--- /dev/null
+package net.jpountz.lz4;
+
+/*
+ * Licensed 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.
+ */
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.util.Arrays;
+
+import net.jpountz.util.Native;
+import net.jpountz.util.Utils;
+import static net.jpountz.lz4.LZ4Constants.DEFAULT_COMPRESSION_LEVEL;
+import static net.jpountz.lz4.LZ4Constants.MAX_COMPRESSION_LEVEL;
+
+/**
+ * Entry point for the LZ4 API.
+ * <p>
+ * This class has 3 instances<ul>
+ * <li>a {@link #nativeInstance() native} instance which is a JNI binding to
+ * <a href="http://code.google.com/p/lz4/">the original LZ4 C implementation</a>.
+ * <li>a {@link #safeInstance() safe Java} instance which is a pure Java port
+ * of the original C library,</li>
+ * <li>an {@link #unsafeInstance() unsafe Java} instance which is a Java port
+ * using the unofficial {@link sun.misc.Unsafe} API.
+ * </ul>
+ * <p>
+ * Only the {@link #safeInstance() safe instance} is guaranteed to work on your
+ * JVM, as a consequence it is advised to use the {@link #fastestInstance()} or
+ * {@link #fastestJavaInstance()} to pull a {@link LZ4Factory} instance.
+ * <p>
+ * All methods from this class are very costly, so you should get an instance
+ * once, and then reuse it whenever possible. This is typically done by storing
+ * a {@link LZ4Factory} instance in a static field.
+ */
+public final class LZ4Factory {
+
+ private static LZ4Factory instance(String impl) {
+ try {
+ return new LZ4Factory(impl);
+ } catch (Exception e) {
+ throw new AssertionError(e);
+ }
+ }
+
+ private static LZ4Factory NATIVE_INSTANCE,
+ JAVA_UNSAFE_INSTANCE,
+ JAVA_SAFE_INSTANCE;
+
+ /**
+ * Return a {@link LZ4Factory} instance that returns compressors and
+ * decompressors that are native bindings to the original C library.
+ * <p>
+ * Please note that this instance has some traps you should be aware of:<ol>
+ * <li>Upon loading this instance, files will be written to the temporary
+ * directory of the system. Although these files are supposed to be deleted
+ * when the JVM exits, they might remain on systems that don't support
+ * removal of files being used such as Windows.
+ * <li>The instance can only be loaded once per JVM. This can be a problem
+ * if your application uses multiple class loaders (such as most servlet
+ * containers): this instance will only be available to the children of the
+ * class loader which has loaded it. As a consequence, it is advised to
+ * either not use this instance in webapps or to put this library in the lib
+ * directory of your servlet container so that it is loaded by the system
+ * class loader.
+ * </ol>
+ */
+ public static synchronized LZ4Factory nativeInstance() {
+ if (NATIVE_INSTANCE == null) {
+ NATIVE_INSTANCE = instance("JNI");
+ }
+ return NATIVE_INSTANCE;
+ }
+
+ /** Return a {@link LZ4Factory} instance that returns compressors and
+ * decompressors that are written with Java's official API. */
+ public static synchronized LZ4Factory safeInstance() {
+ if (JAVA_SAFE_INSTANCE == null) {
+ JAVA_SAFE_INSTANCE = instance("JavaSafe");
+ }
+ return JAVA_SAFE_INSTANCE;
+ }
+
+ /** Return a {@link LZ4Factory} instance that returns compressors and
+ * decompressors that may use {@link sun.misc.Unsafe} to speed up compression
+ * and decompression. */
+ public static synchronized LZ4Factory unsafeInstance() {
+ if (JAVA_UNSAFE_INSTANCE == null) {
+ JAVA_UNSAFE_INSTANCE = instance("JavaUnsafe");
+ }
+ return JAVA_UNSAFE_INSTANCE;
+ }
+
+ /**
+ * Return the fastest available {@link LZ4Factory} instance which does not
+ * rely on JNI bindings. It first tries to load the
+ * {@link #unsafeInstance() unsafe instance}, and then the
+ * {@link #safeInstance() safe Java instance} if the JVM doesn't have a
+ * working {@link sun.misc.Unsafe}.
+ */
+ public static LZ4Factory fastestJavaInstance() {
+ if (Utils.isUnalignedAccessAllowed()) {
+ try {
+ return unsafeInstance();
+ } catch (Throwable t) {
+ return safeInstance();
+ }
+ } else {
+ return safeInstance();
+ }
+ }
+
+ /**
+ * Return the fastest available {@link LZ4Factory} instance. If the class
+ * loader is the system class loader and if the
+ * {@link #nativeInstance() native instance} loads successfully, then the
+ * {@link #nativeInstance() native instance} is returned, otherwise the
+ * {@link #fastestJavaInstance() fastest Java instance} is returned.
+ * <p>
+ * Please read {@link #nativeInstance() javadocs of nativeInstance()} before
+ * using this method.
