RootDelayedReader.h

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#ifndef IOPool_Input_RootDelayedReader_h
#define IOPool_Input_RootDelayedReader_h

/*----------------------------------------------------------------------

RootDelayedReader.h // used by ROOT input sources

----------------------------------------------------------------------*/

#include "DataFormats/Provenance/interface/BranchID.h"
#include "FWCore/Framework/interface/DelayedReader.h"
#include "FWCore/Utilities/interface/InputType.h"
#include "FWCore/Utilities/interface/propagate_const.h"
#include "FWCore/Utilities/interface/thread_safety_macros.h"
#include "RootTree.h"

#include <map>
#include <memory>
#include <string>
#include <exception>

class TClass;
namespace edm {
  class InputFile;
  class RootTree;
  class SharedResourcesAcquirer;
  class Exception;

  //------------------------------------------------------------
  // Class RootDelayedReader: pretends to support file reading.
  //

  class RootDelayedReader : public DelayedReader {
  public:
    typedef roottree::BranchInfo BranchInfo;
    typedef roottree::BranchMap BranchMap;
    typedef roottree::EntryNumber EntryNumber;
    RootDelayedReader(RootTree const& tree, std::shared_ptr<InputFile> filePtr, InputType inputType);

    ~RootDelayedReader() override;

    RootDelayedReader(RootDelayedReader const&) = delete;             // Disallow copying and moving
    RootDelayedReader& operator=(RootDelayedReader const&) = delete;  // Disallow copying and moving

    signalslot::Signal<void(StreamContext const&, ModuleCallingContext const&)> const* preEventReadFromSourceSignal()
        const final {
      return preEventReadFromSourceSignal_;
    }
    signalslot::Signal<void(StreamContext const&, ModuleCallingContext const&)> const* postEventReadFromSourceSignal()
        const final {
      return postEventReadFromSourceSignal_;
    }

    void setSignals(
        signalslot::Signal<void(StreamContext const&, ModuleCallingContext const&)> const* preEventReadSource,
        signalslot::Signal<void(StreamContext const&, ModuleCallingContext const&)> const* postEventReadSource) {
      preEventReadFromSourceSignal_ = preEventReadSource;
      postEventReadFromSourceSignal_ = postEventReadSource;
    }

  private:
    std::shared_ptr<WrapperBase> getProduct_(BranchID const& k, EDProductGetter const* ep) override;
    void mergeReaders_(DelayedReader* other) override { nextReader_ = other; }
    void reset_() override { nextReader_ = nullptr; }
    std::pair<SharedResourcesAcquirer*, std::recursive_mutex*> sharedResources_() const override;

    BranchMap const& branches() const { return tree_.branches(); }
    BranchInfo const* getBranchInfo(BranchID const& k) const { return branches().find(k); }
    // NOTE: filePtr_ appears to be unused, but is needed to prevent
    // the file containing the branch from being reclaimed.
    RootTree const& tree_;
    edm::propagate_const<std::shared_ptr<InputFile>> filePtr_;
    edm::propagate_const<DelayedReader*> nextReader_;
    std::unique_ptr<SharedResourcesAcquirer>
        resourceAcquirer_;  // We do not use propagate_const because the acquirer is itself mutable.
    std::shared_ptr<std::recursive_mutex> mutex_;
    InputType inputType_;
    edm::propagate_const<TClass*> wrapperBaseTClass_;

    signalslot::Signal<void(StreamContext const&, ModuleCallingContext const&)> const* preEventReadFromSourceSignal_ =
        nullptr;
    signalslot::Signal<void(StreamContext const&, ModuleCallingContext const&)> const* postEventReadFromSourceSignal_ =
        nullptr;

    //If a fatal exception happens we need to make a copy so we can
    // rethrow that exception on other threads. This avoids TTree
    // non-exception safety problems on later calls to TTree.
    //All uses of the ROOT file are serialized
    CMS_SA_ALLOW mutable std::exception_ptr lastException_;
  };  // class RootDelayedReader
  //------------------------------------------------------------
}  // namespace edm
#endif