feat: Linux Control Group version 2 API support cgroup v2 (aws-greeng…

…rass#1262)

src/main/java/com/aws/greengrass/util/platforms/unix/linux/CgroupV2.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.aws.greengrass.util.platforms.unix.linux;
+
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+/**
+ * Represents Linux cgroup v2.
+ */
+@SuppressFBWarnings(value = "DMI_HARDCODED_ABSOLUTE_FILENAME", justification = "Cgroup virtual filesystem path "
+        + "cannot be relative")
+public final class CgroupV2 {
+
+    private static final String CGROUP_ROOT = "/sys/fs/cgroup";
+    private static final String GG_NAMESPACE = "greengrass";
+    private static final String CPU_MAX = "cpu.max";
+    private static final String MEMORY_MAX = "memory.max";
+    private static final String CGROUP_PROCS = "cgroup.procs";
+    private static final String CGROUP_SUBTREE_CONTROL = "cgroup.subtree_control";
+    private static final String CGROUP_FREEZE = "cgroup.freeze";
+
+    private CgroupV2() {
+    }
+
+    public static Path getRootPath() {
+        return Paths.get(CGROUP_ROOT);
+    }
+
+    public static String rootMountCmd() {
+        return String.format("mount -t cgroup2 none %s", CGROUP_ROOT);
+    }
+
+    public static Path getSubsystemRootPath() {
+        return Paths.get(CGROUP_ROOT);
+    }
+
+    public static Path getRootSubTreeControlPath() {
+        return getSubsystemRootPath().resolve(CGROUP_SUBTREE_CONTROL);
+    }
+
+    public static Path getSubsystemGGPath() {
+        return getSubsystemRootPath().resolve(GG_NAMESPACE);
+    }
+
+    public static Path getGGSubTreeControlPath() {
+        return getSubsystemGGPath().resolve(CGROUP_SUBTREE_CONTROL);
+    }
+
+    public static Path getSubsystemComponentPath(String componentName) {
+        return getSubsystemGGPath().resolve(componentName);
+    }
+
+    public static Path getComponentCpuMaxPath(String componentName) {
+        return getSubsystemComponentPath(componentName).resolve(CPU_MAX);
+    }
+
+    public static Path getComponentMemoryMaxPath(String componentName) {
+        return getSubsystemComponentPath(componentName).resolve(MEMORY_MAX);
+    }
+
+    public static Path getCgroupProcsPath(String componentName) {
+        return getSubsystemComponentPath(componentName).resolve(CGROUP_PROCS);
+    }
+
+    public static Path getCgroupFreezePath(String componentName) {
+        return getSubsystemComponentPath(componentName).resolve(CGROUP_FREEZE);
+    }
+}

src/main/java/com/aws/greengrass/util/platforms/unix/linux/CgroupV2FreezerState.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.aws.greengrass.util.platforms.unix.linux;
+
+public enum CgroupV2FreezerState {
+    THAWED(0),
+    FROZEN(1);
+
+    private int index;
+
+    CgroupV2FreezerState(int index) {
+        this.index = index;
+    }
+
+    /**
+     * Get the index value associated with this CgroupV2FreezerState.
+     *
+     * @return the integer index value associated with this CgroupV2FreezerState.
+     */
+    public int getIndex() {
+        return index;
+    }
+}

src/main/java/com/aws/greengrass/util/platforms/unix/linux/LinuxPlatform.java

@@ -8,11 +8,29 @@
 import com.aws.greengrass.util.platforms.SystemResourceController;
 import com.aws.greengrass.util.platforms.unix.UnixPlatform;
 
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
 public class LinuxPlatform extends UnixPlatform {
-    SystemResourceController systemResourceController = new LinuxSystemResourceController(this);
+    private static final String CGROUP_ROOT = "/sys/fs/cgroup";
+    private static final String CGROUP_CONTROLLERS = "cgroup.controllers";
+
+    SystemResourceController systemResourceController;
 
     @Override
     public SystemResourceController getSystemResourceController() {
+        //if the path exists, identify it as cgroupv1, otherwise identify it as cgroupv2
+        if (Files.exists(getControllersRootPath())) {
+            systemResourceController = new LinuxSystemResourceControllerV2(this);
+        } else {
+            systemResourceController = new LinuxSystemResourceController(this);
+        }
+
         return systemResourceController;
     }
+
+    private Path getControllersRootPath() {
+        return Paths.get(CGROUP_ROOT).resolve(CGROUP_CONTROLLERS);
+    }
 }