Classes
struct	CloseBeforeDelete

Public Member Functions
	DuplicateTreeSentry (TTree *tree)

TTree *	tree () const

Private Member Functions
void	dup ()

	DuplicateTreeSentry (DuplicateTreeSentry const &)=delete

DuplicateTreeSentry &	operator= (DuplicateTreeSentry const &)=delete

Private Attributes
std::unique_ptr< TFile, CloseBeforeDelete >	file_

std::unique_ptr< TTree >	mytree_ = 0

TTree *	tree_ = 0

Detailed Description

Currently, ROOT doesn't use any latency-hiding optimizations for fast-cloning. This causes a significant slowdown when doing fast-cloning over a high-latency network (30ms latency makes this multiple factors slower).

Accordingly, we allow sites to provide a separate hint on how to treat fast- cloning. The DuplicateTreeSentry allows us to implement it - given a tree we are about to clone, with the appropriate configs, this will re-open the file with lazy-download and re-open the tree. The new tree is appropriate for cloning. When the object is destroyed, the new file and tree are cleaned up.

Definition at line 39 of file RootOutputTree.cc.

Constructor & Destructor Documentation

edm::DuplicateTreeSentry::DuplicateTreeSentry ( TTree * tree )

inline

Definition at line 42 of file RootOutputTree.cc.

References dup().

           : tree_(tree)
         {
             dup();
         }

edm::DuplicateTreeSentry::DuplicateTreeSentry ( DuplicateTreeSentry const & )

privatedelete

Member Function Documentation

void edm::DuplicateTreeSentry::dup ( )

inlineprivate

Definition at line 55 of file RootOutputTree.cc.

References mergeVDriftHistosByStation::file, file_, edm::Service< T >::isAvailable(), mytree_, edm::SiteLocalConfig::sourceCacheHint(), edm::SiteLocalConfig::sourceCloneCacheHint(), tree_, and relmon_authenticated_wget::url.

Referenced by DuplicateTreeSentry().

         {
             edm::Service<edm::SiteLocalConfig> pSLC;
             if (!pSLC.isAvailable()) {return;}
             if (pSLC->sourceCacheHint() && *(pSLC->sourceCacheHint()) == "lazy-download") {return;}
             if (!pSLC->sourceCloneCacheHint() || *(pSLC->sourceCloneCacheHint()) != "lazy-download") {return;}
             edm::LogWarning("DuplicateTreeSentry") << "Re-opening file for fast-cloning";
 
             TFile *file = tree_->GetCurrentFile();
             const TUrl *url = file->GetEndpointUrl();
             if (!url)
             {
                 return;
             }
             file_.reset(TFile::Open(url->GetUrl(), "READWRAP")); // May throw an exception.
             if (!file_)
             {
                 return;
             }
             mytree_.reset(dynamic_cast<TTree*>(file_->Get(tree_->GetName())));
             if (!mytree_) {return;}
         }