Modernize stencil example

Author: hkaiser

examples/03_stencil/CMakeLists.txt

@@ -3,11 +3,11 @@
 # Distributed under the Boost Software License, Version 1.0. (See accompanying
 # file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 3.14)
 
 project(stencil CXX)
 
-find_package(HPX 1.7.0 REQUIRED)
+find_package(HPX 1.9.0 REQUIRED)
 
 add_executable(stencil_serial stencil_serial.cpp)
 target_link_libraries(stencil_serial PRIVATE HPX::hpx HPX::wrap_main)

examples/03_stencil/communicator.hpp

@@ -3,8 +3,7 @@
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef STENCIL_COMMUNICATOR_HPP
-#define STENCIL_COMMUNICATOR_HPP
+#pragma once
 
 #include <hpx/include/lcos.hpp>
 
@@ -13,45 +12,56 @@
 template <typename T>
 struct communicator
 {
-    enum neighbor {
+    enum neighbor
+    {
         up = 0,
         down = 1,
     };
 
-    typedef hpx::lcos::channel<T> channel_type;
+    using channel_type = hpx::distributed::channel<T>;
 
     // rank: our rank in the system
     // num: number of participating partners
     communicator(std::size_t rank, std::size_t num)
     {
-        static const char* up_name = "/stencil/up/";
-        static const char* down_name = "/stencil/down/";
-
         // Only set up channels if we have more than one partner
         if (num > 1)
         {
+            constexpr char const* down_name = "/stencil/down/";
+            constexpr char const* up_name = "/stencil/up/";
+
             // We have an upper neighbor if our rank is greater than zero.
             if (rank > 0)
             {
-                // Retrieve the channel from our upper neighbor from which we receive
-                // the row we need to update the first row in our partition.
-                recv[up] = hpx::find_from_basename<channel_type>(down_name, rank - 1);
+                // Retrieve the channel from our upper neighbor from which we
+                // receive the row we need to update the first row in our
+                // partition.
+                recv[up] =
+                    hpx::find_from_basename<channel_type>(down_name, rank - 1);
 
                 // Create the channel we use to send our first row to our upper
                 // neighbor
                 send[up] = channel_type(hpx::find_here());
-                // Register the channel with a name such that our neighbor can find it.
+
+                // Register the channel with a name such that our neighbor can
+                // find it.
                 hpx::register_with_basename(up_name, send[up], rank);
             }
+
             if (rank < num - 1)
             {
-                // Retrieve the channel from our neighbor below from which we receive
-                // the row we need to update the last row in our partition.
-                recv[down] = hpx::find_from_basename<channel_type>(up_name, rank + 1);
-                // Create the channel we use to send our last row to our neighbor
-                // below
+                // Retrieve the channel from our neighbor below from which we
+                // receive the row we need to update the last row in our
+                // partition.
+                recv[down] =
+                    hpx::find_from_basename<channel_type>(up_name, rank + 1);
+
+                // Create the channel we use to send our last row to our
+                // neighbor below
                 send[down] = channel_type(hpx::find_here());
-                // Register the channel with a name such that our neighbor can find it.
+
+                // Register the channel with a name such that our neighbor can
+                // find it.
                 hpx::register_with_basename(down_name, send[down], rank);
             }
         }
@@ -76,8 +86,6 @@ struct communicator
         return recv[n].get(hpx::launch::async, step);
     }
 
-    std::array<hpx::lcos::channel<T>, 2> recv;
-    std::array<hpx::lcos::channel<T>, 2> send;
+    std::array<hpx::distributed::channel<T>, 2> recv;
+    std::array<hpx::distributed::channel<T>, 2> send;
 };
-
-#endif

examples/03_stencil/line_iterator.hpp

@@ -3,43 +3,40 @@
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef STENCIL_LINE_ITERATOR_HPP
-#define STENCIL_LINE_ITERATOR_HPP
+#pragma once
 
 #include <hpx/include/util.hpp>
 
-template <typename UpIter, typename MiddleIter = UpIter, typename DownIter = UpIter>
+template <typename UpIter, typename MiddleIter = UpIter,
+    typename DownIter = UpIter>
 struct line_iterator
-    // iterator_facade is a facade class that defines the boilerplate needed for
-    // a proper standard C++ iterator. As a user, we only have to define basic
-    // functions
+  // iterator_facade is a facade class that defines the boilerplate needed for a
+  // proper standard C++ iterator. As a user, we only have to define basic
+  // functions
   : hpx::util::iterator_facade<
         // Our type:
         line_iterator<UpIter, MiddleIter, DownIter>,
         // Value type (When dereferencing the iterator)
         double,
         // Our iterator is random access.
-        std::random_access_iterator_tag
-    >
+        std::random_access_iterator_tag>
 {
 private:
-    typedef
-        hpx::util::iterator_facade<
-            // Our type:
-            line_iterator<UpIter, MiddleIter, DownIter>,
-            // Value type (When dereferencing the iterator)
-            double,
-            // Our iterator is random access.
-            std::random_access_iterator_tag
-        >
-        base_type;
+    using base_type = hpx::util::iterator_facade<
+        // Our type:
+        line_iterator<UpIter, MiddleIter, DownIter>,
+        // Value type (When dereferencing the iterator)
+        double,
+        // Our iterator is random access.
+        std::random_access_iterator_tag>;
 
 public:
     line_iterator(UpIter up_, MiddleIter middle_, DownIter down_)
       : up(up_)
       , middle(middle_)
       , down(down_)
-    {}
+    {
+    }
 
