8231111: Cgroups v2: Rework Metrics in java.base so as to recognize unified hierarchy

Reviewed-by: bobv, mchung

src/java.base/linux/classes/jdk/internal/platform/CgroupInfo.java

@@ -0,0 +1,70 @@
+/*
+ * 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
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform;
+
+/**
+ * Data structure to hold info from /proc/self/cgroup
+ *
+ * man 7 cgroups
+ *
+ * @see CgroupSubsystemFactory
+ */
+class CgroupInfo {
+
+    private final String name;
+    private final int hierarchyId;
+    private final boolean enabled;
+
+    private CgroupInfo(String name, int hierarchyId, boolean enabled) {
+        this.name = name;
+        this.hierarchyId = hierarchyId;
+        this.enabled = enabled;
+    }
+
+    String getName() {
+        return name;
+    }
+
+    int getHierarchyId() {
+        return hierarchyId;
+    }
+
+    boolean isEnabled() {
+        return enabled;
+    }
+
+    static CgroupInfo fromCgroupsLine(String line) {
+        String[] tokens = line.split("\\s+");
+        if (tokens.length != 4) {
+            return null;
+        }
+        // discard 3'rd field, num_cgroups
+        return new CgroupInfo(tokens[0] /* name */,
+                              Integer.parseInt(tokens[1]) /* hierarchyId */,
+                              (Integer.parseInt(tokens[3]) == 1) /* enabled */);
+    }
+
+}

src/java.base/linux/classes/jdk/internal/platform/CgroupMetrics.java

@@ -0,0 +1,166 @@
+/*
+ * 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
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform;
+
+import java.util.Objects;
+
+public class CgroupMetrics implements Metrics {
+
+    private final CgroupSubsystem subsystem;
+
+    CgroupMetrics(CgroupSubsystem subsystem) {
+        this.subsystem = Objects.requireNonNull(subsystem);
+    }
+
+    @Override
+    public String getProvider() {
+        return subsystem.getProvider();
+    }
+
+    @Override
+    public long getCpuUsage() {
+        return subsystem.getCpuUsage();
+    }
+
+    @Override
+    public long[] getPerCpuUsage() {
+        return subsystem.getPerCpuUsage();
+    }
+
+    @Override
+    public long getCpuUserUsage() {
+        return subsystem.getCpuUserUsage();
+    }
+
+    @Override
+    public long getCpuSystemUsage() {
+        return subsystem.getCpuSystemUsage();
+    }
+
+    @Override
+    public long getCpuPeriod() {
+        return subsystem.getCpuPeriod();
+    }
+
+    @Override
+    public long getCpuQuota() {
+        return subsystem.getCpuQuota();
+    }
+
+    @Override
+    public long getCpuShares() {
+        return subsystem.getCpuShares();
+    }
+
+    @Override
+    public long getCpuNumPeriods() {
+        return subsystem.getCpuNumPeriods();
+    }
+
+    @Override
+    public long getCpuNumThrottled() {
+        return subsystem.getCpuNumThrottled();
+    }
+
+    @Override
+    public long getCpuThrottledTime() {
+        return subsystem.getCpuThrottledTime();
+    }
+
+    @Override
+    public long getEffectiveCpuCount() {
+        return subsystem.getEffectiveCpuCount();
+    }
+
+    @Override
+    public int[] getCpuSetCpus() {
+        return subsystem.getCpuSetCpus();
+    }
+
+    @Override
+    public int[] getEffectiveCpuSetCpus() {
+        return subsystem.getEffectiveCpuSetCpus();
+    }
+
+    @Override
+    public int[] getCpuSetMems() {
+        return subsystem.getCpuSetMems();
+    }
+
+    @Override
+    public int[] getEffectiveCpuSetMems() {
+        return subsystem.getEffectiveCpuSetMems();
+    }
+
+    public long getMemoryFailCount() {
+        return subsystem.getMemoryFailCount();
+    }
+
+    @Override
+    public long getMemoryLimit() {
+        return subsystem.getMemoryLimit();
+    }
+
+    @Override
+    public long getMemoryUsage() {
+        return subsystem.getMemoryUsage();
+    }
+
+    @Override
+    public long getTcpMemoryUsage() {
+        return subsystem.getTcpMemoryUsage();
+    }
+
+    @Override
+    public long getMemoryAndSwapLimit() {
+        return subsystem.getMemoryAndSwapLimit();
+    }
+
+    @Override
+    public long getMemoryAndSwapUsage() {
+        return subsystem.getMemoryAndSwapUsage();
+    }
+
+    @Override
+    public long getMemorySoftLimit() {
+        return subsystem.getMemorySoftLimit();
+    }
+
+    @Override
+    public long getBlkIOServiceCount() {
+        return subsystem.getBlkIOServiceCount();
+    }
+
+    @Override
+    public long getBlkIOServiced() {
+        return subsystem.getBlkIOServiced();
+    }
+
+    public static Metrics getInstance() {
+        return CgroupSubsystemFactory.create();
+    }
+
+}

src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystem.java

@@ -0,0 +1,40 @@
+/*
+ * 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
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform;
+
+/**
+ * Marker interface for cgroup-based metrics
+ *
+ */
+public interface CgroupSubsystem extends Metrics {
+
+    /**
+     * Returned for metrics of type long if the underlying implementation
+     * has determined that no limit is being imposed.
+     */
+    public static final long LONG_RETVAL_UNLIMITED = -1;
+
+}

