ProductResolvers.cc

Go to the documentation of this file.

/*----------------------------------------------------------------------
----------------------------------------------------------------------*/
#include "ProductResolvers.h"
#include "Worker.h"
#include "UnscheduledAuxiliary.h"
#include "UnscheduledConfigurator.h"
#include "FWCore/Framework/interface/Principal.h"
#include "FWCore/Framework/interface/ProductDeletedException.h"
#include "FWCore/Framework/interface/SharedResourcesAcquirer.h"
#include "FWCore/Framework/interface/DelayedReader.h"
#include "DataFormats/Provenance/interface/ProductProvenanceRetriever.h"
#include "DataFormats/Provenance/interface/BranchKey.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/Concurrency/interface/SerialTaskQueue.h"
#include "FWCore/Concurrency/interface/FunctorTask.h"
#include "FWCore/Utilities/interface/TypeID.h"
#include "FWCore/Utilities/interface/make_sentry.h"

#include <cassert>
#include <utility>

static constexpr unsigned int kUnsetOffset = 0;
static constexpr unsigned int kAmbiguousOffset = 1;
static constexpr unsigned int kMissingOffset = 2;

namespace edm {

  void DataManagingProductResolver::throwProductDeletedException() const {
    ProductDeletedException exception;
    exception << "ProductResolverBase::resolveProduct_: The product matching all criteria was already deleted\n"
    << "Looking for type: " << branchDescription().unwrappedTypeID() << "\n"
    << "Looking for module label: " << moduleLabel() << "\n"
    << "Looking for productInstanceName: " << productInstanceName() << "\n"
    << (processName().empty() ? "" : "Looking for process: ") << processName() << "\n"
    << "This means there is a configuration error.\n"
    << "The module which is asking for this data must be configured to state that it will read this data.";
    throw exception;
    
  }

  //This is a templated function in order to avoid calling another virtual function
  template <bool callResolver, typename FUNC>
  ProductResolverBase::Resolution
  DataManagingProductResolver::resolveProductImpl(FUNC resolver) const {
    
    if(productWasDeleted()) {
      throwProductDeletedException();
    }
    auto presentStatus = status();
    
    if(callResolver && presentStatus == ProductStatus::ResolveNotRun) {
      //if resolver fails because of exception or not setting product
      // make sure the status goes to failed
      auto failedStatusSetter = [this](ProductStatus* presentStatus) {
        if(this->status() == ProductStatus::ResolveNotRun) {
          this->setFailedStatus();
        }
        *presentStatus = this->status();
      };
      std::unique_ptr<ProductStatus, decltype(failedStatusSetter)> failedStatusGuard(&presentStatus, failedStatusSetter);

      //If successful, this will call setProduct
      resolver();
    }
    
    
    if (presentStatus == ProductStatus::ProductSet) {
      auto pd = &getProductData();
      if(pd->wrapper()->isPresent()) {
        return Resolution(pd);
      }
    }

    return Resolution(nullptr);
  }

  void
  DataManagingProductResolver::mergeProduct(std::unique_ptr<WrapperBase> iFrom) const {
    assert(status() == ProductStatus::ProductSet);
    if(not iFrom) { return;}
    
    checkType(*iFrom);
    
    auto original =getProductData().unsafe_wrapper();
    if(original->isMergeable()) {
      original->mergeProduct(iFrom.get());
    } else if(original->hasIsProductEqual()) {
      if(!original->isProductEqual(iFrom.get())) {
        auto const& bd = branchDescription();
        edm::LogError("RunLumiMerging")
        << "ProductResolver::mergeTheProduct\n"
        << "Two run/lumi products for the same run/lumi which should be equal are not\n"
        << "Using the first, ignoring the second\n"
        << "className = " << bd.className() << "\n"
        << "moduleLabel = " << bd.moduleLabel() << "\n"
        << "instance = " << bd.productInstanceName() << "\n"
        << "process = " << bd.processName() << "\n";
      }
    } else {
      auto const& bd = branchDescription();
      edm::LogWarning("RunLumiMerging")
      << "ProductResolver::mergeTheProduct\n"
      << "Run/lumi product has neither a mergeProduct nor isProductEqual function\n"
      << "Using the first, ignoring the second in merge\n"
      << "className = " << bd.className() << "\n"
      << "moduleLabel = " << bd.moduleLabel() << "\n"
      << "instance = " << bd.productInstanceName() << "\n"
      << "process = " << bd.processName() << "\n";
    }
  }
  

