Actual source code: sfgatherv.c
petsc-3.13.6 2020-09-29
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      2:  #include <../src/vec/is/sf/impls/basic/gatherv/sfgatherv.h>

      4: /* Reuse the type. The difference is some fields (displs, recvcounts) are only significant
      5:    on rank 0 in Gatherv. On other ranks they are harmless NULL.
      6:  */
      7: typedef PetscSF_Allgatherv PetscSF_Gatherv;

      9: PETSC_INTERN PetscErrorCode PetscSFBcastAndOpBegin_Gatherv(PetscSF sf,MPI_Datatype unit,PetscMemType rootmtype,const void *rootdata,PetscMemType leafmtype,void *leafdata,MPI_Op op)
     10: {
     11:   PetscErrorCode       ierr;
     12:   PetscSFLink          link;
     13:   PetscMPIInt          sendcount;
     14:   MPI_Comm             comm;
     15:   PetscSF_Gatherv      *dat = (PetscSF_Gatherv*)sf->data;
     16:   void                 *rootbuf = NULL,*leafbuf = NULL; /* buffer seen by MPI */
     17:   MPI_Request          *req;

     20:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_BCAST,&link);
     21:   PetscSFLinkPackRootData(sf,link,PETSCSF_REMOTE,rootdata);
     22:   PetscObjectGetComm((PetscObject)sf,&comm);
     23:   PetscMPIIntCast(sf->nroots,&sendcount);
     24:   PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_../../../../../..2LEAF,&rootbuf,&leafbuf,&req,NULL);
     25:   MPIU_Igatherv(rootbuf,sendcount,unit,leafbuf,dat->recvcounts,dat->displs,unit,0/*rank 0*/,comm,req);
     26:   return(0);
     27: }

     29: static PetscErrorCode PetscSFReduceBegin_Gatherv(PetscSF sf,MPI_Datatype unit,PetscMemType leafmtype,const void *leafdata,PetscMemType rootmtype,void *rootdata,MPI_Op op)
     30: {
     31:   PetscErrorCode       ierr;
     32:   PetscSFLink          link;
     33:   PetscMPIInt          recvcount;
     34:   MPI_Comm             comm;
     35:   PetscSF_Gatherv      *dat = (PetscSF_Gatherv*)sf->data;
     36:   void                 *rootbuf = NULL,*leafbuf = NULL; /* buffer seen by MPI */
     37:   MPI_Request          *req;

     40:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_REDUCE,&link);
     41:   PetscSFLinkPackLeafData(sf,link,PETSCSF_REMOTE,leafdata);
     42:   PetscObjectGetComm((PetscObject)sf,&comm);
     43:   PetscMPIIntCast(sf->nroots,&recvcount);
     44:   PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_LEAF2../../../../../..,&rootbuf,&leafbuf,&req,NULL);
     45:   MPIU_Iscatterv(leafbuf,dat->recvcounts,dat->displs,unit,rootbuf,recvcount,unit,0,comm,req);
     46:   return(0);
     47: }

     49: PETSC_INTERN PetscErrorCode PetscSFFetchAndOpBegin_Gatherv(PetscSF sf,MPI_Datatype unit,PetscMemType rootmtype,void *rootdata,PetscMemType leafmtype,const void *leafdata,void *leafupdate,MPI_Op op)
     50: {
     51:   PetscErrorCode      ierr;

     54:   /* In Gatherv, each root only has one leaf. So we just need to bcast rootdata to leafupdate and then reduce leafdata to rootdata */
     55:   PetscSFBcastAndOpBegin(sf,unit,rootdata,leafupdate,MPIU_REPLACE);
     56:   PetscSFBcastAndOpEnd(sf,unit,rootdata,leafupdate,MPIU_REPLACE);
     57:   PetscSFReduceBegin(sf,unit,leafdata,rootdata,op);
     58:   return(0);
     59: }

     61: PETSC_INTERN PetscErrorCode PetscSFCreate_Gatherv(PetscSF sf)
     62: {
     63:   PetscErrorCode  ierr;
     64:   PetscSF_Gatherv *dat = (PetscSF_Gatherv*)sf->data;

     67:   sf->ops->BcastAndOpEnd   = PetscSFBcastAndOpEnd_Basic;
     68:   sf->ops->ReduceEnd       = PetscSFReduceEnd_Basic;

     70:   /* Inherit from Allgatherv */
     71:   sf->ops->SetUp           = PetscSFSetUp_Allgatherv;
     72:   sf->ops->Reset           = PetscSFReset_Allgatherv;
     73:   sf->ops->Destroy         = PetscSFDestroy_Allgatherv;
     74:   sf->ops->GetGraph        = PetscSFGetGraph_Allgatherv;
     75:   sf->ops->GetLeafRanks    = PetscSFGetLeafRanks_Allgatherv;
     76:   sf->ops->GetRootRanks    = PetscSFGetRootRanks_Allgatherv;
     77:   sf->ops->FetchAndOpEnd   = PetscSFFetchAndOpEnd_Allgatherv;
     78:   sf->ops->CreateLocalSF   = PetscSFCreateLocalSF_Allgatherv;

     80:   /* Gatherv stuff */
     81:   sf->ops->BcastAndOpBegin = PetscSFBcastAndOpBegin_Gatherv;
     82:   sf->ops->ReduceBegin     = PetscSFReduceBegin_Gatherv;
     83:   sf->ops->FetchAndOpBegin = PetscSFFetchAndOpBegin_Gatherv;

     85:   PetscNewLog(sf,&dat);
     86:   sf->data = (void*)dat;
     87:   return(0);
     88: }