src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystemController.java

@@ -0,0 +1,253 @@
+/*
+ * 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
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform;
+
+import java.io.IOException;
+import java.math.BigInteger;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import java.util.function.Function;
+import java.util.stream.Stream;
+
+/**
+ * Cgroup version agnostic controller logic
+ *
+ */
+public interface CgroupSubsystemController {
+
+    public static final String EMPTY_STR = "";
+
+    public String path();
+
+    /**
+     * getStringValue
+     *
+     * Return the first line of the file "param" argument from the controller.
+     *
+     * TODO:  Consider using weak references for caching BufferedReader object.
+     *
+     * @param controller
+     * @param param
+     * @return Returns the contents of the file specified by param or null if
+     *         an error occurs.
+     */
+    public static String getStringValue(CgroupSubsystemController controller, String param) {
+        if (controller == null) return null;
+
+        try {
+            return CgroupUtil.readStringValue(controller, param);
+        }
+        catch (IOException e) {
+            return null;
+        }
+
+    }
+
+    /**
+     * Get an entry from file "param" within the "controller" directory path
+     * which matches string "match". Applies "conversion" to the matching line.
+     *
+     * @param controller
+     * @param param
+     * @param match
+     * @param conversion
+     * @param defaultRetval
+     * @return The long value as derived by applying "conversion" to the matching
+     *         line or "defaultRetval" if there was an error or no match found.
+     */
+    public static long getLongValueMatchingLine(CgroupSubsystemController controller,
+                                                     String param,
+                                                     String match,
+                                                     Function<String, Long> conversion,
+                                                     long defaultRetval) {
+        long retval = defaultRetval;
+        if (controller == null) {
+            return retval;
+        }
+        try {
+            Path filePath = Paths.get(controller.path(), param);
+            List<String> lines = CgroupUtil.readAllLinesPrivileged(filePath);
+            for (String line : lines) {
+                if (line.startsWith(match)) {
+                    retval = conversion.apply(line);
+                    break;
+                }
+            }
+        } catch (IOException e) {
+            // Ignore. Default is unlimited.
+        }
+        return retval;
+    }
+
+    /**
+     * Get a long value from directory "controller" and file "param", by
+     * applying "conversion" to the string value within the file.
+     *
+     * @param controller
+     * @param param
+     * @param conversion
+     * @param defaultRetval
+     * @return The converted long value or "defaultRetval" if there was an
+     *         error.
+     */
+    public static long getLongValue(CgroupSubsystemController controller,
+                                    String param,
+                                    Function<String, Long> conversion,
+                                    long defaultRetval) {
+        String strval = getStringValue(controller, param);
+        if (strval == null) return defaultRetval;
+        return conversion.apply(strval);
+    }
+
+    /**
+     * Get a double value from file "param" within "controller".
+     *
+     * @param controller
+     * @param param
+     * @param defaultRetval
+     * @return The double value or "defaultRetval" if there was an error.
+     */
+    public static double getDoubleValue(CgroupSubsystemController controller, String param, double defaultRetval) {
+        String strval = getStringValue(controller, param);
+
+        if (strval == null) return defaultRetval;
+
+        double retval = Double.parseDouble(strval);
+
+        return retval;
+    }
+
+    /**
+     * getLongEntry
+     *
+     * Return the long value from the line containing the string "entryname"
+     * within file "param" in the "controller".
+     *
+     * TODO:  Consider using weak references for caching BufferedReader object.
+     *
+     * @param controller
+     * @param param
+     * @param entryname
+     * @return long value or "defaultRetval" if there was an error or no match
+     *         was found.
+     */
+    public static long getLongEntry(CgroupSubsystemController controller, String param, String entryname, long defaultRetval) {
+        if (controller == null) return defaultRetval;
+
+        try (Stream<String> lines = CgroupUtil.readFilePrivileged(Paths.get(controller.path(), param))) {
+
+            Optional<String> result = lines.map(line -> line.split(" "))
+                                           .filter(line -> (line.length == 2 &&
+                                                   line[0].equals(entryname)))
+                                           .map(line -> line[1])
+                                           .findFirst();
+
+            return result.isPresent() ? Long.parseLong(result.get()) : defaultRetval;
+        }
+        catch (IOException e) {
+            return defaultRetval;
+        }
+    }
+
+    /**
+     * stringRangeToIntArray
+     *
+     * Convert a string in the form of  1,3-4,6 to an array of
+     * integers containing all the numbers in the range.
+     *
+     * @param range
+     * @return int[] containing a sorted list of numbers as represented by
+     *         the string range. Returns null if there was an error or the input
+     *         was an empty string.
+     */
+    public static int[] stringRangeToIntArray(String range) {
+        if (range == null || EMPTY_STR.equals(range)) return null;
+
+        ArrayList<Integer> results = new ArrayList<>();
+        String strs[] = range.split(",");
+        for (String str : strs) {
+            if (str.contains("-")) {
+                String lohi[] = str.split("-");
+                // validate format
+                if (lohi.length != 2) {
+                    continue;
+                }
+                int lo = Integer.parseInt(lohi[0]);
+                int hi = Integer.parseInt(lohi[1]);
+                for (int i = lo; i <= hi; i++) {
+                    results.add(i);
+                }
+            }
+            else {
+                results.add(Integer.parseInt(str));
+            }
+        }
+
+        // sort results
+        results.sort(null);
+
+        // convert ArrayList to primitive int array
+        int[] ints = new int[results.size()];
+        int i = 0;
+        for (Integer n : results) {
+            ints[i++] = n;
+        }
+
+        return ints;
+    }
+
+    /**
+     * Convert a number from its string representation to a long.
+     *
+     * @param strval
+     * @param overflowRetval
+     * @param defaultRetval
+     * @return The converted long value. "overflowRetval" is returned if the
+     *         string representation exceeds the range of type long.
+     *         "defaultRetval" is returned if another type of error occurred
+     *         during conversion.
+     */
+    public static long convertStringToLong(String strval, long overflowRetval, long defaultRetval) {
+        long retval = defaultRetval;
+        if (strval == null) return retval;
+
+        try {
+            retval = Long.parseLong(strval);
+        } catch (NumberFormatException e) {
+            // For some properties (e.g. memory.limit_in_bytes, cgroups v1) we may overflow
+            // the range of signed long. In this case, return overflowRetval
+            BigInteger b = new BigInteger(strval);
+            if (b.compareTo(BigInteger.valueOf(Long.MAX_VALUE)) > 0) {
+                return overflowRetval;
+            }
+        }
+        return retval;
+    }
+
+}

src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystemFactory.java

@@ -0,0 +1,101 @@
+/*
+ * 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
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform;
+
+import java.io.IOException;
+import java.lang.System.Logger;
+import java.lang.System.Logger.Level;
+import java.nio.file.Paths;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import jdk.internal.platform.cgroupv1.CgroupV1Subsystem;
+import jdk.internal.platform.cgroupv2.CgroupV2Subsystem;
+
+class CgroupSubsystemFactory {
+
+    private static final String CPU_CTRL = "cpu";
+    private static final String CPUACCT_CTRL = "cpuacct";
+    private static final String CPUSET_CTRL = "cpuset";
+    private static final String BLKIO_CTRL = "blkio";
+    private static final String MEMORY_CTRL = "memory";
+
+    static CgroupMetrics create() {
+        Map<String, CgroupInfo> infos = new HashMap<>();
+        try {
+            List<String> lines = CgroupUtil.readAllLinesPrivileged(Paths.get("/proc/cgroups"));
+            for (String line : lines) {
+                if (line.startsWith("#")) {
+                    continue;
+                }
+                CgroupInfo info = CgroupInfo.fromCgroupsLine(line);
+                switch (info.getName()) {
+                case CPU_CTRL:      infos.put(CPU_CTRL, info); break;
+                case CPUACCT_CTRL:  infos.put(CPUACCT_CTRL, info); break;
+                case CPUSET_CTRL:   infos.put(CPUSET_CTRL, info); break;
+                case MEMORY_CTRL:   infos.put(MEMORY_CTRL, info); break;
+                case BLKIO_CTRL:    infos.put(BLKIO_CTRL, info); break;
+                }
+            }
+        } catch (IOException e) {
+            return null;
+        }
+
+        // For cgroups v1 all controllers need to have non-zero hierarchy id
+        boolean isCgroupsV2 = true;
+        boolean anyControllersEnabled = false;
+        boolean anyCgroupsV2Controller = false;
+        boolean anyCgroupsV1Controller = false;
+        for (CgroupInfo info: infos.values()) {
+            anyCgroupsV1Controller = anyCgroupsV1Controller || info.getHierarchyId() != 0;
+            anyCgroupsV2Controller = anyCgroupsV2Controller || info.getHierarchyId() == 0;
+            isCgroupsV2 = isCgroupsV2 && info.getHierarchyId() == 0;
+            anyControllersEnabled = anyControllersEnabled || info.isEnabled();
+        }
+
+        // If no controller is enabled, return no metrics.
+        if (!anyControllersEnabled) {
+            return null;
+        }
+        // Warn about mixed cgroups v1 and cgroups v2 controllers. The code is
+        // not ready to deal with that on a per-controller basis. Return no metrics
+        // in that case
+        if (anyCgroupsV1Controller && anyCgroupsV2Controller) {
+            Logger logger = System.getLogger("jdk.internal.platform");
+            logger.log(Level.DEBUG, "Mixed cgroupv1 and cgroupv2 not supported. Metrics disabled.");
+            return null;
+        }
+
+        if (isCgroupsV2) {
+            CgroupSubsystem subsystem = CgroupV2Subsystem.getInstance();
+            return subsystem != null ? new CgroupMetrics(subsystem) : null;
+        } else {
+            CgroupV1Subsystem subsystem = CgroupV1Subsystem.getInstance();
+            return subsystem != null ? new CgroupV1MetricsImpl(subsystem) : null;
+        }
+    }
+}