  ProductResolverBase::Resolution
  InputProductResolver::resolveProduct_(Principal const& principal,
                                        bool,
                                        SharedResourcesAcquirer* ,
                                        ModuleCallingContext const* mcc) const {
    return resolveProductImpl<true>([this,&principal,mcc]() {
      auto branchType = principal.branchType();
      if(branchType != InEvent) {
        //delayed get has not been allowed with Run or Lumis
        // The file may already be closed so the reader is invalid
        return;
      }
      if(mcc and (branchType == InEvent) and aux_) {
        aux_->preModuleDelayedGetSignal_.emit(*(mcc->getStreamContext()),*mcc);
      }

      auto sentry( make_sentry(mcc,
                               [this, branchType](ModuleCallingContext const* iContext){
                                 if(branchType == InEvent and aux_) {
                                   aux_->postModuleDelayedGetSignal_.emit(*(iContext->getStreamContext()), *iContext); }
                               }));

      if(auto reader=principal.reader()) {
        std::unique_lock<std::recursive_mutex> guard;
        if(auto sr = reader->sharedResources().second) {
          guard =std::unique_lock<std::recursive_mutex>(*sr);
        }
        if ( not productResolved()) {
          //another thread could have beaten us here
          putProduct( reader->getProduct(BranchKey(branchDescription()), &principal, mcc));
        }
      }
    });
                              
  }
  
  void
  InputProductResolver::retrieveAndMerge_(Principal const& principal) const {
    if(auto reader = principal.reader()) {

      std::unique_lock<std::recursive_mutex> guard;
      if(auto sr = reader->sharedResources().second) {
        guard =std::unique_lock<std::recursive_mutex>(*sr);
      }

      //Can't use resolveProductImpl since it first checks to see
      // if the product was already retrieved and then returns if it is
      BranchKey const bk = BranchKey(branchDescription());
      std::unique_ptr<WrapperBase> edp(reader->getProduct(bk, &principal));
      
      if(edp.get() != nullptr) {
        putOrMergeProduct(std::move(edp));
      } else if( status()== defaultStatus()) {
        setFailedStatus();
      }
    }
  }

  
  void InputProductResolver::prefetchAsync_(WaitingTask* waitTask,
                                            Principal const& principal,
                                            bool skipCurrentProcess,
                                            SharedResourcesAcquirer* sra,
                                            ModuleCallingContext const* mcc) const {
    m_waitingTasks.add(waitTask);
    
    bool expected = false;
    if( m_prefetchRequested.compare_exchange_strong(expected, true) ) {
      
      //need to make sure Service system is activated on the reading thread
      auto token = ServiceRegistry::instance().presentToken();
      auto workToDo = [this, mcc, &principal, token] () {
        ServiceRegistry::Operate guard(token);
        try {
          resolveProductImpl<true>([this,&principal,mcc]() {
            if(principal.branchType() != InEvent) { return; }
            if(auto reader = principal.reader()) {
              std::unique_lock<std::recursive_mutex> guard;
              if(auto sr = reader->sharedResources().second) {
                guard =std::unique_lock<std::recursive_mutex>(*sr);
              }
              if ( not productResolved()) {
                //another thread could have finished this while we were waiting
                putProduct( reader->getProduct(BranchKey(branchDescription()), &principal, mcc));
              }
            }
          });
        } catch(...) {
          this->m_waitingTasks.doneWaiting(std::current_exception());
          return;
        }
        this->m_waitingTasks.doneWaiting(nullptr);
      };
      
      SerialTaskQueueChain* queue = nullptr;
      if(auto reader = principal.reader()) {
        if (auto shared_res = reader->sharedResources().first) {
          queue = &(shared_res->serialQueueChain());
        }
      }
      if(queue) {
        queue->push(workToDo);
      } else {
        //Have to create a new task
        auto t = make_functor_task(tbb::task::allocate_root(),
                                   workToDo);
        tbb::task::spawn(*t);
      }
    }
  }

  void
  InputProductResolver::resetProductData_(bool deleteEarly) {
    m_prefetchRequested = false;
    m_waitingTasks.reset();
    DataManagingProductResolver::resetProductData_(deleteEarly);
  }

  void
  InputProductResolver::setupUnscheduled(UnscheduledConfigurator const& iConfigure) {
    aux_ = iConfigure.auxiliary();
  }

  
  bool
  InputProductResolver::isFromCurrentProcess() const {
    return false;
  }

  
  ProductResolverBase::Resolution
  PuttableProductResolver::resolveProduct_(Principal const&,
                                           bool skipCurrentProcess,
                                           SharedResourcesAcquirer*,
                                           ModuleCallingContext const*) const {
    if (!skipCurrentProcess) {
      //'false' means never call the lambda function
      return resolveProductImpl<false>([](){return;});
    }
    return Resolution(nullptr);
  }

  void PuttableProductResolver::prefetchAsync_(WaitingTask* waitTask,
                                               Principal const& principal,
                                               bool skipCurrentProcess,
                                               SharedResourcesAcquirer* sra,
                                               ModuleCallingContext const* mcc) const {
    if(not skipCurrentProcess) {
      if(branchDescription().availableOnlyAtEndTransition() and
         not principal.atEndTransition()) {
        return;
      }
      m_waitingTasks.add(waitTask);
      
      bool expected = false;
      if(worker_ and prefetchRequested_.compare_exchange_strong(expected,true)) {
        //using a waiting task to do a callback guarantees that
        // the m_waitingTasks list will be released from waiting even
        // if the module does not put this data product or the
        // module has an exception while running
        
