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 * Copyright (c) 2019, 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.  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
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package com.oracle.svm.core.posix;

import java.util.Arrays;
import java.util.List;
import java.util.concurrent.TimeUnit;

import org.graalvm.nativeimage.Platform;
import org.graalvm.nativeimage.StackValue;
import org.graalvm.nativeimage.hosted.Feature;

import com.oracle.svm.core.CErrorNumber;
import com.oracle.svm.core.annotate.AutomaticFeature;
import com.oracle.svm.core.jdk.management.ManagementFeature;
import com.oracle.svm.core.jdk.management.ManagementSupport;
import com.oracle.svm.core.jdk.management.SubstrateOperatingSystemMXBean;
import com.oracle.svm.core.posix.headers.Errno;
import com.oracle.svm.core.posix.headers.Resource;
import com.oracle.svm.core.posix.headers.Times;
import com.oracle.svm.core.posix.headers.Unistd;
import com.oracle.svm.core.posix.headers.darwin.DarwinStat;
import com.oracle.svm.core.posix.headers.linux.LinuxStat;
import com.oracle.svm.core.util.VMError;
import com.sun.management.UnixOperatingSystemMXBean;

class PosixSubstrateOperatingSystemMXBean extends SubstrateOperatingSystemMXBean implements UnixOperatingSystemMXBean {

    
Returns the CPU time used by the process on which the SVM process is running in nanoseconds.
The returned value is of nanoseconds precision but not necessarily nanoseconds accuracy. This
method returns -1 if the the platform does not support this operation.
Returns:
the CPU time used by the process in nanoseconds, or -1 if this operation is
        not supported./**
     * Returns the CPU time used by the process on which the SVM process is running in nanoseconds.
     * The returned value is of nanoseconds precision but not necessarily nanoseconds accuracy. This
     * method returns <tt>-1</tt> if the the platform does not support this operation.
     *
     * @return the CPU time used by the process in nanoseconds, or <tt>-1</tt> if this operation is
     *         not supported.
     */
    @Override
    public long getProcessCpuTime() {
        long clkTck = Unistd.sysconf(Unistd._SC_CLK_TCK());
        if (clkTck == -1) {
            // sysconf failed - not able to get clock tick
            return -1;
        }
        long nsPerTick = TimeUnit.SECONDS.toNanos(1) / clkTck;
        Times.tms time = StackValue.get(Times.tms.class);
        Times.times(time);
        return (time.tms_utime() + time.tms_stime()) * nsPerTick;
    }

    @Override
    public long getMaxFileDescriptorCount() {
        Resource.rlimit rlp = StackValue.get(Resource.rlimit.class);
        if (Resource.getrlimit(Resource.RLIMIT_NOFILE(), rlp) < 0) {
            throwUnchecked(PosixUtils.newIOExceptionWithLastError("getrlimit failed"));
        }
        return rlp.rlim_cur().rawValue();
    }

    @Override
    public long getOpenFileDescriptorCount() {
        int maxFileDescriptor = (int) Unistd.sysconf(Unistd._SC_OPEN_MAX());
        long count = 0;
        for (int i = 0; i <= maxFileDescriptor; i++) {
            if (fstat(i) == 0 || CErrorNumber.getCErrorNumber() != Errno.EBADF()) {
                count++;
            }
        }
        return count;
    }

    private static int fstat(int fd) {
        if (Platform.includedIn(Platform.LINUX.class)) {
            LinuxStat.stat64 stat = StackValue.get(LinuxStat.stat64.class);
            return LinuxStat.fstat64(fd, stat);
        } else if (Platform.includedIn(Platform.DARWIN.class)) {
            DarwinStat.stat64 stat = StackValue.get(DarwinStat.stat64.class);
            return DarwinStat.fstat64(fd, stat);
        } else {
            throw VMError.shouldNotReachHere("Unsupported platform");
        }
    }

    @SuppressWarnings("unchecked")
    private static <T extends Throwable> void throwUnchecked(Throwable exception) throws T {
        throw (T) exception;
    }
}

@AutomaticFeature
class PosixSubstrateOperatingSystemMXBeanFeature implements Feature {
    @Override
    public List<Class<? extends Feature>> getRequiredFeatures() {
        return Arrays.asList(ManagementFeature.class);
    }

    @Override
    public void afterRegistration(Feature.AfterRegistrationAccess access) {
        ManagementSupport.getSingleton().addPlatformManagedObjectSingleton(UnixOperatingSystemMXBean.class, new PosixSubstrateOperatingSystemMXBean());
    }
}