Hi Youssef, You might want to review the code for BlockPlacementPolicyDefault to get a sense for how an implementation works. Perhaps you could even start your own work by copying and modifying that class. This code would show you how to get ahold of a DatanodeDescriptor and then use it to call getStorageInfos.
Hope this helps. Chris Nauroth Hortonworks http://hortonworks.com/ On Fri, Jan 2, 2015 at 10:12 AM, Youssef Hatem <yousef.ha...@gmail.com> wrote: > Hi, > > I am working on implementing a custom placement policy. So I created a > class that extends BlockPlacementPolicy. I am trying to get a list of all > DatanodeStorageInfo objects in order to be able to decide which one to > choose for placement (based on certain criteria), this is the logic of > chooseTarget method. > > Could you please tell me how can I get this list? I tried to do the > following but I got none of these objects: > > DistributedFileSystem fs = (DistributedFileSystem)FileSystem.get(conf); > //conf is passed in initialize method > List<DatanodeStorageInfo> storageInfos = new ArrayList<>(); > for(DatanodeInfo node : > fs.getDataNodeStats(HdfsConstants.DatanodeReportType.LIVE)){ > if(node instanceof DatanodeDescriptor){ > > > > storageInfos.addAll(Arrays.asList(((DatanodeDescriptor)node).getStorageInfo())); > } > > It seems though that none of the resulting DatanodeInfo objects are > actually a DatanodeDescriptor therefor the storageInfos list is always > empty. > > It would be great if you could provide me with more information on how to > get a list of DatanodeStorageInfo objects. > > Thanks a lot in advance, > Youssef > -- CONFIDENTIALITY NOTICE NOTICE: This message is intended for the use of the individual or entity to which it is addressed and may contain information that is confidential, privileged and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any printing, copying, dissemination, distribution, disclosure or forwarding of this communication is strictly prohibited. If you have received this communication in error, please contact the sender immediately and delete it from your system. Thank You.