        auto waiting = make_waiting_task(tbb::task::allocate_root(),
                                         [this](std::exception_ptr const *  iException) {
                                           if(nullptr != iException) {
                                             m_waitingTasks.doneWaiting(*iException);
                                           } else {
                                             m_waitingTasks.doneWaiting(std::exception_ptr());
                                           }
                                         });
        worker_->callWhenDoneAsync(waiting);
      }
    }
  }
  
  void
  PuttableProductResolver::putProduct_(std::unique_ptr<WrapperBase> edp) const {
    ProducedProductResolver::putProduct_(std::move(edp));
    bool expected = false;
    if(prefetchRequested_.compare_exchange_strong(expected,true)) {
      m_waitingTasks.doneWaiting(std::exception_ptr());
    }
  }

  
  void
  PuttableProductResolver::resetProductData_(bool deleteEarly) {
    m_waitingTasks.reset();
    DataManagingProductResolver::resetProductData_(deleteEarly);
    prefetchRequested_ = false;
  }

  void
  PuttableProductResolver::setupUnscheduled(UnscheduledConfigurator const& iConfigure) {
    worker_ = iConfigure.findWorker(branchDescription().moduleLabel());
  }

  
  void
  UnscheduledProductResolver::setupUnscheduled(UnscheduledConfigurator const& iConfigure) {
    aux_ = iConfigure.auxiliary();
    worker_ = iConfigure.findWorker(branchDescription().moduleLabel());
    assert(worker_ != nullptr);
    
  }  
  
  ProductResolverBase::Resolution
  UnscheduledProductResolver::resolveProduct_(Principal const& principal,
                                              bool skipCurrentProcess,
                                              SharedResourcesAcquirer* sra,
                                              ModuleCallingContext const* mcc) const {
    if (!skipCurrentProcess and worker_) {
      return resolveProductImpl<true>(
        [&principal,this,sra,mcc]() {
          try {
            auto const& event = static_cast<EventPrincipal const&>(principal);
            ParentContext parentContext(mcc);
            aux_->preModuleDelayedGetSignal_.emit(*(mcc->getStreamContext()),*mcc);

            auto workCall = [this,&event,&parentContext,mcc] () {
              auto sentry( make_sentry(mcc,[this](ModuleCallingContext const* iContext){aux_->postModuleDelayedGetSignal_.emit(*(iContext->getStreamContext()), *iContext); }));
              
              worker_->doWork<OccurrenceTraits<EventPrincipal, BranchActionStreamBegin> >(
                                           event,
                                           *(aux_->eventSetup()),
                                           event.streamID(),
                                           parentContext,
                                           mcc->getStreamContext());
            };
            
            if (sra) {
              assert(false);
            } else {
              workCall();
            }

          }
          catch (cms::Exception & ex) {
            std::ostringstream ost;
            ost << "Calling produce method for unscheduled module "
            << worker_->description().moduleName() << "/'"
            << worker_->description().moduleLabel() << "'";
            ex.addContext(ost.str());
            throw;
          }
        });
    }
    return Resolution(nullptr);
  }
  
  void
  UnscheduledProductResolver::prefetchAsync_(WaitingTask* waitTask,
                                             Principal const& principal,
                                             bool skipCurrentProcess,
                                             SharedResourcesAcquirer* sra,
                                             ModuleCallingContext const* mcc) const
  {
    if(skipCurrentProcess) { return; }
    waitingTasks_.add(waitTask);
    bool expected = false;
    if(prefetchRequested_.compare_exchange_strong(expected, true)) {
      
      //Have to create a new task which will make sure the state for UnscheduledProductResolver
      // is properly set after the module has run
      auto t = make_waiting_task(tbb::task::allocate_root(),
                                 [this](std::exception_ptr const* iPtr)
      {
        //The exception is being rethrown because resolveProductImpl sets the ProductResolver to a failed
        // state for the case where an exception occurs during the call to the function.
        try {
          resolveProductImpl<true>([iPtr]() {
            if ( iPtr) {
              std::rethrow_exception(*iPtr);
            }
          });
        } catch(...) {
          waitingTasks_.doneWaiting(std::current_exception());
          return;
        }
        waitingTasks_.doneWaiting(nullptr);
      } );
      auto const& event = static_cast<EventPrincipal const&>(principal);
      ParentContext parentContext(mcc);

      worker_->doWorkAsync<OccurrenceTraits<EventPrincipal, BranchActionStreamBegin> >(t,
                                                                                       event,
                                                                                       *(aux_->eventSetup()),
                                                                                       event.streamID(),
                                                                                       parentContext,
                                                                                       mcc->getStreamContext());
    }
  }
  
  void
  UnscheduledProductResolver::resetProductData_(bool deleteEarly) {
    prefetchRequested_ = false;
    waitingTasks_.reset();
    DataManagingProductResolver::resetProductData_(deleteEarly);
  }


