HADOOP-6881. Make WritableComparator initialize classes when looking for their raw comparator, as classes often register raw comparators in their initializer, which are no longer automatically run in Java 6 when a class is referenced. Contributed by omalley.
git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@979485 13f79535-47bb-0310-9956-ffa450edef68
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@ -151,6 +151,11 @@ Trunk (unreleased changes)
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HADOOP-6536. Fixes FileUtil.fullyDelete() not to delete the contents of
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HADOOP-6536. Fixes FileUtil.fullyDelete() not to delete the contents of
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the sym-linked directory. (Ravi Gummadi via amareshwari)
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the sym-linked directory. (Ravi Gummadi via amareshwari)
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HADOOP-6881. Make WritableComparator intialize classes when
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looking for their raw comparator, as classes often register raw
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comparators in initializers, which are no longer automatically run
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in Java 6 when a class is referenced. (cutting via omalley)
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Release 0.21.0 - Unreleased
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Release 0.21.0 - Unreleased
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INCOMPATIBLE CHANGES
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INCOMPATIBLE CHANGES
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@ -42,13 +42,38 @@ public class WritableComparator implements RawComparator {
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new HashMap<Class, WritableComparator>(); // registry
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new HashMap<Class, WritableComparator>(); // registry
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/** Get a comparator for a {@link WritableComparable} implementation. */
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/** Get a comparator for a {@link WritableComparable} implementation. */
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public static synchronized WritableComparator get(Class<? extends WritableComparable> c) {
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public static synchronized
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WritableComparator get(Class<? extends WritableComparable> c) {
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WritableComparator comparator = comparators.get(c);
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WritableComparator comparator = comparators.get(c);
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if (comparator == null)
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if (comparator == null) {
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// force the static initializers to run
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forceInit(c);
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// look to see if it is defined now
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comparator = comparators.get(c);
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// if not, use the generic one
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if (comparator == null) {
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comparator = new WritableComparator(c, true);
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comparator = new WritableComparator(c, true);
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comparators.put(c, comparator);
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}
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}
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return comparator;
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return comparator;
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}
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}
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/**
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* Force initialization of the static members.
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* As of Java 5, referencing a class doesn't force it to initialize. Since
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* this class requires that the classes be initialized to declare their
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* comparators, we force that initialization to happen.
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* @param cls the class to initialize
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*/
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private static void forceInit(Class<?> cls) {
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try {
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Class.forName(cls.getName(), true, cls.getClassLoader());
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} catch (ClassNotFoundException e) {
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throw new IllegalArgumentException("Can't initialize class " + cls, e);
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}
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}
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/** Register an optimized comparator for a {@link WritableComparable}
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/** Register an optimized comparator for a {@link WritableComparable}
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* implementation. */
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* implementation. */
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public static synchronized void define(Class c,
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public static synchronized void define(Class c,
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@ -96,4 +96,27 @@ public static Writable testWritable(Writable before
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return after;
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return after;
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}
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}
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private static class FrobComparator extends WritableComparator {
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public FrobComparator() { super(Frob.class); }
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@Override public int compare(byte[] b1, int s1, int l1,
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byte[] b2, int s2, int l2) {
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return 0;
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}
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}
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private static class Frob implements WritableComparable {
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static { // register default comparator
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WritableComparator.define(Frob.class, new FrobComparator());
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}
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@Override public void write(DataOutput out) throws IOException {}
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@Override public void readFields(DataInput in) throws IOException {}
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@Override public int compareTo(Object o) { return 0; }
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}
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/** Test that comparator is defined. */
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public static void testGetComparator() throws Exception {
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assert(WritableComparator.get(Frob.class) instanceof FrobComparator);
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}
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}
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}
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