     UpIter up;
     MiddleIter middle;
@@ -84,5 +81,3 @@ struct line_iterator
         return other.middle - middle;
     }
 };
-
-#endif

examples/03_stencil/output.hpp

@@ -3,24 +3,21 @@
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef STENCIL_OUTPUT_HPP
-#define STENCIL_OUTPUT_HPP
+#pragma once
 
 #include <fstream>
 #include <string>
 
 template <typename Container>
-void output(std::string name, Container const& data, std::size_t Nx, std::size_t Ny)
+void output(std::string const& name, Container const& data, std::size_t Nx,
+    std::size_t Ny)
 {
     std::ofstream file(name);
-
-    for(std::size_t y = 0; y != Ny; ++y)
+    for (std::size_t y = 0; y != Ny; ++y)
     {
-        for(std::size_t x = 0; x != Nx; ++x)
+        for (std::size_t x = 0; x != Nx; ++x)
         {
             file << x << " " << y << " " << data[y * Nx + x] << '\n';
         }
     }
 }
-
-#endif

examples/03_stencil/row_iterator.hpp

@@ -3,18 +3,18 @@
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef STENCIL_ROW_ITERATOR_HPP
-#define STENCIL_ROW_ITERATOR_HPP
+#pragma once
 
 #include "line_iterator.hpp"
 
 #include <hpx/include/util.hpp>
 
-template <typename UpIter, typename MiddleIter = UpIter, typename DownIter = UpIter>
+template <typename UpIter, typename MiddleIter = UpIter,
+    typename DownIter = UpIter>
 struct row_iterator
-    // iterator_facade is a facade class that defines the boilerplate needed for
-    // a proper standard C++ iterator. As a user, we only have to define basic
-    // functions
+  // iterator_facade is a facade class that defines the boilerplate needed for a
+  // proper standard C++ iterator. As a user, we only have to define basic
+  // functions
   : hpx::util::iterator_facade<
         // Our type:
         row_iterator<UpIter, MiddleIter, DownIter>,
@@ -24,17 +24,17 @@ struct row_iterator
         std::random_access_iterator_tag,
         // Since dereferencing should return a new line_iterator, we need to
         // explicitly set the reference type.
-        line_iterator<UpIter, MiddleIter, DownIter>
-    >
+        line_iterator<UpIter, MiddleIter, DownIter>>
 {
-    typedef line_iterator<UpIter, MiddleIter, DownIter> line_iterator_type;
+    using line_iterator_type = line_iterator<UpIter, MiddleIter, DownIter>;
 
     row_iterator(std::size_t Nx, MiddleIter middle_)
-      : up_(middle - Nx)
-      , middle(middle_)
+      : middle(middle_)
+      , up_(middle - Nx)
       , down_(middle + Nx)
       , Nx_(Nx)
-    {}
+    {
+    }
 
     line_iterator<UpIter, MiddleIter, DownIter> line() const
     {
@@ -45,16 +45,16 @@ struct row_iterator
     line_iterator<typename Container::const_iterator, MiddleIter, DownIter>
     top_boundary(Container const& cont) const
     {
-        return line_iterator<typename Container::const_iterator, MiddleIter, DownIter>(
-            cont.begin(), middle, down_);
+        return line_iterator<typename Container::const_iterator, MiddleIter,
+            DownIter>(cont.begin(), middle, down_);
     }
 
     template <typename Container>
     line_iterator<UpIter, MiddleIter, typename Container::const_iterator>
     bottom_boundary(Container const& cont) const
     {
-        return line_iterator<UpIter, MiddleIter, typename Container::const_iterator>(
-            up_, middle, cont.begin());
+        return line_iterator<UpIter, MiddleIter,
+            typename Container::const_iterator>(up_, middle, cont.begin());
     }
 
     MiddleIter middle;
@@ -102,5 +102,3 @@ struct row_iterator
     DownIter down_;
     std::size_t Nx_;
 };
-
-#endif

examples/03_stencil/stencil.hpp

@@ -3,15 +3,16 @@
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
+#pragma once
+
 #include "line_iterator.hpp"
 #include "row_iterator.hpp"
 
 #include <algorithm>
 #include <array>
 
 template <typename Container>
-void init(
-    std::array<Container, 2>& U, std::size_t Nx, std::size_t Ny,
+void init(std::array<Container, 2>& U, std::size_t Nx, std::size_t Ny,
     std::size_t rank = 0, std::size_t num_localities = 1)
 {
     // Initialize: Boundaries are set to 1, interior is 0
@@ -20,6 +21,7 @@ void init(
         std::fill(U[0].begin(), U[0].begin() + Nx, 1.0);
         std::fill(U[1].begin(), U[1].begin() + Nx, 1.0);
     }
+
     for (std::size_t y = 0; y < Ny; ++y)
     {
         U[0][y * Nx + 0] = 1.0;
@@ -28,6 +30,7 @@ void init(
         U[0][y * Nx + (Nx - 1)] = 1.0;
         U[1][y * Nx + (Nx - 1)] = 1.0;
     }
+
     if (rank == num_localities - 1)
     {
         std::fill(U[0].end() - Nx, U[0].end(), 1.0);
@@ -39,12 +42,14 @@ template <typename InIter, typename OutIter>
 OutIter line_update(InIter begin, InIter end, OutIter result)
 {
     ++result;
+
     // Iterate over the interior: skip the last and first element
-    for(InIter it = begin + 1; it != end - 1; ++it, ++result)
+    for (InIter it = begin + 1; it != end - 1; ++it, ++result)
     {
-        *result = 0.25 * (it.up[-1] + it.up[+1] + it.down[-1]  + it.down[+1])
-            - *it.middle;
+        *result = 0.25 * (it.up[-1] + it.up[+1] + it.down[-1] + it.down[+1]) -
+            *it.middle;
     }
+
     ++result;
 
     return result;