#include <petsc/private/petscimpl.h>              /*I "petscsys.h" I*/

/* Logging support */
PetscLogEvent PETSC_Barrier=0;

static int hash(const char *str)
{
  int c,hash = 5381;

  while ((c = *str++)) hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
  return hash;
}

PetscErrorCode PetscAllreduceBarrierCheck(MPI_Comm comm,PetscMPIInt ctn,int line,const char *func,const char *file)
{
  PetscMPIInt err;
  PetscMPIInt b1[2],b2[2];
  b1[0] = -(PetscMPIInt)line; b1[1] = (PetscMPIInt)line;
  err = MPI_Allreduce(b1,b2,2,MPI_INT,MPI_MAX,comm);
  if (err) {
    return PetscError(PETSC_COMM_SELF,line,func,file,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL,"MPI_Allreduced() failed");
  }
  if (-b2[0] != b2[1]) {
    return PetscError(PETSC_COMM_SELF,line,func,file,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL,"MPI_Allreduced() called in different locations on different processors");
  }
  b1[0] = -(PetscMPIInt)hash(func); b1[1] = -b1[0];
  err = MPI_Allreduce(b1,b2,2,MPI_INT,MPI_MAX,comm);
  if (err) {
    return PetscError(PETSC_COMM_SELF,line,func,file,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL,"MPI_Allreduced() failed");
  }
  if (-b2[0] != b2[1]) {
    return PetscError(PETSC_COMM_SELF,line,func,file,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL,"MPI_Allreduced() called in different locations on different processors");
  }
  b1[0] = -(PetscMPIInt)ctn; b1[1] = (PetscMPIInt)ctn;
  err = MPI_Allreduce(b1,b2,2,MPI_INT,MPI_MAX,comm);
  if (err) {
    return PetscError(PETSC_COMM_SELF,line,func,file,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL,"MPI_Allreduced() failed");
  }
  if (-b2[0] != b2[1]) {
    return PetscError(PETSC_COMM_SELF,line,func,file,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL,"MPI_Allreduced() called with different counts %d on different processors",ctn);
  }
  return 0;
}

#undef __FUNCT__
#define __FUNCT__ "PetscBarrier"
/*@C
    PetscBarrier - Blocks until this routine is executed by all
                   processors owning the object A.

   Input Parameters:
.  A - PETSc object  (Mat, Vec, IS, SNES etc...)
        Must be caste with a (PetscObject), can use NULL (for MPI_COMM_WORLD)

  Level: intermediate

  Notes:
  This routine calls MPI_Barrier with the communicator of the PETSc Object "A".

  With fortran Use NULL_OBJECT (instead of NULL)

   Concepts: barrier

@*/
PetscErrorCode  PetscBarrier(PetscObject obj)
{
  PetscErrorCode ierr;
  MPI_Comm       comm;

  PetscFunctionBegin;
  if (obj) PetscValidHeader(obj,1);
  ierr = PetscLogEventBegin(PETSC_Barrier,obj,0,0,0);CHKERRQ(ierr);
  if (obj) {
    ierr = PetscObjectGetComm(obj,&comm);CHKERRQ(ierr);
  } else comm = PETSC_COMM_WORLD;
  ierr = MPI_Barrier(comm);CHKERRQ(ierr);
  ierr = PetscLogEventEnd(PETSC_Barrier,obj,0,0,0);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}