| /* |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* |
| * This file is available under and governed by the GNU General Public |
| * License version 2 only, as published by the Free Software Foundation. |
| * However, the following notice accompanied the original version of this |
| * file: |
| * |
| * Written by Martin Buchholz with assistance from members of JCP |
| * JSR-166 Expert Group and released to the public domain, as |
| * explained at http://creativecommons.org/publicdomain/zero/1.0/ |
| */ |
| |
| /* |
| * @test |
| * @modules java.base/java.util.concurrent:open |
| * @run testng WhiteBox |
| * @summary White box tests of implementation details |
| */ |
| |
| import static org.testng.Assert.*; |
| import org.testng.annotations.Test; |
| |
| import java.io.ByteArrayInputStream; |
| import java.io.ByteArrayOutputStream; |
| import java.io.ObjectInputStream; |
| import java.io.ObjectOutputStream; |
| import java.lang.invoke.MethodHandle; |
| import java.lang.invoke.MethodHandles; |
| import java.lang.invoke.MethodType; |
| import java.lang.invoke.VarHandle; |
| import java.util.List; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.ThreadLocalRandom; |
| import java.util.function.Supplier; |
| |
| @Test |
| public class WhiteBox { |
| final ThreadLocalRandom rnd = ThreadLocalRandom.current(); |
| final VarHandle TABLE, NEXTTABLE, SIZECTL; |
| final MethodHandle TABLE_SIZE_FOR; |
| |
| WhiteBox() throws ReflectiveOperationException { |
| Class<?> mClass = ConcurrentHashMap.class; |
| String nodeClassName = mClass.getName() + "$Node"; |
| Class<?> nodeClass = Class.forName(nodeClassName); |
| Class<?> nodeArrayClass = Class.forName("[L" + nodeClassName + ";"); |
| MethodHandles.Lookup lookup |
| = MethodHandles.privateLookupIn(mClass, MethodHandles.lookup()); |
| TABLE = lookup.findVarHandle(mClass, "table", nodeArrayClass); |
| NEXTTABLE = lookup.findVarHandle(mClass, "nextTable", nodeArrayClass); |
| SIZECTL = lookup.findVarHandle(mClass, "sizeCtl", int.class); |
| TABLE_SIZE_FOR = lookup.findStatic( |
| mClass, "tableSizeFor", |
| MethodType.methodType(int.class, int.class)); |
| } |
| |
| Object[] table(ConcurrentHashMap m) { return (Object[]) TABLE.getVolatile(m); } |
| Object[] nextTable(ConcurrentHashMap m) { return (Object[]) NEXTTABLE.getVolatile(m); } |
| int sizeCtl(ConcurrentHashMap m) { return (int) SIZECTL.getVolatile(m); } |
| int tableSizeFor(int n) { |
| try { |
| return (int) TABLE_SIZE_FOR.invoke(n); |
| } catch (Throwable t) { throw new AssertionError(t); } |
| } |
| |
| List<Supplier<ConcurrentHashMap>> newConcurrentHashMapSuppliers( |
| int initialCapacity) { |
| return List.of( |
| () -> new ConcurrentHashMap(initialCapacity), |
| () -> new ConcurrentHashMap(initialCapacity, 0.75f), |
| () -> new ConcurrentHashMap(initialCapacity, 0.75f, 1)); |
| } |
| |
| ConcurrentHashMap newConcurrentHashMap(int initialCapacity) { |
| List<Supplier<ConcurrentHashMap>> suppliers |
| = newConcurrentHashMapSuppliers(initialCapacity); |
| return suppliers.get(rnd.nextInt(suppliers.size())).get(); |
| } |
| |
| @Test |
| public void defaultConstructor() { |
| ConcurrentHashMap m = new ConcurrentHashMap(); |
