Fixes xerial/snappy-java#326 Add option to disable fallback to PureJa…

README.md

@@ -172,7 +172,7 @@ A file `target/snappy-java-$(version).jar` is the product additionally containin
 ### Using pure-java Snappy implementation
 
 snappy-java can optionally use a pure-java implementation of Snappy based on [aircompressor](https://github.com/airlift/aircompressor/tree/master/src/main/java/io/airlift/compress/snappy). This implementation is selected when no native Snappy library for your platform is found. You can also force using this pure-java implementation by setting a JVM property `org.xerial.snappy.purejava=true` before loading any class of Snappy (e.g., using `-Dorg.xerial.snappy.purejava=true` option when launching JVM).
-
+The pure-java implementation is also used as a fallback when no native Snappy library can be loaded. You can disable this fallback by setting the JVM property `org.xerial.snappy.purejava.fallback=false`
 
 ### Using snappy-java with Tomcat 6 (or higher) Web Server
 

build.sbt

@@ -61,6 +61,7 @@ crossPaths := false
 
 libraryDependencies ++= Seq(
   "junit"               % "junit"              % "4.13.2"  % "test",
+  "org.mockito"         % "mockito-inline"     % "4.6.1"   % "test",
   "org.codehaus.plexus" % "plexus-classworlds" % "2.4"     % "test",
   "org.xerial.java"     % "xerial-core"        % "2.1"     % "test",
   "org.wvlet.airframe" %% "airframe-log"       % "21.12.1" % "test",

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

@@ -78,6 +78,7 @@ public class SnappyLoader
     public static final String KEY_SNAPPY_LIB_PATH = "org.xerial.snappy.lib.path";
     public static final String KEY_SNAPPY_LIB_NAME = "org.xerial.snappy.lib.name";
     public static final String KEY_SNAPPY_PUREJAVA = "org.xerial.snappy.purejava";
+    public static final String KEY_SNAPPY_PUREJAVA_FALLBACK = "org.xerial.snappy.purejava.fallback";
     public static final String KEY_SNAPPY_TEMPDIR = "org.xerial.snappy.tempdir";
     public static final String KEY_SNAPPY_USE_SYSTEMLIB = "org.xerial.snappy.use.systemlib";
     public static final String KEY_SNAPPY_DISABLE_BUNDLED_LIBS = "org.xerial.snappy.disable.bundled.libs"; // Depreciated, but preserved for backward compatibility
@@ -170,7 +171,11 @@ static synchronized SnappyApi loadSnappyApi()
         }
         catch(Throwable e) {
             // Fall-back to pure-java Snappy implementation
-            setSnappyApi(new PureJavaSnappy());
+            if(Boolean.parseBoolean(System.getProperty(KEY_SNAPPY_PUREJAVA_FALLBACK, "true"))) {
+                setSnappyApi(new PureJavaSnappy());
+            } else {
+                throw e;
+            }
         }
         return snappyApi;
     }
@@ -188,7 +193,8 @@ static synchronized BitShuffleNative loadBitShuffleApi()
     /**
      * Load a native library of snappy-java
      */
-    private synchronized static void loadNativeLibrary()
+    // VisibleForTesting
+    static synchronized void loadNativeLibrary()
     {
         if (!isLoaded) {
             try {

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

@@ -27,6 +27,8 @@
 import org.codehaus.plexus.classworlds.ClassWorld;
 import org.codehaus.plexus.classworlds.realm.ClassRealm;
 import org.junit.Test;
+import org.mockito.MockedStatic;
+import org.mockito.Mockito;
 import org.xerial.util.FileResource;
 import org.xerial.util.log.Logger;
 
@@ -35,8 +37,7 @@
 import java.net.URL;
 import java.net.URLClassLoader;
 
-import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
 
 public class SnappyLoaderTest
 {
@@ -128,6 +129,53 @@ public void autoLoad()
         _logger.debug(Snappy.maxCompressedLength(1024));
     }
 
+    @Test
+    public void loadSnappySimulateLoadingFailedCheckIfFallbackIsDisabledThrowsException()
+    {
+        try(MockedStatic<SnappyLoader> mock = Mockito.mockStatic(SnappyLoader.class, Mockito.CALLS_REAL_METHODS)) {
+            String mockedErrorMessage = "The static method loadNativeLibrary is mocked and throws an exception";
+            mock.when(() -> SnappyLoader.loadNativeLibrary()).thenThrow(new SnappyError(SnappyErrorCode.FAILED_TO_LOAD_NATIVE_LIBRARY, mockedErrorMessage));
+
+            try {
+                SnappyLoader.setSnappyApi(null); // force reload
+                System.setProperty(SnappyLoader.KEY_SNAPPY_PUREJAVA, "false");
+                System.setProperty(SnappyLoader.KEY_SNAPPY_PUREJAVA_FALLBACK, "false");
+
+                SnappyLoader.loadSnappyApi();
+
+                fail("Code should have thrown an exception");
+            } catch (SnappyError e) {
+                assertEquals(SnappyError.class, e.getClass());
+                assertTrue(e.getMessage().contains(mockedErrorMessage));
+            } finally {
+                System.clearProperty(SnappyLoader.KEY_SNAPPY_PUREJAVA);
+                System.clearProperty(SnappyLoader.KEY_SNAPPY_PUREJAVA_FALLBACK);
+            }
+        }
+    }
+
+    @Test
+    public void loadSnappySimulateLoadingFailedCheckIfFallbackIsUsed()
+    {
+        try(MockedStatic<SnappyLoader> mock = Mockito.mockStatic(SnappyLoader.class, Mockito.CALLS_REAL_METHODS)) {
+            String mockedErrorMessage = "The static method loadNativeLibrary is mocked and throws an exception";
+            mock.when(() -> SnappyLoader.loadNativeLibrary()).thenThrow(new SnappyError(SnappyErrorCode.FAILED_TO_LOAD_NATIVE_LIBRARY, mockedErrorMessage));
+
+            try {
+                SnappyLoader.setSnappyApi(null); // force reload
+                System.setProperty(SnappyLoader.KEY_SNAPPY_PUREJAVA, "false");
+                System.clearProperty(SnappyLoader.KEY_SNAPPY_PUREJAVA_FALLBACK); // default is true
+
+                SnappyLoader.loadSnappyApi();
+
+                assertTrue("Fallback to pure java implementation did not work!", SnappyLoader.isPureJava());
+            } finally {
+                System.clearProperty(SnappyLoader.KEY_SNAPPY_PUREJAVA);
+                System.clearProperty(SnappyLoader.KEY_SNAPPY_PUREJAVA_FALLBACK);
+            }
+        }
+    }
+
     public static void main(String[] args)
     {
         // Test for loading native library specified in -Djava.library.path