protected void shutDown()

in twill-yarn/src/main/java/org/apache/twill/internal/appmaster/ApplicationMasterMain.java [249:293]
29 lines of code
7 McCabe index (conditional complexity)

    protected void shutDown() throws Exception {
      super.shutDown();

      // Deletes ZK nodes created for the application execution.
      // We don't have to worry about a race condition if another instance of the same app starts at the same time
      // as when removal is performed. This is because we always create nodes with "createParent == true",
      // which takes care of the parent node recreation if it is removed from here.

      // Try to delete the /instances path. It may throws NotEmptyException if there are other instances of the
      // same app running, which we can safely ignore and return.
      if (!delete(Constants.INSTANCES_PATH_PREFIX)) {
        return;
      }

      // Try to delete children under /discovery. It may fail with NotEmptyException if there are other instances
      // of the same app running that has discovery services running.
      List<String> children = zkClient.getChildren(Constants.DISCOVERY_PATH_PREFIX)
                                      .get(TIMEOUT_SECONDS, TimeUnit.SECONDS).getChildren();
      List<OperationFuture<?>> deleteFutures = new ArrayList<>();
      for (String child : children) {
        String path = Constants.DISCOVERY_PATH_PREFIX + "/" + child;
        LOG.info("Removing ZK path: {}{}", zkClient.getConnectString(), path);
        deleteFutures.add(zkClient.delete(path));
      }
      Futures.successfulAsList(deleteFutures).get(TIMEOUT_SECONDS, TimeUnit.SECONDS);
      for (OperationFuture<?> future : deleteFutures) {
        try {
          future.get();
        } catch (ExecutionException e) {
          if (e.getCause() instanceof KeeperException.NotEmptyException) {
            return;
          }
          throw e;
        }
      }

      // Delete the /discovery. It may fail with NotEmptyException (due to race between apps),
      // which can safely ignore and return.
      if (!delete(Constants.DISCOVERY_PATH_PREFIX)) {
        return;
      }

      // Delete the ZK path for the app namespace.
      delete("/");
    }