8154096: Extend WhiteBox API with methods which retrieve from VM information about available GC
Reviewed-by: kbarrett, iignatyev
--- a/test/lib/sun/hotspot/WhiteBox.java Wed Jul 05 21:46:49 2017 +0200
+++ b/test/lib/sun/hotspot/WhiteBox.java Mon May 30 19:39:09 2016 +0400
@@ -377,6 +377,12 @@
public native long incMetaspaceCapacityUntilGC(long increment);
public native long metaspaceCapacityUntilGC();
+ // Don't use these methods directly
+ // Use sun.hotspot.gc.GC class instead.
+ public native int currentGC();
+ public native int allSupportedGC();
+ public native boolean gcSelectedByErgo();
+
// Force Young GC
public native void youngGC();
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/test/lib/sun/hotspot/gc/GC.java Mon May 30 19:39:09 2016 +0400
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2016, 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
+ * questions.
+ *
+ */
+
+package sun.hotspot.gc;
+
+import java.util.ArrayList;
+import java.util.List;
+import sun.hotspot.WhiteBox;
+
+/**
+ * API to obtain information about selected and supported Garbage Collectors
+ * retrieved from the VM with the WhiteBox API.
+ */
+public enum GC {
+ Serial(1),
+ Parallel(2),
+ ConcMarkSweep(4),
+ G1(8);
+
+ private static final GC CURRENT_GC;
+ private static final int ALL_GC_CODES;
+ private static final boolean IS_BY_ERGO;
+ static {
+ WhiteBox WB = WhiteBox.getWhiteBox();
+ ALL_GC_CODES = WB.allSupportedGC();
+ IS_BY_ERGO = WB.gcSelectedByErgo();
+
+ int currentCode = WB.currentGC();
+ GC tmp = null;
+ for (GC gc: GC.values()) {
+ if (gc.code == currentCode) {
+ tmp = gc;
+ break;
+ }
+ }
+ if (tmp == null) {
+ throw new Error("Unknown current GC code " + currentCode);
+ }
+ CURRENT_GC = tmp;
+ }
+
+ private final int code;
+ private GC(int code) {
+ this.code = code;
+ }
+
+ /**
+ * @return true if the collector is supported by the VM, false otherwise.
+ */
+ public boolean isSupported() {
+ return (ALL_GC_CODES & code) != 0;
+ }
+
+
+ /**
+ * @return the current collector used by VM.
+ */
+ public static GC current() {
+ return CURRENT_GC;
+ }
+
+ /**
+ * @return true if GC was selected by ergonomic, false if specified
+ * explicitly by the command line flag.
+ */
+ public static boolean currentSetByErgo() {
+ return IS_BY_ERGO;
+ }
+
+ /**
+ * @return List of collectors supported by the VM.
+ */
+ public static List<GC> allSupported() {
+ List<GC> list = new ArrayList<>();
+ for (GC gc: GC.values()) {
+ if (gc.isSupported()) {
+ list.add(gc);
+ }
+ }
+ return list;
+ }
+}
+