Merge fixes for #27

pom.xml

@@ -182,12 +182,22 @@
                         <Import-Package>org.osgi.framework;version="[1.5,2)"</Import-Package>
                         <Bundle-ActivationPolicy>lazy</Bundle-ActivationPolicy>
                         <Bundle-NativeCode>
+<<<<<<< HEAD
                         	org/xerial/snappy/native/Windows/amd64/snappyjava.dll;osname=win32;processor=x86-64,
                         	org/xerial/snappy/native/Windows/x86/snappyjava.dll;osname=win32;processor=x86,
                         	org/xerial/snappy/native/Mac/x86_64/libsnappyjava.jnilib;osname=macosx;processor=x86-64,
                         	org/xerial/snappy/native/Linux/amd64/libsnappyjava.so;osname=linux;processor=x86-64,
                         	org/xerial/snappy/native/Linux/i386/libsnappyjava.so;osname=linux;processor=x86,
                         	org/xerial/snappy/native/Linux/arm/libsnappyjava.so;osname=linux;processor=arm
+=======
+                        	org/xerial/snappy/native/Windows/x86_64/snappyjava.dll;selection-filter="(&amp;(osgi.arch=x86_64)(osgi.os=win32))",
+                        	org/xerial/snappy/native/Windows/x86/snappyjava.dll;selection-filter="(&amp;(osgi.arch=x86)(osgi.os=win32))",
+                        	org/xerial/snappy/native/Mac/x86/libsnappyjava.jnilib;selection-filter="(&amp;(osgi.arch=x86)(osgi.os=macosx))",
+                        	org/xerial/snappy/native/Mac/x86_64/libsnappyjava.jnilib;selection-filter="(&amp;(osgi.arch=x86_64)(osgi.os=macosx))",
+                        	org/xerial/snappy/native/Linux/x86_64/libsnappyjava.so;selection-filter="(&amp;(osgi.arch=x86_64)(osgi.os=linux))",
+                        	org/xerial/snappy/native/Linux/x86/libsnappyjava.so;selection-filter="(&amp;(osgi.arch=x86)(osgi.os=linux))",
+                        	org/xerial/snappy/native/Linux/arm/libsnappyjava.so;selection-filter="(&amp;(osgi.arch=arm)(osgi.os=linux))"
+>>>>>>> feature/lib-loader
                         </Bundle-NativeCode>
                         <!-- TODO: unsure about ARMHF -->
                     </instructions>

src/main/java/org/xerial/snappy/OSInfo.java

@@ -25,6 +25,8 @@
 package org.xerial.snappy;
 
 import java.io.IOException;
+import java.util.HashMap;
+import java.util.Locale;
 
 /**
  * Provides OS name and architecture name.
@@ -34,6 +36,48 @@ import java.io.IOException;
  */
 public class OSInfo
 {
+    private static HashMap<String, String> archMapping = new HashMap<String, String>();
+
+    public static final String X86 = "x86";
+    public static final String X86_64 = "x86_64";
+    public static final String IA64_32 = "ia64_32";
+    public static final String IA64 = "ia64";
+    public static final String PPC = "ppc";
+
+    static {
+        // x86 mappings
+        archMapping.put(X86, X86);
+        archMapping.put("i386", X86);
+        archMapping.put("i486", X86);
+        archMapping.put("i586", X86);
+        archMapping.put("i686", X86);
+        archMapping.put("pentium", X86);
+
+        // x86_64 mappings
+        archMapping.put(X86_64, X86_64);
+        archMapping.put("amd64", X86_64);
+        archMapping.put("em64t", X86_64);
+        archMapping.put("universal", X86_64); // Needed for openjdk7 in Mac
+
+        // Itenium 64-bit mappings
+        archMapping.put(IA64, IA64);
+        archMapping.put("ia64w", IA64);
+
+        // Itenium 32-bit mappings, usually an HP-UX construct
+        archMapping.put(IA64_32, IA64_32);
+        archMapping.put("ia64n", IA64_32);
+
+        // PowerPC mappings
+        archMapping.put(PPC, PPC);
+        archMapping.put("pwoer", PPC);
+        archMapping.put("powerpc", PPC);
+        archMapping.put("power_pc", PPC);
+        archMapping.put("power_rs", PPC);
+
+        // TODO: PowerPC 64bit mappings
+    }
+
+
     public static void main(String[] args) {
         if (args.length >= 1) {
             if ("--os".equals(args[0])) {
@@ -78,8 +122,10 @@ public class OSInfo
                 // ignored: fall back to "arm" arch (soft-float ABI)
             }
         } 
-        else if(getOSName().equals("Mac") && (osArch.equals("universal") || osArch.equals("amd64"))) {
+        else {
-            return "x86_64"; // Fix for openjdk7
+            String lc = osArch.toLowerCase(Locale.US);
+            if(archMapping.containsKey(lc))
+                return archMapping.get(lc);
         }
         return translateArchNameToFolderName(osArch);
     }

