LUCENE-2510: Use a custom ServiceLoader in oal.util to replace java.util.ServiceLoader: It does not instantiate the classes, it only loads them without initializing them and it 100% respects classpath order, so the IBM J9/Harmony workaround is gone.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene2510@1365122 13f79535-47bb-0310-9956-ffa450edef68

lucene/analysis/common/src/java/org/apache/lucene/analysis/util/AnalysisSPILoader.java

@@ -22,7 +22,7 @@ import java.util.Locale;
 import java.util.Map;
 import java.util.LinkedHashMap;
 import java.util.Set;
-import java.util.ServiceLoader;
+import org.apache.lucene.util.SPIClassIterator;
 
 /**
  * Helper class for loading named SPIs from classpath (e.g. Tokenizers, TokenStreams).
@@ -39,10 +39,11 @@ final class AnalysisSPILoader<S extends AbstractAnalysisFactory> {
 
   public AnalysisSPILoader(Class<S> clazz, String[] suffixes) {
     this.clazz = clazz;
-    final ServiceLoader<S> loader = ServiceLoader.load(clazz);
+    final SPIClassIterator<S> loader = SPIClassIterator.get(clazz);
     final LinkedHashMap<String,Class<? extends S>> services = new LinkedHashMap<String,Class<? extends S>>();
-    for (final S service : loader) {
+    while (loader.hasNext()) {
-      final String clazzName = service.getClass().getSimpleName();
+      final Class<? extends S> service = loader.next();
+      final String clazzName = service.getSimpleName();
       int suffixIndex = -1;
       for (String suffix : suffixes) {
         suffixIndex = clazzName.lastIndexOf(suffix);
@@ -56,7 +57,7 @@ final class AnalysisSPILoader<S extends AbstractAnalysisFactory> {
       // them used instead of others
       if (!services.containsKey(name)) {
         assert checkServiceName(name);
-        services.put(name, service.getClass().asSubclass(clazz));
+        services.put(name, service);
       }
     }
     this.services = Collections.unmodifiableMap(services);

lucene/core/src/java/org/apache/lucene/util/NamedSPILoader.java

@@ -22,7 +22,7 @@ import java.util.Iterator;
 import java.util.Map;
 import java.util.LinkedHashMap;
 import java.util.Set;
-import java.util.ServiceLoader;
+import java.util.ServiceConfigurationError;
 
 /**
  * Helper class for loading named SPIs from classpath (e.g. Codec, PostingsFormat).
@@ -32,21 +32,22 @@ import java.util.ServiceLoader;
 public final class NamedSPILoader<S extends NamedSPILoader.NamedSPI> implements Iterable<S> {
 
   private final Map<String,S> services;
-
-  /** This field is a hack for LuceneTestCase to get access
-   * to the modifiable map (to work around bugs in IBM J9) */
-  @SuppressWarnings("unused")
-  @Deprecated
-  // Hackidy-Häck-Hack for bugs in IBM J9 ServiceLoader
-  private final Map<String,S> modifiableServices;
-  
   private final Class<S> clazz;
 
   public NamedSPILoader(Class<S> clazz) {
     this.clazz = clazz;
-    final ServiceLoader<S> loader = ServiceLoader.load(clazz);
+    final SPIClassIterator<S> loader = SPIClassIterator.get(clazz);
     final LinkedHashMap<String,S> services = new LinkedHashMap<String,S>();
-    for (final S service : loader) {
+    while (loader.hasNext()) {
+      final Class<? extends S> c = loader.next();
+      final S service;
+      try {
+        service = c.newInstance();
+      } catch (InstantiationException ie) {
+        throw new ServiceConfigurationError("Cannot instantiate SPI class: " + c.getName(), ie); 
+      } catch (IllegalAccessException iae) {
+        throw new ServiceConfigurationError("Cannot instantiate SPI class: " + c.getName(), iae); 
+      }
       final String name = service.getName();
       // only add the first one for each name, later services will be ignored
       // this allows to place services before others in classpath to make 
@@ -56,7 +57,6 @@ public final class NamedSPILoader<S extends NamedSPILoader.NamedSPI> implements
         services.put(name, service);
       }
     }
-    this.modifiableServices = services; // hack, remove when IBM J9 is fixed!
     this.services = Collections.unmodifiableMap(services);
   }
   

