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 * Copyright (c) 2014, 2019, 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
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 */
package jdk.vm.ci.common;

import java.util.concurrent.atomic.AtomicInteger;

import jdk.vm.ci.services.Services;

A facility for timing a step in the runtime initialization sequence. This is independent from all other JVMCI code so as to not perturb the initialization sequence. It is enabled by setting the "jvmci.inittimer" system property to "true". /**
 * A facility for timing a step in the runtime initialization sequence. This is independent from all
 * other JVMCI code so as to not perturb the initialization sequence. It is enabled by setting the
 * {@code "jvmci.inittimer"} system property to {@code "true"}.
 */
public final class InitTimer implements AutoCloseable {
    private final String name;
    private final long start;

    private InitTimer(String name) {
        int n = nesting.getAndIncrement();
        if (n == 0) {
            initializingThread = Thread.currentThread();
            System.out.println("INITIALIZING THREAD: " + initializingThread);
        } else {
            assert Thread.currentThread() == initializingThread : Thread.currentThread() + " != " + initializingThread;
        }
        this.name = name;
        this.start = System.currentTimeMillis();
        System.out.println("START: " + SPACES.substring(0, n * 2) + name);
    }

    @Override
    @SuppressFBWarnings(value = "ST_WRITE_TO_STATIC_FROM_INSTANCE_METHOD", justification = "only the initializing thread accesses this field")
    public void close() {
        final long end = System.currentTimeMillis();
        int n = nesting.decrementAndGet();
        System.out.println(" DONE: " + SPACES.substring(0, n * 2) + name + " [" + (end - start) + " ms]");
        if (n == 0) {
            initializingThread = null;
        }
    }

    public static InitTimer timer(String name) {
        return isEnabled() ? new InitTimer(name) : null;
    }

    public static InitTimer timer(String name, Object suffix) {
        return isEnabled() ? new InitTimer(name + suffix) : null;
    }

    
Determines if initialization timing is enabled. Note: This property cannot use HotSpotJVMCIRuntime.Option since that class is not visible from this package. /**
     * Determines if initialization timing is enabled. Note: This property cannot use
     * {@code HotSpotJVMCIRuntime.Option} since that class is not visible from this package.
     */
    private static boolean isEnabled() {
        if (enabledPropertyValue == null) {
            enabledPropertyValue = Boolean.parseBoolean(Services.getSavedProperty("jvmci.InitTimer"));
            nesting = new AtomicInteger();
        }
        return enabledPropertyValue;
    }

    
Cache for value of jvmci.InitTimer system property. /**
     * Cache for value of {@code jvmci.InitTimer} system property.
     */
    @NativeImageReinitialize private static Boolean enabledPropertyValue;

    private static AtomicInteger nesting;
    private static final String SPACES = "                                            ";

    
Used to assert the invariant that all related initialization happens on the same thread.
/**
     * Used to assert the invariant that all related initialization happens on the same thread.
     */
    static Thread initializingThread;
}