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 * Copyright (c) 2020, Red Hat Inc.
 * 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
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 * 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,
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package jdk.internal.platform.cgroupv2;

import java.io.IOException;
import java.io.UncheckedIOException;
import java.nio.file.Paths;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;
import java.util.stream.Collectors;

import jdk.internal.platform.CgroupInfo;
import jdk.internal.platform.CgroupSubsystem;
import jdk.internal.platform.CgroupSubsystemController;
import jdk.internal.platform.CgroupUtil;

public class CgroupV2Subsystem implements CgroupSubsystem {

    private static volatile CgroupV2Subsystem INSTANCE;
    private static final long[] LONG_ARRAY_NOT_SUPPORTED = null;
    private static final int[] INT_ARRAY_UNAVAILABLE = null;
    private final CgroupSubsystemController unified;
    private static final String PROVIDER_NAME = "cgroupv2";
    private static final int PER_CPU_SHARES = 1024;
    private static final String MAX_VAL = "max";
    private static final Object EMPTY_STR = "";
    private static final long NO_SWAP = 0;

    private CgroupV2Subsystem(CgroupSubsystemController unified) {
        this.unified = unified;
    }

    private long getLongVal(String file, long defaultValue) {
        return CgroupSubsystemController.getLongValue(unified,
                                                      file,
                                                      CgroupV2SubsystemController::convertStringToLong,
                                                      defaultValue);
    }

    private long getLongVal(String file) {
        return getLongVal(file, CgroupSubsystem.LONG_RETVAL_UNLIMITED);
    }

    
Get the singleton instance of a cgroups v2 subsystem. On initialization,
a new object from the given cgroup information 'anyController' is being
created. Note that the cgroup information has been parsed from cgroup
interface files ahead of time.
See CgroupSubsystemFactory.determineType() for the cgroup interface
files parsing logic.
Returns:
A singleton CgroupSubsystem instance, never null./**
     * Get the singleton instance of a cgroups v2 subsystem. On initialization,
     * a new object from the given cgroup information 'anyController' is being
     * created. Note that the cgroup information has been parsed from cgroup
     * interface files ahead of time.
     *
     * See CgroupSubsystemFactory.determineType() for the cgroup interface
     * files parsing logic.
     *
     * @return A singleton CgroupSubsystem instance, never null.
     */
    public static CgroupSubsystem getInstance(CgroupInfo anyController) {
        if (INSTANCE == null) {
            CgroupSubsystemController unified = new CgroupV2SubsystemController(
                    anyController.getMountPoint(),
                    anyController.getCgroupPath());
            CgroupV2Subsystem tmpCgroupSystem = new CgroupV2Subsystem(unified);
            synchronized (CgroupV2Subsystem.class) {
                if (INSTANCE == null) {
                    INSTANCE = tmpCgroupSystem;
                }
            }
        }
        return INSTANCE;
    }

    @Override
    public String getProvider() {
        return PROVIDER_NAME;
    }

    @Override
    public long getCpuUsage() {
        long micros = CgroupV2SubsystemController.getLongEntry(unified, "cpu.stat", "usage_usec");
        if (micros < 0) {
            return micros;
        }
        return TimeUnit.MICROSECONDS.toNanos(micros);
    }

    @Override
    public long[] getPerCpuUsage() {
        return LONG_ARRAY_NOT_SUPPORTED;
    }

    @Override
    public long getCpuUserUsage() {
        long micros = CgroupV2SubsystemController.getLongEntry(unified, "cpu.stat", "user_usec");
        if (micros < 0) {
            return micros;
        }
        return TimeUnit.MICROSECONDS.toNanos(micros);
    }

    @Override
    public long getCpuSystemUsage() {
        long micros = CgroupV2SubsystemController.getLongEntry(unified, "cpu.stat", "system_usec");
        if (micros < 0) {
            return micros;
        }
        return TimeUnit.MICROSECONDS.toNanos(micros);
    }

    @Override
    public long getCpuPeriod() {
        return getFromCpuMax(1 /* $PERIOD index */);
    }

