static const char help[] = "Test embedded sf with one leaf data item connnected to multiple roots\n\n";

#include <petscsf.h>

int main(int argc,char **argv)
{
  PetscSF        sf,newsf;
  PetscInt       i,nroots,nleaves,ilocal[2],leafdata,rootdata[2],nselected,selected,errors=0;
  PetscSFNode    iremote[2];
  PetscMPIInt    myrank,next,nproc;
  PetscErrorCode ierr;
  MPI_Info       info;

  ierr = PetscInitialize(&argc,&argv,NULL,help);if (ierr) return ierr;
  ierr = MPI_Comm_size(PETSC_COMM_WORLD,&nproc);CHKERRQ(ierr);
  ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&myrank);CHKERRQ(ierr);

  /* Create an SF that each process has two roots and two leaves. The two leaves are connected to the two
     roots on next process. The special thing is each process only has one data item in its leaf data buffer.
   */
  nroots    = 2;
  nleaves   = 2;
  ilocal[0] = 0; /* One leaf data item serves two leaves */
  ilocal[1] = 0;
  next      = (myrank+1)%nproc;
  for (i=0; i<nleaves; i++) {
    iremote[i].rank  = next;
    iremote[i].index = i;
  }

  ierr = PetscSFCreate(PETSC_COMM_WORLD,&sf);CHKERRQ(ierr);
  ierr = PetscSFSetGraph(sf,nroots,nleaves,ilocal,PETSC_COPY_VALUES,iremote,PETSC_COPY_VALUES);CHKERRQ(ierr);
  ierr = PetscSFSetFromOptions(sf);CHKERRQ(ierr);

  /* Test PetscSFWindowSetInfo */
  ierr = MPI_Info_create(&info);CHKERRQ(ierr);
  ierr = MPI_Info_set(info,"petsc_test_info1","info1");CHKERRQ(ierr);
  ierr = MPI_Info_set(info,"petsc_test_info2","info2");CHKERRQ(ierr);
  ierr = PetscSFWindowSetInfo(sf,info);CHKERRQ(ierr);
  ierr = MPI_Info_free(&info);CHKERRQ(ierr);

  ierr = PetscSFSetUp(sf);CHKERRQ(ierr);
  ierr = PetscSFViewFromOptions(sf,NULL,"-sf_view");CHKERRQ(ierr);

  /* Create an embedded sf by only selecting the first root on each process */
  nselected = 1;
  selected  = 0;
  ierr = PetscSFCreateEmbeddedSF(sf,nselected,&selected,&newsf);CHKERRQ(ierr);
  ierr = PetscSFViewFromOptions(newsf,NULL,"-esf_view");CHKERRQ(ierr);

  /* Do reduce */
  leafdata    = 1;
  rootdata[0] = rootdata[1] = 0;

  ierr = PetscSFReduceBegin(newsf,MPIU_INT,&leafdata,rootdata,MPIU_REPLACE);CHKERRQ(ierr);
  ierr = PetscSFReduceEnd(newsf,MPIU_INT,&leafdata,rootdata,MPIU_REPLACE);CHKERRQ(ierr);

  /* Check rootdata */
  if (rootdata[0] != 1 || rootdata[1] != 0) errors = 1;
  ierr = MPI_Allreduce(MPI_IN_PLACE,&errors,1,MPIU_INT,MPI_SUM,PETSC_COMM_WORLD);CHKERRQ(ierr);
  if (errors) {ierr = PetscPrintf(PETSC_COMM_WORLD,"Error: Unexpected rootdata on processors\n");CHKERRQ(ierr);}

  ierr = PetscSFDestroy(&sf);CHKERRQ(ierr);
  ierr = PetscSFDestroy(&newsf);CHKERRQ(ierr);
  ierr = PetscFinalize();
  return ierr;
}

/*TEST

   build:
      requires: mpi

   test:
      nsize: 2

   test:
      suffix: 1_window
      nsize: 2
      filter: grep -v "type" | grep -v "sort"
      output_file: output/ex2_1_window.out
      args: -sf_type window -sf_window_sync {{fence lock active}} -sf_window_flavor {{create dynamic allocate}} -sf_view ::ascii_info_detail -esf_view ::ascii_info_detail
      requires: define(PETSC_HAVE_MPI_ONE_SIDED)

   # The nightly test suite with MPICH uses ch3:sock, which is broken when winsize == 0 in some of the processes
   test:
      suffix: 1_window_shared
      nsize: 2
      output_file: output/ex2_1.out
      args: -sf_type window -sf_window_sync {{fence lock active}} -sf_window_flavor shared
      requires: define(PETSC_HAVE_MPI_PROCESS_SHARED_MEMORY) !define(PETSC_HAVE_MPICH_NUMVERSION) define(PETSC_HAVE_MPI_ONE_SIDED)

TEST*/