src/main/java/org/xerial/snappy/Snappy.java

@@ -26,7 +26,6 @@ package org.xerial.snappy;
 
 import java.io.IOException;
 import java.io.UnsupportedEncodingException;
-import java.lang.ExceptionInInitializerError;
 import java.net.URL;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
@@ -35,7 +34,7 @@ import java.util.Properties;
 /**
  * Snappy API for data compression/decompression
  *
- * Note: if the native libraries cannot be loaded, then an ExceptionInInitializerError
+ * Note: if the native libraries cannot be loaded, an ExceptionInInitializerError
  * will be thrown at first use of this class.
  * 
  * @author leo
@@ -53,9 +52,22 @@ public class Snappy
     }
 
     /**
-     * An instance of SnappyNativeAPI
+     * An instance of SnappyNative
      */
-    private static Object impl;
+    private static SnappyNative impl;
+
+
+    /**
+     * Clean up a temporary file (native lib) generated by snappy-java.
+     * General users do not need to call this method, since the native library extracted in snappy-java
+     * is deleted upon JVM termination (vie deleteOnExit()).
+     * This method is useful when using a J2EE container, which will restart servlet containers multiple times without
+     * restarting JVM.
+     */
+    static void cleanUp() {
+        SnappyLoader.cleanUpExtractedNativeLib();
+    }
+
 
     /**
      * Copy bytes from source to destination
@@ -74,7 +86,7 @@ public class Snappy
      */
     public static void arrayCopy(Object src, int offset, int byteLength, Object dest, int dest_offset)
             throws IOException {
-        ((SnappyNativeAPI) impl).arrayCopy(src, offset, byteLength, dest, dest_offset);
+        impl.arrayCopy(src, offset, byteLength, dest, dest_offset);
     }
 
     /**
@@ -135,7 +147,7 @@ public class Snappy
         // output: compressed
         int uPos = uncompressed.position();
         int uLen = uncompressed.remaining();
-        int compressedSize = ((SnappyNativeAPI) impl).rawCompress(uncompressed, uPos, uLen, compressed,
+        int compressedSize = impl.rawCompress(uncompressed, uPos, uLen, compressed,
                 compressed.position());
 
         //         pos  limit
@@ -284,7 +296,7 @@ public class Snappy
     public static boolean isValidCompressedBuffer(byte[] input, int offset, int length) throws IOException {
         if (input == null)
             throw new NullPointerException("input is null");
-        return ((SnappyNativeAPI) impl).isValidCompressedBuffer(input, offset, length);
+        return impl.isValidCompressedBuffer(input, offset, length);
     }
 
     /**
@@ -304,7 +316,7 @@ public class Snappy
      * factor of four faster than actual decompression.
      */
     public static boolean isValidCompressedBuffer(ByteBuffer compressed) throws IOException {
-        return ((SnappyNativeAPI) impl).isValidCompressedBuffer(compressed, compressed.position(),
+        return impl.isValidCompressedBuffer(compressed, compressed.position(),
                 compressed.remaining());
     }
 
@@ -317,7 +329,7 @@ public class Snappy
      * @return maximum byte size of the compressed data
      */
     public static int maxCompressedLength(int byteSize) {
-        return ((SnappyNativeAPI) impl).maxCompressedLength(byteSize);
+        return impl.maxCompressedLength(byteSize);
     }
 
     /**
@@ -329,7 +341,7 @@ public class Snappy
      * @throws IOException
      */
     public static long rawCompress(long inputAddr, long inputSize, long destAddr) throws IOException {
-        return ((SnappyNativeAPI) impl).rawCompress(inputAddr, inputSize, destAddr);
+        return impl.rawCompress(inputAddr, inputSize, destAddr);
     }
 
     /**
@@ -341,7 +353,7 @@ public class Snappy
      * @throws IOException
      */
     public static long rawUncompress(long inputAddr, long inputSize, long destAddr) throws IOException {
-        return ((SnappyNativeAPI) impl).rawUncompress(inputAddr, inputSize, destAddr);
+        return impl.rawUncompress(inputAddr, inputSize, destAddr);
     }
 