src/java.base/linux/classes/jdk/internal/platform/CgroupUtil.java

@@ -0,0 +1,83 @@
+/*
+ * 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
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.security.AccessController;
+import java.security.PrivilegedActionException;
+import java.security.PrivilegedExceptionAction;
+import java.util.List;
+import java.util.stream.Stream;
+
+public final class CgroupUtil {
+
+    public static Stream<String> readFilePrivileged(Path path) throws IOException {
+        try {
+            PrivilegedExceptionAction<Stream<String>> pea = () -> Files.lines(path);
+            return AccessController.doPrivileged(pea);
+        } catch (PrivilegedActionException e) {
+            unwrapIOExceptionAndRethrow(e);
+            throw new InternalError(e.getCause());
+        }
+    }
+
+    static void unwrapIOExceptionAndRethrow(PrivilegedActionException pae) throws IOException {
+        Throwable x = pae.getCause();
+        if (x instanceof IOException)
+            throw (IOException) x;
+        if (x instanceof RuntimeException)
+            throw (RuntimeException) x;
+        if (x instanceof Error)
+            throw (Error) x;
+    }
+
+    static String readStringValue(CgroupSubsystemController controller, String param) throws IOException {
+        PrivilegedExceptionAction<BufferedReader> pea = () ->
+                Files.newBufferedReader(Paths.get(controller.path(), param));
+        try (BufferedReader bufferedReader =
+                     AccessController.doPrivileged(pea)) {
+            String line = bufferedReader.readLine();
+            return line;
+        } catch (PrivilegedActionException e) {
+            unwrapIOExceptionAndRethrow(e);
+            throw new InternalError(e.getCause());
+        }
+    }
+
+    public static List<String> readAllLinesPrivileged(Path path) throws IOException {
+        try {
+            PrivilegedExceptionAction<List<String>> pea = () -> Files.readAllLines(path);
+            return AccessController.doPrivileged(pea);
+        } catch (PrivilegedActionException e) {
+            unwrapIOExceptionAndRethrow(e);
+            throw new InternalError(e.getCause());
+        }
+    }
+}

src/java.base/linux/classes/jdk/internal/platform/CgroupV1Metrics.java

@@ -0,0 +1,168 @@
+/*
+ * Copyright (c) 2018, 2020, 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform;
+
+/**
+ *
+ * Cgroup v1 extensions to the Metrics interface. Linux, only.
+ *
+ */
+public interface CgroupV1Metrics extends Metrics {
+
+    /**
+     * Returns the largest amount of physical memory, in bytes, that
+     * have been allocated in the Isolation Group.
+     *
+     * @return The largest amount of memory in bytes or -1 if this
+     *         metric is not available. Returns -2 if this metric is not
+     *         supported.
+     *
+     */
+    public long getMemoryMaxUsage();
+
+    /**
+     * Returns the number of times that kernel memory requests in the
+     * Isolation Group have exceeded the kernel memory limit.
+     *
+     * @return The number of exceeded requests or -1 if metric
+     *         is not available.
+     *
+     */
+    public long getKernelMemoryFailCount();
+
+    /**
+     * Returns the maximum amount of kernel physical memory, in bytes, that
+     * can be allocated in the Isolation Group.
+     *
+     * @return The maximum amount of memory in bytes or -1 if
+     *         there is no limit set.
+     *
+     */
+    public long getKernelMemoryLimit();
+
+    /**
+     * Returns the largest amount of kernel physical memory, in bytes, that
+     * have been allocated in the Isolation Group.
+     *
+     * @return The largest amount of memory in bytes or -1 if this
+     *         metric is not available.
+     *
+     */
+    public long getKernelMemoryMaxUsage();
+
+    /**
+     * Returns the amount of kernel physical memory, in bytes, that
+     * is currently allocated in the current Isolation Group.
+     *
+     * @return The amount of memory in bytes allocated or -1 if this
+     *         metric is not available.
+     *
+     */
+    public long getKernelMemoryUsage();
+
+    /**
+     * Returns the number of times that networking memory requests in the
+     * Isolation Group have exceeded the kernel memory limit.
+     *
+     * @return The number of exceeded requests or -1 if the metric
+     *         is not available.
+     *
+     */
+    public long getTcpMemoryFailCount();
+
+    /**
+     * Returns the maximum amount of networking physical memory, in bytes,
+     * that can be allocated in the Isolation Group.
+     *
+     * @return The maximum amount of memory in bytes or -1 if
+     *         there is no limit.
+     *
+     */
+    public long getTcpMemoryLimit();
+
+    /**
+     * Returns the largest amount of networking physical memory, in bytes,
+     * that have been allocated in the Isolation Group.
+     *
+     * @return The largest amount of memory in bytes or -1 if this
+     *         metric is not available.
+     *
+     */
+    public long getTcpMemoryMaxUsage();
+
+    /**
+     * Returns the number of times that user memory requests in the
+     * Isolation Group have exceeded the memory + swap limit.
+     *
+     * @return The number of exceeded requests or -1 if the metric
+     *         is not available.
+     *
+     */
+    public long getMemoryAndSwapFailCount();
+
+    /**
+     * Returns the largest amount of physical memory and swap space,
+     * in bytes, that have been allocated in the Isolation Group.
+     *
+     * @return The largest amount of memory in bytes or -1 if this
+     *         metric is not available.
+     *
+     */
+    public long getMemoryAndSwapMaxUsage();
+
+    /**
+     * Returns the state of the Operating System Out of Memory termination
+     * policy.
+     *
+     * @return Returns true if operating system will terminate processes
+     *         in the Isolation Group that exceed the amount of available
+     *         memory, otherwise false. null will be returned if this
+     *         capability is not available on the current operating system.
+     *
+     */
+    public Boolean isMemoryOOMKillEnabled();
+
+    /**
+     * Returns the (attempts per second * 1000), if enabled, that the
+     * operating system tries to satisfy a memory request for any
+     * process in the current Isolation Group when no free memory is
+     * readily available.  Use {@link #isCpuSetMemoryPressureEnabled()} to
+     * determine if this support is enabled.
+     *
+     * @return Memory pressure or 0 if not enabled or -1 if metric is not
+     *         available.
+     *
+     */
+    public double getCpuSetMemoryPressure();
+
+    /**
+     * Returns the state of the memory pressure detection support.
+     *
+     * @return true if support is available and enabled. false otherwise.
+     *
+     */
+    public Boolean isCpuSetMemoryPressureEnabled();
+}

src/java.base/linux/classes/jdk/internal/platform/CgroupV1MetricsImpl.java

@@ -0,0 +1,106 @@
+/*
+ * 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
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform;
+
+/**
+ * Cgroup v1 Metrics extensions
+ *
+ */
+public class CgroupV1MetricsImpl extends CgroupMetrics implements CgroupV1Metrics {
+
+    private final CgroupV1Metrics metrics;
+
+    CgroupV1MetricsImpl(CgroupV1Metrics metrics) {
+        super((CgroupSubsystem)metrics);
+        this.metrics = metrics;
+    }
+
+    @Override
+    public long getMemoryMaxUsage() {
+        return metrics.getMemoryMaxUsage();
+    }
+
+    @Override
+    public long getKernelMemoryFailCount() {
+        return metrics.getKernelMemoryFailCount();
+    }
+
+    @Override
+    public long getKernelMemoryLimit() {
+        return metrics.getKernelMemoryLimit();
+    }
+
+    @Override
+    public long getKernelMemoryMaxUsage() {
+        return metrics.getKernelMemoryMaxUsage();
+    }
+
+    @Override
+    public long getKernelMemoryUsage() {
+        return metrics.getKernelMemoryUsage();
+    }
+
+    @Override
+    public long getTcpMemoryFailCount() {
+        return metrics.getTcpMemoryFailCount();
+    }
+
+    @Override
+    public long getTcpMemoryLimit() {
+        return metrics.getTcpMemoryLimit();
+    }
+
+    @Override
+    public long getTcpMemoryMaxUsage() {
+        return metrics.getTcpMemoryMaxUsage();
+    }
+
+    @Override
+    public long getMemoryAndSwapFailCount() {
+        return metrics.getMemoryAndSwapFailCount();
+    }
+
+    @Override
+    public long getMemoryAndSwapMaxUsage() {
+        return metrics.getMemoryAndSwapMaxUsage();
+    }
+
+    @Override
+    public Boolean isMemoryOOMKillEnabled() {
+        return metrics.isMemoryOOMKillEnabled();
+    }
+
+    @Override
+    public double getCpuSetMemoryPressure() {
+        return metrics.getCpuSetMemoryPressure();
+    }
+
+    @Override
+    public Boolean isCpuSetMemoryPressureEnabled() {
+        return metrics.isCpuSetMemoryPressureEnabled();
+    }
+
+}

src/java.base/linux/classes/jdk/internal/platform/cgroupv1/CgroupV1MemorySubSystemController.java

