globalIndex.H

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/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
-------------------------------------------------------------------------------
    Copyright (C) 2011-2017 OpenFOAM Foundation
    Copyright (C) 2018-2022 OpenCFD Ltd.
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

Class
    Foam::globalIndex

Description
    Calculates a unique integer (label so might not have enough room - 2G max)
    for processor + local index. E.g.

    globalIndex globalFaces(mesh.nFaces());
    label globalFacei = globalFaces.toGlobal(facei);

SourceFiles
    globalIndex.C
    globalIndexI.H
    globalIndexTemplates.C

\*---------------------------------------------------------------------------*/

#ifndef Foam_globalIndex_H
#define Foam_globalIndex_H

#include "Pstream.H"
#include "CompactListList.H"
#include "DynamicList.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

// Forward Declarations
class globalIndex;
class labelRange;

Istream& operator>>(Istream& is, globalIndex& gi);
Ostream& operator<<(Ostream& os, const globalIndex& gi);


/*---------------------------------------------------------------------------*\
                           Class globalIndex Declaration
\*---------------------------------------------------------------------------*/

class globalIndex
{
    // Private Data

        //- Start of proci. Size is nProcs()+1. (so like CompactListList)
        labelList offsets_;


    // Private Member Functions

        //- Sort and bin. validBins contains bins with non-zero size.
        static CompactListList<label>
        bin
        (
            const labelUList& offsets,
            const labelUList& globalIds,
            labelList& order,
            DynamicList<label>& validBins
        );

        //- Report overflow at specified index
        static void reportOverflowAndExit
        (
            const label idx,
            const labelUList& localLens = labelUList::null()
        );

public:

    // Public Data Types

        //- Disambiguation tag (list construction dispatch)
        enum accessType : char { OFFSETS, SIZES };

        //- Dispatch tag.
        //- Construct with a single (local size) entry, no communication.
        struct gatherNone{};

        //- Dispatch tag.
        //- Construct 'one-sided' from local sizes,
        //- using gather but no broadcast.
        struct gatherOnly{};

        //- Dispatch tag.
        //- Construct 'one-sided' from the non-master local sizes
        //- using gather but no broadcast.
        struct gatherNonLocal{};


    // Constructors

        //- Default construct (empty)
        globalIndex() noexcept = default;

        //- Copy construct from a list of offsets.
        //- No communication required
        inline explicit globalIndex(const labelUList& listOffsets);

        //- Move construct from a list of offsets.
        //- No communication required
        inline explicit globalIndex(labelList&& listOffsets);

        //- Copy construct from a list of offsets or sizes.
        //- No communication required
        inline globalIndex
        (
            const labelUList& offsetsOrSizes,
            enum accessType accType
        );

        //- Construct from local size, using gather/broadcast
        //- with default/specified communicator if parallel.
        inline explicit globalIndex
        (
            const label localSize,
            const label comm = UPstream::worldComm,   
            const bool parallel = UPstream::parRun()  
        );

        //- Construct with a single (local size) entry, no communication
        inline globalIndex
        (
            const globalIndex::gatherNone,
            const label localSize,
            const label comm = -1   
        );

        //- Construct 'one-sided' from local sizes.
        //- Uses UPstream::listGatherValues, but no broadcast.
        //- Will be empty on non-master processes.
        //
        //  \note can be used when Pstream::parRun() is false.
        inline globalIndex
        (
            const globalIndex::gatherOnly,
            const label localSize,
            const label comm = UPstream::worldComm  
        );

        //- Construct 'one-sided' from the non-master local sizes
        //- (ie, master size is treated as 0).
        //- Uses UPstream::listGatherValues, but no broadcast.
        //- Will be empty on non-master processes.
        //
        //  \note can be used when Pstream::parRun() is false.
        inline globalIndex
        (
            const globalIndex::gatherNonLocal,
            const label localSize,
            const label comm = UPstream::worldComm  
        );

        //- Construct from Istream.
        //- No communication required
        explicit globalIndex(Istream& is);


    // Member Functions

        //- Check for default constructed or global sum == 0
        inline bool empty() const;

        //- Global sum of localSizes. Same as totalSize()
        inline label size() const;

        //- Global sum of localSizes.
        inline label totalSize() const;

        //- The local sizes. Same as localSizes()
        inline labelList sizes() const;

        //- The local starts
        inline const labelUList localStarts() const;

        //- The local sizes
        labelList localSizes() const;

        //- Global max of localSizes
        inline label maxSize() const;