lucene/core/src/java/org/apache/lucene/util/SPIClassIterator.java

@@ -0,0 +1,135 @@
+package org.apache.lucene.util;
+
+/*
+ * 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.
+ */
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.ServiceConfigurationError;
+
+/**
+ * Helper class for loading SPI classes from classpath (META-INF files).
+ * This is a light impl of {@link java.util.ServiceLoader} but is guaranteed to
+ * be bug-free regarding classpath order and does not instantiate or initialize
+ * the classes found.
+ *
+ * @lucene.internal
+ */
+public final class SPIClassIterator<S> implements Iterator<Class<? extends S>> {
+  private static final String META_INF_SERVICES = "META-INF/services/";
+
+  private final Class<S> clazz;
+  private final ClassLoader loader;
+  private final Enumeration<URL> profilesEnum;
+  private Iterator<String> linesIterator;
+  
+  public static <S> SPIClassIterator<S> get(Class<S> clazz) {
+    return new SPIClassIterator<S>(clazz, Thread.currentThread().getContextClassLoader());
+  }
+  
+  public static <S> SPIClassIterator<S> get(Class<S> clazz, ClassLoader loader) {
+    return new SPIClassIterator<S>(clazz, loader);
+  }
+  
+  private SPIClassIterator(Class<S> clazz, ClassLoader loader) {
+    if (loader == null)
+      throw new IllegalArgumentException("You must provide a ClassLoader.");
+    this.clazz = clazz;
+    this.loader = loader;
+    try {
+      this.profilesEnum = loader.getResources(META_INF_SERVICES + clazz.getName());
+    } catch (IOException ioe) {
+      throw new ServiceConfigurationError("Error loading SPI classes.", ioe);
+    }
+    this.linesIterator = Collections.<String>emptySet().iterator();
+  }
+  
+  private boolean loadNextProfile() {
+    ArrayList<String> lines = null;
+    while (profilesEnum.hasMoreElements()) {
+      if (lines != null) {
+        lines.clear();
+      } else {
+        lines = new ArrayList<String>();
+      }
+      try {
+        final URL url = profilesEnum.nextElement();
+        final InputStream in = url.openStream();
+        IOException priorE = null;
+        try {
+          final BufferedReader reader = new BufferedReader(new InputStreamReader(in, IOUtils.CHARSET_UTF_8));
+          String line;
+          while ((line = reader.readLine()) != null) {
+            final String[] prts = line.trim().split("#");
+            if (0 != prts.length) {
+              final String c = prts[0].trim();
+              if (!(0 == c.length() || c.startsWith("#"))) {
+                lines.add(c);
+              }
+            }
+          }
+        } catch (IOException ioe) {
+          priorE = ioe;
+        } finally {
+          IOUtils.closeWhileHandlingException(priorE, in);
+        }
+      } catch (IOException ioe) {
+        throw new ServiceConfigurationError("Error loading SPI classes.", ioe);
+      }
+      if (!lines.isEmpty()) {
+        this.linesIterator = lines.iterator();
+        return true;
+      }
+    }
+    return false;
+  }
+  
+  @Override
+  public boolean hasNext() {
+    return linesIterator.hasNext() || loadNextProfile();
+  }
+  
+  @Override
+  public Class<? extends S> next() {
+    // hasNext() implicitely loads the next profile, so it is essential to call this here!
+    if (!hasNext()) {
+      throw new NoSuchElementException();
+    }
+    assert linesIterator.hasNext();
+    final String c = linesIterator.next();
+    try {
+      // don't initialize the class:
+      return Class.forName(c, false, loader).asSubclass(clazz);
+    } catch (ClassNotFoundException cnfe) {
+      throw new ServiceConfigurationError("SPI class not found: " + c);
+    }
+  }
+  
+  @Override
+  public void remove() {
+    throw new UnsupportedOperationException();
+  }
+  
+}

lucene/test-framework/src/java/org/apache/lucene/util/TestRuleSetupAndRestoreClassEnv.java

@@ -87,33 +87,6 @@ final class TestRuleSetupAndRestoreClassEnv extends AbstractBeforeAfterRule {
     restoreProperties.put("solr.solr.home", System.getProperty("solr.solr.home"));
     restoreProperties.put("solr.data.dir", System.getProperty("solr.data.dir"));
 
-    // enable the Lucene 3.x PreflexRW codec explicitly, to work around bugs in IBM J9 / Harmony ServiceLoader:
-    try {
-      final java.lang.reflect.Field spiLoaderField = Codec.class.getDeclaredField("loader");
-      spiLoaderField.setAccessible(true);
-      final Object spiLoader = spiLoaderField.get(null);
-      final java.lang.reflect.Field modifiableServicesField = NamedSPILoader.class.getDeclaredField("modifiableServices");
-      modifiableServicesField.setAccessible(true);
-      /* note: re-enable this if we make a Lucene4x impersonator 
-      @SuppressWarnings({"unchecked","rawtypes"}) final Map<String,Codec> serviceMap =
-        (Map) modifiableServicesField.get(spiLoader);
-      if (!(Codec.forName("Lucene3x") instanceof PreFlexRWCodec)) {
-        if (Constants.JAVA_VENDOR.startsWith("IBM")) {
-          // definitely a buggy version
-          System.err.println("ERROR: Your VM's java.util.ServiceLoader implementation is buggy"+
-            " and does not respect classpath order, please report this to the vendor.");
-        } else {
-          // could just be a classpath issue
-          System.err.println("ERROR: fix your classpath to have tests-framework.jar before lucene-core.jar!"+
-              " If you have already done this, then your VM's java.util.ServiceLoader implementation is buggy"+
-              " and does not respect classpath order, please report this to the vendor.");
-        }
-        serviceMap.put("Lucene3x", new PreFlexRWCodec());
-      } */
-    } catch (Exception e) {
-      throw new RuntimeException("Cannot access internals of Codec and NamedSPILoader classes", e);
-    }
-    
     // if verbose: print some debugging stuff about which codecs are loaded.
     if (VERBOSE) {
       Set<String> codecs = Codec.availableCodecs();