  void
  ProducedProductResolver::putProduct_(std::unique_ptr<WrapperBase> edp) const {
    if(status() != defaultStatus()) {
      throw Exception(errors::InsertFailure)
          << "Attempt to insert more than one product on branch " << branchDescription().branchName() << "\n";
    }
    
    setProduct(std::move(edp));  // ProductResolver takes ownership
  }

  void
  InputProductResolver::putProduct_(std::unique_ptr<WrapperBase> edp) const {
    if ( not productResolved()) {
      //Another thread could have set this
      setProduct(std::move(edp));
    }
  }
  
  bool
  ProducedProductResolver::isFromCurrentProcess() const {
    return true;
  }
  
  void
  ProducedProductResolver::resetFailedFromThisProcess() {
    if(ProductStatus::ResolveFailed == status()) {
      resetProductData_(false);
    }
  }

  
  void
  DataManagingProductResolver::connectTo(ProductResolverBase const& iOther, Principal const*) {
    assert(false);
  }
  
  void
  DataManagingProductResolver::putOrMergeProduct_(std::unique_ptr<WrapperBase> prod) const {
    if(not prod) {return;}
    if(status() == defaultStatus()) {
      //resolveProduct has not been called or it failed
      putProduct(std::move(prod));
    } else {
      mergeProduct(std::move(prod));
    }
  }
  

  
  void
  DataManagingProductResolver::checkType(WrapperBase const& prod) const {
    // Check if the types match.
    TypeID typeID(prod.dynamicTypeInfo());
    if(typeID !=TypeID{branchDescription().unwrappedType().unvalidatedTypeInfo()}) {
      // Types do not match.
      throw Exception(errors::EventCorruption)
      << "Product on branch " << branchDescription().branchName() << " is of wrong type.\n"
      << "It is supposed to be of type " << branchDescription().className() << ".\n"
      << "It is actually of type " << typeID.className() << ".\n";
    }
  }
  

  void
  DataManagingProductResolver::setProduct(std::unique_ptr<WrapperBase> edp) const {
    if(edp) {
      checkType(*edp);
      productData_.unsafe_setWrapper(std::move(edp));
      theStatus_ = ProductStatus::ProductSet;
    } else {
      setFailedStatus();
    }
  }
  // This routine returns true if it is known that currently there is no real product.
  // If there is a real product, it returns false.
  // If it is not known if there is a real product, it returns false.
  bool
  DataManagingProductResolver::productUnavailable_() const {
    auto presentStatus = status();
    if(presentStatus == ProductStatus::ProductSet) {
      return !(getProductData().wrapper()->isPresent());
    }
    return presentStatus != ProductStatus::ResolveNotRun;
  }
    
  bool
  DataManagingProductResolver::productResolved_() const {
    auto s = status();
    return (s != defaultStatus() ) or (s == ProductStatus::ProductDeleted);
  }

  
  // This routine returns true if the product was deleted early in order to save memory
  bool
  DataManagingProductResolver::productWasDeleted_() const {
    return status() == ProductStatus::ProductDeleted;
  }
  
  bool
  DataManagingProductResolver::productWasFetchedAndIsValid_(bool iSkipCurrentProcess) const {
    if (iSkipCurrentProcess and isFromCurrentProcess() ) {
      return false;
    }
    if (status() == ProductStatus::ProductSet) {
      if(getProductData().wrapper()->isPresent()) {
        return true;
      }
    }
    return false;
  }

  
  void DataManagingProductResolver::setProvenance_(ProductProvenanceRetriever const* provRetriever, ProcessHistory const& ph, ProductID const& pid) {
    productData_.setProvenance(provRetriever,ph,pid);
  }
  
  void DataManagingProductResolver::setProcessHistory_(ProcessHistory const& ph) {
    productData_.setProcessHistory(ph);
  }
  
  ProductProvenance const* DataManagingProductResolver::productProvenancePtr_() const {
    return provenance()->productProvenance();
  }
  
  void DataManagingProductResolver::resetProductData_(bool deleteEarly) {
    if(theStatus_ == ProductStatus::ProductSet) {
      productData_.resetProductData();
    }
    if(deleteEarly) {
      theStatus_ = ProductStatus::ProductDeleted;
    } else {
      resetStatus();
    }
  }
  
  bool DataManagingProductResolver::singleProduct_() const {
    return true;
  }

  void AliasProductResolver::setProvenance_(ProductProvenanceRetriever const* provRetriever, ProcessHistory const& ph, ProductID const& pid) {
    realProduct_.setProvenance(provRetriever,ph,pid);
  }

  void AliasProductResolver::setProcessHistory_(ProcessHistory const& ph) {
    realProduct_.setProcessHistory(ph);
  }