 
@@ -356,7 +368,7 @@ public class Snappy
      */
     public static byte[] rawCompress(Object data, int byteSize) throws IOException {
         byte[] buf = new byte[Snappy.maxCompressedLength(byteSize)];
-        int compressedByteSize = ((SnappyNativeAPI) impl).rawCompress(data, 0, byteSize, buf, 0);
+        int compressedByteSize = impl.rawCompress(data, 0, byteSize, buf, 0);
         byte[] result = new byte[compressedByteSize];
         System.arraycopy(buf, 0, result, 0, compressedByteSize);
         return result;
@@ -384,7 +396,7 @@ public class Snappy
         if (input == null || output == null)
             throw new NullPointerException("input or output is null");
 
-        int compressedSize = ((SnappyNativeAPI) impl)
+        int compressedSize = impl
                 .rawCompress(input, inputOffset, inputLength, output, outputOffset);
         return compressedSize;
     }
@@ -417,7 +429,7 @@ public class Snappy
             throws IOException {
         if (input == null || output == null)
             throw new NullPointerException("input or output is null");
-        return ((SnappyNativeAPI) impl).rawUncompress(input, inputOffset, inputLength, output, outputOffset);
+        return impl.rawUncompress(input, inputOffset, inputLength, output, outputOffset);
     }
 
     /**
@@ -489,7 +501,7 @@ public class Snappy
 
         //         pos  limit
         // [ ......UUUUUU.........]
-        int decompressedSize = ((SnappyNativeAPI) impl).rawUncompress(compressed, cPos, cLen, uncompressed,
+        int decompressedSize = impl.rawUncompress(compressed, cPos, cLen, uncompressed,
                 uncompressed.position());
         uncompressed.limit(uncompressed.position() + decompressedSize);
 
@@ -519,7 +531,7 @@ public class Snappy
     public static char[] uncompressCharArray(byte[] input, int offset, int length) throws IOException {
         int uncompressedLength = Snappy.uncompressedLength(input, offset, length);
         char[] result = new char[uncompressedLength / 2];
-        int byteSize = ((SnappyNativeAPI) impl).rawUncompress(input, offset, length, result, 0);
+        int byteSize = impl.rawUncompress(input, offset, length, result, 0);
         return result;
     }
 
@@ -533,7 +545,7 @@ public class Snappy
     public static double[] uncompressDoubleArray(byte[] input) throws IOException {
         int uncompressedLength = Snappy.uncompressedLength(input, 0, input.length);
         double[] result = new double[uncompressedLength / 8];
-        int byteSize = ((SnappyNativeAPI) impl).rawUncompress(input, 0, input.length, result, 0);
+        int byteSize = impl.rawUncompress(input, 0, input.length, result, 0);
         return result;
     }
 
@@ -548,7 +560,7 @@ public class Snappy
      *             {@link SnappyErrorCode#PARSING_ERROR}
      */
     public static int uncompressedLength(byte[] input) throws IOException {
-        return ((SnappyNativeAPI) impl).uncompressedLength(input, 0, input.length);
+        return impl.uncompressedLength(input, 0, input.length);
     }
 
     /**
@@ -567,7 +579,7 @@ public class Snappy
         if (input == null)
             throw new NullPointerException("input is null");
 
-        return ((SnappyNativeAPI) impl).uncompressedLength(input, offset, length);
+        return impl.uncompressedLength(input, offset, length);
     }
 
     /**
@@ -587,7 +599,7 @@ public class Snappy
         if (!compressed.isDirect())
             throw new SnappyError(SnappyErrorCode.NOT_A_DIRECT_BUFFER, "input is not a direct buffer");
 
-        return ((SnappyNativeAPI) impl).uncompressedLength(compressed, compressed.position(), compressed.remaining());
+        return impl.uncompressedLength(compressed, compressed.position(), compressed.remaining());
     }
 
     /**
@@ -599,7 +611,7 @@ public class Snappy
      *             {@link SnappyErrorCode#PARSING_ERROR}
      */
     public static long uncompressedLength(long inputAddr, long len) throws IOException {
-        return ((SnappyNativeAPI) impl).uncompressedLength(inputAddr, len);
+        return impl.uncompressedLength(inputAddr, len);
     }
 
