HDFS-3408. BKJM : Namenode format fails, if there is no BK root. Contributed by Rakesh R.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1349456 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/main/java/org/apache/hadoop/contrib/bkjournal/BookKeeperJournalManager.java

@@ -28,6 +28,7 @@ import org.apache.bookkeeper.conf.ClientConfiguration;
 import org.apache.bookkeeper.client.BKException;
 import org.apache.bookkeeper.client.BookKeeper;
 import org.apache.bookkeeper.client.LedgerHandle;
+import org.apache.bookkeeper.util.ZkUtils;
 
 import org.apache.zookeeper.data.Stat;
 import org.apache.zookeeper.ZooKeeper;
@@ -36,6 +37,7 @@ import org.apache.zookeeper.WatchedEvent;
 import org.apache.zookeeper.KeeperException;
 import org.apache.zookeeper.CreateMode;
 import org.apache.zookeeper.ZooDefs.Ids;
+import org.apache.zookeeper.AsyncCallback.StringCallback;
 
 import java.util.Collection;
 import java.util.Collections;
@@ -124,6 +126,12 @@ public class BookKeeperJournalManager implements JournalManager {
 
   private static final String BKJM_EDIT_INPROGRESS = "inprogress_";
 
+  public static final String BKJM_ZK_LEDGERS_AVAILABLE_PATH
+    = "dfs.namenode.bookkeeperjournal.zk.availablebookies";
+
+  public static final String BKJM_ZK_LEDGERS_AVAILABLE_PATH_DEFAULT
+    = "/ledgers/available";
+
   private ZooKeeper zkc;
   private final Configuration conf;
   private final BookKeeper bkc;
@@ -196,7 +204,7 @@ public class BookKeeperJournalManager implements JournalManager {
         zkc.create(ledgerPath, new byte[] {'0'},
             Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
       }
-
+      prepareBookKeeperEnv();
       bkc = new BookKeeper(new ClientConfiguration(),
                            zkc);
     } catch (KeeperException e) {
@@ -210,6 +218,50 @@ public class BookKeeperJournalManager implements JournalManager {
     maxTxId = new MaxTxId(zkc, maxTxIdPath);
   }
 
+  /**
+   * Pre-creating bookkeeper metadata path in zookeeper.
+   */
+  private void prepareBookKeeperEnv() throws IOException {
+    // create bookie available path in zookeeper if it doesn't exists
+    final String zkAvailablePath = conf.get(BKJM_ZK_LEDGERS_AVAILABLE_PATH,
+        BKJM_ZK_LEDGERS_AVAILABLE_PATH_DEFAULT);
+    final CountDownLatch zkPathLatch = new CountDownLatch(1);
+
+    StringCallback callback = new StringCallback() {
+      @Override
+      public void processResult(int rc, String path, Object ctx, String name) {
+        if (KeeperException.Code.OK.intValue() == rc
+            || KeeperException.Code.NODEEXISTS.intValue() == rc) {
+          LOG.info("Successfully created bookie available path : "
+              + zkAvailablePath);
+          zkPathLatch.countDown();
+        } else {
+          KeeperException.Code code = KeeperException.Code.get(rc);
+          LOG
+              .error("Error : "
+                  + KeeperException.create(code, path).getMessage()
+                  + ", failed to create bookie available path : "
+                  + zkAvailablePath);
+        }
+      }
+    };
+    ZkUtils.createFullPathOptimistic(zkc, zkAvailablePath, new byte[0],
+        Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT, callback, null);
+
+    try {
+      if (!zkPathLatch.await(zkc.getSessionTimeout(), TimeUnit.MILLISECONDS)) {
+        throw new IOException("Couldn't create bookie available path :"
+            + zkAvailablePath + ", timed out " + zkc.getSessionTimeout()
+            + " millis");
+      }
+    } catch (InterruptedException e) {
+      Thread.currentThread().interrupt();
+      throw new IOException(
+          "Interrupted when creating the bookie available path : "
+              + zkAvailablePath, e);
+    }
+  }
+
   /**
    * Start a new log segment in a BookKeeper ledger.
    * First ensure that we have the write lock for this journal.