    // Access

        //- Const-access to the offsets
        inline const labelList& offsets() const noexcept;

        //- Write-access to the offsets, for changing after construction
        inline labelList& offsets() noexcept;


    // Dimensions

        //- The number of processors covered by the offsets
        inline label nProcs() const noexcept;

        //- Range of process indices for all addressed offsets (processes)
        inline labelRange allProcs() const noexcept;

        //- Range of process indices for addressed sub-offsets (processes)
        inline labelRange subProcs() const noexcept;


    // Edit

        //- Reset to be empty (no offsets)
        inline void clear();

        //- Reset from local size, using gather/broadcast
        //- with default/specified communicator if parallel.
        void reset
        (
            const label localSize,
            const label comm = UPstream::worldComm,   
            const bool parallel = UPstream::parRun()  
        );

        //- Reset from list of local sizes,
        //- with optional check for label overflow.
        //- No communication required
        void reset
        (
            const labelUList& localLens,
            const bool checkOverflow = false
        );

        //- Reset to a single (local size) entry, no communication
        inline void reset
        (
            const globalIndex::gatherNone,
            const label localSize,
            const label comm = -1   
        );

        //- Reset as 'one-sided' from local sizes.
        //- Uses UPstream::listGatherValues, but no broadcast.
        //- Will be empty on non-master processes.
        //
        //  \note can be used when Pstream::parRun() is false.
        inline void reset
        (
            const globalIndex::gatherOnly,
            const label localSize,
            const label comm = UPstream::worldComm  
        );

        //- Reset as 'one-sided' from the non-master local sizes
        //- (ie, master size is treated as 0).
        //- Uses UPstream::listGatherValues, but no broadcast.
        //- Will be empty on non-master processes.
        //
        //  \note can be used when Pstream::parRun() is false.
        inline void reset
        (
            const globalIndex::gatherNonLocal,
            const label localSize,
            const label comm = UPstream::worldComm  
        );

        //- Alter local size for given processor
        void setLocalSize(const label proci, const label len);


    // Queries

        // Queries relating to my processor (using world communicator)

            //- My local start
            inline label localStart() const;

            //- My local size
            inline label localSize() const;

            //- The max of localSizes, excluding current processor
            inline label maxNonLocalSize() const;

            //- Return start/size range of local processor data
            inline labelRange range() const;

            //- Return start/size ranges for all data
            List<labelRange> ranges() const;

            //- Is on local processor
            inline bool isLocal(const label i) const;

            //- From local to global index
            inline label toGlobal(const label i) const;

            //- From local to global index
            inline labelList toGlobal(const labelUList& labels) const;

            //- From local to global index (inplace)
            inline void inplaceToGlobal(labelUList& labels) const;

            //- From global to local on current processor.
            //  FatalError if not on local processor.
            inline label toLocal(const label i) const;


        // Global (off-processor) queries

            //- Start of proci data
            inline label localStart(const label proci) const;

            //- Size of proci data
            inline label localSize(const label proci) const;

            //- The max of localSizes, excluding the specified processor
            label maxNonLocalSize(const label proci) const;

            //- Return start/size range of proci data
            inline labelRange range(const label proci) const;

            //- Is on processor proci
            inline bool isLocal(const label proci, const label i) const;

            //- From local to global on proci
            inline label toGlobal(const label proci, const label i) const;

            //- From local to global on proci
            inline labelList toGlobal
            (
                const label proci,
                const labelUList& labels
            ) const;

            //- From local to global index on proci (inplace)
            inline void inplaceToGlobal
            (
                const label proci,
                labelUList& labels
            ) const;


            //- From global to local on proci
            inline label toLocal(const label proci, const label i) const;

            //- Which processor does global id come from?
            //  Does an initial check for isLocal first (assumed to occur
            //  reasonably frequently) followed by a binary search.
            //- Fatal for out of range ids (eg, negative or >= totalSize()
            inline label whichProcID(const label i) const;


    // Iteration

        //- Forward input iterator with const access
        class const_iterator
        {
            //- The parent class for which this is an iterator
            const globalIndex* parent_;

            //- The index into the parent
            label proci_;


        public:

        // Constructors

            //- Construct from globalIndex list at given index
            explicit const_iterator
            (
                const globalIndex* globalIdx,
                const label proci = 0
            ) noexcept;


        // Member Operators

            //- The associated local proc
            inline label proci() const noexcept;

            //- The local start
            inline label start() const;

            //- The local size
            inline label size() const;

            //- The local range
            inline labelRange range() const;

