xref: /petsc/src/vec/is/sf/impls/basic/gather/sfgather.c (revision 58c0e5077dcf40d6a880c19c87f1075ae1d22c8e)
1 #include <../src/vec/is/sf/impls/basic/gatherv/sfgatherv.h>
2 
3 typedef PetscSFPack_Allgatherv PetscSFPack_Gather;
4 #define PetscSFPackGet_Gather PetscSFPackGet_Allgatherv
5 
6 /* Reuse the type. The difference is some fields (i.e., displs, recvcounts) are not used in Gather, which is not a big deal */
7 typedef PetscSF_Allgatherv PetscSF_Gather;
8 
9 PETSC_INTERN PetscErrorCode PetscSFBcastAndOpBegin_Gather(PetscSF sf,MPI_Datatype unit,const void *rootdata,void *leafdata,MPI_Op op)
10 {
11   PetscErrorCode       ierr;
12   PetscSFPack_Gatherv  link;
13   PetscMPIInt          rank,sendcount;
14   MPI_Comm             comm;
15   void                 *recvbuf;
16 
17   PetscFunctionBegin;
18   ierr = PetscSFPackGet_Gatherv(sf,unit,rootdata,leafdata,&link);CHKERRQ(ierr);
19   ierr = PetscObjectGetComm((PetscObject)sf,&comm);CHKERRQ(ierr);
20 
21   if (op == MPIU_REPLACE) {
22     recvbuf = leafdata;
23   } else {
24     ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
25     if (!link->leaf && !rank) {ierr = PetscMalloc(sf->nleaves*link->unitbytes,&link->leaf);CHKERRQ(ierr);}
26     recvbuf = link->leaf;
27   }
28 
29   ierr = PetscMPIIntCast(sf->nroots,&sendcount);CHKERRQ(ierr);
30   ierr = MPIU_Igather(rootdata,sendcount,unit,recvbuf,sendcount,unit,0/*rank 0*/,comm,&link->request);CHKERRQ(ierr);
31   PetscFunctionReturn(0);
32 }
33 
34 static PetscErrorCode PetscSFReduceBegin_Gather(PetscSF sf,MPI_Datatype unit,const void *leafdata,void *rootdata,MPI_Op op)
35 {
36   PetscErrorCode       ierr;
37   PetscSFPack_Gatherv  link;
38   PetscMPIInt          recvcount;
39   MPI_Comm             comm;
40   void                 *recvbuf;
41 
42   PetscFunctionBegin;
43   ierr = PetscSFPackGet_Gatherv(sf,unit,rootdata,leafdata,&link);CHKERRQ(ierr);
44   ierr = PetscObjectGetComm((PetscObject)sf,&comm);CHKERRQ(ierr);
45 
46   if (op == MPIU_REPLACE) {
47     recvbuf = rootdata;
48   } else {
49     if (!link->root) {ierr = PetscMalloc(sf->nroots*link->unitbytes,&link->root);CHKERRQ(ierr);}
50     recvbuf = link->root;
51   }
52 
53   ierr = PetscMPIIntCast(sf->nroots,&recvcount);CHKERRQ(ierr);
54   ierr = MPIU_Iscatter(leafdata,recvcount,unit,recvbuf,recvcount,unit,0/*rank 0*/,comm,&link->request);CHKERRQ(ierr);
55   PetscFunctionReturn(0);
56 }
57 
58 PETSC_INTERN PetscErrorCode PetscSFCreate_Gather(PetscSF sf)
59 {
60   PetscErrorCode  ierr;
61   PetscSF_Gather  *dat = (PetscSF_Gather*)sf->data;
62 
63   PetscFunctionBegin;
64   /* Inherit from Allgatherv */
65   sf->ops->Reset           = PetscSFReset_Allgatherv;
66   sf->ops->Destroy         = PetscSFDestroy_Allgatherv;
67   sf->ops->GetGraph        = PetscSFGetGraph_Allgatherv;
68   sf->ops->GetRootRanks    = PetscSFGetRootRanks_Allgatherv;
69   sf->ops->GetLeafRanks    = PetscSFGetLeafRanks_Allgatherv;
70   sf->ops->BcastAndOpEnd   = PetscSFBcastAndOpEnd_Allgatherv;
71   sf->ops->ReduceEnd       = PetscSFReduceEnd_Allgatherv;
72   sf->ops->FetchAndOpEnd   = PetscSFFetchAndOpEnd_Allgatherv;
73   sf->ops->CreateLocalSF   = PetscSFCreateLocalSF_Allgatherv;
74 
75   /* Inherit from Gatherv */
76   sf->ops->FetchAndOpBegin = PetscSFFetchAndOpBegin_Gatherv;
77 
78   /* Gather stuff */
79   sf->ops->BcastAndOpBegin = PetscSFBcastAndOpBegin_Gather;
80   sf->ops->ReduceBegin     = PetscSFReduceBegin_Gather;
81 
82   ierr     = PetscNewLog(sf,&dat);CHKERRQ(ierr);
83   sf->data = (void*)dat;
84   PetscFunctionReturn(0);
85 }
86 
87