + * @param entity the HTTP entity to compress. + * @param contentEncoding the compression format. + * @return a compressed {@link HttpEntity}, or {@code null} if the compression format is unsupported. + */ + public HttpEntity compressEntity(final HttpEntity entity, final String contentEncoding) { + Args.notNull(entity, "Entity"); + Args.notNull(contentEncoding, "Content Encoding"); + if (!isSupported(contentEncoding, true)) { + LOG.warn("Unsupported compression type: {}", contentEncoding); + return null; + } + return new CompressingEntity(entity, contentEncoding); + } + + /** + * Decompresses the provided HTTP entity using the specified compression format. + * + * @param entity the HTTP entity to decompress. + * @param contentEncoding the compression format. + * @return a decompressed {@link HttpEntity}, or {@code null} if the compression format is unsupported. + */ + public HttpEntity decompressEntity(final HttpEntity entity, final String contentEncoding) { + return decompressEntity(entity, contentEncoding, false); + } + + /** + * Decompresses the provided HTTP entity using the specified compression format with the option for deflate streams. + * + * @param entity the HTTP entity to decompress. + * @param contentEncoding the compression format. + * @param nowrap if true, disables the zlib header and trailer for deflate streams. + * @return a decompressed {@link HttpEntity}, or {@code null} if the compression format is unsupported. + */ + public HttpEntity decompressEntity(final HttpEntity entity, final String contentEncoding, final boolean nowrap) { + Args.notNull(entity, "Entity"); + Args.notNull(contentEncoding, "Content Encoding"); + if (!isSupported(contentEncoding, false)) { + LOG.warn("Unsupported decompression type: {}", contentEncoding); + return null; + } + return new DecompressEntity(entity, contentEncoding, nowrap); + } + + /** + * Creates a compressor input stream for the given compression format and input stream. + * <p> + * This method handles the special case for deflate compression where the zlib header can be skipped. + * </p> + * + * @param name the compression format. + * @param inputStream the input stream to decompress. + * @param nowrap if true, disables the zlib header and trailer for deflate streams. + * @return a decompressed input stream, or null if an error occurs. + */ + private InputStream createCompressorInputStream(final String name, final InputStream inputStream, final boolean nowrap) { + try { + if ("deflate".equalsIgnoreCase(name)) { + final DeflateParameters parameters = new DeflateParameters(); + parameters.setWithZlibHeader(nowrap); + return new DeflateCompressorInputStream(inputStream, parameters); + } + return compressorStreamFactory.createCompressorInputStream(name, inputStream, true); + } catch (final Exception ex) { + LOG.warn("Could not create compressor {} input stream", name, ex); Review Comment: Why not let the exception percolate up? 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