From 13760c480274176b29a6c6b8ff0d4bbf6f9d276d Mon Sep 17 00:00:00 2001
From: Sebastian Eibl <sebastian.eibl@fau.de>
Date: Mon, 29 Jun 2020 11:03:57 +0200
Subject: [PATCH] allToAll and allToLower test for communication with unknown
 sender ranks

---
 src/core/mpi/BufferSystem.h         |  1 +
 src/core/mpi/BufferSystem.impl.h    | 14 +++++
 tests/core/mpi/BufferSystemTest.cpp | 90 +++++++++++++++++++++++++++++
 3 files changed, 105 insertions(+)

diff --git a/src/core/mpi/BufferSystem.h b/src/core/mpi/BufferSystem.h
index 8be65ea4a..e37c3a76a 100644
--- a/src/core/mpi/BufferSystem.h
+++ b/src/core/mpi/BufferSystem.h
@@ -129,6 +129,7 @@ public:
    template<typename RankIter> void setReceiverInfo( RankIter begin, RankIter end,              bool changingSize );
    template<typename Range>    void setReceiverInfo( const Range & range,                       bool changingSize );
               void setReceiverInfo( const std::set<MPIRank> & ranksToRecvFrom, bool changingSize );
+              void setReceiverInfo( const int numReceives );
 
    void setReceiverInfo( const std::map<MPIRank,MPISize> & ranksToRecvFrom );
    void setReceiverInfoFromSendBufferState( bool useSizeFromSendBuffers, bool changingSize );
diff --git a/src/core/mpi/BufferSystem.impl.h b/src/core/mpi/BufferSystem.impl.h
index f3d753986..242df47c8 100644
--- a/src/core/mpi/BufferSystem.impl.h
+++ b/src/core/mpi/BufferSystem.impl.h
@@ -219,6 +219,20 @@ void GenericBufferSystem<Rb, Sb>::setReceiverInfo( const std::set<MPIRank> & ran
 
 
 
+//**********************************************************************************************************************
+/*! Sets receiver information, when the number of receives is known but the ranks are unknown
+*
+* \param numReceives number of expected messages
+*/
+//**********************************************************************************************************************
+template< typename Rb, typename Sb>
+void GenericBufferSystem<Rb, Sb>::setReceiverInfo( const int numReceives )
+{
+   WALBERLA_ABORT("NOT IMPLEMENTED!");
+}
+
+
+
 //**********************************************************************************************************************
 /*! Sets receiver information, when message sizes are known
 *
diff --git a/tests/core/mpi/BufferSystemTest.cpp b/tests/core/mpi/BufferSystemTest.cpp
index a2e95dc63..fab4340bf 100644
--- a/tests/core/mpi/BufferSystemTest.cpp
+++ b/tests/core/mpi/BufferSystemTest.cpp
@@ -301,6 +301,90 @@ void gatherUsingAsymmetricCommunication(const bool useIProbe)
 }
 
 
+/**
+ * Test for communication when only the number of receives is known but not the ranks.
+ */
+
+void unknownRanksAllToAll()
+{
+   const int rank         = MPIManager::instance()->worldRank();
+   const int numProcesses = MPIManager::instance()->numProcesses();
+
+   WALBERLA_CHECK_GREATER_EQUAL(numProcesses, 3);
+
+   BufferSystem bs(MPI_COMM_WORLD, 42);
+
+   for (auto targetRank = 0; targetRank < numProcesses; ++targetRank)
+   {
+      auto& sb = bs.sendBuffer(targetRank);
+      for (int i = 0; i < rank + 1; ++i)
+         sb << rank;
+   }
+
+   //we await numProcesses messages on every rank
+   bs.setReceiverInfo(numProcesses);
+   //equivalent to
+   //bs.setReceiverInfoFromSendBufferState(false, true);
+   
+   bs.sendAll();
+
+   auto numReceives = 0;
+   for (auto it = bs.begin(); it != bs.end(); ++it)
+   {
+      WALBERLA_CHECK_EQUAL(it.buffer().size(), (it.rank() + 1) * 4);
+      for (int i = 0; i < it.rank() + 1; ++i)
+      {
+         int received = -1;
+         it.buffer() >> received;
+         WALBERLA_CHECK_EQUAL(received, it.rank());
+      }
+      ++numReceives;
+   }
+   WALBERLA_CHECK_EQUAL(numReceives, numProcesses);
+}
+void unknownRanksAllToLower()
+{
+   const int rank         = MPIManager::instance()->worldRank();
+   const int numProcesses = MPIManager::instance()->numProcesses();
+
+   WALBERLA_CHECK_GREATER_EQUAL(numProcesses, 3);
+
+   BufferSystem bs(MPI_COMM_WORLD, 42);
+
+   for (auto targetRank = 0; targetRank < rank + 1; ++targetRank)
+   {
+      auto& sb = bs.sendBuffer(targetRank);
+      for (int i = 0; i < rank + 1; ++i)
+         sb << rank;
+   }
+
+   //we await numProcesses messages on every rank
+   bs.setReceiverInfo(numProcesses);
+   //equivalent to
+   //std::set<mpi::MPIRank> recvs;
+   //for (auto targetRank = numProcesses - 1; targetRank >=rank; --targetRank)
+   //{
+   //   recvs.emplace(targetRank);
+   //}
+   //bs.setReceiverInfo(recvs, true);
+   
+   bs.sendAll();
+
+   auto numReceives = 0;
+   for (auto it = bs.begin(); it != bs.end(); ++it)
+   {
+      WALBERLA_CHECK_EQUAL(it.buffer().size(), (it.rank() + 1) * 4);
+      for (int i = 0; i < it.rank() + 1; ++i)
+      {
+         int received = -1;
+         it.buffer() >> received;
+         WALBERLA_CHECK_EQUAL(received, it.rank());
+      }
+      ++numReceives;
+   }
+   WALBERLA_CHECK_EQUAL(numReceives, numProcesses - rank);
+}
+
 void selfSend()
 {
    int rank          = MPIManager::instance()->worldRank();
@@ -395,6 +479,12 @@ int main(int argc, char**argv)
    gatherUsingAsymmetricCommunication(false);
    gatherUsingAsymmetricCommunication(true);
 
+   WALBERLA_LOG_INFO_ON_ROOT("Testing Unknown Sender Ranks...");
+   WALBERLA_LOG_INFO_ON_ROOT("AllToAll...");
+   unknownRanksAllToAll();
+   WALBERLA_LOG_INFO_ON_ROOT("AllToLower...");
+   unknownRanksAllToLower();
+
    WALBERLA_LOG_INFO_ON_ROOT("Testing self-send...");
    selfSend();
 
-- 
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