#include <ESProductHost.h>

Inheritance diagram for edm::ESProductHost< Product, RecordTypes >:

Public Member Functions
template<typename... Args>
	ESProductHost (Args &&... args)

template<typename RecordType , typename ContainingRecordType , typename FUNC >
void	ifRecordChanges (ContainingRecordType const &containingRecord, FUNC func)

Static Public Member Functions
template<typename U >
constexpr static std::size_t	index ()

template<std::size_t I, typename U , typename TST , typename... M>
constexpr static std::size_t	indexLoop ()

constexpr static std::size_t	numberOfRecordTypes ()

Private Attributes
std::vector< unsigned long long >	cacheIDs_

Detailed Description

template<typename Product, typename... RecordTypes>
class edm::ESProductHost< Product, RecordTypes >

Description: Helps an ESProducer produce an ESProduct that has complex dependences on multiple record types. In particular, it helps it manage what is executed in the produce function based on which records changed and which did not.

This was designed as a replacement for the EventSetup "dependsOn" functionality and is needed in some cases where the "dependsOn" callbacks would not work well when processing multiple IOVs concurrently.

Usage:

An ESProducer class would use this class.

Add to the ESProducer header

include "FWCore/Framework/interface/ESProductHost.h" include "FWCore/Utilities/interface/ReusableObjectHolder.h"
Assume the following only for purposes of this usage example (the actual types in your case would be different). If the produced function was defined as follows:
```
std::shared_ptr<ESTestDataB> produce(ESTestRecordB const&);
```

and assume there is some special dependence on ESTestRecordC and ESTestRecordD.

Then you would add a data member to the ESProducer similar to the following:

using HostType = edm::ESProductHost<ESTestDataB,
                                    ESTestRecordC,
                                    ESTestRecordD>;

edm::ReusableObjectHolder<HostType> holder_;

Then the produce function would be defined something similar to this:
```
std::shared_ptr<ESTestDataB> ESTestProducerBUsingHost::produce(ESTestRecordB const& record) {

  auto host = holder_.makeOrGet([]() {
    return new HostType;
  });

  host->ifRecordChanges<ESTestRecordC>(record,
                                       [this, h=host.get()](auto const& rec) {
```
Do whatever special needs to be done only when record C changes (If you are using this class to replace a dependsOn callback, you could call the function that dependsOn used as a callback here) });

host->ifRecordChanges<ESTestRecordD>(record, [this, h=host.get()](auto const& rec) { Do whatever special needs to be done only when record D changes });

... repeat for as many record types as you need.

Definition at line 93 of file ESProductHost.h.

Constructor & Destructor Documentation

◆ ESProductHost()

template<typename Product , typename... RecordTypes>

template<typename... Args>

edm::ESProductHost< Product, RecordTypes >::ESProductHost ( Args &&... args )

inline

Definition at line 96 of file ESProductHost.h.

96 : Product(std::forward<Args>(args)...), cacheIDs_(numberOfRecordTypes(), 0) {}

Member Function Documentation

◆ ifRecordChanges()

template<typename Product , typename... RecordTypes>

template<typename RecordType , typename ContainingRecordType , typename FUNC >

void edm::ESProductHost< Product, RecordTypes >::ifRecordChanges	(	ContainingRecordType const &	containingRecord,
		FUNC	func
	)

inline

Definition at line 103 of file ESProductHost.h.

                                                                                   {
       RecordType const& record = containingRecord.template getRecord<RecordType>();
       unsigned long long cacheIdentifier = record.cacheIdentifier();
       std::size_t iRecord = index<RecordType>();
       if (cacheIdentifier != cacheIDs_[iRecord]) {
         cacheIDs_[iRecord] = cacheIdentifier;
         func(record);
       }
     }

References edm::ESProductHost< Product, RecordTypes >::cacheIDs_, TrackCollections2monitor_cff::func, and GlobalPosition_Frontier_DevDB_cff::record.

◆ index()

template<typename Product , typename... RecordTypes>

template<typename U >

constexpr static std::size_t edm::ESProductHost< Product, RecordTypes >::index ( )

inlinestaticconstexpr

Definition at line 129 of file ESProductHost.h.

                                        {
       static_assert(numberOfRecordTypes() > 0, "no record types in ESProductHost");
       return indexLoop<0, U, RecordTypes...>();
     }

References edm::ESProductHost< Product, RecordTypes >::indexLoop(), edm::ESProductHost< Product, RecordTypes >::numberOfRecordTypes(), and mitigatedMETSequence_cff::U.

Referenced by BeautifulSoup.PageElement::insert().

◆ indexLoop()

template<typename Product , typename... RecordTypes>

template<std::size_t I, typename U , typename TST , typename... M>

constexpr static std::size_t edm::ESProductHost< Product, RecordTypes >::indexLoop ( )

inlinestaticconstexpr

Definition at line 135 of file ESProductHost.h.

                                            {
       if constexpr (std::is_same_v<U, TST>) {
         return I;
       } else {
         static_assert(I + 1 < numberOfRecordTypes(), "unknown record type passed to ESProductHost::index");
         return indexLoop<I + 1, U, M...>();
       }
     }