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

@  rev 54202 : 8217338: [Containers] Improve systemd slice memory limit support
|  Summary: Use hierachical memory limit in addition to memory_limits_in_bytes
~  Reviewed-by: duke

@@ -27,14 +27,15 @@
 
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.math.BigInteger;
 import java.nio.file.Files;
-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;
 
 public class SubSystem {
     String root;
     String mountPoint;

@@ -97,14 +98,36 @@
             return null;
         }
 
     }
 
+    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 = Files.readAllLines(Paths.get(subsystem.path(), param));
+            for (String line: lines) {
+                if (line.contains(match)) {
+                    retval = conversion.apply(line);
+                    break;
+                }
+            }
+        } catch (IOException e) {
+            // Ignore. Default is unlimited.
+        }
+        return retval;
+    }
+
     public static long getLongValue(SubSystem subsystem, String parm) {
         String strval = getStringValue(subsystem, parm);
-        long retval = 0;
+        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) {

@@ -213,6 +236,24 @@
             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;
+        }
+
+    }
 }