    @Override
    public long getCpuQuota() {
        return getFromCpuMax(0 /* $MAX index */);
    }

    private long getFromCpuMax(int tokenIdx) {
        String cpuMaxRaw = CgroupSubsystemController.getStringValue(unified, "cpu.max");
        if (cpuMaxRaw == null) {
            // likely file not found
            return CgroupSubsystem.LONG_RETVAL_UNLIMITED;
        }
        // $MAX $PERIOD
        String[] tokens = cpuMaxRaw.split("\\s+");
        if (tokens.length != 2) {
            return CgroupSubsystem.LONG_RETVAL_UNLIMITED;
        }
        String quota = tokens[tokenIdx];
        return limitFromString(quota);
    }

    private long limitFromString(String strVal) {
        if (strVal == null || MAX_VAL.equals(strVal)) {
            return CgroupSubsystem.LONG_RETVAL_UNLIMITED;
        }
        return Long.parseLong(strVal);
    }

    @Override
    public long getCpuShares() {
        long sharesRaw = getLongVal("cpu.weight");
        if (sharesRaw == 100 || sharesRaw <= 0) {
            return CgroupSubsystem.LONG_RETVAL_UNLIMITED;
        }
        int shares = (int)sharesRaw;
        // CPU shares (OCI) value needs to get translated into
        // a proper Cgroups v2 value. See:
        // https://github.com/containers/crun/blob/master/crun.1.md#cpu-controller
        //
        // Use the inverse of (x == OCI value, y == cgroupsv2 value):
        // ((262142 * y - 1)/9999) + 2 = x
        //
        int x = 262142 * shares - 1;
        double frac = x/9999.0;
        x = ((int)frac) + 2;
        if ( x <= PER_CPU_SHARES ) {
            return PER_CPU_SHARES; // mimic cgroups v1
        }
        int f = x/PER_CPU_SHARES;
        int lower_multiple = f * PER_CPU_SHARES;
        int upper_multiple = (f + 1) * PER_CPU_SHARES;
        int distance_lower = Math.max(lower_multiple, x) - Math.min(lower_multiple, x);
        int distance_upper = Math.max(upper_multiple, x) - Math.min(upper_multiple, x);
        x = distance_lower <= distance_upper ? lower_multiple : upper_multiple;
        return x;
    }

    @Override
    public long getCpuNumPeriods() {
        return CgroupV2SubsystemController.getLongEntry(unified, "cpu.stat", "nr_periods");
    }

    @Override
    public long getCpuNumThrottled() {
        return CgroupV2SubsystemController.getLongEntry(unified, "cpu.stat", "nr_throttled");
    }

    @Override
    public long getCpuThrottledTime() {
        long micros = CgroupV2SubsystemController.getLongEntry(unified, "cpu.stat", "throttled_usec");
        if (micros < 0) {
            return micros;
        }
        return TimeUnit.MICROSECONDS.toNanos(micros);
    }

    @Override
    public long getEffectiveCpuCount() {
        return Runtime.getRuntime().availableProcessors();
    }

    @Override
    public int[] getCpuSetCpus() {
        String cpuSetVal = CgroupSubsystemController.getStringValue(unified, "cpuset.cpus");
        return getCpuSet(cpuSetVal);
    }

    @Override
    public int[] getEffectiveCpuSetCpus() {
        String effCpuSetVal = CgroupSubsystemController.getStringValue(unified, "cpuset.cpus.effective");
        return getCpuSet(effCpuSetVal);
    }

    @Override
    public int[] getCpuSetMems() {
        String cpuSetMems = CgroupSubsystemController.getStringValue(unified, "cpuset.mems");
        return getCpuSet(cpuSetMems);
    }

    @Override
    public int[] getEffectiveCpuSetMems() {
        String effCpuSetMems = CgroupSubsystemController.getStringValue(unified, "cpuset.mems.effective");
        return getCpuSet(effCpuSetMems);
    }

    private int[] getCpuSet(String cpuSetVal) {
        if (cpuSetVal == null || EMPTY_STR.equals(cpuSetVal)) {
            return INT_ARRAY_UNAVAILABLE;
        }
        return CgroupSubsystemController.stringRangeToIntArray(cpuSetVal);
    }

    @Override
    public long getMemoryFailCount() {
        return CgroupV2SubsystemController.getLongEntry(unified, "memory.events", "max");
    }

    @Override
    public long getMemoryLimit() {
        String strVal = CgroupSubsystemController.getStringValue(unified, "memory.max");
        return limitFromString(strVal);
    }

    @Override
    public long getMemoryUsage() {
        return getLongVal("memory.current");
    }

    @Override
    public long getTcpMemoryUsage() {
        return CgroupV2SubsystemController.getLongEntry(unified, "memory.stat", "sock");
    }