@@ -0,0 +1,44 @@
+/*
+ * 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
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform.cgroupv1;
+
+public class CgroupV1MemorySubSystemController extends CgroupV1SubsystemController {
+
+    private boolean hierarchical;
+
+    public CgroupV1MemorySubSystemController(String root, String mountPoint) {
+        super(root, mountPoint);
+    }
+
+    boolean isHierarchical() {
+        return hierarchical;
+    }
+
+    void setHierarchical(boolean hierarchical) {
+        this.hierarchical = hierarchical;
+    }
+
+}

src/java.base/linux/classes/jdk/internal/platform/cgroupv1/CgroupV1Subsystem.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2020, 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
@@ -26,41 +26,37 @@
 package jdk.internal.platform.cgroupv1;
 
 import java.io.IOException;
-import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.security.AccessController;
-import java.security.PrivilegedActionException;
-import java.security.PrivilegedExceptionAction;
 import java.util.stream.Stream;
 
-import jdk.internal.platform.cgroupv1.SubSystem.MemorySubSystem;
+import jdk.internal.platform.CgroupSubsystem;
+import jdk.internal.platform.CgroupSubsystemController;
+import jdk.internal.platform.CgroupUtil;
+import jdk.internal.platform.CgroupV1Metrics;
 
-public class Metrics implements jdk.internal.platform.Metrics {
-    private MemorySubSystem memory;
-    private SubSystem cpu;
-    private SubSystem cpuacct;
-    private SubSystem cpuset;
-    private SubSystem blkio;
+public class CgroupV1Subsystem implements CgroupSubsystem, CgroupV1Metrics {
+    private CgroupV1MemorySubSystemController memory;
+    private CgroupV1SubsystemController cpu;
+    private CgroupV1SubsystemController cpuacct;
+    private CgroupV1SubsystemController cpuset;
+    private CgroupV1SubsystemController blkio;
     private boolean activeSubSystems;
 
-    // Values returned larger than this number are unlimited.
-    static long unlimited_minimum = 0x7FFFFFFFFF000000L;
-
-    private static final Metrics INSTANCE = initContainerSubSystems();
+    private static final CgroupV1Subsystem INSTANCE = initSubSystem();
 
     private static final String PROVIDER_NAME = "cgroupv1";
 
-    private Metrics() {
+    private CgroupV1Subsystem() {
         activeSubSystems = false;
     }
 
-    public static Metrics getInstance() {
+    public static CgroupV1Subsystem getInstance() {
         return INSTANCE;
     }
 
-    private static Metrics initContainerSubSystems() {
-        Metrics metrics = new Metrics();
+    private static CgroupV1Subsystem initSubSystem() {
+        CgroupV1Subsystem subsystem = new CgroupV1Subsystem();
 
         /**
          * Find the cgroup mount points for subsystems
@@ -73,11 +69,11 @@ public class Metrics implements jdk.internal.platform.Metrics {
          * 34 28 0:29 / /sys/fs/cgroup/MemorySubSystem rw,nosuid,nodev,noexec,relatime shared:16 - cgroup cgroup rw,MemorySubSystem
          */
         try (Stream<String> lines =
-             readFilePrivileged(Paths.get("/proc/self/mountinfo"))) {
+                CgroupUtil.readFilePrivileged(Paths.get("/proc/self/mountinfo"))) {
 
             lines.filter(line -> line.contains(" - cgroup "))
                  .map(line -> line.split(" "))
-                 .forEach(entry -> createSubSystem(metrics, entry));
+                 .forEach(entry -> createSubSystemController(subsystem, entry));
 
         } catch (IOException e) {
             return null;
@@ -107,47 +103,28 @@ public class Metrics implements jdk.internal.platform.Metrics {
          *
          */
         try (Stream<String> lines =
-             readFilePrivileged(Paths.get("/proc/self/cgroup"))) {
+                CgroupUtil.readFilePrivileged(Paths.get("/proc/self/cgroup"))) {
 
             lines.map(line -> line.split(":"))
                  .filter(line -> (line.length >= 3))
-                 .forEach(line -> setSubSystemPath(metrics, line));
+                 .forEach(line -> setSubSystemControllerPath(subsystem, line));
 
         } catch (IOException e) {
             return null;
         }
 
         // Return Metrics object if we found any subsystems.
-        if (metrics.activeSubSystems()) {
-            return metrics;
+        if (subsystem.activeSubSystems()) {
+            return subsystem;
         }
 
         return null;
     }
 
-    static Stream<String> readFilePrivileged(Path path) throws IOException {
-        try {
-            PrivilegedExceptionAction<Stream<String>> pea = () -> Files.lines(path);
-            return AccessController.doPrivileged(pea);
-        } catch (PrivilegedActionException e) {
-            unwrapIOExceptionAndRethrow(e);
-            throw new InternalError(e.getCause());
-        }
-    }
-
-    static void unwrapIOExceptionAndRethrow(PrivilegedActionException pae) throws IOException {
-        Throwable x = pae.getCause();
-        if (x instanceof IOException)
-            throw (IOException) x;
-        if (x instanceof RuntimeException)
-            throw (RuntimeException) x;
-        if (x instanceof Error)
-            throw (Error) x;
-    }
     /**
      * createSubSystem objects and initialize mount points
      */
-    private static void createSubSystem(Metrics metric, String[] mountentry) {
+    private static void createSubSystemController(CgroupV1Subsystem subsystem, String[] mountentry) {
         if (mountentry.length < 5) return;
 
         Path p = Paths.get(mountentry[4]);
@@ -156,19 +133,19 @@ public class Metrics implements jdk.internal.platform.Metrics {
         for (String subsystemName: subsystemNames) {
             switch (subsystemName) {
                 case "memory":
-                    metric.setMemorySubSystem(new MemorySubSystem(mountentry[3], mountentry[4]));
+                    subsystem.setMemorySubSystem(new CgroupV1MemorySubSystemController(mountentry[3], mountentry[4]));
                     break;
                 case "cpuset":
-                    metric.setCpuSetSubSystem(new SubSystem(mountentry[3], mountentry[4]));
+                    subsystem.setCpuSetController(new CgroupV1SubsystemController(mountentry[3], mountentry[4]));
                     break;
                 case "cpuacct":
-                    metric.setCpuAcctSubSystem(new SubSystem(mountentry[3], mountentry[4]));
+                    subsystem.setCpuAcctController(new CgroupV1SubsystemController(mountentry[3], mountentry[4]));
                     break;
                 case "cpu":
-                    metric.setCpuSubSystem(new SubSystem(mountentry[3], mountentry[4]));
+                    subsystem.setCpuController(new CgroupV1SubsystemController(mountentry[3], mountentry[4]));
                     break;
                 case "blkio":
-                    metric.setBlkIOSubSystem(new SubSystem(mountentry[3], mountentry[4]));
+                    subsystem.setBlkIOController(new CgroupV1SubsystemController(mountentry[3], mountentry[4]));
                     break;
                 default:
                     // Ignore subsystems that we don't support
@@ -180,35 +157,35 @@ public class Metrics implements jdk.internal.platform.Metrics {
     /**
      * setSubSystemPath based on the contents of /proc/self/cgroup
      */
-    private static void setSubSystemPath(Metrics metric, String[] entry) {
-        String controller;
+    private static void setSubSystemControllerPath(CgroupV1Subsystem subsystem, String[] entry) {
+        String controllerName;
         String base;
-        SubSystem subsystem = null;
-        SubSystem subsystem2 = null;
+        CgroupV1SubsystemController controller = null;
+        CgroupV1SubsystemController controller2 = null;
 