  ProductProvenance const* AliasProductResolver::productProvenancePtr_() const {
    return provenance()->productProvenance();
  }

  void AliasProductResolver::resetProductData_(bool deleteEarly) {
    realProduct_.resetProductData_(deleteEarly);
  }

  bool AliasProductResolver::singleProduct_() const {
    return true;
  }
  
  void AliasProductResolver::putProduct_(std::unique_ptr<WrapperBase> ) const {
    throw Exception(errors::LogicError)
    << "AliasProductResolver::putProduct_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  void AliasProductResolver::putOrMergeProduct_(std::unique_ptr<WrapperBase> edp) const {
    throw Exception(errors::LogicError)
    << "AliasProductResolver::putOrMergeProduct_(std::unique_ptr<WrapperBase> edp) not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  

  
  void ParentProcessProductResolver::setProvenance_(ProductProvenanceRetriever const* provRetriever, ProcessHistory const& ph, ProductID const& pid) {
    provRetriever_ = provRetriever;
  }
  
  void ParentProcessProductResolver::setProcessHistory_(ProcessHistory const& ph) {
  }
  
  ProductProvenance const* ParentProcessProductResolver::productProvenancePtr_() const {
    return provRetriever_? provRetriever_->branchIDToProvenance(bd_->originalBranchID()): nullptr;
  }
  
  void ParentProcessProductResolver::resetProductData_(bool deleteEarly) {
  }
  
  bool ParentProcessProductResolver::singleProduct_() const {
    return true;
  }

  void ParentProcessProductResolver::putProduct_(std::unique_ptr<WrapperBase> ) const {
    throw Exception(errors::LogicError)
    << "ParentProcessProductResolver::putProduct_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  void ParentProcessProductResolver::putOrMergeProduct_(std::unique_ptr<WrapperBase> edp) const {
    throw Exception(errors::LogicError)
    << "ParentProcessProductResolver::putOrMergeProduct_(std::unique_ptr<WrapperBase> edp) not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }

  void ParentProcessProductResolver::throwNullRealProduct() const {
    // In principle, this ought to be fixed. I noticed one hits this error
    // when in a SubProcess and calling the Event::getProvenance function
    // with a BranchID to a branch from an earlier SubProcess or the top
    // level process and this branch is not kept in this SubProcess. It might
    // be possible to hit this in other contexts. I say it ought to be
    // fixed because one does not encounter this issue if the SubProcesses
    // are split into genuinely different processes (in principle that
    // ought to give identical behavior and results). No user has ever
    // reported this issue which has been around for some time and it was only
    // noticed when testing some rare corner cases after modifying Core code.
    // After discussing this with Chris we decided that at least for the moment
    // there are higher priorities than fixing this ... I converted it so it
    // causes an exception instead of a seg fault. The issue that may need to
    // be addressed someday is how ProductResolvers for non-kept branches are
    // connected to earlier SubProcesses.
    throw Exception(errors::LogicError)
      << "ParentProcessProductResolver::throwNullRealProduct RealProduct pointer not set in this context.\n"
      << "Contact a Framework developer\n";
  }

  NoProcessProductResolver::
  NoProcessProductResolver(std::vector<ProductResolverIndex> const&  matchingHolders,
                           std::vector<bool> const& ambiguous) :
  matchingHolders_(matchingHolders),
  ambiguous_(ambiguous),
  lastCheckIndex_(ambiguous_.size() + kUnsetOffset),
  lastSkipCurrentCheckIndex_(lastCheckIndex_.load()),
  prefetchRequested_(false),
  skippingPrefetchRequested_(false),
  recheckedAtEnd_(false) {
    assert(ambiguous_.size() == matchingHolders_.size());
  }
  
  ProductResolverBase::Resolution
  NoProcessProductResolver::tryResolver(unsigned int index,
                                        Principal const& principal,
                                        bool skipCurrentProcess,
                                        SharedResourcesAcquirer* sra,
                                        ModuleCallingContext const* mcc) const {
    ProductResolverBase const* productResolver = principal.getProductResolverByIndex(matchingHolders_[index]);
    return productResolver->resolveProduct(principal, skipCurrentProcess, sra, mcc);
  }
  
  
  ProductResolverBase::Resolution
  NoProcessProductResolver::resolveProduct_(Principal const& principal,
                                            bool skipCurrentProcess,
                                            SharedResourcesAcquirer* sra,
                                            ModuleCallingContext const* mcc) const {
    //See if we've already cached which Resolver we should call or if
    // we know it is ambiguous
    const unsigned int choiceSize = ambiguous_.size();
    {
      if( (not principal.atEndTransition()) or
         recheckedAtEnd_) {
        unsigned int checkCacheIndex = skipCurrentProcess? lastSkipCurrentCheckIndex_.load() : lastCheckIndex_.load();
        if( checkCacheIndex != choiceSize +kUnsetOffset) {
          if (checkCacheIndex == choiceSize+kAmbiguousOffset) {
            return ProductResolverBase::Resolution::makeAmbiguous();
          } else if(checkCacheIndex == choiceSize+kMissingOffset) {
            return Resolution(nullptr);
          }
          return tryResolver(checkCacheIndex, principal, skipCurrentProcess,
                             sra,mcc);
        }
      }
    }

    std::atomic<unsigned int>& updateCacheIndex = skipCurrentProcess? lastSkipCurrentCheckIndex_ : lastCheckIndex_;