+ */
+ public static LZ4Factory fastestInstance() {
+ if (Native.isLoaded()
+ || Native.class.getClassLoader() == ClassLoader.getSystemClassLoader()) {
+ try {
+ return nativeInstance();
+ } catch (Throwable t) {
+ return fastestJavaInstance();
+ }
+ } else {
+ return fastestJavaInstance();
+ }
+ }
+
+ @SuppressWarnings("unchecked")
+ private static <T> T classInstance(String cls) throws NoSuchFieldException, SecurityException, ClassNotFoundException, IllegalArgumentException, IllegalAccessException {
+ ClassLoader loader = LZ4Factory.class.getClassLoader();
+ loader = loader == null ? ClassLoader.getSystemClassLoader() : loader;
+ final Class<?> c = loader.loadClass(cls);
+ Field f = c.getField("INSTANCE");
+ return (T) f.get(null);
+ }
+
+ private final String impl;
+ private final LZ4Compressor fastCompressor;
+ private final LZ4Compressor highCompressor;
+ private final LZ4FastDecompressor fastDecompressor;
+ private final LZ4SafeDecompressor safeDecompressor;
+ private final LZ4Compressor[] highCompressors = new LZ4Compressor[MAX_COMPRESSION_LEVEL+1];
+
+ private LZ4Factory(String impl) throws ClassNotFoundException, NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException, NoSuchMethodException, InstantiationException, InvocationTargetException {
+ this.impl = impl;
+ fastCompressor = classInstance("net.jpountz.lz4.LZ4" + impl + "Compressor");
+ highCompressor = classInstance("net.jpountz.lz4.LZ4HC" + impl + "Compressor");
+ fastDecompressor = classInstance("net.jpountz.lz4.LZ4" + impl + "FastDecompressor");
+ safeDecompressor = classInstance("net.jpountz.lz4.LZ4" + impl + "SafeDecompressor");
+ Constructor<? extends LZ4Compressor> highConstructor = highCompressor.getClass().getDeclaredConstructor(int.class);
+ highCompressors[DEFAULT_COMPRESSION_LEVEL] = highCompressor;
+ for(int level = 1; level <= MAX_COMPRESSION_LEVEL; level++) {
+ if(level == DEFAULT_COMPRESSION_LEVEL) continue;
+ highCompressors[level] = highConstructor.newInstance(level);
+ }
+
+ // quickly test that everything works as expected
+ final byte[] original = new byte[] {'a','b','c','d',' ',' ',' ',' ',' ',' ','a','b','c','d','e','f','g','h','i','j'};
+ for (LZ4Compressor compressor : Arrays.asList(fastCompressor, highCompressor)) {
+ final int maxCompressedLength = compressor.maxCompressedLength(original.length);
+ final byte[] compressed = new byte[maxCompressedLength];
+ final int compressedLength = compressor.compress(original, 0, original.length, compressed, 0, maxCompressedLength);
+ final byte[] restored = new byte[original.length];
+ fastDecompressor.decompress(compressed, 0, restored, 0, original.length);
+ if (!Arrays.equals(original, restored)) {
+ throw new AssertionError();
+ }
+ Arrays.fill(restored, (byte) 0);
+ final int decompressedLength = safeDecompressor.decompress(compressed, 0, compressedLength, restored, 0);
+ if (decompressedLength != original.length || !Arrays.equals(original, restored)) {
+ throw new AssertionError();
+ }
+ }
+
+ }
+
+ /** Return a blazing fast {@link LZ4Compressor}. */
+ public LZ4Compressor fastCompressor() {
+ return fastCompressor;
+ }
+
+ /** Return a {@link LZ4Compressor} which requires more memory than
+ * {@link #fastCompressor()} and is slower but compresses more efficiently. */
+ public LZ4Compressor highCompressor() {
+ return highCompressor;
+ }
+
+ /** Return a {@link LZ4Compressor} which requires more memory than
+ * {@link #fastCompressor()} and is slower but compresses more efficiently.
+ * The compression level can be customized.
+ * <p>For current implementations, the following is true about compression level:<ol>
+ * <li>It should be in range [1, 17]</li>
+ * <li>A compression level higher than 17 would be treated as 17.</li>
+ * <li>A compression level lower than 1 would be treated as 9.</li>
+ * </ol></p>
+ */
+ public LZ4Compressor highCompressor(int compressionLevel) {
+ if(compressionLevel > MAX_COMPRESSION_LEVEL) {
+ compressionLevel = MAX_COMPRESSION_LEVEL;
+ } else if(compressionLevel < 1) {
+ compressionLevel = DEFAULT_COMPRESSION_LEVEL;
+ }
+ return highCompressors[compressionLevel];
+ }
+
+ /** Return a {@link LZ4FastDecompressor} instance. */
+ public LZ4FastDecompressor fastDecompressor() {
+ return fastDecompressor;
+ }
+
+ /** Return a {@link LZ4SafeDecompressor} instance. */
+ public LZ4SafeDecompressor safeDecompressor() {
+ return safeDecompressor;
+ }
+
+ /** Return a {@link LZ4UnknownSizeDecompressor} instance.
+ * @deprecated use {@link #safeDecompressor()} */
+ public LZ4UnknownSizeDecompressor unknownSizeDecompressor() {
+ return safeDecompressor();
+ }
+
+ /** Return a {@link LZ4Decompressor} instance.
+ * @deprecated use {@link #fastDecompressor()} */
+ public LZ4Decompressor decompressor() {
+ return fastDecompressor();
+ }
+
+ /** Prints the fastest instance. */
+ public static void main(String[] args) {
+ System.out.println("Fastest instance is " + fastestInstance());
+ System.out.println("Fastest Java instance is " + fastestJavaInstance());
+ }
+
+ @Override
+ public String toString() {
+ return getClass().getSimpleName() + ":" + impl;
+ }
+
+}
Code Review / simantics / platform.git / blobdiff