-        controller = entry[1];
+        controllerName = entry[1];
         base = entry[2];
-        if (controller != null && base != null) {
-            switch (controller) {
+        if (controllerName != null && base != null) {
+            switch (controllerName) {
                 case "memory":
-                    subsystem = metric.MemorySubSystem();
+                    controller = subsystem.memoryController();
                     break;
                 case "cpuset":
-                    subsystem = metric.CpuSetSubSystem();
+                    controller = subsystem.cpuSetController();
                     break;
                 case "cpu,cpuacct":
                 case "cpuacct,cpu":
-                    subsystem = metric.CpuSubSystem();
-                    subsystem2 = metric.CpuAcctSubSystem();
+                    controller = subsystem.cpuController();
+                    controller2 = subsystem.cpuAcctController();
                     break;
                 case "cpuacct":
-                    subsystem = metric.CpuAcctSubSystem();
+                    controller = subsystem.cpuAcctController();
                     break;
                 case "cpu":
-                    subsystem = metric.CpuSubSystem();
+                    controller = subsystem.cpuController();
                     break;
                 case "blkio":
-                    subsystem = metric.BlkIOSubSystem();
+                    controller = subsystem.blkIOController();
                     break;
                 // Ignore subsystems that we don't support
                 default:
@@ -216,23 +193,23 @@ public class Metrics implements jdk.internal.platform.Metrics {
             }
         }
 
-        if (subsystem != null) {
-            subsystem.setPath(base);
-            if (subsystem instanceof MemorySubSystem) {
-                MemorySubSystem memorySubSystem = (MemorySubSystem)subsystem;
+        if (controller != null) {
+            controller.setPath(base);
+            if (controller instanceof CgroupV1MemorySubSystemController) {
+                CgroupV1MemorySubSystemController memorySubSystem = (CgroupV1MemorySubSystemController)controller;
                 boolean isHierarchial = getHierarchical(memorySubSystem);
                 memorySubSystem.setHierarchical(isHierarchial);
             }
-            metric.setActiveSubSystems();
+            subsystem.setActiveSubSystems();
         }
-        if (subsystem2 != null) {
-            subsystem2.setPath(base);
+        if (controller2 != null) {
+            controller2.setPath(base);
         }
     }
 
 
-    private static boolean getHierarchical(MemorySubSystem subsystem) {
-        long hierarchical = SubSystem.getLongValue(subsystem, "memory.use_hierarchy");
+    private static boolean getHierarchical(CgroupV1MemorySubSystemController controller) {
+        long hierarchical = getLongValue(controller, "memory.use_hierarchy");
         return hierarchical > 0;
     }
 
@@ -244,46 +221,54 @@ public class Metrics implements jdk.internal.platform.Metrics {
         return activeSubSystems;
     }
 
-    private void setMemorySubSystem(MemorySubSystem memory) {
+    private void setMemorySubSystem(CgroupV1MemorySubSystemController memory) {
         this.memory = memory;
     }
 
-    private void setCpuSubSystem(SubSystem cpu) {
+    private void setCpuController(CgroupV1SubsystemController cpu) {
         this.cpu = cpu;
     }
 
-    private void setCpuAcctSubSystem(SubSystem cpuacct) {
+    private void setCpuAcctController(CgroupV1SubsystemController cpuacct) {
         this.cpuacct = cpuacct;
     }
 
-    private void setCpuSetSubSystem(SubSystem cpuset) {
+    private void setCpuSetController(CgroupV1SubsystemController cpuset) {
         this.cpuset = cpuset;
     }
 
-    private void setBlkIOSubSystem(SubSystem blkio) {
+    private void setBlkIOController(CgroupV1SubsystemController blkio) {
         this.blkio = blkio;
     }
 
-    private SubSystem MemorySubSystem() {
+    private CgroupV1SubsystemController memoryController() {
         return memory;
     }
 
-    private SubSystem CpuSubSystem() {
+    private CgroupV1SubsystemController cpuController() {
         return cpu;
     }
 
-    private SubSystem CpuAcctSubSystem() {
+    private CgroupV1SubsystemController cpuAcctController() {
         return cpuacct;
     }
 
-    private SubSystem CpuSetSubSystem() {
+    private CgroupV1SubsystemController cpuSetController() {
         return cpuset;
     }
 
-    private SubSystem BlkIOSubSystem() {
+    private CgroupV1SubsystemController blkIOController() {
         return blkio;
     }
 
+    private static long getLongValue(CgroupSubsystemController controller,
+                              String parm) {
+        return CgroupSubsystemController.getLongValue(controller,
+                                                      parm,
+                                                      CgroupV1SubsystemController::convertStringToLong,
+                                                      CgroupSubsystem.LONG_RETVAL_UNLIMITED);
+    }
+
     public String getProvider() {
         return PROVIDER_NAME;
     }
@@ -294,13 +279,13 @@ public class Metrics implements jdk.internal.platform.Metrics {
 
 
     public long getCpuUsage() {
-        return SubSystem.getLongValue(cpuacct, "cpuacct.usage");
+        return getLongValue(cpuacct, "cpuacct.usage");
     }
 
     public long[] getPerCpuUsage() {
-        String usagelist = SubSystem.getStringValue(cpuacct, "cpuacct.usage_percpu");
+        String usagelist = CgroupSubsystemController.getStringValue(cpuacct, "cpuacct.usage_percpu");
         if (usagelist == null) {
-            return new long[0];
+            return null;
         }
 
         String list[] = usagelist.split(" ");
@@ -312,11 +297,11 @@ public class Metrics implements jdk.internal.platform.Metrics {
     }
 
     public long getCpuUserUsage() {
-        return SubSystem.getLongEntry(cpuacct, "cpuacct.stat", "user");
+        return CgroupV1SubsystemController.getLongEntry(cpuacct, "cpuacct.stat", "user");
     }
 
     public long getCpuSystemUsage() {
-        return SubSystem.getLongEntry(cpuacct, "cpuacct.stat", "system");
+        return CgroupV1SubsystemController.getLongEntry(cpuacct, "cpuacct.stat", "system");
     }
 
 
@@ -326,31 +311,31 @@ public class Metrics implements jdk.internal.platform.Metrics {
 
 
     public long getCpuPeriod() {
-        return SubSystem.getLongValue(cpu, "cpu.cfs_period_us");
+        return getLongValue(cpu, "cpu.cfs_period_us");
     }
 
     public long getCpuQuota() {
-        return SubSystem.getLongValue(cpu, "cpu.cfs_quota_us");
+        return getLongValue(cpu, "cpu.cfs_quota_us");
     }
 
     public long getCpuShares() {
-        long retval = SubSystem.getLongValue(cpu, "cpu.shares");
+        long retval = getLongValue(cpu, "cpu.shares");
         if (retval == 0 || retval == 1024)
-            return -1;
+            return CgroupSubsystem.LONG_RETVAL_UNLIMITED;
         else
             return retval;
     }
 
     public long getCpuNumPeriods() {
-        return SubSystem.getLongEntry(cpu, "cpu.stat", "nr_periods");
+        return CgroupV1SubsystemController.getLongEntry(cpu, "cpu.stat", "nr_periods");
     }
 
     public long getCpuNumThrottled() {
-        return SubSystem.getLongEntry(cpu, "cpu.stat", "nr_throttled");
+        return CgroupV1SubsystemController.getLongEntry(cpu, "cpu.stat", "nr_throttled");
     }
 
     public long getCpuThrottledTime() {
-        return SubSystem.getLongEntry(cpu, "cpu.stat", "throttled_time");
+        return CgroupV1SubsystemController.getLongEntry(cpu, "cpu.stat", "throttled_time");
     }
 
     public long getEffectiveCpuCount() {
@@ -363,27 +348,27 @@ public class Metrics implements jdk.internal.platform.Metrics {
      ****************************************************************/
 
