com.facebook.buck.timing.DefaultPerfTimer.java Source code

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Here is the source code for com.facebook.buck.timing.DefaultPerfTimer.java

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/*
 * Copyright 2015-present Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License. You may obtain
 * a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package com.facebook.buck.timing;

import com.facebook.buck.util.TriState;
import com.google.common.base.Optional;

import java.lang.management.ManagementFactory;
import java.lang.management.ThreadMXBean;

public class DefaultPerfTimer implements PerfTimer {
    private static TriState jvmSupportsCpuTime = TriState.UNSPECIFIED;
    private static Object lock = new Object();
    private static Optional<ThreadMXBean> bean = Optional.absent();

    private static boolean jvmSupportsCpuTime() {
        if (jvmSupportsCpuTime == TriState.UNSPECIFIED) {
            synchronized (lock) {
                if (jvmSupportsCpuTime == TriState.UNSPECIFIED) {
                    bean = Optional.fromNullable(ManagementFactory.getThreadMXBean());
                    jvmSupportsCpuTime = TriState
                            .forBooleanValue(bean.isPresent() && bean.get().isThreadCpuTimeSupported());
                    if (jvmSupportsCpuTime.asBoolean()) {
                        bean.get().setThreadCpuTimeEnabled(true);
                    }
                }
            }
        }
        return jvmSupportsCpuTime.asBoolean();
    }

    public DefaultPerfTimer() {
        jvmSupportsCpuTime();
    }

    @Override
    public AbsolutePerfTime getCurrentPerfTimeForThreadId(long threadId) {
        if (jvmSupportsCpuTime()) {
            long userCpuTime = bean.get().getThreadUserTime(threadId);
            long systemCpuTime = bean.get().getThreadCpuTime(threadId) - userCpuTime;
            return AbsolutePerfTime.of(userCpuTime, systemCpuTime);
        } else {
            return AbsolutePerfTime.of(AbsolutePerfTime.UNSUPPORTED, AbsolutePerfTime.UNSUPPORTED);
        }
    }
}