/// <summary>Select a datanode to service this request.</summary>
/// <remarks>
/// Select a datanode to service this request.
/// Currently, this looks at no more than the first five blocks of a file,
/// selecting a datanode randomly from the most represented.
/// </remarks>
/// <param name="conf"></param>
/// <exception cref="System.IO.IOException"/>
private DatanodeID PickSrcDatanode(LocatedBlocks blks, HdfsFileStatus i, Configuration
conf)
{
if (i.GetLen() == 0 || blks.GetLocatedBlocks().Count <= 0)
{
// pick a random datanode
NameNode nn = NameNodeHttpServer.GetNameNodeFromContext(GetServletContext());
return(NamenodeJspHelper.GetRandomDatanode(nn));
}
return(JspHelper.BestNode(blks, conf));
}
/// <exception cref="Javax.Servlet.ServletException"/>
/// <exception cref="System.IO.IOException"/>
protected override void DoGet(HttpServletRequest request, HttpServletResponse response
)
{
ServletContext context = GetServletContext();
Configuration conf = NameNodeHttpServer.GetConfFromContext(context);
UserGroupInformation ugi = GetUGI(request, conf);
NameNode namenode = NameNodeHttpServer.GetNameNodeFromContext(context);
DatanodeID datanode = NamenodeJspHelper.GetRandomDatanode(namenode);
try
{
response.SendRedirect(CreateRedirectURL(ugi, datanode, request, namenode).ToString
());
}
catch (IOException e)
{
response.SendError(400, e.Message);
}
}