     public int[] getCpuSetCpus() {
-        return SubSystem.StringRangeToIntArray(SubSystem.getStringValue(cpuset, "cpuset.cpus"));
+        return CgroupSubsystemController.stringRangeToIntArray(CgroupSubsystemController.getStringValue(cpuset, "cpuset.cpus"));
     }
 
     public int[] getEffectiveCpuSetCpus() {
-        return SubSystem.StringRangeToIntArray(SubSystem.getStringValue(cpuset, "cpuset.effective_cpus"));
+        return CgroupSubsystemController.stringRangeToIntArray(CgroupSubsystemController.getStringValue(cpuset, "cpuset.effective_cpus"));
     }
 
     public int[] getCpuSetMems() {
-        return SubSystem.StringRangeToIntArray(SubSystem.getStringValue(cpuset, "cpuset.mems"));
+        return CgroupSubsystemController.stringRangeToIntArray(CgroupSubsystemController.getStringValue(cpuset, "cpuset.mems"));
     }
 
     public int[] getEffectiveCpuSetMems() {
-        return SubSystem.StringRangeToIntArray(SubSystem.getStringValue(cpuset, "cpuset.effective_mems"));
+        return CgroupSubsystemController.stringRangeToIntArray(CgroupSubsystemController.getStringValue(cpuset, "cpuset.effective_mems"));
     }
 
     public double getCpuSetMemoryPressure() {
-        return SubSystem.getDoubleValue(cpuset, "cpuset.memory_pressure");
+        return CgroupV1SubsystemController.getDoubleValue(cpuset, "cpuset.memory_pressure");
     }
 
-    public boolean isCpuSetMemoryPressureEnabled() {
-        long val = SubSystem.getLongValue(cpuset, "cpuset.memory_pressure_enabled");
+    public Boolean isCpuSetMemoryPressureEnabled() {
+        long val = getLongValue(cpuset, "cpuset.memory_pressure_enabled");
         return (val == 1);
     }
 
@@ -394,112 +379,98 @@ public class Metrics implements jdk.internal.platform.Metrics {
 
 
     public long getMemoryFailCount() {
-        return SubSystem.getLongValue(memory, "memory.failcnt");
+        return getLongValue(memory, "memory.failcnt");
     }
 
     public long getMemoryLimit() {
-        long retval = SubSystem.getLongValue(memory, "memory.limit_in_bytes");
-        if (retval > unlimited_minimum) {
+        long retval = getLongValue(memory, "memory.limit_in_bytes");
+        if (retval > CgroupV1SubsystemController.UNLIMITED_MIN) {
             if (memory.isHierarchical()) {
                 // memory.limit_in_bytes returned unlimited, attempt
                 // hierarchical memory limit
                 String match = "hierarchical_memory_limit";
-                retval = SubSystem.getLongValueMatchingLine(memory,
+                retval = CgroupV1SubsystemController.getLongValueMatchingLine(memory,
                                                             "memory.stat",
-                                                            match,
-                                                            Metrics::convertHierachicalLimitLine);
+                                                            match);
             }
         }
-        return retval > unlimited_minimum ? -1L : retval;
-    }
-
-    public static long convertHierachicalLimitLine(String line) {
-        String[] tokens = line.split("\\s");
-        if (tokens.length == 2) {
-            String strVal = tokens[1];
-            return SubSystem.convertStringToLong(strVal);
-        }
-        return unlimited_minimum + 1; // unlimited
+        return CgroupV1SubsystemController.longValOrUnlimited(retval);
     }
 
     public long getMemoryMaxUsage() {
-        return SubSystem.getLongValue(memory, "memory.max_usage_in_bytes");
+        return getLongValue(memory, "memory.max_usage_in_bytes");
     }
 
     public long getMemoryUsage() {
-        return SubSystem.getLongValue(memory, "memory.usage_in_bytes");
+        return getLongValue(memory, "memory.usage_in_bytes");
     }
 
     public long getKernelMemoryFailCount() {
-        return SubSystem.getLongValue(memory, "memory.kmem.failcnt");
+        return getLongValue(memory, "memory.kmem.failcnt");
     }
 
     public long getKernelMemoryLimit() {
-        long retval = SubSystem.getLongValue(memory, "memory.kmem.limit_in_bytes");
-        return retval > unlimited_minimum ? -1L : retval;
+        return CgroupV1SubsystemController.longValOrUnlimited(getLongValue(memory, "memory.kmem.limit_in_bytes"));
     }
 
     public long getKernelMemoryMaxUsage() {
-        return SubSystem.getLongValue(memory, "memory.kmem.max_usage_in_bytes");
+        return getLongValue(memory, "memory.kmem.max_usage_in_bytes");
     }
 
     public long getKernelMemoryUsage() {
-        return SubSystem.getLongValue(memory, "memory.kmem.usage_in_bytes");
+        return getLongValue(memory, "memory.kmem.usage_in_bytes");
     }
 
     public long getTcpMemoryFailCount() {
-        return SubSystem.getLongValue(memory, "memory.kmem.tcp.failcnt");
+        return getLongValue(memory, "memory.kmem.tcp.failcnt");
     }
 
     public long getTcpMemoryLimit() {
-        long retval =  SubSystem.getLongValue(memory, "memory.kmem.tcp.limit_in_bytes");
-        return retval > unlimited_minimum ? -1L : retval;
+        return CgroupV1SubsystemController.longValOrUnlimited(getLongValue(memory, "memory.kmem.tcp.limit_in_bytes"));
     }
 
     public long getTcpMemoryMaxUsage() {
-        return SubSystem.getLongValue(memory, "memory.kmem.tcp.max_usage_in_bytes");
+        return getLongValue(memory, "memory.kmem.tcp.max_usage_in_bytes");
     }
 
     public long getTcpMemoryUsage() {
-        return SubSystem.getLongValue(memory, "memory.kmem.tcp.usage_in_bytes");
+        return getLongValue(memory, "memory.kmem.tcp.usage_in_bytes");
     }
 
     public long getMemoryAndSwapFailCount() {
-        return SubSystem.getLongValue(memory, "memory.memsw.failcnt");
+        return getLongValue(memory, "memory.memsw.failcnt");
     }
 
     public long getMemoryAndSwapLimit() {
-        long retval = SubSystem.getLongValue(memory, "memory.memsw.limit_in_bytes");
-        if (retval > unlimited_minimum) {
+        long retval = getLongValue(memory, "memory.memsw.limit_in_bytes");
+        if (retval > CgroupV1SubsystemController.UNLIMITED_MIN) {
             if (memory.isHierarchical()) {
                 // memory.memsw.limit_in_bytes returned unlimited, attempt
                 // hierarchical memory limit
                 String match = "hierarchical_memsw_limit";
-                retval = SubSystem.getLongValueMatchingLine(memory,
+                retval = CgroupV1SubsystemController.getLongValueMatchingLine(memory,
                                                             "memory.stat",
-                                                            match,
-                                                            Metrics::convertHierachicalLimitLine);
+                                                            match);
             }
         }
-        return retval > unlimited_minimum ? -1L : retval;
+        return CgroupV1SubsystemController.longValOrUnlimited(retval);
     }
 
     public long getMemoryAndSwapMaxUsage() {
-        return SubSystem.getLongValue(memory, "memory.memsw.max_usage_in_bytes");
+        return getLongValue(memory, "memory.memsw.max_usage_in_bytes");
     }
 
     public long getMemoryAndSwapUsage() {
-        return SubSystem.getLongValue(memory, "memory.memsw.usage_in_bytes");
+        return getLongValue(memory, "memory.memsw.usage_in_bytes");
     }
 
-    public boolean isMemoryOOMKillEnabled() {
-        long val = SubSystem.getLongEntry(memory, "memory.oom_control", "oom_kill_disable");
+    public Boolean isMemoryOOMKillEnabled() {
+        long val = CgroupV1SubsystemController.getLongEntry(memory, "memory.oom_control", "oom_kill_disable");
         return (val == 0);
     }
 
     public long getMemorySoftLimit() {
-        long retval = SubSystem.getLongValue(memory, "memory.soft_limit_in_bytes");
-        return retval > unlimited_minimum ? -1L : retval;
+        return CgroupV1SubsystemController.longValOrUnlimited(getLongValue(memory, "memory.soft_limit_in_bytes"));
     }
 
