Support broadcasting value of first perforation for distributed well

This needed to e.g. determine bottom hole pressure, pvt region, etc.

opm/simulators/wells/ParallelWellInfo.cpp

@@ -45,7 +45,8 @@ void ParallelWellInfo::DestroyComm::operator()(Communication* comm)
 ParallelWellInfo::ParallelWellInfo(const std::string& name,
                                    bool hasLocalCells)
     : name_(name), hasLocalCells_ (hasLocalCells),
-      isOwner_(true), comm_(new Communication(Dune::MPIHelper::getLocalCommunicator()))
+      isOwner_(true), rankWithFirstPerf_(-1),
+      comm_(new Communication(Dune::MPIHelper::getLocalCommunicator()))
     {}
 
 ParallelWellInfo::ParallelWellInfo(const std::pair<std::string,bool>& well_info,
@@ -63,6 +64,16 @@ ParallelWellInfo::ParallelWellInfo(const std::pair<std::string,bool>& well_info,
     isOwner_ = (comm_->rank() == 0);
 }
 
+void ParallelWellInfo::communicateFirstPerforation(bool hasFirst)
+{
+    int first = hasFirst;
+    std::vector<int> firstVec(comm_->size());
+    comm_->allgather(&first, 1, firstVec.data());
+    auto found = std::find_if(firstVec.begin(), firstVec.end(),
+                              [](int i) -> bool{ return i;});
+    rankWithFirstPerf_ = found - firstVec.begin();
+}
+
 bool operator<(const ParallelWellInfo& well1, const ParallelWellInfo& well2)
 {
     return well1.name() < well2.name() || (! (well2.name() < well1.name()) && well1.hasLocalCells() < well2.hasLocalCells());

opm/simulators/wells/ParallelWellInfo.hpp

@@ -61,6 +61,17 @@ public:
         return *comm_;
     }
 
+    /// \brief Collectively decide which ran has first perforation.
+    void communicateFirstPerforation(bool hasFirst);
+
+    template<class T>
+    T broadcastFirstPerforationValue(const T& t) const
+    {
+        T res=t;
+        comm_->broadcast(&res, 1, rankWithFirstPerf_);
+        return res;
+    }
+
     /// \brief Name of the well.
     const std::string& name() const
     {
@@ -92,6 +103,8 @@ private:
     bool hasLocalCells_;
     /// \brief Whether we own the well and should do reports etc.
     bool isOwner_;
+    /// \brief Rank with the first perforation on it.
+    int rankWithFirstPerf_;
     /// \brief Communication object for the well
     ///
     /// Contains only ranks where this well will perforate local cells.