    //make sure recheckedAtEnd_ set to true if needed
    auto setTrue = [](std::atomic<bool>* iBool) { *iBool = true; };
    using TrueGuard = std::unique_ptr<std::atomic<bool>, decltype(setTrue)>;
    TrueGuard guard( principal.atEndTransition()?&recheckedAtEnd_:nullptr,setTrue);
    
    std::vector<unsigned int> const& lookupProcessOrder = principal.lookupProcessOrder();
    for(unsigned int k : lookupProcessOrder) {
      assert(k < ambiguous_.size());
      if(k == 0) break; // Done
      if(ambiguous_[k]) {
        updateCacheIndex = choiceSize + kAmbiguousOffset;
        return ProductResolverBase::Resolution::makeAmbiguous();
      }
      if (matchingHolders_[k] != ProductResolverIndexInvalid) {
        auto resolution = tryResolver(k,principal, skipCurrentProcess, sra,mcc);
        if(resolution.data() != nullptr) {
          updateCacheIndex = k;
          return resolution;
        }
      }
    }
    
    updateCacheIndex = choiceSize + kMissingOffset;
    return Resolution(nullptr);
  }
  
  void
  NoProcessProductResolver::prefetchAsync_(WaitingTask* waitTask,
                                           Principal const& principal,
                                           bool skipCurrentProcess,
                                           SharedResourcesAcquirer* sra,
                                           ModuleCallingContext const* mcc) const {
    if(not skipCurrentProcess) {
      waitingTasks_.add(waitTask);
      
      //It is possible that a new product was added at then end transition
      // so we need to recheck what to return
      bool needToRecheckAtEnd = false;
      if(principal.atEndTransition()) {
        bool expected = false;
        needToRecheckAtEnd = recheckedAtEnd_.compare_exchange_strong(expected,true);
        if(needToRecheckAtEnd) {
          prefetchRequested_=true;
        }
      }
      
      bool expected = false;
      if( needToRecheckAtEnd or prefetchRequested_.compare_exchange_strong(expected,true)) {
        //we are the first thread to request
        tryPrefetchResolverAsync(0, principal, skipCurrentProcess, sra, mcc, ServiceRegistry::instance().presentToken());
      }
    } else {
      skippingWaitingTasks_.add(waitTask);
      bool expected = false;
      if( skippingPrefetchRequested_.compare_exchange_strong(expected,true)) {
      //we are the first thread to request
        tryPrefetchResolverAsync(0, principal, skipCurrentProcess, sra, mcc, ServiceRegistry::instance().presentToken());
      }
    }
  }
  
  void NoProcessProductResolver::setCache(bool iSkipCurrentProcess, 
                                          ProductResolverIndex iIndex, 
                                          std::exception_ptr iExceptPtr) const {
    if( not iSkipCurrentProcess) {
      lastCheckIndex_ = iIndex;
      waitingTasks_.doneWaiting(iExceptPtr);
    } else {
      lastSkipCurrentCheckIndex_ = iIndex;
      skippingWaitingTasks_.doneWaiting(iExceptPtr);
    }
  }

  namespace {
    class TryNextResolverWaitingTask : public edm::WaitingTask {
    public:
      
      TryNextResolverWaitingTask(NoProcessProductResolver const* iResolver,
                                 unsigned int iResolverIndex,
                                 Principal const* iPrincipal,
                                 SharedResourcesAcquirer* iSRA,
                                 ModuleCallingContext const* iMCC,
                                 bool iSkipCurrentProcess,
                                 ServiceToken iToken) :
      resolver_(iResolver),
      principal_(iPrincipal),
      sra_(iSRA),
      mcc_(iMCC),
      serviceToken_(iToken),
      index_(iResolverIndex),
      skipCurrentProcess_(iSkipCurrentProcess){}
      
      tbb::task* execute() override {
        auto exceptPtr =exceptionPtr();
        if(exceptPtr) {
          resolver_->prefetchFailed(index_, *principal_, skipCurrentProcess_, *exceptPtr);
        } else {
          if(not resolver_->dataValidFromResolver(index_, *principal_, skipCurrentProcess_)) {
            resolver_->tryPrefetchResolverAsync(index_+1,
                                                *principal_,
                                                skipCurrentProcess_,
                                                sra_,
                                                mcc_,
                                                serviceToken_);
          }
        }
        return nullptr;
      }
      
    private:
      NoProcessProductResolver const* resolver_;
      Principal const* principal_;
      SharedResourcesAcquirer* sra_;
      ModuleCallingContext const* mcc_;
      ServiceToken serviceToken_;
      unsigned int index_;
      bool skipCurrentProcess_;
    };
  }