 
@@ -509,11 +480,11 @@ public class Metrics implements jdk.internal.platform.Metrics {
 
 
     public long getBlkIOServiceCount() {
-        return SubSystem.getLongEntry(blkio, "blkio.throttle.io_service_bytes", "Total");
+        return CgroupV1SubsystemController.getLongEntry(blkio, "blkio.throttle.io_service_bytes", "Total");
     }
 
     public long getBlkIOServiced() {
-        return SubSystem.getLongEntry(blkio, "blkio.throttle.io_serviced", "Total");
+        return CgroupV1SubsystemController.getLongEntry(blkio, "blkio.throttle.io_serviced", "Total");
     }
 
 }

src/java.base/linux/classes/jdk/internal/platform/cgroupv1/CgroupV1SubsystemController.java

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2018, 2020, 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform.cgroupv1;
+
+import jdk.internal.platform.CgroupSubsystem;
+import jdk.internal.platform.CgroupSubsystemController;
+
+public class CgroupV1SubsystemController implements CgroupSubsystemController {
+
+    private static final double DOUBLE_RETVAL_UNLIMITED = CgroupSubsystem.LONG_RETVAL_UNLIMITED;
+    // Values returned larger than this number are unlimited.
+    static long UNLIMITED_MIN = 0x7FFFFFFFFF000000L;
+    String root;
+    String mountPoint;
+    String path;
+
+    public CgroupV1SubsystemController(String root, String mountPoint) {
+        this.root = root;
+        this.mountPoint = mountPoint;
+    }
+
+    public void setPath(String cgroupPath) {
+        if (root != null && cgroupPath != null) {
+            if (root.equals("/")) {
+                if (!cgroupPath.equals("/")) {
+                    path = mountPoint + cgroupPath;
+                }
+                else {
+                    path = mountPoint;
+                }
+            }
+            else {
+                if (root.equals(cgroupPath)) {
+                    path = mountPoint;
+                }
+                else {
+                    if (cgroupPath.startsWith(root)) {
+                        if (cgroupPath.length() > root.length()) {
+                            String cgroupSubstr = cgroupPath.substring(root.length());
+                            path = mountPoint + cgroupSubstr;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    @Override
+    public String path() {
+        return path;
+    }
+
+    public static long getLongEntry(CgroupSubsystemController controller, String param, String entryname) {
+        return CgroupSubsystemController.getLongEntry(controller,
+                                                      param,
+                                                      entryname,
+                                                      CgroupSubsystem.LONG_RETVAL_UNLIMITED /* retval on error */);
+    }
+
+    public static double getDoubleValue(CgroupSubsystemController controller, String parm) {
+        return CgroupSubsystemController.getDoubleValue(controller,
+                                                        parm,
+                                                        DOUBLE_RETVAL_UNLIMITED /* retval on error */);
+    }
+
+    public static long convertStringToLong(String strval) {
+        return CgroupSubsystemController.convertStringToLong(strval,
+                                                             Long.MAX_VALUE /* overflow value */,
+                                                             CgroupSubsystem.LONG_RETVAL_UNLIMITED /* retval on error */);
+    }
+
+    public static long longValOrUnlimited(long value) {
+        return value > UNLIMITED_MIN ? CgroupSubsystem.LONG_RETVAL_UNLIMITED : value;
+    }
+
+    public static long getLongValueMatchingLine(CgroupSubsystemController controller,
+                                                String param,
+                                                String match) {
+        return CgroupSubsystemController.getLongValueMatchingLine(controller,
+                                                                  param,
+                                                                  match,
+                                                                  CgroupV1SubsystemController::convertHierachicalLimitLine,
+                                                                  CgroupSubsystem.LONG_RETVAL_UNLIMITED);
+    }
+
+    public static long convertHierachicalLimitLine(String line) {
+        String[] tokens = line.split("\\s");
+        if (tokens.length == 2) {
+            String strVal = tokens[1];
+            return CgroupV1SubsystemController.convertStringToLong(strVal);
+        }
+        return CgroupV1SubsystemController.UNLIMITED_MIN + 1; // unlimited
+    }
+
+}

