/// <summary>
/// Get a partial listing of the indicated directory
/// We will stop when any of the following conditions is met:
/// 1) this.lsLimit files have been added
/// 2) needLocation is true AND enough files have been added such
/// that at least this.lsLimit block locations are in the response
/// </summary>
/// <param name="fsd">FSDirectory</param>
/// <param name="iip">
/// the INodesInPath instance containing all the INodes along the
/// path
/// </param>
/// <param name="src">the directory name</param>
/// <param name="startAfter">the name to start listing after</param>
/// <param name="needLocation">if block locations are returned</param>
/// <returns>a partial listing starting after startAfter</returns>
/// <exception cref="System.IO.IOException"/>
private static DirectoryListing GetListing(FSDirectory fsd, INodesInPath iip, string
src, byte[] startAfter, bool needLocation, bool isSuperUser)
{
string srcs = FSDirectory.NormalizePath(src);
bool isRawPath = FSDirectory.IsReservedRawName(src);
fsd.ReadLock();
try
{
if (srcs.EndsWith(HdfsConstants.SeparatorDotSnapshotDir))
{
return(GetSnapshotsListing(fsd, srcs, startAfter));
}
int snapshot = iip.GetPathSnapshotId();
INode targetNode = iip.GetLastINode();
if (targetNode == null)
{
return(null);
}
byte parentStoragePolicy = isSuperUser ? targetNode.GetStoragePolicyID() : BlockStoragePolicySuite
.IdUnspecified;
if (!targetNode.IsDirectory())
{
return(new DirectoryListing(new HdfsFileStatus[] { CreateFileStatus(fsd, src, HdfsFileStatus
.EmptyName, targetNode, needLocation, parentStoragePolicy, snapshot, isRawPath,
iip) }, 0));
}
INodeDirectory dirInode = targetNode.AsDirectory();
ReadOnlyList <INode> contents = dirInode.GetChildrenList(snapshot);
int startChild = INodeDirectory.NextChild(contents, startAfter);
int totalNumChildren = contents.Size();
int numOfListing = Math.Min(totalNumChildren - startChild, fsd.GetLsLimit());
int locationBudget = fsd.GetLsLimit();
int listingCnt = 0;
HdfsFileStatus[] listing = new HdfsFileStatus[numOfListing];
for (int i = 0; i < numOfListing && locationBudget > 0; i++)
{
INode cur = contents.Get(startChild + i);
byte curPolicy = isSuperUser && !cur.IsSymlink() ? cur.GetLocalStoragePolicyID() :
BlockStoragePolicySuite.IdUnspecified;
listing[i] = CreateFileStatus(fsd, src, cur.GetLocalNameBytes(), cur, needLocation
, GetStoragePolicyID(curPolicy, parentStoragePolicy), snapshot, isRawPath, iip);
listingCnt++;
if (needLocation)
{
// Once we hit lsLimit locations, stop.
// This helps to prevent excessively large response payloads.
// Approximate #locations with locatedBlockCount() * repl_factor
LocatedBlocks blks = ((HdfsLocatedFileStatus)listing[i]).GetBlockLocations();
locationBudget -= (blks == null) ? 0 : blks.LocatedBlockCount() * listing[i].GetReplication
();
}
}
// truncate return array if necessary
if (listingCnt < numOfListing)
{
listing = Arrays.CopyOf(listing, listingCnt);
}
return(new DirectoryListing(listing, totalNumChildren - startChild - listingCnt));
}
finally
{
fsd.ReadUnlock();
}
}