Actual source code: pbarrier.c
petsc-3.7.1 2016-05-15
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      2: #include <petsc/private/petscimpl.h>              /*I "petscsys.h" I*/

      4: /* Logging support */
      5: PetscLogEvent PETSC_Barrier=0;

      7: static int hash(const char *str)
      8: {
      9:   int c,hash = 5381;

     11:   while ((c = *str++)) hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
     12:   return hash;
     13: }

     15: PetscErrorCode PetscAllreduceBarrierCheck(MPI_Comm comm,PetscMPIInt ctn,int line,const char *func,const char *file)
     16: {
     17:   PetscMPIInt err;
     18:   PetscMPIInt b1[6],b2[6];

     20:   b1[0] = -(PetscMPIInt)line;       b1[1] = -b1[0];
     21:   b1[2] = -(PetscMPIInt)hash(func); b1[3] = -b1[2];
     22:   b1[4] = -(PetscMPIInt)ctn;        b1[5] = -b1[4];
     23:   err = MPI_Allreduce(b1,b2,6,MPI_INT,MPI_MAX,comm);
     24:   if (err) return PetscError(PETSC_COMM_SELF,line,func,file,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL,"MPI_Allreduced() failed");
     25:   if (-b2[0] != b2[1]) return PetscError(PETSC_COMM_SELF,line,func,file,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL,"MPI_Allreduce() called in different locations (code lines) on different processors");
     26:   if (-b2[2] != b2[3]) return PetscError(PETSC_COMM_SELF,line,func,file,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL,"MPI_Allreduce() called in different locations (functions) on different processors");
     27:   if (-b2[4] != b2[5]) return PetscError(PETSC_COMM_SELF,line,func,file,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL,"MPI_Allreduce() called with different counts %d on different processors",ctn);
     28:   return 0;
     29: }

     33: /*@C
     34:     PetscBarrier - Blocks until this routine is executed by all
     35:                    processors owning the object A.

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

     41:   Level: intermediate

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

     46:   With fortran Use NULL_OBJECT (instead of NULL)

     48:    Concepts: barrier

     50: @*/
     51: PetscErrorCode  PetscBarrier(PetscObject obj)
     52: {
     54:   MPI_Comm       comm;

     58:   PetscLogEventBegin(PETSC_Barrier,obj,0,0,0);
     59:   if (obj) {
     60:     PetscObjectGetComm(obj,&comm);
     61:   } else comm = PETSC_COMM_WORLD;
     62:   MPI_Barrier(comm);
     63:   PetscLogEventEnd(PETSC_Barrier,obj,0,0,0);
     64:   return(0);
     65: }