            //- The local range
            inline labelRange operator*() const;

            inline const_iterator& operator++();
            inline const_iterator operator++(int);

            inline const_iterator& operator--();
            inline const_iterator operator--(int);

            inline bool operator==(const const_iterator& iter) const noexcept;
            inline bool operator!=(const const_iterator& iter) const noexcept;
        };


        //- A const_iterator set to the beginning
        inline const_iterator cbegin() const noexcept;

        //- A const_iterator set to beyond the end
        inline const const_iterator cend() const noexcept;

        //- A const_iterator set to the beginning
        inline const_iterator begin() const noexcept;

        //- A const_iterator set to beyond the end
        inline const const_iterator end() const noexcept;


    // Helper Functions

        //- Calculate offsets from a list of local sizes,
        //- with optional check for label overflow
        static labelList calcOffsets
        (
            const labelUList& localLens,
            const bool checkOverflow = false
        );

        //- Calculate offsets from list of lists,
        //- with optional check for label overflow
        template<class SubListType>
        static labelList calcListOffsets
        (
            const List<SubListType>& lists,
            const bool checkOverflow = false
        );

        //- Calculate ranges (offset/size) from a list of local sizes,
        //- with optional check for label overflow
        static List<labelRange> calcRanges
        (
            const labelUList& localLens,
            const bool checkOverflow = false
        );

        //- Collect single values in processor order on master (== procIDs[0]).
        //  Handles contiguous/non-contiguous data.
        template<class ProcIDsContainer, class Type>
        static void gatherValues
        (
            const label comm,           
            const ProcIDsContainer& procIDs,
            const Type& localValue,
            List<Type>& allValues,      
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking
        );

        //- Collect data in processor order on master (== procIDs[0]).
        //  Handles contiguous/non-contiguous data, skips empty fields.
        template<class ProcIDsContainer, class Type>
        static void gather
        (
            const labelUList& offsets,  
            const label comm,           
            const ProcIDsContainer& procIDs,
            const UList<Type>& fld,
            List<Type>& allFld,         
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking
        );

        //- Collect indirect data in processor order on master
        //  Handles contiguous/non-contiguous data, skips empty fields.
        template<class Type, class Addr>
        static void gather
        (
            const labelUList& offsets,  
            const label comm,           
            const UList<int>& procIDs,
            const IndirectListBase<Type, Addr>& fld,
            List<Type>& allFld,         
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking
        );


    // Misc low-level gather routines

        //- Inplace collect in processor order on master (== procIDs[0]).
        //  Note: adjust naming?
        template<class ProcIDsContainer, class Type>
        static void gather
        (
            const labelUList& offsets,  
            const label comm,           
            const ProcIDsContainer& procIDs,
            List<Type>& fld,            
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes ct = UPstream::commsTypes::nonBlocking
        )
        {
            List<Type> allData;
            gather(offsets, comm, procIDs, fld, allData, tag, ct);
            if (Pstream::myProcNo(comm) == procIDs[0])
            {
                fld.transfer(allData);
            }
        }

        //- Collect data in processor order on master (== procIDs[0]).
        //  \note the globalIndex offsets needed on master only.
        template<class ProcIDsContainer, class Type>
        void gather
        (
            const label comm,           
            const ProcIDsContainer& procIDs,
            const UList<Type>& fld,     
            List<Type>& allFld,         
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes ct = UPstream::commsTypes::nonBlocking
        ) const
        {
            gather(offsets_, comm, procIDs, fld, allFld, tag, ct);
        }

        //- Inplace collect in processor order on master (== procIDs[0]).
        //  \note the globalIndex offsets needed on master only.
        //  Note: adjust naming?
        template<class ProcIDsContainer, class Type>
        void gather
        (
            const label comm,           
            const ProcIDsContainer& procIDs,
            List<Type>& fld,            
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes ct = UPstream::commsTypes::nonBlocking
        ) const
        {
            gather(offsets_, comm, procIDs, fld, tag, ct);
        }


    // Gather

        //- Collect data in processor order on master
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator, message tag.
        template<class Type>
        void gather
        (
            const UList<Type>& sendData,
            List<Type>& allData,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        ) const;

        //- Collect data indirectly in processor order on master
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator, message tag.
        template<class Type, class Addr>
        void gather
        (
            const IndirectListBase<Type, Addr>& sendData,
            List<Type>& allData,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        ) const;

        //- Collect data in processor order on master
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator, message tag.
        //
        //  \return output (master), zero-sized on non-master
        template<class Type, class OutputContainer = List<Type>>
        OutputContainer gather
        (
            const UList<Type>& sendData,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        ) const;