     /**
@@ -625,7 +637,7 @@ public class Snappy
     public static float[] uncompressFloatArray(byte[] input, int offset, int length) throws IOException {
         int uncompressedLength = Snappy.uncompressedLength(input, offset, length);
         float[] result = new float[uncompressedLength / 4];
-        int byteSize = ((SnappyNativeAPI) impl).rawUncompress(input, offset, length, result, 0);
+        int byteSize = impl.rawUncompress(input, offset, length, result, 0);
         return result;
     }
 
@@ -652,7 +664,7 @@ public class Snappy
     public static int[] uncompressIntArray(byte[] input, int offset, int length) throws IOException {
         int uncompressedLength = Snappy.uncompressedLength(input, offset, length);
         int[] result = new int[uncompressedLength / 4];
-        int byteSize = ((SnappyNativeAPI) impl).rawUncompress(input, offset, length, result, 0);
+        int byteSize = impl.rawUncompress(input, offset, length, result, 0);
         return result;
     }
 
@@ -679,7 +691,7 @@ public class Snappy
     public static long[] uncompressLongArray(byte[] input, int offset, int length) throws IOException {
         int uncompressedLength = Snappy.uncompressedLength(input, offset, length);
         long[] result = new long[uncompressedLength / 8];
-        int byteSize = ((SnappyNativeAPI) impl).rawUncompress(input, offset, length, result, 0);
+        int byteSize = impl.rawUncompress(input, offset, length, result, 0);
         return result;
     }
 
@@ -706,7 +718,7 @@ public class Snappy
     public static short[] uncompressShortArray(byte[] input, int offset, int length) throws IOException {
         int uncompressedLength = Snappy.uncompressedLength(input, offset, length);
         short[] result = new short[uncompressedLength / 2];
-        int byteSize = ((SnappyNativeAPI) impl).rawUncompress(input, offset, length, result, 0);
+        int byteSize = impl.rawUncompress(input, offset, length, result, 0);
         return result;
     }
 

src/main/java/org/xerial/snappy/SnappyBundleActivator.java

@@ -24,12 +24,12 @@
 //--------------------------------------
 package org.xerial.snappy;
 
-import java.util.jar.Manifest;
-
 import org.osgi.framework.Bundle;
 import org.osgi.framework.BundleActivator;
 import org.osgi.framework.BundleContext;
 
+import java.util.jar.Manifest;
+
 /**
  * OSGi bundle entry point
  * 
@@ -56,5 +56,6 @@ public class SnappyBundleActivator implements BundleActivator
     public void stop(BundleContext context) throws Exception
     {
     	SnappyLoader.setApi(null);
+        Snappy.cleanUp();
     }
 }

src/main/java/org/xerial/snappy/SnappyLoader.java

@@ -24,24 +24,11 @@
 //--------------------------------------
 package org.xerial.snappy;
 
-import java.io.BufferedInputStream;
+import java.io.*;
-import java.io.ByteArrayOutputStream;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
 import java.net.URL;
-import java.security.DigestInputStream;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
-import java.security.ProtectionDomain;
-import java.util.ArrayList;
 import java.util.Enumeration;
-import java.util.List;
 import java.util.Properties;
+import java.util.UUID;
 
 /**
  * <b>Internal only - Do not use this class.</b> This class loads a native
@@ -94,14 +81,21 @@ public class SnappyLoader
     public static final String KEY_SNAPPY_DISABLE_BUNDLED_LIBS = "org.xerial.snappy.disable.bundled.libs"; // Depreciated, but preserved for backward compatibility
 
     private static volatile boolean     isLoaded                        = false;
-    private static volatile Object api                             = null;
+    private static volatile SnappyNative api                             = null;
+
+    private static File nativeLibFile = null;
+
+    static void cleanUpExtractedNativeLib() {
+        if(nativeLibFile != null && nativeLibFile.exists())
+            nativeLibFile.delete();
+    }
 
     /**
      * Set the api instance.
      * 
      * @param nativeCode
      */
-    static synchronized void setApi(Object nativeCode)
+    static synchronized void setApi(SnappyNative nativeCode)
     {
     	api = nativeCode;
     }
@@ -142,97 +136,16 @@ public class SnappyLoader
         loadSnappySystemProperties();
     }
 
