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Tpetra_Details_gathervPrint.cpp
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43 
44 #include <Tpetra_Details_gathervPrint.hpp>
45 #include <Teuchos_CommHelpers.hpp>
46 #include <algorithm>
47 
48 namespace Tpetra {
49 namespace Details {
50 
51 void
52 gathervPrint (std::ostream& out,
53  const std::string& s,
54  const Teuchos::Comm<int>& comm)
55 {
56  using Teuchos::ArrayRCP;
57  using Teuchos::CommRequest;
58  using Teuchos::ireceive;
59  using Teuchos::isend;
60  using Teuchos::outArg;
61  using Teuchos::RCP;
62  using Teuchos::wait;
63 
64  const int myRank = comm.getRank ();
65  const int rootRank = 0;
66  if (myRank == rootRank) {
67  out << s; // Proc 0 prints its buffer first
68  }
69 
70  const int numProcs = comm.getSize ();
71  const int sizeTag = 42;
72  const int msgTag = 43;
73 
74  ArrayRCP<size_t> sizeBuf (1);
75  ArrayRCP<char> msgBuf; // to be resized later
76  RCP<CommRequest<int> > req;
77 
78  for (int p = 1; p < numProcs; ++p) {
79  if (myRank == p) {
80  sizeBuf[0] = s.size ();
81  req = isend<int, size_t> (sizeBuf, rootRank, sizeTag, comm);
82  (void) wait<int> (comm, outArg (req));
83 
84  const size_t msgSize = s.size ();
85  msgBuf.resize (msgSize + 1); // for the '\0'
86  std::copy (s.begin (), s.end (), msgBuf.begin ());
87  msgBuf[msgSize] = '\0';
88 
89  req = isend<int, char> (msgBuf, rootRank, msgTag, comm);
90  (void) wait<int> (comm, outArg (req));
91  }
92  else if (myRank == rootRank) {
93  sizeBuf[0] = 0; // just a precaution
94  req = ireceive<int, size_t> (sizeBuf, p, sizeTag, comm);
95  (void) wait<int> (comm, outArg (req));
96 
97  const size_t msgSize = sizeBuf[0];
98  msgBuf.resize (msgSize + 1); // for the '\0'
99  req = ireceive<int, char> (msgBuf, p, msgTag, comm);
100  (void) wait<int> (comm, outArg (req));
101 
102  std::string msg (msgBuf.getRawPtr ());
103  out << msg;
104  }
105  }
106 }
107 
108 } // namespace Details
109 } // namespace Tpetra
void gathervPrint(std::ostream &out, const std::string &s, const Teuchos::Comm< int > &comm)
On Process 0 in the given communicator, print strings from each process in that communicator, in rank order.