        //- Collect data indirectly in processor order on master.
        //  Communication with default/specified communicator, message tag.
        //
        //  \return output (master), zero-sized on non-master
        template<class Type, class Addr, class OutputContainer = List<Type>>
        OutputContainer gather
        (
            const IndirectListBase<Type, Addr>& sendData,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        ) const;

        //- Inplace collect data in processor order on master
        //- (in serial: a no-op).
        //  Communication with default/specified communicator, message tag.
        //  After the gather, the field is zero-sized on the slaves.
        template<class Type>
        void gatherInplace
        (
            List<Type>& fld,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        ) const;

        //- Use MPI_Gatherv call for contiguous data when possible
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator.
        //  \attention The nProcs for globalIndex and communicator
        //      must match!!
        //
        //  The allData is output (master), zero-sized on non-master
        template<class Type, class OutputContainer = List<Type>>
        void mpiGather
        (
            const UList<Type>& sendData,
            OutputContainer& allData,
            const label comm = UPstream::worldComm,  

            // For fallback routines:
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const int tag = UPstream::msgType()
        ) const;

        //- Use MPI_Gatherv call for contiguous data when possible
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator.
        //  \attention The nProcs for globalIndex and communicator
        //      must match!!
        //
        //  \return output (master), zero-sized on non-master
        template<class Type, class OutputContainer = List<Type>>
        OutputContainer mpiGather
        (
            const UList<Type>& sendData,
            const label comm = UPstream::worldComm,  

            // For fallback routines:
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const int tag = UPstream::msgType()
        ) const;

        //- Use MPI_Gatherv call to inplace collect contiguous data
        //- when possible.
        //- (in serial: a no-op).
        //  Communication with default/specified communicator.
        //  \attention The nProcs for globalIndex and communicator
        //      must match!!
        //
        //  After the gather, the field is zero-sized on non-master.
        template<class Type>
        void mpiGatherInplace
        (
            List<Type>& fld,
            const label comm = UPstream::worldComm,  

            // For fallback routines:
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const int tag = UPstream::msgType()
        ) const;


    // Gather Operations

        //- Use MPI_Gatherv call to collect contiguous data when possible
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator.
        //
        //  The allData is output (master), zero-sized on non-master
        template<class Type, class OutputContainer = List<Type>>
        static void mpiGatherOp
        (
            const UList<Type>& sendData,
            OutputContainer& allData,
            const label comm = UPstream::worldComm,  

            // For fallback routines:
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const int tag = UPstream::msgType()
        );

        //- Use MPI_Gatherv call to collect contiguous data when possible
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator.
        //
        //  \return output (master), zero-sized on non-master
        template<class Type, class OutputContainer = List<Type>>
        static OutputContainer mpiGatherOp
        (
            const UList<Type>& sendData,
            const label comm = UPstream::worldComm,  

            // For fallback routines:
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const int tag = UPstream::msgType()
        );

        //- Use MPI_Gatherv call to inplace collect contiguous data
        //- when possible.
        //- (in serial: a no-op).
        //  Communication with default/specified communicator.
        //
        //  After the gather, the field is zero-sized on non-master.
        template<class Type>
        static void mpiGatherInplaceOp
        (
            List<Type>& fld,
            const label comm = UPstream::worldComm,  

            // For fallback routines:
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const int tag = UPstream::msgType()
        );

        //- Collect data in processor order on master
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator, message tag.
        //
        //  The allFld is output (master), zero-sized on non-master
        template<class Type>
        static void gatherOp
        (
            const UList<Type>& sendData,
            List<Type>& allData,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        );

        //- Collect data in processor order on master
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator, message tag.
        //
        //  The allFld is output (master), zero-sized on non-master
        template<class Type, class Addr>
        static void gatherOp
        (
            const IndirectListBase<Type, Addr>& sendData,
            List<Type>& allData,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        );

        //- Collect and return data in processor order on master
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator, message tag.
        //
        //  \return output (master), zero-sized on non-master
        template<class Type, class OutputContainer = List<Type>>
        static OutputContainer gatherOp
        (
            const UList<Type>& sendData,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        );

        //- Collect and return data in processor order on master
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator, message tag.
        //
        //  \return output (master), zero-sized on non-master
        template<class Type, class Addr, class OutputContainer = List<Type>>
        static OutputContainer gatherOp
        (
            const IndirectListBase<Type, Addr>& sendData,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        );