    
Note that for cgroups v2 the actual limits set for swap and
memory live in two different files, memory.swap.max and memory.max
respectively. In order to properly report a cgroup v1 like
compound value we need to sum the two values. Setting a swap limit
without also setting a memory limit is not allowed.
/**
     * Note that for cgroups v2 the actual limits set for swap and
     * memory live in two different files, memory.swap.max and memory.max
     * respectively. In order to properly report a cgroup v1 like
     * compound value we need to sum the two values. Setting a swap limit
     * without also setting a memory limit is not allowed.
     */
    @Override
    public long getMemoryAndSwapLimit() {
        String strVal = CgroupSubsystemController.getStringValue(unified, "memory.swap.max");
        // We only get a null string when file memory.swap.max doesn't exist.
        // In that case we return the memory limit without any swap.
        if (strVal == null) {
            return getMemoryLimit();
        }
        long swapLimit = limitFromString(strVal);
        if (swapLimit >= 0) {
            long memoryLimit = getMemoryLimit();
            assert memoryLimit >= 0;
            return memoryLimit + swapLimit;
        }
        return swapLimit;
    }

    
Note that for cgroups v2 the actual values set for swap usage and
memory usage live in two different files, memory.current and memory.swap.current
respectively. In order to properly report a cgroup v1 like
compound value we need to sum the two values. Setting a swap limit
without also setting a memory limit is not allowed.
/**
     * Note that for cgroups v2 the actual values set for swap usage and
     * memory usage live in two different files, memory.current and memory.swap.current
     * respectively. In order to properly report a cgroup v1 like
     * compound value we need to sum the two values. Setting a swap limit
     * without also setting a memory limit is not allowed.
     */
    @Override
    public long getMemoryAndSwapUsage() {
        long memoryUsage = getMemoryUsage();
        if (memoryUsage >= 0) {
            // If file memory.swap.current doesn't exist, only return the regular
            // memory usage (without swap). Thus, use default value of NO_SWAP.
            long swapUsage = getLongVal("memory.swap.current", NO_SWAP);
            return memoryUsage + swapUsage;
        }
        return memoryUsage; // case of no memory limits
    }

    @Override
    public long getMemorySoftLimit() {
        String softLimitStr = CgroupSubsystemController.getStringValue(unified, "memory.low");
        return limitFromString(softLimitStr);
    }

    @Override
    public long getBlkIOServiceCount() {
        return sumTokensIOStat(CgroupV2Subsystem::lineToRandWIOs);
    }


    @Override
    public long getBlkIOServiced() {
        return sumTokensIOStat(CgroupV2Subsystem::lineToRBytesAndWBytesIO);
    }

    private long sumTokensIOStat(Function<String, Long> mapFunc) {
        try {
            return CgroupUtil.readFilePrivileged(Paths.get(unified.path(), "io.stat"))
                                .map(mapFunc)
                                .collect(Collectors.summingLong(e -> e));
        } catch (UncheckedIOException e) {
            return CgroupSubsystem.LONG_RETVAL_UNLIMITED;
        } catch (IOException e) {
            return CgroupSubsystem.LONG_RETVAL_UNLIMITED;
        }
    }

    private static String[] getRWIOMatchTokenNames() {
        return new String[] { "rios", "wios" };
    }

    private static String[] getRWBytesIOMatchTokenNames() {
        return new String[] { "rbytes", "wbytes" };
    }

    public static Long lineToRandWIOs(String line) {
        String[] matchNames = getRWIOMatchTokenNames();
        return ioStatLineToLong(line, matchNames);
    }

    public static Long lineToRBytesAndWBytesIO(String line) {
        String[] matchNames = getRWBytesIOMatchTokenNames();
        return ioStatLineToLong(line, matchNames);
    }

    private static Long ioStatLineToLong(String line, String[] matchNames) {
        if (line == null || EMPTY_STR.equals(line)) {
            return Long.valueOf(0);
        }
        String[] tokens = line.split("\\s+");
        long retval = 0;
        for (String t: tokens) {
            String[] valKeys = t.split("=");
            if (valKeys.length != 2) {
                // ignore device ids $MAJ:$MIN
                continue;
            }
            for (String match: matchNames) {
                if (match.equals(valKeys[0])) {
                    retval += longOrZero(valKeys[1]);
                }
            }
        }
        return Long.valueOf(retval);
    }

    private static long longOrZero(String val) {
        long lVal = 0;
        try {
            lVal = Long.parseLong(val);
        } catch (NumberFormatException e) {
            // keep at 0
        }
        return lVal;
    }
}