-    private static ClassLoader getRootClassLoader() {
+    static synchronized SnappyNative load()
-        ClassLoader cl = Thread.currentThread().getContextClassLoader();
-        while (cl.getParent() != null) {
-            cl = cl.getParent();
-        }
-        return cl;
-    }
-
-    private static byte[] getByteCode(String resourcePath) throws IOException {
-
-        InputStream in = SnappyLoader.class.getResourceAsStream(resourcePath);
-        if (in == null)
-            throw new IOException(resourcePath + " is not found");
-        byte[] buf = new byte[1024];
-        ByteArrayOutputStream byteCodeBuf = new ByteArrayOutputStream();
-        for (int readLength; (readLength = in.read(buf)) != -1;) {
-            byteCodeBuf.write(buf, 0, readLength);
-        }
-        in.close();
-
-        return byteCodeBuf.toByteArray();
-    }
-
-    public static boolean isNativeLibraryLoaded() {
-        return isLoaded;
-    }
-
-    private static boolean hasInjectedNativeLoader() {
-        try {
-            final String nativeLoaderClassName = "org.xerial.snappy.SnappyNativeLoader";
-            Class< ? > c = Class.forName(nativeLoaderClassName);
-            // If this native loader class is already defined, it means that another class loader already loaded the native library of snappy
-            return true;
-        }
-        catch (ClassNotFoundException e) {
-            // do loading
-            return false;
-        }
-    }
-
-    /**
-     * Load SnappyNative and its JNI native implementation using the root class
-     * loader. This hack is for avoiding the JNI multi-loading issue when the
-     * same JNI library is loaded by different class loaders.
-     * 
-     * In order to load native code in the root class loader, this method first
-     * inject SnappyNativeLoader class into the root class loader, because
-     * {@link System#load(String)} method uses the class loader of the caller
-     * class when loading native libraries.
-     * 
-     * <pre>
-     * (root class loader) -> [SnappyNativeLoader (load JNI code), SnappyNative (has native methods), SnappyNativeAPI, SnappyErrorCode]  (injected by this method)
-     *    |
-     *    |
-     * (child class loader) -> Sees the above classes loaded by the root class loader.
-     *   Then creates SnappyNativeAPI implementation by instantiating SnappyNaitive class.
-     * </pre>
-     * 
-     * 
-     * <pre>
-     * (root class loader) -> [SnappyNativeLoader, SnappyNative ...]  -> native code is loaded by once in this class loader 
-     *   |   \
-     *   |    (child2 class loader)      
-     * (child1 class loader)
-     * 
-     * child1 and child2 share the same SnappyNative code loaded by the root class loader.
-     * </pre>
-     * 
-     * Note that Java's class loader first delegates the class lookup to its
-     * parent class loader. So once SnappyNativeLoader is loaded by the root
-     * class loader, no child class loader initialize SnappyNativeLoader again.
-     * 
-     * @return
-     */
-    static synchronized Object load() 
     {
         if (api != null)
             return api;
 
         try {
-            if (!hasInjectedNativeLoader()) {
+            loadNativeLibrary();
-                // Inject SnappyNativeLoader (src/main/resources/org/xerial/snappy/SnappyNativeLoader.bytecode) to the root class loader  
-                Class< ? > nativeLoader = injectSnappyNativeLoader();
-                // Load the JNI code using the injected loader
-                loadNativeLibrary(nativeLoader);
-            }
 
+            setApi(new SnappyNative());
             isLoaded = true;
-            // Look up SnappyNative, injected to the root classloder, using reflection in order to avoid the initialization of SnappyNative class in this context class loader.
-            Object nativeCode = Class.forName("org.xerial.snappy.SnappyNative").newInstance();
-            setApi(nativeCode);
         }
         catch (Exception e) {
             e.printStackTrace();
@@ -243,119 +156,40 @@ public class SnappyLoader
     }
 
     /**
-     * Inject SnappyNativeLoader class to the root class loader
+     * Load a native library of snappy-java
-     * 
-     * @return native code loader class initialized in the root class loader
      */
-    private static Class< ? > injectSnappyNativeLoader() {
+    private static void loadNativeLibrary() {
 
