BlockManager#removeStoredBlock(CDH4.4.0)

BlockManager.java

  /**
   * Modify (block-->datanode) map. Possibly generate replication tasks, if the
   * removed block is still valid.
   */
  public void removeStoredBlock(Block block, DatanodeDescriptor node) {
    if(blockLog.isDebugEnabled()) {
      blockLog.debug("BLOCK* removeStoredBlock: "
          + block + " from " + node);
    }
    assert (namesystem.hasWriteLock());
    {
      if (!blocksMap.removeNode(block, node)) { 
        if(blockLog.isDebugEnabled()) {
          blockLog.debug("BLOCK* removeStoredBlock: "
              + block + " has already been removed from node " + node);
        }
        return;
      }

      //
      // It's possible that the block was removed because of a datanode
      // failure. If the block is still valid, check if replication is
      // necessary. In that case, put block on a possibly-will-
      // be-replicated list.
      //
      BlockCollection bc = blocksMap.getBlockCollection(block);
      if (bc != null) {
        namesystem.decrementSafeBlockCount(block);
        updateNeededReplications(block, -1, 0);
      }

      //
      // We've removed a block from a node, so it's definitely no longer
      // in "excess" there.
      //
      LightWeightLinkedSet<Block> excessBlocks = excessReplicateMap.get(node
          .getStorageID());
      if (excessBlocks != null) {
        if (excessBlocks.remove(block)) {
          excessBlocksCount--;
          if(blockLog.isDebugEnabled()) {
            blockLog.debug("BLOCK* removeStoredBlock: "
                + block + " is removed from excessBlocks");
          }
          if (excessBlocks.size() == 0) {
            excessReplicateMap.remove(node.getStorageID());
          }
        }
      }

      // Remove the replica from corruptReplicas
      corruptReplicas.removeFromCorruptReplicasMap(block, node);
    }
  }