[HAMA-499] Refactor clearZKNodes() in BSPMaster

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.4.0
• Fix Version/s: 0.5.0
• Component/s: bsp core
• Labels: newbie
• Assignee: Apurv Verma
• Reporter: Edward J. Yoon
• Created: 02/Feb/12 01:04
• Updated: 15/Mar/12 23:08
• Resolved: 15/Mar/12 17:40

Description

As you know, Hama uses ZooKeepr for a barrier synchronization. User can use Hama ZK, or their own existing ZK cluster. To avoid some potential problems, BSPMaster calls clearZKNodes() to delete all remained sub-nodes of 'bspRoot' at initialization stage. That code is here and very ugly:

  public void clearZKNodes() {
    try {
      for (String node : zk.getChildren(bspRoot, this)) {
        for (String subnode : zk.getChildren(bspRoot + "/" + node, this)) {
          for (String subnode2 : zk.getChildren(bspRoot + "/" + node, this)) {
            for (String subnode3 : zk.getChildren(bspRoot + "/" + node + "/" + subnode2, this)) {
              zk.delete(bspRoot + "/" + node + "/" + subnode + "/" + subnode2 + "/" + subnode3, 0);
            }
            zk.delete(bspRoot + "/" + node + "/" + subnode + "/" + subnode2, 0);
          }
          zk.delete(bspRoot + "/" + node + "/" + subnode, 0);
        }
        zk.delete(bspRoot + "/" + node, 0);
      }
    } catch (KeeperException e) {
    } catch (InterruptedException e) {
    }
  }

In this issue, we'll refactor this method. For example, you can delete recursively.

P.S., must use '-1' to delete all version of each node like this:

zk.delete(node, -1);