-        try {
+        nativeLibFile = findNativeLibrary();
-            // Use parent class loader to load SnappyNative, since Tomcat, which uses different class loaders for each webapps, cannot load JNI interface twice
+        if (nativeLibFile != null) {
-
-            final String nativeLoaderClassName = "org.xerial.snappy.SnappyNativeLoader";
-            ClassLoader rootClassLoader = getRootClassLoader();
-            // Load a byte code 
-            byte[] byteCode = getByteCode("/org/xerial/snappy/SnappyNativeLoader.bytecode");
-            // In addition, we need to load the other dependent classes (e.g., SnappyNative and SnappyException) using the system class loader
-            final String[] classesToPreload = new String[] { "org.xerial.snappy.SnappyNativeAPI",
-                    "org.xerial.snappy.SnappyNative", "org.xerial.snappy.SnappyErrorCode" };
-            List<byte[]> preloadClassByteCode = new ArrayList<byte[]>(classesToPreload.length);
-            for (String each : classesToPreload) {
-                preloadClassByteCode.add(getByteCode(String.format("/%s.class", each.replaceAll("\\.", "/"))));
-            }
-
-            // Create SnappyNativeLoader class from a byte code
-            Class< ? > classLoader = Class.forName("java.lang.ClassLoader");
-            Method defineClass = classLoader.getDeclaredMethod("defineClass", new Class[] { String.class, byte[].class,
-                    int.class, int.class, ProtectionDomain.class });
-
-            ProtectionDomain pd = System.class.getProtectionDomain();
-
-            // ClassLoader.defineClass is a protected method, so we have to make it accessible
-            defineClass.setAccessible(true);
-            try {
-                // Create a new class using a ClassLoader#defineClass
-                defineClass.invoke(rootClassLoader, nativeLoaderClassName, byteCode, 0, byteCode.length, pd);
-
-                // And also define dependent classes in the root class loader
-                for (int i = 0; i < classesToPreload.length; ++i) {
-                    byte[] b = preloadClassByteCode.get(i);
-                    defineClass.invoke(rootClassLoader, classesToPreload[i], b, 0, b.length, pd);
-                }
-            }
-            finally {
-                // Reset the accessibility to defineClass method
-                defineClass.setAccessible(false);
-            }
-
-            // Load the SnappyNativeLoader class
-            return rootClassLoader.loadClass(nativeLoaderClassName);
-
-        }
-        catch (Exception e) {
-            e.printStackTrace(System.err);
-            throw new SnappyError(SnappyErrorCode.FAILED_TO_LOAD_NATIVE_LIBRARY, e.getMessage());
-        }
-
-    }
-
-    /**
-     * Load snappy-java's native code using load method of the
-     * SnappyNativeLoader class injected to the root class loader.
-     * 
-     * @param loaderClass
-     * @throws SecurityException
-     * @throws NoSuchMethodException
-     * @throws IllegalArgumentException
-     * @throws IllegalAccessException
-     * @throws InvocationTargetException
-     */
-    private static void loadNativeLibrary(Class< ? > loaderClass) throws SecurityException, NoSuchMethodException,
-            IllegalArgumentException, IllegalAccessException, InvocationTargetException {
-        if (loaderClass == null)
-            throw new SnappyError(SnappyErrorCode.FAILED_TO_LOAD_NATIVE_LIBRARY, "missing snappy native loader class");
-
-        File nativeLib = findNativeLibrary();
-        if (nativeLib != null) {
             // Load extracted or specified snappyjava native library.
-            Method loadMethod = loaderClass.getDeclaredMethod("load", new Class[] { String.class });
+            System.load(nativeLibFile.getAbsolutePath());
-            loadMethod.invoke(null, nativeLib.getAbsolutePath());
         }
         else {
             // Load preinstalled snappyjava (in the path -Djava.library.path)
-            Method loadMethod = loaderClass.getDeclaredMethod("loadLibrary", new Class[] { String.class });
+            System.loadLibrary("snappyjava");
-            loadMethod.invoke(null, "snappyjava");
         }
     }
 
-    /**
-     * Computes the MD5 value of the input stream
-     * 
-     * @param input
-     * @return
-     * @throws IOException
-     * @throws NoSuchAlgorithmException
-     */
-    static String md5sum(InputStream input) throws IOException {
-        BufferedInputStream in = new BufferedInputStream(input);
-        try {
-            MessageDigest digest = java.security.MessageDigest.getInstance("MD5");
-            DigestInputStream digestInputStream = new DigestInputStream(in, digest);
-            for (; digestInputStream.read() >= 0;) {
 
+    private static boolean contentsEquals(InputStream in1, InputStream in2) throws IOException {
+        if(!(in1 instanceof  BufferedInputStream)) {
+           in1 = new BufferedInputStream(in1);
         }
-            ByteArrayOutputStream md5out = new ByteArrayOutputStream();
+        if(!(in2 instanceof BufferedInputStream)) {
-            md5out.write(digest.digest());
+           in2 = new BufferedInputStream(in2);
-            return md5out.toString();
-        }
-        catch (NoSuchAlgorithmException e) {
-            throw new IllegalStateException("MD5 algorithm is not available: " + e);
-        }
-        finally {
-            in.close();
-        }
         }
 
