[flink] 06/10: [hotfix][core] Minor cleanups to the ResourceSpec class

[sewen]

This is an automated email from the ASF dual-hosted git repository.

sewen pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/flink.git

commit 5654e0f4750cd9fbe7cba2bdebd16ea3cb4011d6
Author: Stephan Ewen <se...@apache.org>
AuthorDate: Thu Jul 11 17:40:41 2019 +0200

    [hotfix][core] Minor cleanups to the ResourceSpec class
    
      - Some JavaDoc comments
      - Make the class final, because several methods are not designed to 
handle inheritence well.
      - Avoid repeated string concatenation/building
---
 .../apache/flink/api/common/operators/ResourceSpec.java   | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git 
a/flink-core/src/main/java/org/apache/flink/api/common/operators/ResourceSpec.java
 
b/flink-core/src/main/java/org/apache/flink/api/common/operators/ResourceSpec.java
index dc6a611..2d56746 100755
--- 
a/flink-core/src/main/java/org/apache/flink/api/common/operators/ResourceSpec.java
+++ 
b/flink-core/src/main/java/org/apache/flink/api/common/operators/ResourceSpec.java
@@ -50,12 +50,19 @@ import static 
org.apache.flink.util.Preconditions.checkArgument;
  * </ol>
  */
 @Internal
-public class ResourceSpec implements Serializable {
+public final class ResourceSpec implements Serializable {
 
        private static final long serialVersionUID = 1L;
 
+       /**
+        * A ResourceSpec that indicates an unknown set of resources.
+        */
        public static final ResourceSpec UNKNOWN = new ResourceSpec();
 
+       /**
+        * The default ResourceSpec used for operators and transformation 
functions.
+        * Currently equal to {@link #UNKNOWN}.
+        */
        public static final ResourceSpec DEFAULT = UNKNOWN;
 
        public static final String GPU_NAME = "GPU";
@@ -91,7 +98,7 @@ public class ResourceSpec implements Serializable {
         * @param managedMemoryInMB The size of managed memory, in megabytes.
         * @param extendedResources The extended resources, associated with the 
resource manager used
         */
-       protected ResourceSpec(
+       private ResourceSpec(
                        double cpuCores,
                        int heapMemoryInMB,
                        int directMemoryInMB,
@@ -273,9 +280,9 @@ public class ResourceSpec implements Serializable {
 
        @Override
        public String toString() {
-               String extend = "";
+               StringBuilder extend = new StringBuilder();
                for (Resource resource : extendedResources.values()) {
-                       extend += ", " + resource.getName() + "=" + 
resource.getValue();
+                       extend.append(", 
").append(resource.getName()).append("=").append(resource.getValue());
                }
                return "ResourceSpec{" +
                                "cpuCores=" + cpuCores +