        //- Inplace collect data in processor order on master
        //- (in serial: a no-op).
        //  Communication with default/specified communicator, message tag.
        //
        //  After the gather, the field is zero-sized on the slaves.
        template<class Type>
        static void gatherInplaceOp
        (
            List<Type>& fld,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        );


    // Scatter

        //- Distribute data in processor order.
        //  Requires fld to be correctly sized!
        //  Communication with default/specified communicator, message tag.
        template<class ProcIDsContainer, class Type>
        static void scatter
        (
            const labelUList& offsets,  
            const label comm,           
            const ProcIDsContainer& procIDs,
            const UList<Type>& allFld,
            UList<Type>& fld,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking
        );

        //- Distribute data in processor order.
        //  Requires fld to be correctly sized!
        //  Communication with default/specified communicator, message tag.
        //  \note the globalIndex offsets needed on master only.
        template<class ProcIDsContainer, class Type>
        void scatter
        (
            const label comm,           
            const ProcIDsContainer& procIDs,
            const UList<Type>& allFld,
            UList<Type>& fld,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes ct =
                UPstream::commsTypes::nonBlocking
        ) const
        {
            scatter(offsets_, comm, procIDs, allFld, fld, tag, ct);
        }

        //- Distribute data in processor order.
        //  Requires fld to be correctly sized!
        //  Communication with default/specified communicator, message tag.
        //  \note the globalIndex offsets needed on master only.
        template<class Type>
        void scatter
        (
            const UList<Type>& allData,
            UList<Type>& localData,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        ) const;

        //- Distribute data in processor order
        //- (in serial: performs a simple copy).
        //  Communication with default/specified communicator, message tag.
        //  \note the globalIndex offsets needed on master only.
        template<class Type, class OutputContainer = List<Type>>
        OutputContainer scatter
        (
            const UList<Type>& allData,
            const int tag = UPstream::msgType(),
            const UPstream::commsTypes = UPstream::commsTypes::nonBlocking,
            const label comm = UPstream::worldComm  
        ) const;


    // Scatter

        //- Get (potentially remote) data.
        //- Elements required given as global indices
        //  Communication with default/specified communicator, message tag.
        template<class Type, class CombineOp>
        void get
        (
            List<Type>& allFld,
            const labelUList& globalIds,
            const CombineOp& cop,
            const label comm = UPstream::worldComm,  
            const int tag = UPstream::msgType()
        ) const;


    // IOstream Operators

        friend Istream& operator>>(Istream& is, globalIndex& gi);
        friend Ostream& operator<<(Ostream& os, const globalIndex& gi);


    // Housekeeping

        //- Construct with a single (local size) entry, no communication
        globalIndex
        (
            const label localSize,
            const globalIndex::gatherNone,
            const label comm = -1   
        )
        :
            globalIndex(gatherNone{}, localSize, comm)
        {}

        //- Construct 'one-sided' from local sizes.
        globalIndex
        (
            const label localSize,
            const globalIndex::gatherOnly,
            const label comm = UPstream::worldComm
        )
        :
            globalIndex(gatherOnly{}, localSize, comm)
        {}

        //- Construct from local size, using gather/broadcast
        //- with default/specified communicator if parallel.
        FOAM_DEPRECATED_FOR(2022-03, "construct without message tag")
        globalIndex
        (
            const label localSize,
            const int tag,          // message tag (unused)
            const label comm,       // communicator
            const bool parallel     // use parallel comms
        )
        {
            reset(localSize, comm, parallel);
        }

        //- Reset from local size, using gather/broadcast
        //- with default/specified communicator if parallel.
        FOAM_DEPRECATED_FOR(2022-03, "reset without message tag")
        void reset
        (
            const label localSize,
            const int tag,          // message tag (unused)
            const label comm,       // communicator
            const bool parallel     // use parallel comms
        )
        {
            reset(localSize, comm, parallel);
        }

        //- Prefer localStart() to avoid confusing with offsets()
        FOAM_DEPRECATED_FOR(2022-02, "use localStart()")
        label offset(const label proci) const { return localStart(proci); }

        //- Reset as 'one-sided' from local sizes [gather, but no broadcast]
        //- Will be empty on non-master processes.
        //
        //  \note can be used when Pstream::parRun() is false.
        void reset
        (
            const label localSize,
            const globalIndex::gatherOnly,
            const label comm = UPstream::worldComm  
        )
        {
            reset(globalIndex::gatherOnly{}, localSize, comm);
        }
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#include "globalIndexI.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#ifdef NoRepository
    #include "globalIndexTemplates.C"
#endif

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //