HDFS-9091. Erasure Coding: Provide DistributedFilesystem API to getAllErasureCodingPolicies. Contributed by Rakesh R.

Change-Id: Id30a1ce9e2ce676d00a9220a2d3f14b8d9f00527

hadoop-hdfs-project/hadoop-hdfs/CHANGES-HDFS-EC-7285.txt

@@ -441,3 +441,6 @@
 
     HDFS-9113. ErasureCodingWorker#processErasureCodingTasks should not fail to process
     remaining tasks due to one invalid ECTask (umamahesh)
+
+    HDFS-9091. Erasure Coding: Provide DistributedFilesystem API to 
+    getAllErasureCodingPolicies. (Rakesh R via zhz)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DistributedFileSystem.java

@@ -2324,4 +2324,15 @@ public class DistributedFileSystem extends FileSystem {
       }
     }.resolve(this, absF);
   }
+
+  /**
+   * Retrieve all the erasure coding policies supported by this file system.
+   *
+   * @return all erasure coding policies supported by this file system.
+   * @throws IOException
+   */
+  public Collection<ErasureCodingPolicy> getAllErasureCodingPolicies()
+      throws IOException {
+    return Arrays.asList(dfs.getErasureCodingPolicies());
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestErasureCodingPolicies.java

@@ -32,6 +32,7 @@ import org.junit.Before;
 import org.junit.Test;
 
 import java.io.IOException;
+import java.util.Collection;
 
 import static org.apache.hadoop.test.GenericTestUtils.assertExceptionContains;
 import static org.junit.Assert.*;
@@ -231,4 +232,18 @@ public class TestErasureCodingPolicies {
     }
   }
 
+  @Test
+  public void testGetAllErasureCodingPolicies() throws Exception {
+    ErasureCodingPolicy[] sysECPolicies = ErasureCodingPolicyManager
+        .getSystemPolices();
+    assertTrue("System ecPolicies should be of only 1 for now",
+        sysECPolicies.length == 1);
+
+    Collection<ErasureCodingPolicy> allECPolicies = fs
+        .getAllErasureCodingPolicies();
+    assertTrue("All ecPolicies should be of only 1 for now",
+        allECPolicies.size() == 1);
+    assertEquals("Erasure coding policy mismatches",
+        sysECPolicies[0], allECPolicies.iterator().next());
+  }
 }