src/java.base/linux/classes/jdk/internal/platform/cgroupv1/SubSystem.java

@@ -1,283 +0,0 @@
-/*
- * Copyright (c) 2018, 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
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-package jdk.internal.platform.cgroupv1;
-
-import java.io.BufferedReader;
-import java.io.IOException;
-import java.math.BigInteger;
-import java.nio.file.Files;
-import java.nio.file.Paths;
-import java.security.AccessController;
-import java.security.PrivilegedActionException;
-import java.security.PrivilegedExceptionAction;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Optional;
-import java.util.function.Function;
-import java.util.stream.Stream;
-
-public class SubSystem {
-    String root;
-    String mountPoint;
-    String path;
-
-    public SubSystem(String root, String mountPoint) {
-        this.root = root;
-        this.mountPoint = mountPoint;
-    }
-
-    public void setPath(String cgroupPath) {
-        if (root != null && cgroupPath != null) {
-            if (root.equals("/")) {
-                if (!cgroupPath.equals("/")) {
-                    path = mountPoint + cgroupPath;
-                }
-                else {
-                    path = mountPoint;
-                }
-            }
-            else {
-                if (root.equals(cgroupPath)) {
-                    path = mountPoint;
-                }
-                else {
-                    if (cgroupPath.startsWith(root)) {
-                        if (cgroupPath.length() > root.length()) {
-                            String cgroupSubstr = cgroupPath.substring(root.length());
-                            path = mountPoint + cgroupSubstr;
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-    public String path() {
-        return path;
-    }
-
-    /**
-     * getSubSystemStringValue
-     *
-     * Return the first line of the file "parm" argument from the subsystem.
-     *
-     * TODO:  Consider using weak references for caching BufferedReader object.
-     *
-     * @param subsystem
-     * @param parm
-     * @return Returns the contents of the file specified by param.
-     */
-    public static String getStringValue(SubSystem subsystem, String parm) {
-        if (subsystem == null) return null;
-
-        try {
-            return subsystem.readStringValue(parm);
-        } catch (IOException e) {
-            return null;
-        }
-    }
-
-    private String readStringValue(String param) throws IOException {
-        PrivilegedExceptionAction<BufferedReader> pea = () ->
-                Files.newBufferedReader(Paths.get(path(), param));
-        try (BufferedReader bufferedReader =
-                     AccessController.doPrivileged(pea)) {
-            String line = bufferedReader.readLine();
-            return line;
-        } catch (PrivilegedActionException e) {
-            Metrics.unwrapIOExceptionAndRethrow(e);
-            throw new InternalError(e.getCause());
-        }
-    }
-
-    public static long getLongValueMatchingLine(SubSystem subsystem,
-                                                     String param,
-                                                     String match,
-                                                     Function<String, Long> conversion) {
-        long retval = Metrics.unlimited_minimum + 1; // default unlimited
-        try {
-            List<String> lines = subsystem.readMatchingLines(param);
-            for (String line : lines) {
-                if (line.startsWith(match)) {
-                    retval = conversion.apply(line);
-                    break;
-                }
-            }
-        } catch (IOException e) {
-            // Ignore. Default is unlimited.
-        }
-        return retval;
-    }
-
-    private List<String> readMatchingLines(String param) throws IOException {
-        try {
-            PrivilegedExceptionAction<List<String>> pea = () ->
-                    Files.readAllLines(Paths.get(path(), param));
-            return AccessController.doPrivileged(pea);
-        } catch (PrivilegedActionException e) {
-            Metrics.unwrapIOExceptionAndRethrow(e);
-            throw new InternalError(e.getCause());
-        }
-    }
-
-    public static long getLongValue(SubSystem subsystem, String parm) {
-        String strval = getStringValue(subsystem, parm);
-        return convertStringToLong(strval);
-    }
-
-    public static long convertStringToLong(String strval) {
-        long retval = 0;
-        if (strval == null) return 0L;
-
-        try {
-            retval = Long.parseLong(strval);
-        } catch (NumberFormatException e) {
-            // For some properties (e.g. memory.limit_in_bytes) we may overflow the range of signed long.
-            // In this case, return Long.MAX_VALUE
-            BigInteger b = new BigInteger(strval);
-            if (b.compareTo(BigInteger.valueOf(Long.MAX_VALUE)) > 0) {
-                return Long.MAX_VALUE;
-            }
-        }
-        return retval;
-    }
-
-    public static double getDoubleValue(SubSystem subsystem, String parm) {
-        String strval = getStringValue(subsystem, parm);
-
-        if (strval == null) return 0L;
-
-        double retval = Double.parseDouble(strval);
-
-        return retval;
-    }
-
-    /**
-     * getSubSystemlongEntry
-     *
-     * Return the long value from the line containing the string "entryname"
-     * within file "parm" in the "subsystem".
-     *
-     * TODO:  Consider using weak references for caching BufferedReader object.
-     *
-     * @param subsystem
-     * @param parm
-     * @param entryname
-     * @return long value
-     */
-    public static long getLongEntry(SubSystem subsystem, String parm, String entryname) {
-        String val = null;
-
-        if (subsystem == null) return 0L;
-
-        try (Stream<String> lines = Metrics.readFilePrivileged(Paths.get(subsystem.path(), parm))) {
-
-            Optional<String> result = lines.map(line -> line.split(" "))
-                                           .filter(line -> (line.length == 2 &&
-                                                   line[0].equals(entryname)))
-                                           .map(line -> line[1])
-                                           .findFirst();
-
-            return result.isPresent() ? Long.parseLong(result.get()) : 0L;
-        }
-        catch (IOException e) {
-            return 0L;
-        }
-    }
-
-    public static int getIntValue(SubSystem subsystem, String parm) {
-        String val = getStringValue(subsystem, parm);
-
-        if (val == null) return 0;
-
-        return Integer.parseInt(val);
-    }
-
-    /**
-     * StringRangeToIntArray
-     *
-     * Convert a string in the form of  1,3-4,6 to an array of
-     * integers containing all the numbers in the range.
-     *
-     * @param range
-     * @return int[] containing a sorted list of processors or memory nodes
-     */
-    public static int[] StringRangeToIntArray(String range) {
-        int[] ints = new int[0];
-
-        if (range == null) return ints;
-
-        ArrayList<Integer> results = new ArrayList<>();
-        String strs[] = range.split(",");
-        for (String str : strs) {
-            if (str.contains("-")) {
-                String lohi[] = str.split("-");
-                // validate format
-                if (lohi.length != 2) {
-                    continue;
-                }
-                int lo = Integer.parseInt(lohi[0]);
-                int hi = Integer.parseInt(lohi[1]);
-                for (int i = lo; i <= hi; i++) {
-                    results.add(i);
-                }
-            }
-            else {
-                results.add(Integer.parseInt(str));
-            }
-        }
-
-        // sort results
-        results.sort(null);
-
-        // convert ArrayList to primitive int array
-        ints = new int[results.size()];
-        int i = 0;
-        for (Integer n : results) {
-            ints[i++] = n;
-        }
-
-        return ints;
-    }
-
-    public static class MemorySubSystem extends SubSystem {
-
-        private boolean hierarchical;
-
-        public MemorySubSystem(String root, String mountPoint) {
-            super(root, mountPoint);
-        }
-
-        boolean isHierarchical() {
-            return hierarchical;
-        }
-
-        void setHierarchical(boolean hierarchical) {
-            this.hierarchical = hierarchical;
-        }
-
-    }
-}

src/java.base/linux/classes/jdk/internal/platform/cgroupv2/CgroupV2Subsystem.java

@@ -0,0 +1,363 @@
+/*
+ * 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
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform.cgroupv2;
+
+import java.io.IOException;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import jdk.internal.platform.CgroupSubsystem;
+import jdk.internal.platform.CgroupSubsystemController;
+import jdk.internal.platform.CgroupUtil;
+
+public class CgroupV2Subsystem implements CgroupSubsystem {
+
+    private static final CgroupV2Subsystem INSTANCE = initSubsystem();
+    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 CgroupV2Subsystem(CgroupSubsystemController unified) {
+        this.unified = unified;
+    }
+
+    private long getLongVal(String file) {
+        return CgroupSubsystemController.getLongValue(unified,
+                                                      file,
+                                                      CgroupV2SubsystemController::convertStringToLong,
+                                                      CgroupSubsystem.LONG_RETVAL_UNLIMITED);
+    }
+
+    private static CgroupV2Subsystem initSubsystem() {
+        // read mountinfo so as to determine root mount path
+        String mountPath = null;
+        try (Stream<String> lines =
+                CgroupUtil.readFilePrivileged(Paths.get("/proc/self/mountinfo"))) {
+
+            String l = lines.filter(line -> line.contains(" - cgroup2 "))
+                            .collect(Collectors.joining());
+            String[] tokens = l.split(" ");
+            mountPath = tokens[4];
+        } catch (IOException e) {
+            return null;
+        }
+        String cgroupPath = null;
+        try {
+            List<String> lines = CgroupUtil.readAllLinesPrivileged(Paths.get("/proc/self/cgroup"));
+            for (String line: lines) {
+                String[] tokens = line.split(":");
+                if (tokens.length != 3) {
+                    return null; // something is not right.
+                }
+                if (!"0".equals(tokens[0])) {
+                    // hierarchy must be zero for cgroups v2
+                    return null;
+                }
+                cgroupPath = tokens[2];
+                break;
+            }
+        } catch (IOException e) {
+            return null;
+        }
+        CgroupSubsystemController unified = new CgroupV2SubsystemController(
+                mountPath,
+                cgroupPath);
+        return new CgroupV2Subsystem(unified);
+    }
+
+    public static CgroupSubsystem getInstance() {
+        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");
+    }
+
+    @Override
+    public long getMemoryAndSwapLimit() {
+        String strVal = CgroupSubsystemController.getStringValue(unified, "memory.swap.max");
+        return limitFromString(strVal);
+    }
+
+    @Override
+    public long getMemoryAndSwapUsage() {
+        return getLongVal("memory.swap.current");
+    }
+
+    @Override
+    public long getMemorySoftLimit() {
+        String softLimitStr = CgroupSubsystemController.getStringValue(unified, "memory.high");
+        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 (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;
+    }
+}

src/java.base/linux/classes/jdk/internal/platform/cgroupv2/CgroupV2SubsystemController.java

@@ -0,0 +1,58 @@
+/*
+ * 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
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.platform.cgroupv2;
+
+import java.nio.file.Paths;
+
+import jdk.internal.platform.CgroupSubsystem;
+import jdk.internal.platform.CgroupSubsystemController;
+
+public class CgroupV2SubsystemController implements CgroupSubsystemController {
+
+    private final String path;
+
+    public CgroupV2SubsystemController(String mountPath, String cgroupPath) {
+        this.path = Paths.get(mountPath, cgroupPath).toString();
+    }
+
+    @Override
+    public String path() {
+        return path;
+    }
+
+    public static long convertStringToLong(String strval) {
+        return CgroupSubsystemController.convertStringToLong(strval,
+                                                             CgroupSubsystem.LONG_RETVAL_UNLIMITED /* overflow retval */,
+                                                             CgroupSubsystem.LONG_RETVAL_UNLIMITED /* default retval on error */);
+    }
+
+    public static long getLongEntry(CgroupSubsystemController controller, String param, String entryname) {
+        return CgroupSubsystemController.getLongEntry(controller,
+                                                      param,
+                                                      entryname,
+                                                      CgroupSubsystem.LONG_RETVAL_UNLIMITED /* retval on error */);
+    }
+}