[java] Support resources management in raylet mode. (#2606)

java/common/src/main/java/org/ray/util/ResourceItem.java

@@ -0,0 +1,7 @@
+package org.ray.util;
+
+public @interface ResourceItem {
+  public String name() default "";
+  public double value() default 0;
+
+}

java/common/src/main/java/org/ray/util/ResourceUtil.java

@@ -0,0 +1,102 @@
+package org.ray.util;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class ResourceUtil {
+  public static final String CPU_LITERAL = "CPU";
+  public static final String GPU_LITERAL = "GPU";
+
+  /**
+   * Convert the array that contains resource items to a map.
+   *
+   * @param resourceArray The resources list to be converted.
+   * @return The map whose key represents the resource name
+   *     and the value represents the resource quantity.
+   */
+  public static Map<String, Double> getResourcesMapFromArray(ResourceItem[] resourceArray) {
+    Map<String, Double> resourceMap = new HashMap<>();
+    if (resourceArray != null) {
+      for (ResourceItem item : resourceArray) {
+        if (!item.name().isEmpty()) {
+          resourceMap.put(item.name(), item.value());
+        }
+      }
+    }
+
+    return resourceMap;
+  }
+
+  /**
+   * Convert the resources map to a format string.
+   *
+   * @param resources The resource map to be Converted.
+   * @return The format resources string, like "{CPU:4, GPU:0}".
+   */
+  public static String getResourcesFromatStringFromMap(Map<String, Double> resources) {
+    StringBuilder builder = new StringBuilder();
+    builder.append("{");
+    int count = 1;
+    for (Map.Entry<String, Double> entry : resources.entrySet()) {
+      builder.append(entry.getKey()).append(":").append(entry.getValue());
+      count++;
+      if (count != resources.size()) {
+        builder.append(", ");
+      }
+    }
+    builder.append("}");
+    return builder.toString();
+  }
+
+  /**
+   * Convert resources map to a string that is used
+   * for the command line argument of starting raylet.
+   *
+   * @param resources The resources map to be converted.
+   * @return The starting-raylet command line argument, like "CPU,4,GPU,0".
+   */
+  public static String getResourcesStringFromMap(Map<String, Double> resources) {
+    StringBuilder builder = new StringBuilder();
+    if (resources != null) {
+      int count = 1;
+      for (Map.Entry<String, Double> entry : resources.entrySet()) {
+        builder.append(entry.getKey()).append(",").append(entry.getValue());
+        if (count != resources.size()) {
+          builder.append(",");
+        }
+        count++;
+      }
+    }
+    return builder.toString();
+  }
+
+  /**
+   * Parse the static resources configure field and convert to the resources map.
+   *
+   * @param resources The static resources string to be parsed.
+   * @return The map whose key represents the resource name
+   *     and the value represents the resource quantity.
+   * @throws IllegalArgumentException If the resources string's format does match,
+   *     it will throw an IllegalArgumentException.
+   */
+  public static Map<String, Double> getResourcesMapFromString(String resources)
+      throws IllegalArgumentException {
+    Map<String, Double> ret = new HashMap<>();
+    if (resources != null) {
+      String[] items = resources.split(",");
+      for (String item : items) {
+        String trimItem = item.trim();
+        String[] resourcePair = trimItem.split(":");
+
+        if (resourcePair.length != 2) {
+          throw new IllegalArgumentException("Format of static resurces configure is invalid.");
+        }
+
+        final String resourceName = resourcePair[0].trim();
+        final Double resourceValue = Double.valueOf(resourcePair[1].trim());
+        ret.put(resourceName, resourceValue);
+      }
+    }
+    return ret;
+  }
+}