| /* |
| * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved. |
| * 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 |
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| */ |
| |
| /* @test |
| * @bug 8166188 8178813 |
| * @summary Test return of JNI weak global refs during concurrent |
| * marking, verifying the use of the G1 load barrier to keep the |
| * referent alive. |
| * @key gc |
| * @requires vm.gc.G1 |
| * @modules java.base |
| * @library /test/lib |
| * @build sun.hotspot.WhiteBox |
| * @run main ClassFileInstaller sun.hotspot.WhiteBox |
| * sun.hotspot.WhiteBox$WhiteBoxPermission |
| * @run main/othervm/native |
| * -Xbootclasspath/a:. |
| * -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI |
| * -XX:+UseG1GC -XX:MaxTenuringThreshold=2 |
| * -Xint |
| * TestJNIWeakG1 |
| * @run main/othervm/native |
| * -Xbootclasspath/a:. |
| * -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI |
| * -XX:+UseG1GC -XX:MaxTenuringThreshold=2 |
| * -Xcomp |
| * TestJNIWeakG1 |
| */ |
| |
| import sun.hotspot.WhiteBox; |
| |
| import java.lang.ref.Reference; |
| |
| public final class TestJNIWeakG1 { |
| |
| static { |
| System.loadLibrary("TestJNIWeakG1"); |
| } |
| |
| private static final WhiteBox WB = WhiteBox.getWhiteBox(); |
| |
| private static final class TestObject { |
| public final int value; |
| |
| public TestObject(int value) { |
| this.value = value; |
| } |
| } |
| |
| private volatile TestObject testObject = null; |
| |
| private static native void registerObject(Object o); |
| private static native void unregisterObject(); |
| private static native Object getReturnedWeak(); |
| private static native Object getResolvedWeak(); |
| |
| // resolve controls whether getObject returns an explicitly |
| // resolved jweak value (when resolve is true), or returns the |
| // jweak directly and invokes the implicit resolution in the |
| // native call return value handling path (when resolve is false). |
| private boolean resolve = true; |
| |
| TestJNIWeakG1(boolean resolve) { |
| this.resolve = resolve; |
| } |
| |
| private Object getObject() { |
| if (resolve) { |
| return getResolvedWeak(); |
| } else { |
| return getReturnedWeak(); |
| } |
| } |
| |
| // Create the test object and record it both strongly and weakly. |
| private void remember(int value) { |
| TestObject o = new TestObject(value); |
| registerObject(o); |
| testObject = o; |
| } |
| |
| // Remove both strong and weak references to the current test object. |
| private void forget() { |
| unregisterObject(); |
| testObject = null; |
| } |
| |
| // Repeatedly perform young-only GC until o is in the old generation. |
| private void gcUntilOld(Object o) { |
| while (!WB.isObjectInOldGen(o)) { |
| WB.youngGC(); |
| } |
| } |
| |
| // Verify the weakly recorded object |
| private void checkValue(int value) throws Exception { |
| Object o = getObject(); |
| if (o == null) { |
| throw new RuntimeException("Weak reference unexpectedly null"); |
| } |
| TestObject t = (TestObject)o; |
| if (t.value != value) { |
| throw new RuntimeException("Incorrect value"); |
| } |
| } |
| |
| // Verify we can create a weak reference and get it back. |
| private void checkSanity() throws Exception { |
| System.out.println("running checkSanity"); |
| try { |
| // Inhibit concurrent GC during this check. |
| WB.requestConcurrentGCPhase("IDLE"); |
| |
| int value = 5; |
| try { |
| remember(value); |
| checkValue(value); |
| } finally { |
| forget(); |
| } |
| |
| } finally { |
| // Remove request. |
| WB.requestConcurrentGCPhase("ANY"); |
| } |
| } |
| |
| // Verify weak ref value survives across collection if strong ref exists. |