  void
  NoProcessProductResolver::prefetchFailed(unsigned int iProcessingIndex,
                                           Principal const& principal,
                                           bool iSkipCurrentProcess,
                                           std::exception_ptr iExceptPtr) const {
    std::vector<unsigned int> const& lookupProcessOrder = principal.lookupProcessOrder();
    auto k = lookupProcessOrder[iProcessingIndex];

    setCache(iSkipCurrentProcess, k, iExceptPtr);
  }

  
  bool
  NoProcessProductResolver::dataValidFromResolver(unsigned int iProcessingIndex,
                                                  Principal const& principal,
                                                  bool iSkipCurrentProcess) const {
    std::vector<unsigned int> const& lookupProcessOrder = principal.lookupProcessOrder();
    auto k = lookupProcessOrder[iProcessingIndex];
    ProductResolverBase const* productResolver = principal.getProductResolverByIndex(matchingHolders_[k]);

    if(productResolver->productWasFetchedAndIsValid(iSkipCurrentProcess)) {

      setCache(iSkipCurrentProcess, k, nullptr);
      return true;
    }
    return false;
  }

  
  void
  NoProcessProductResolver::tryPrefetchResolverAsync(unsigned int iProcessingIndex,
                                                     Principal const& principal,
                                                     bool skipCurrentProcess,
                                                     SharedResourcesAcquirer* sra,
                                                     ModuleCallingContext const* mcc,
                                                     ServiceToken token) const {
    std::vector<unsigned int> const& lookupProcessOrder = principal.lookupProcessOrder();
    auto index = iProcessingIndex;

    const unsigned int choiceSize = ambiguous_.size();
    unsigned int newCacheIndex = choiceSize + kMissingOffset;
    while(index < lookupProcessOrder.size()) {
      auto k = lookupProcessOrder[index];
      if(k==0) {
        break;
      }
      assert(k < ambiguous_.size());
      if(ambiguous_[k]) {
        newCacheIndex = choiceSize + kAmbiguousOffset;
        break;
      }
      if (matchingHolders_[k] != ProductResolverIndexInvalid) {
        //make new task
        
        auto task = new (tbb::task::allocate_root()) TryNextResolverWaitingTask(
                                                                                this,
                                                                                index,
                                                                                &principal,
                                                                                sra,
                                                                                mcc,
                                                                                skipCurrentProcess,
                                                                                token
                                                                                );
        task->increment_ref_count();
        ProductResolverBase const* productResolver = principal.getProductResolverByIndex(matchingHolders_[k]);

        //Make sure the Services are available on this thread
        ServiceRegistry::Operate guard(token);

        productResolver->prefetchAsync(task,
                                       principal,
                                       skipCurrentProcess,
                                       sra, mcc);
        if(0 == task->decrement_ref_count()) {
          tbb::task::spawn(*task);
        }
        return;
      }
      ++index;
    }
    //data product unavailable
    setCache(skipCurrentProcess, newCacheIndex, nullptr);
  }
  
  void NoProcessProductResolver::setProvenance_(ProductProvenanceRetriever const* , ProcessHistory const& , ProductID const& ) {
  }

  void NoProcessProductResolver::setProcessHistory_(ProcessHistory const& ) {
  }

  ProductProvenance const* NoProcessProductResolver::productProvenancePtr_() const {
    return nullptr;
  }

  inline unsigned int NoProcessProductResolver::unsetIndexValue() const { return ambiguous_.size()+kUnsetOffset; }

  void NoProcessProductResolver::resetProductData_(bool) {
    const auto resetValue = unsetIndexValue();
    lastCheckIndex_ = resetValue;
    lastSkipCurrentCheckIndex_ = resetValue;
    prefetchRequested_ = false;
    skippingPrefetchRequested_ = false;
    recheckedAtEnd_ = false;
    waitingTasks_.reset();
    skippingWaitingTasks_.reset();
  }

  bool NoProcessProductResolver::singleProduct_() const {
    return false;
  }

  bool NoProcessProductResolver::unscheduledWasNotRun_() const {
    throw Exception(errors::LogicError)
      << "NoProcessProductResolver::unscheduledWasNotRun_() not implemented and should never be called.\n"
      << "Contact a Framework developer\n";
  }

  bool NoProcessProductResolver::productUnavailable_() const {
    throw Exception(errors::LogicError)
      << "NoProcessProductResolver::productUnavailable_() not implemented and should never be called.\n"
      << "Contact a Framework developer\n";
  }

  bool NoProcessProductResolver::productResolved_() const {
    throw Exception(errors::LogicError)
    << "NoProcessProductResolver::productResolved_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }

  bool NoProcessProductResolver::productWasDeleted_() const {
    throw Exception(errors::LogicError)
      << "NoProcessProductResolver::productWasDeleted_() not implemented and should never be called.\n"
      << "Contact a Framework developer\n";
  }

  bool NoProcessProductResolver::productWasFetchedAndIsValid_(bool /*iSkipCurrentProcess*/) const {
    throw Exception(errors::LogicError)
    << "NoProcessProductResolver::productWasFetchedAndIsValid_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }

  void NoProcessProductResolver::putProduct_(std::unique_ptr<WrapperBase> ) const {
    throw Exception(errors::LogicError)
      << "NoProcessProductResolver::putProduct_() not implemented and should never be called.\n"
      << "Contact a Framework developer\n";
  }

  void NoProcessProductResolver::putOrMergeProduct_(std::unique_ptr<WrapperBase> edp) const {
    throw Exception(errors::LogicError)
      << "NoProcessProductResolver::putOrMergeProduct_(std::unique_ptr<WrapperBase> edp) not implemented and should never be called.\n"
      << "Contact a Framework developer\n";
  }

