/*
 * Copyright (c) 2022, 2023, 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.
 *
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package com.oracle.svm.core.posix;

import com.oracle.svm.core.jdk.LoadAverageSupport;
import com.oracle.svm.core.posix.headers.Stdlib;
import com.oracle.svm.core.feature.AutomaticallyRegisteredImageSingleton;
import com.oracle.svm.core.handles.PrimitiveArrayView;

@AutomaticallyRegisteredImageSingleton(LoadAverageSupport.class)
class PosixLoadAverageSupport implements LoadAverageSupport {
    @Override
    public int getLoadAverage(double[] loadavg, int nelems) {
        /*
         * Adapted from `os::loadavg` which is the same in both `src/hotspot/os/linux/os_linux.cpp`
         * and `src/hotspot/os/bsd/os_bsd.cpp`.
         */
        try (PrimitiveArrayView refLoadavg = PrimitiveArrayView.createForReadingAndWriting(loadavg)) {
            return Stdlib.getloadavg(refLoadavg.addressOfArrayElement(0), nelems);
        }
    }
}