| private void checkSurvival() throws Exception { |
| System.out.println("running checkSurvival"); |
| try { |
| int value = 10; |
| try { |
| remember(value); |
| checkValue(value); |
| gcUntilOld(testObject); |
| // Run a concurrent collection after object is old. |
| WB.requestConcurrentGCPhase("CONCURRENT_CYCLE"); |
| WB.requestConcurrentGCPhase("IDLE"); |
| // Verify weak ref still has expected value. |
| checkValue(value); |
| } finally { |
| forget(); |
| } |
| } finally { |
| // Remove request. |
| WB.requestConcurrentGCPhase("ANY"); |
| } |
| } |
| |
| // Verify weak ref cleared if no strong ref exists. |
| private void checkClear() throws Exception { |
| System.out.println("running checkClear"); |
| try { |
| int value = 15; |
| try { |
| remember(value); |
| checkValue(value); |
| gcUntilOld(testObject); |
| // Run a concurrent collection after object is old. |
| WB.requestConcurrentGCPhase("CONCURRENT_CYCLE"); |
| WB.requestConcurrentGCPhase("IDLE"); |
| checkValue(value); |
| testObject = null; |
| // Run a concurrent collection after strong ref removed. |
| WB.requestConcurrentGCPhase("CONCURRENT_CYCLE"); |
| WB.requestConcurrentGCPhase("IDLE"); |
| // Verify weak ref cleared as expected. |
| Object recorded = getObject(); |
| if (recorded != null) { |
| throw new RuntimeException("expected clear"); |
| } |
| } finally { |
| forget(); |
| } |
| } finally { |
| // Remove request. |
| WB.requestConcurrentGCPhase("ANY"); |
| } |
| } |
| |
| // Verify weak ref not cleared if no strong ref at start of |
| // collection but weak ref read during marking. |
| private void checkShouldNotClear() throws Exception { |
| System.out.println("running checkShouldNotClear"); |
| try { |
| int value = 20; |
| try { |
| remember(value); |
| checkValue(value); |
| gcUntilOld(testObject); |
| // Block concurrent cycle until we're ready. |
| WB.requestConcurrentGCPhase("IDLE"); |
| checkValue(value); |
| testObject = null; // Discard strong ref |
| // Run through mark_from_roots. |
| WB.requestConcurrentGCPhase("BEFORE_REMARK"); |
| // Fetch weak ref'ed object. Should be kept alive now. |
| Object recovered = getObject(); |
| if (recovered == null) { |
| throw new RuntimeException("unexpected clear during mark"); |
| } |
| // Finish collection, including reference processing. |
| // Block any further cycles while we finish check. |
| WB.requestConcurrentGCPhase("IDLE"); |
| // Fetch weak ref'ed object. Referent is manifestly |
| // live in recovered; the earlier fetch should have |
| // kept it alive through collection, so weak ref |
| // should not have been cleared. |
| if (getObject() == null) { |
| // 8166188 problem results in not doing the |
| // keep-alive of earlier getObject result, so |
| // recovered is now reachable but not marked. |
| // We may eventually crash. |
| throw new RuntimeException("cleared jweak for live object"); |
| } |
| Reference.reachabilityFence(recovered); |
| } finally { |
| forget(); |
| } |
| } finally { |
| // Remove request. |
| WB.requestConcurrentGCPhase("ANY"); |
| } |
| } |
| |
| private void check() throws Exception { |
| checkSanity(); |
| checkSurvival(); |
| checkClear(); |
| checkShouldNotClear(); |
| System.out.println("Check passed"); |
| } |
| |
| public static void main(String[] args) throws Exception { |
| // Perform check with direct jweak resolution. |
| System.out.println("Check with jweak resolved"); |
| new TestJNIWeakG1(true).check(); |
| |
| // Perform check with implicit jweak resolution by native |
| // call's return value handling. |
| System.out.println("Check with jweak returned"); |
| new TestJNIWeakG1(false).check(); |
| } |
| } |