+        int ch = in1.read();
+        while(ch != -1) {
+           int ch2 = in2.read();
+            if(ch != ch2)
+                return false;
+            ch = in1.read();
+        }
+        int ch2 = in2.read();
+        return ch2 == -1;
+    }
     /**
      * Extract the specified library file to the target folder
      * 
@@ -366,40 +200,31 @@ public class SnappyLoader
      */
     private static File extractLibraryFile(String libFolderForCurrentOS, String libraryFileName, String targetFolder) {
         String nativeLibraryFilePath = libFolderForCurrentOS + "/" + libraryFileName;
-        final String prefix = "snappy-" + getVersion() + "-";
+
-        String extractedLibFileName = prefix + libraryFileName;
+        // Attach UUID to the native library file to ensure multiple class loaders can read the libsnappy-java multiple times.
+        String uuid = UUID.randomUUID().toString();
+        String extractedLibFileName = String.format("snappy-%s-%s-%s", getVersion(), uuid, libraryFileName);
         File extractedLibFile = new File(targetFolder, extractedLibFileName);
-
+        // Delete extracted lib file on exit.
+        extractedLibFile.deleteOnExit();
         try {
-            if (extractedLibFile.exists()) {
-                // test md5sum value
-                String md5sum1 = md5sum(SnappyLoader.class.getResourceAsStream(nativeLibraryFilePath));
-                String md5sum2 = md5sum(new FileInputStream(extractedLibFile));
-
-                if (md5sum1.equals(md5sum2)) {
-                    return new File(targetFolder, extractedLibFileName);
-                }
-                else {
-                    // remove old native library file
-                    boolean deletionSucceeded = extractedLibFile.delete();
-                    if (!deletionSucceeded) {
-                        throw new IOException("failed to remove existing native library file: "
-                                + extractedLibFile.getAbsolutePath());
-                    }
-                }
-            }
 
             // Extract a native library file into the target directory
             InputStream reader = SnappyLoader.class.getResourceAsStream(nativeLibraryFilePath);
             FileOutputStream writer = new FileOutputStream(extractedLibFile);
+            try {
                 byte[] buffer = new byte[8192];
                 int bytesRead = 0;
                 while ((bytesRead = reader.read(buffer)) != -1) {
                     writer.write(buffer, 0, bytesRead);
                 }
-
+            }
+            finally {
+                if(writer != null)
                     writer.close();
+                if(reader != null)
                     reader.close();
+            }
 
             // Set executable (x) flag to enable Java to load the native library
             if (!System.getProperty("os.name").contains("Windows")) {
@@ -410,6 +235,22 @@ public class SnappyLoader
                 catch (Throwable e) {}
             }
 
+            // Check the contents
+            {
+                InputStream nativeIn = SnappyLoader.class.getResourceAsStream(nativeLibraryFilePath);
+                InputStream extractedLibIn = new FileInputStream(extractedLibFile);
+                try {
+                    if(!contentsEquals(nativeIn, extractedLibIn))
+                        throw new SnappyError(SnappyErrorCode.FAILED_TO_LOAD_NATIVE_LIBRARY, String.format("Failed to write a native library file at %s", extractedLibFile));
+                }
+                finally {
+                    if(nativeIn != null)
+                        nativeIn.close();
+                    if(extractedLibIn != null)
+                        extractedLibIn.close();
+                }
+            }
+
             return new File(targetFolder, extractedLibFileName);
         }
         catch (IOException e) {
@@ -460,7 +301,7 @@ public class SnappyLoader
             throw new SnappyError(SnappyErrorCode.FAILED_TO_LOAD_NATIVE_LIBRARY, errorMessage);
         }
 
-        // Temporary library folder. Use the value of org.xerial.snappy.tempdir or java.io.tmpdir
+        // Temporary folder for the native lib. Use the value of org.xerial.snappy.tempdir or java.io.tmpdir
         String tempFolder = new File(System.getProperty(KEY_SNAPPY_TEMPDIR,
                 System.getProperty("java.io.tmpdir"))).getAbsolutePath();
 
@@ -475,8 +316,6 @@ public class SnappyLoader
 
 
 
