HADOOP-10111. Allow DU to be initialized with an initial value (Kihwal Lee via jeagles)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1544241 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -95,6 +95,9 @@ Release 2.3.0 - UNRELEASED
 
     HADOOP-10103. update commons-lang to 2.6 (Akira AJISAKA via stevel)
 
+    HADOOP-10111. Allow DU to be initialized with an initial value (Kihwal Lee
+    via jeagles)
+
   OPTIMIZATIONS
 
     HADOOP-9748. Reduce blocking on UGI.ensureInitialized (daryn)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/DU.java

@@ -47,17 +47,32 @@ public class DU extends Shell {
    * @throws IOException if we fail to refresh the disk usage
    */
   public DU(File path, long interval) throws IOException {
+    this(path, interval, -1L);
+  }
+  
+  /**
+   * Keeps track of disk usage.
+   * @param path the path to check disk usage in
+   * @param interval refresh the disk usage at this interval
+   * @param initialUsed use this value until next refresh
+   * @throws IOException if we fail to refresh the disk usage
+   */
+  public DU(File path, long interval, long initialUsed) throws IOException { 
     super(0);
-    
+
     //we set the Shell interval to 0 so it will always run our command
     //and use this one to set the thread sleep interval
     this.refreshInterval = interval;
     this.dirPath = path.getCanonicalPath();
-    
-    //populate the used variable
-    run();
+
+    //populate the used variable if the initial value is not specified.
+    if (initialUsed < 0) {
+      run();
+    } else {
+      this.used.set(initialUsed);
+    }
   }
-  
+
   /**
    * Keeps track of disk usage.
    * @param path the path to check disk usage in
@@ -65,9 +80,23 @@ public class DU extends Shell {
    * @throws IOException if we fail to refresh the disk usage
    */
   public DU(File path, Configuration conf) throws IOException {
+    this(path, conf, -1L);
+  }
+
+  /**
+   * Keeps track of disk usage.
+   * @param path the path to check disk usage in
+   * @param conf configuration object
+   * @param initialUsed use it until the next refresh.
+   * @throws IOException if we fail to refresh the disk usage
+   */
+  public DU(File path, Configuration conf, long initialUsed)
+      throws IOException {
     this(path, conf.getLong(CommonConfigurationKeys.FS_DU_INTERVAL_KEY,
-                CommonConfigurationKeys.FS_DU_INTERVAL_DEFAULT));
+                CommonConfigurationKeys.FS_DU_INTERVAL_DEFAULT), initialUsed);
   }
+    
+  
 
   /**
    * This thread refreshes the "used" variable.

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestDU.java

@@ -116,4 +116,19 @@ public class TestDU extends TestCase {
     long duSize = du.getUsed();
     assertTrue(String.valueOf(duSize), duSize >= 0L);
   }
+
+  public void testDUSetInitialValue() throws IOException {
+    File file = new File(DU_DIR, "dataX");
+    createFile(file, 8192);
+    DU du = new DU(file, 3000, 1024);
+    du.start();
+    assertTrue("Initial usage setting not honored", du.getUsed() == 1024);
+
+    // wait until the first du runs.
+    try {
+      Thread.sleep(5000);
+    } catch (InterruptedException ie) {}
+
+    assertTrue("Usage didn't get updated", du.getUsed() == 8192);
+  }
 }