HBASE-14347 Add a switch to DynamicClassLoader to disable it (huaxiang sun)

hbase-common/src/main/java/org/apache/hadoop/hbase/util/DynamicClassLoader.java

@@ -66,6 +66,11 @@ public class DynamicClassLoader extends ClassLoaderBase {
 
   private static final String DYNAMIC_JARS_DIR_KEY = "hbase.dynamic.jars.dir";
 
+  private static final String DYNAMIC_JARS_OPTIONAL_CONF_KEY = "hbase.use.dynamic.jars";
+  private static final boolean DYNAMIC_JARS_OPTIONAL_DEFAULT = true;
+
+  private boolean useDynamicJars;
+
   private File localDir;
 
   // FileSystem of the remote path, set only if remoteDir != null
@@ -86,6 +91,15 @@ public class DynamicClassLoader extends ClassLoaderBase {
       final Configuration conf, final ClassLoader parent) {
     super(parent);
 
+    useDynamicJars = conf.getBoolean(
+        DYNAMIC_JARS_OPTIONAL_CONF_KEY, DYNAMIC_JARS_OPTIONAL_DEFAULT);
+
+    if (useDynamicJars) {
+      initTempDir(conf);
+    }
+  }
+
+  private void initTempDir(final Configuration conf) {
     jarModifiedTime = new HashMap<String, Long>();
     String localDirPath = conf.get(
       LOCAL_DIR_KEY, DEFAULT_LOCAL_DIR) + DYNAMIC_JARS_DIR;
@@ -120,7 +134,17 @@ public class DynamicClassLoader extends ClassLoaderBase {
         LOG.debug("Class " + name + " not found - using dynamical class loader");
       }
 
-      synchronized (getClassLoadingLock(name)) {
+      if (useDynamicJars) {
+        return tryRefreshClass(name);
+      }
+      throw e;
+    }
+  }
+
+
+  private Class<?> tryRefreshClass(String name)
+      throws ClassNotFoundException {
+    synchronized (getClassLoadingLock(name)) {
         // Check whether the class has already been loaded:
         Class<?> clasz = findLoadedClass(name);
         if (clasz != null) {
@@ -149,7 +173,6 @@ public class DynamicClassLoader extends ClassLoaderBase {
         }
         return clasz;
       }
-    }
   }
 
   private synchronized void loadNewJars() {

hbase-common/src/test/java/org/apache/hadoop/hbase/util/TestDynamicClassLoader.java

@@ -29,6 +29,7 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HBaseCommonTestingUtility;
 import org.apache.hadoop.hbase.testclassification.SmallTests;
 import org.junit.Test;
+import org.junit.Before;
 import org.junit.experimental.categories.Category;
 
 /**
@@ -39,10 +40,16 @@ public class TestDynamicClassLoader {
   private static final Log LOG = LogFactory.getLog(TestDynamicClassLoader.class);
 
   private static final HBaseCommonTestingUtility TEST_UTIL = new HBaseCommonTestingUtility();
-  private static final Configuration conf = TEST_UTIL.getConfiguration();
+  private Configuration conf;
 
   static {
-    conf.set("hbase.dynamic.jars.dir", TEST_UTIL.getDataTestDir().toString());
+    TEST_UTIL.getConfiguration().set(
+        "hbase.dynamic.jars.dir", TEST_UTIL.getDataTestDir().toString());
+  }
+
+  @Before
+  public void initializeConfiguration() {
+    conf = new Configuration(TEST_UTIL.getConfiguration());
   }
 
   @Test
@@ -94,6 +101,26 @@ public class TestDynamicClassLoader {
     }
   }
 
+  @Test
+  public void testLoadClassFromLocalPathWithDynamicDirOff() throws Exception {
+    conf.setBoolean("hbase.use.dynamic.jars", false);
+    ClassLoader parent = TestDynamicClassLoader.class.getClassLoader();
+    DynamicClassLoader classLoader = new DynamicClassLoader(conf, parent);
+
+    String className = "TestLoadClassFromLocalPath";
+    deleteClass(className);
+
+    try {
+      String folder = TEST_UTIL.getDataTestDir().toString();
+      ClassLoaderTestHelper.buildJar(
+          folder, className, null, ClassLoaderTestHelper.localDirPath(conf));
+      classLoader.loadClass(className);
+      fail("Should not be able to load class " + className);
+    } catch (ClassNotFoundException cnfe) {
+      // expected, move on
+    }
+  }
+
   private void deleteClass(String className) throws Exception {
     String jarFileName = className + ".jar";
     File file = new File(TEST_UTIL.getDataTestDir().toString(), jarFileName);