-
-
     /**
      * Get the snappy-java version by reading pom.properties embedded in jar.
      * This version data is used as a suffix of a dll file extracted from the

src/main/java/org/xerial/snappy/SnappyNative.java

@@ -28,8 +28,7 @@ import java.io.IOException;
 import java.nio.ByteBuffer;
 
 /**
- * <b>Internal only - Do not use this class.</b> JNI interface of the
+ * JNI interface of the {@link Snappy} implementation. The native method in this class is
- * {@link SnappyNativeAPI} implementation. The native method in this class is
  * defined in SnappyNative.h (genereted by javah) and SnappyNative.cpp
  * 
  * <p>
@@ -40,7 +39,7 @@ import java.nio.ByteBuffer;
  * @author leo
  * 
  */
-public class SnappyNative implements SnappyNativeAPI
+public class SnappyNative
 {
 
     public native String nativeLibraryVersion();

src/main/java/org/xerial/snappy/SnappyNativeAPI.java

@@ -1,82 +0,0 @@
-/*--------------------------------------------------------------------------
- *  Copyright 2011 Taro L. Saito
- *
- *  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.
- *--------------------------------------------------------------------------*/
-//--------------------------------------
-// snappy-java Project
-//
-// SnappyNative.java
-// Since: 2011/03/30
-//
-// $URL$ 
-// $Author$
-//--------------------------------------
-package org.xerial.snappy;
-
-import java.io.IOException;
-import java.nio.ByteBuffer;
-
-/**
- * <b>Internal only - Do not use this class.</b>
- * 
- * Interface to access the native code of Snappy. Although this class members
- * are public, do not use them directly. Use {@link Snappy} API instead.
- * 
- * 
- * @author leo
- * 
- */
-public interface SnappyNativeAPI
-{
-
-    public String nativeLibraryVersion();
-
-    // ------------------------------------------------------------------------
-    // Generic compression/decompression routines.
-    // ------------------------------------------------------------------------
-    public long rawCompress(long inputAddr, long inputSize, long destAddr) throws IOException;
-    public long rawUncompress(long inputAddr, long inputSize, long destAddr) throws IOException;
-
-    public int rawCompress(ByteBuffer input, int inputOffset, int inputLength, ByteBuffer compressed, int outputOffset)
-            throws IOException;
-
-    public int rawCompress(Object input, int inputOffset, int inputByteLength, Object output, int outputOffset) throws IOException;
-
-    public int rawUncompress(ByteBuffer compressed, int inputOffset, int inputLength, ByteBuffer uncompressed,
-            int outputOffset) throws IOException;
-
-    public int rawUncompress(Object input, int inputOffset, int inputLength, Object output, int outputOffset)
-            throws IOException;
-
-    // Returns the maximal size of the compressed representation of
-    // input data that is "source_bytes" bytes in length;
-    public int maxCompressedLength(int source_bytes);
-
-    // This operation takes O(1) time.
-    public int uncompressedLength(ByteBuffer compressed, int offset, int len) throws IOException;
-
-    public int uncompressedLength(Object input, int offset, int len) throws IOException;
-
-    public long uncompressedLength(long inputAddr, long len) throws IOException;
-
-
-    public boolean isValidCompressedBuffer(ByteBuffer compressed, int offset, int len) throws IOException;
-
-    public boolean isValidCompressedBuffer(Object input, int offset, int len) throws IOException;
-
-    public void arrayCopy(Object src, int offset, int byteLength, Object dest, int dOffset) throws IOException;
-
-    public void throw_error(int errorCode) throws IOException;
-
-}

src/test/java/org/xerial/snappy/SnappyLoaderTest.java

@@ -24,23 +24,20 @@
 //--------------------------------------
 package org.xerial.snappy;
 
-import static org.junit.Assert.*;
-
-import java.io.BufferedInputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.File;
-import java.io.FileNotFoundException;
-import java.io.IOException;
-import java.lang.reflect.Method;
-import java.net.URL;
-import java.net.URLClassLoader;
-
 import org.codehaus.plexus.classworlds.ClassWorld;
 import org.codehaus.plexus.classworlds.realm.ClassRealm;
 import org.junit.Test;
 import org.xerial.util.FileResource;
 import org.xerial.util.log.Logger;
 
+import java.io.*;
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.net.URLClassLoader;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.fail;
+
 public class SnappyLoaderTest
 {
     private static Logger _logger = Logger.getLogger(SnappyLoaderTest.class);