Carpet: Add function AllGatherString

Add function AllGatherString, which gathers strings from multiple
processors.  Use this function when determining the models.

darcs-hash:20070423184045-dae7b-0364dcfe7ba6c79ca986e83da380dae0565c1a7b.gz

4 files changed, 80 insertions, 37 deletions

diff --git a/Carpet/Carpet/src/AllGatherString.cc b/Carpet/Carpet/src/AllGatherString.cc
new file mode 100644
index 000000000..5efa96114
--- /dev/null
+++ b/Carpet/Carpet/src/AllGatherString.cc
@@ -0,0 +1,69 @@
+#include <cassert>
+#include <cstring>
+//#include <iostream>
+//#include <map>
+#include <string>
+#include <vector>
+
+#include <mpi.h>
+
+#include "cctk.h"
+
+#include "functions.hh"
+
+
+
+namespace Carpet
+{
+  
+  using namespace std;
+  
+  
+  
+  vector <string>
+  AllGatherString (MPI_Comm const world,
+                   string const & data)
+  {
+    // Get the total number of processors
+    int num_procs;
+    MPI_Comm_size (world, & num_procs);
+    
+    // Gather the lengths of the data strings
+    int const length = data.length();
+    vector <int> lengths (num_procs);
+    
+    MPI_Allgather (const_cast <int *> (& length), 1, MPI_INT,
+                   & lengths.front(), 1, MPI_INT,
+                   world);
+    
+    // Allocate space for all data strings
+    vector <int> offsets (num_procs + 1);
+    offsets.at(0) = 0;
+    for (int n = 0; n < num_procs; ++ n)
+    {
+      offsets.at(n + 1) = offsets.at(n) + lengths.at(n);
+    }
+    int const total_length = offsets.at(num_procs);
+    
+    // Gather all data strings
+    vector <char> alldata_buffer (total_length);
+    
+    MPI_Allgatherv (const_cast <char *> (data.c_str()), length, MPI_CHAR,
+                    & alldata_buffer.front(),
+                    const_cast <int *> (& lengths.front()),
+                    const_cast <int *> (& offsets.front()),
+                    MPI_CHAR,
+                    world);
+    
+    // Convert data buffer with C strings to C++ strings
+    vector <string> alldata  (num_procs);
+    for (int n = 0; n < num_procs; ++ n)
+    {
+      alldata.at(n) =
+        string (& alldata_buffer.at (offsets.at(n)), lengths.at(n));
+    }
+    
+    return alldata;
+  }
+  
+} // namespace Carpet
diff --git a/Carpet/Carpet/src/MultiModel.cc b/Carpet/Carpet/src/MultiModel.cc
index 492e953ea..aa2d7c096 100644
--- a/Carpet/Carpet/src/MultiModel.cc
+++ b/Carpet/Carpet/src/MultiModel.cc
@@ -71,40 +71,8 @@ namespace Carpet
     int my_proc;
     MPI_Comm_rank (world, & my_proc);
     
-    // Gather the lengths of the model strings
-    int const length = model.length();
-    vector <int> lengths (num_procs);
-    
-    MPI_Allgather (const_cast <int *> (& length), 1, MPI_INT,
-                   & lengths.front(), 1, MPI_INT,
-                   world);
-    
-    // Allocate space for all model strings
-    vector <int> offsets (num_procs + 1);
-    offsets.at(0) = 0;
-    for (int n = 0; n < num_procs; ++ n)
-    {
-      offsets.at(n + 1) = offsets.at(n) + lengths.at(n);
-    }
-    int const total_length = offsets.at(num_procs);
-    
-    // Gather all model strings
-    vector <char> models_buffer (total_length);
-    
-    MPI_Allgatherv (const_cast <char *> (model.c_str()), length, MPI_CHAR,
-                    & models_buffer.front(),
-                    const_cast <int *> (& lengths.front()),
-                    const_cast <int *> (& offsets.front()),
-                    MPI_CHAR,
-                    world);
-    
-    // Convert model name buffer with C strings to C++ strings
-    models.resize (num_procs);
-    for (int n = 0; n < num_procs; ++ n)
-    {
-      models.at(n)
-        = string (& models_buffer.at (offsets.at(n)), lengths.at(n));
-    }
+    // Gather all model names
+    models = AllGatherString (world, model);
     
     // Map model strings to small integers
     int num_models = 0;
diff --git a/Carpet/Carpet/src/functions.hh b/Carpet/Carpet/src/functions.hh
index 89bf3eff1..0f43ff281 100644
--- a/Carpet/Carpet/src/functions.hh
+++ b/Carpet/Carpet/src/functions.hh
@@ -45,8 +45,13 @@ namespace Carpet {
   
   void Restrict (const cGH* cgh);
   
-   
-   
+  
+  
+  // Strings
+  vector <string>
+  AllGatherString (MPI_Comm const world,
+                   string const & data);
+  
   // Multi-Model
   void
   SplitUniverse (MPI_Comm const world, string const model, MPI_Comm & comm,
diff --git a/Carpet/Carpet/src/make.code.defn b/Carpet/Carpet/src/make.code.defn
index 46dd195a8..1259cc1c8 100644
--- a/Carpet/Carpet/src/make.code.defn
+++ b/Carpet/Carpet/src/make.code.defn
@@ -1,7 +1,8 @@
 # Main make.code.defn file for thorn Carpet   -*-Makefile-*-
 
 # Source files in this directory
-SRCS =	CallFunction.cc				\
+SRCS =	AllGatherString.cc			\
+	CallFunction.cc				\
 	CarpetParamCheck.cc			\
 	CarpetStartup.cc			\
 	Checksum.cc				\