| /* |
| * Copyright (c) 2016, 2018, 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. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * 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 jdk.jfr.internal; |
| |
| import java.io.IOException; |
| |
| /** |
| * Checks if the running VM supports Flight Recorder. |
| * |
| * Purpose of this helper class is to detect early and cleanly if the VM has |
| * support for Flight Recorder, i.e. not throw {@link UnsatisfiedLinkError} in |
| * unexpected places. |
| * <p> |
| * This is needed so a disabled-jfr.jar can be built for non Oracle JDKs. |
| */ |
| public final class JVMSupport { |
| |
| private static final String UNSUPPORTED_VM_MESSAGE = "Flight Recorder is not supported on this VM"; |
| private static final boolean notAvailable = !checkAvailability(); |
| |
| private static boolean checkAvailability() { |
| // set jfr.unsupported.vm to true to test API on an unsupported VM |
| try { |
| if (SecuritySupport.getBooleanProperty("jfr.unsupported.vm")) { |
| return false; |
| } |
| } catch (NoClassDefFoundError cnfe) { |
| // May happen on JDK 8, where jdk.internal.misc.Unsafe can't be found |
| return false; |
| } |
| try { |
| // Will typically throw UnsatisfiedLinkError if |
| // there is no native implementation |
| JVM.getJVM().isAvailable(); |
| return true; |
| } catch (Throwable t) { |
| return false; |
| } |
| } |
| |
| public static void ensureWithInternalError() { |
| if (notAvailable) { |
| throw new InternalError(UNSUPPORTED_VM_MESSAGE); |
| } |
| } |
| |
| public static void ensureWithIOException() throws IOException { |
| if (notAvailable) { |
| throw new IOException(UNSUPPORTED_VM_MESSAGE); |
| } |
| } |
| |
| public static void ensureWithIllegalStateException() { |
| if (notAvailable) { |
| throw new IllegalStateException(UNSUPPORTED_VM_MESSAGE); |
| } |
| } |
| |
| public static boolean isNotAvailable() { |
| return notAvailable; |
| } |
| |
| public static void tryToInitializeJVM() { |
| } |
| } |