  BranchDescription const& NoProcessProductResolver::branchDescription_() const {
    throw Exception(errors::LogicError)
      << "NoProcessProductResolver::branchDescription_() not implemented and should never be called.\n"
      << "Contact a Framework developer\n";
  }

  void NoProcessProductResolver::resetBranchDescription_(std::shared_ptr<BranchDescription const>) {
    throw Exception(errors::LogicError)
      << "NoProcessProductResolver::resetBranchDescription_() not implemented and should never be called.\n"
      << "Contact a Framework developer\n";
  }

  Provenance const* NoProcessProductResolver::provenance_() const {
    throw Exception(errors::LogicError)
    << "NoProcessProductResolver::provenance_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }

  void NoProcessProductResolver::connectTo(ProductResolverBase const&, Principal const*) {
    throw Exception(errors::LogicError)
    << "NoProcessProductResolver::connectTo() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
    
  }
  
  //---- SingleChoiceNoProcessProductResolver ----------------
  ProductResolverBase::Resolution SingleChoiceNoProcessProductResolver::resolveProduct_(
                                             Principal const& principal,
                                             bool skipCurrentProcess,
                                             SharedResourcesAcquirer* sra,
                                             ModuleCallingContext const* mcc) const
  {
    //NOTE: Have to lookup the other ProductResolver each time rather than cache
    // it's pointer since it appears the pointer can change at some later stage
    return principal.getProductResolverByIndex(realResolverIndex_)
      ->resolveProduct(principal,
                       skipCurrentProcess, sra, mcc);
  }
  
  void SingleChoiceNoProcessProductResolver::prefetchAsync_(WaitingTask* waitTask,
                                                            Principal const& principal,
                                                            bool skipCurrentProcess,
                                                            SharedResourcesAcquirer* sra,
                                                            ModuleCallingContext const* mcc) const {
    principal.getProductResolverByIndex(realResolverIndex_)
    ->prefetchAsync(waitTask,principal,
                    skipCurrentProcess, sra, mcc);
  }
  
  void SingleChoiceNoProcessProductResolver::setProvenance_(ProductProvenanceRetriever const* , ProcessHistory const& , ProductID const& ) {
  }
  
  void SingleChoiceNoProcessProductResolver::setProcessHistory_(ProcessHistory const& ) {
  }
  
  ProductProvenance const* SingleChoiceNoProcessProductResolver::productProvenancePtr_() const {
    return nullptr;
  }
  
  void SingleChoiceNoProcessProductResolver::resetProductData_(bool) {
  }
  
  bool SingleChoiceNoProcessProductResolver::singleProduct_() const {
    return false;
  }
  
  bool SingleChoiceNoProcessProductResolver::unscheduledWasNotRun_() const {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::unscheduledWasNotRun_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  bool SingleChoiceNoProcessProductResolver::productUnavailable_() const {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::productUnavailable_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  bool SingleChoiceNoProcessProductResolver::productResolved_() const {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::productResolved_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  bool SingleChoiceNoProcessProductResolver::productWasDeleted_() const {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::productWasDeleted_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  bool SingleChoiceNoProcessProductResolver::productWasFetchedAndIsValid_(bool /*iSkipCurrentProcess*/) const {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::productWasFetchedAndIsValid_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }

  
  void SingleChoiceNoProcessProductResolver::putProduct_(std::unique_ptr<WrapperBase> ) const {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::putProduct_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  void SingleChoiceNoProcessProductResolver::putOrMergeProduct_(std::unique_ptr<WrapperBase> edp) const {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::putOrMergeProduct_(std::unique_ptr<WrapperBase> edp) not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  BranchDescription const& SingleChoiceNoProcessProductResolver::branchDescription_() const {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::branchDescription_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  void SingleChoiceNoProcessProductResolver::resetBranchDescription_(std::shared_ptr<BranchDescription const>) {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::resetBranchDescription_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  Provenance const* SingleChoiceNoProcessProductResolver::provenance_() const {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::provenance_() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
  }
  
  void SingleChoiceNoProcessProductResolver::connectTo(ProductResolverBase const&, Principal const*) {
    throw Exception(errors::LogicError)
    << "SingleChoiceNoProcessProductResolver::connectTo() not implemented and should never be called.\n"
    << "Contact a Framework developer\n";
    
  }

}