| assertNull(table(m)); |
| assertEquals(sizeCtl(m), 0); |
| assertResizeNotInProgress(m); |
| } |
| |
| @Test |
| public void shouldNotResizeWhenInitialCapacityProvided() { |
| int initialCapacity = rnd.nextInt(1, 100); |
| Object[] initialTable = null; |
| ConcurrentHashMap m = newConcurrentHashMap(initialCapacity); |
| |
| // table is lazily initialized |
| assertNull(table(m)); |
| int expectedInitialTableLength = sizeCtl(m); |
| |
| assertInvariants(m); |
| for (int i = 0; i < initialCapacity; i++) { |
| m.put(i * 100 + rnd.nextInt(100), i); |
| if (i == 0) |
| initialTable = table(m); |
| else |
| assertSame(table(m), initialTable); |
| assertInvariants(m); |
| } |
| assertEquals(initialTable.length, expectedInitialTableLength); |
| } |
| |
| @Test |
| public void constructorsShouldGiveSameInitialCapacity() { |
| int initialCapacity = rnd.nextInt(1, 256); |
| long distinctTableLengths |
| = newConcurrentHashMapSuppliers(initialCapacity).stream() |
| .map(Supplier::get) |
| .mapToInt(map -> { map.put(42, 42); return table(map).length; }) |
| .distinct() |
| .count(); |
| assertEquals(1L, distinctTableLengths); |
| } |
| |
| @Test |
| public void testTableSizeFor() { |
| assertEquals(1, tableSizeFor(0)); |
| assertEquals(1, tableSizeFor(1)); |
| assertEquals(2, tableSizeFor(2)); |
| assertEquals(4, tableSizeFor(3)); |
| assertEquals(16, tableSizeFor(15)); |
| assertEquals(16, tableSizeFor(16)); |
| assertEquals(32, tableSizeFor(17)); |
| int maxSize = 1 << 30; |
| assertEquals(maxSize, tableSizeFor(maxSize - 1)); |
| assertEquals(maxSize, tableSizeFor(maxSize)); |
| assertEquals(maxSize, tableSizeFor(maxSize + 1)); |
| assertEquals(maxSize, tableSizeFor(Integer.MAX_VALUE)); |
| } |
| |
| byte[] serialBytes(Object o) { |
| try { |
| ByteArrayOutputStream bos = new ByteArrayOutputStream(); |
| ObjectOutputStream oos = new ObjectOutputStream(bos); |
| oos.writeObject(o); |
| oos.flush(); |
| oos.close(); |
| return bos.toByteArray(); |
| } catch (Exception fail) { |
| throw new AssertionError(fail); |
| } |
| } |
| |
| @SuppressWarnings("unchecked") |
| <T> T serialClone(T o) { |
| try { |
| ObjectInputStream ois = new ObjectInputStream |
| (new ByteArrayInputStream(serialBytes(o))); |
| T clone = (T) ois.readObject(); |
| assertNotSame(o, clone); |
| assertSame(o.getClass(), clone.getClass()); |
| return clone; |
| } catch (Exception fail) { |
| throw new AssertionError(fail); |
| } |
| } |
| |
| @Test |
| public void testSerialization() { |
| assertInvariants(serialClone(new ConcurrentHashMap())); |
| |
| ConcurrentHashMap m = newConcurrentHashMap(rnd.nextInt(100)); |
| m.put(1, 1); |
| ConcurrentHashMap clone = serialClone(m); |
| assertInvariants(clone); |
| assertNotSame(table(m), table(clone)); |
| assertEquals(m, clone); |
| assertResizeNotInProgress(m); |
| assertResizeNotInProgress(clone); |
| } |
| |
| /** Checks conditions which should always be true. */ |
| void assertInvariants(ConcurrentHashMap m) { |
| if (!m.isEmpty()) |
| assertNotNull(table(m)); |
| } |
| |
| void assertResizeNotInProgress(ConcurrentHashMap m) { |
| assertTrue(sizeCtl(m) >= 0); |
| assertNull(nextTable(m)); |
| } |
| } |