Try to stay out of parallel_implementation.h. Generally you don't need to
go down that far unless you are adding new type specializations. The
signatures you need for most communication patterns are in parallel.h:
/**
* Blocking-send to one processor with data-defined type.
*/
template <typename T>
void send (const unsigned int dest_processor_id,
T &buf,
const MessageTag &tag=no_tag) const;
/**
* Blocking-receive from one processor with data-defined type.
*/
template <typename T>
Status receive (const unsigned int dest_processor_id,
T &buf,
const MessageTag &tag=any_tag) const;
So sending/recieving looks more like this:
_communicator.send(rank, some_vector);
_communicator.receive(rank, some_vector):
BTW - When you are using MOOSE, you'll have a built-in Communicator in
every object. It's simply "_comm".
Cody
On Thu, Mar 12, 2015 at 10:40 AM Lei Zhao <leizhao...@gmail.com> wrote:
> Hi All,
>
> I am working on some parallelism with Communicator. But I don't understand
> exactly the syntax of _communicator.send and _communicator.receive. This is
> the definition of send for sending a vector in parallel_implementation.h.
>
> *template <typename T>*
> *inline void Communicator::send (const unsigned int dest_processor_id,*
> * std::vector<T> &buf,*
> * const DataType &type,*
> * Request &req,*
> * const MessageTag &tag) const*
> *{*
> * START_LOG("send()", "Parallel");*
>
> *#ifndef NDEBUG*
> * // Only catch the return value when asserts are active.*
> * const int ierr =*
> *#endif*
> * ((this->send_mode() == SYNCHRONOUS) ?*
> * MPI_Issend : MPI_Isend) (buf.empty() ? NULL : &buf[0],*
> * cast_int<int>(buf.size()),*
> * type,*
> * dest_processor_id,*
> * tag.value(),*
> * this->get(),*
> * req.get());*
>
> * libmesh_assert (ierr == MPI_SUCCESS);*
>
> * STOP_LOG("send()", "Parallel");*
> *}*
>
>
> Suppose I want to send a vector<double> from processor 0 to processor 1. I
> tried the following:
>
> if (_communicator.rank() == 0)
> {
> std::vector<double> sender;
> sender.push_back(1.1);
> sender.push_back(2.2);
> Request & req;
> * _communicator.send(1, &sender, MPI::DOUBLE, req, 10.231);*
> }
> else if (_communicator.rank() == 1)
> {
> std::vector<double> receiver(2);
> Request & req;
> * _communicator.receive(0, &receiver, MPI::DOUBLE, req, 10.231);*
> }
>
>
> I encountered the compilation errors as follows. Does anyone know how to
> setup the correct syntax for this case?
>
>
> *'Request' was not declared in this scope'MPI' has not been declared*
>
>
> Thank you very much,
> Lei
>
>
> -------------------------------------------------------------------
> Lei Zhao
> Research Assistant
> University of Wisconsin-Madison
> 206 Materials Science & Engineering
> 1509 University Avenue
> Madison, WI 53706, US
> Email: lzha...@wisc.edu
> Tel.: (608)332-8385
> ------------------------------------------------------------
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news, videos, case studies, tutorials and more. Take a look and join the
conversation now. http://goparallel.sourceforge.net/
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