From 0cb58f5161233b54daf4ec85b66967051c6313fc Mon Sep 17 00:00:00 2001
From: Tobias Fuchs <fuchst@nm.ifi.lmu.de>
Date: Fri, 24 Feb 2017 01:34:30 +0100
Subject: [PATCH] Introducing execution- and launch policies

---
 .../ex.06.pattern-visualizer/main.cpp         |  3 +
 dash/include/dash/Execution.h                 | 69 +++++++++++++++++++
 dash/include/dash/Future.h                    |  8 ++-
 dash/include/dash/LaunchPolicy.h              | 18 +++--
 dash/include/dash/algorithm/Copy.h            | 40 ++++++-----
 dash/include/libdash.h                        | 17 +++--
 6 files changed, 123 insertions(+), 32 deletions(-)
 create mode 100644 dash/include/dash/Execution.h

diff --git a/dash/examples/ex.06.pattern-visualizer/main.cpp b/dash/examples/ex.06.pattern-visualizer/main.cpp
index db5c46e35..f4a7e424e 100644
--- a/dash/examples/ex.06.pattern-visualizer/main.cpp
+++ b/dash/examples/ex.06.pattern-visualizer/main.cpp
@@ -5,6 +5,9 @@
 
 #include <libdash.h>
 
+#include <dash/tools/PatternVisualizer.h>
+
+
 using std::cout;
 using std::cerr;
 using std::endl;
diff --git a/dash/include/dash/Execution.h b/dash/include/dash/Execution.h
new file mode 100644
index 000000000..32b4625ed
--- /dev/null
+++ b/dash/include/dash/Execution.h
@@ -0,0 +1,69 @@
+#ifndef DASH__EXECUTION_H__INCLUDED
+#define DASH__EXECUTION_H__INCLUDED
+
+#include <type_traits>
+
+
+namespace dash {
+
+/**
+ * Execution policy type trait.
+ */
+template<class T>
+struct is_execution_policy
+: public std::integral_constant<bool, false>
+{ };
+
+namespace execution {
+
+  /**
+   * Sequential execution policy.
+   */
+  class sequenced_policy { };
+
+  /**
+   * Parallel execution policy.
+   */
+  class parallel_policy { };
+
+  /**
+   * Parallel non-sequential execution policy.
+   */
+  class parallel_unsequenced_policy { };
+
+  constexpr sequenced_policy             seq;
+  constexpr parallel_policy              par;
+  constexpr parallel_unsequenced_policy  par_unseq;
+
+} // namespace execution
+
+/**
+ * Specialization of execution policy type trait for sequential execution
+ * policy.
+ */
+template<>
+struct is_execution_policy<dash::execution::sequenced_policy>
+: public std::integral_constant<bool, true>
+{ };
+
+/**
+ * Specialization of execution policy type trait for parallel execution
+ * policy.
+ */
+template<>
+struct is_execution_policy<dash::execution::parallel_policy>
+: public std::integral_constant<bool, true>
+{ };
+
+/**
+ * Specialization of execution policy type trait for parallel non-sequential
+ * execution policy.
+ */
+template<>
+struct is_execution_policy<dash::execution::parallel_unsequenced_policy>
+: public std::integral_constant<bool, true>
+{ };
+
+} // namespace dash
+
+#endif // DASH__EXECUTION_H__INCLUDED
diff --git a/dash/include/dash/Future.h b/dash/include/dash/Future.h
index ab796ba25..b8cc3b58e 100644
--- a/dash/include/dash/Future.h
+++ b/dash/include/dash/Future.h
@@ -1,14 +1,16 @@
 #ifndef DASH__FUTURE_H__INCLUDED
 #define DASH__FUTURE_H__INCLUDED
 
+#include <dash/Exception.h>
+#include <dash/LaunchPolicy.h>
+
+#include <dash/internal/Logging.h>
+
 #include <cstddef>
 #include <functional>
 #include <sstream>
 #include <iostream>
 
-#include <dash/Exception.h>
-#include <dash/internal/Logging.h>
-
 
 namespace dash {
 
diff --git a/dash/include/dash/LaunchPolicy.h b/dash/include/dash/LaunchPolicy.h
index 6e7e11c43..9cf9f2954 100644
--- a/dash/include/dash/LaunchPolicy.h
+++ b/dash/include/dash/LaunchPolicy.h
@@ -1,18 +1,22 @@
-#ifndef DASH__LAUNCH__H__INCLUDED
-#define DASH__LAUNCH__H__INCLUDED
+#ifndef DASH__LAUNCH_POLICY_H__INCLUDED
+#define DASH__LAUNCH_POLICY_H__INCLUDED
 
 #include <cstdint>
 
 namespace dash {
 
 enum class launch : uint16_t {
-/// synchronous launch policy
-sync     = 0x1,
-/// async launch policy
-async    = 0x2
+  /// synchronous launch policy
+  sync      = 0x1,
+  /// async launch policy
+  async     = 0x2,
+  /// deferred launch policy
+  deferred  = 0x4,
+  /// unspecified launch policy
+  any       = sync | async | deferred
 };
 
 }
 
 
-#endif // DASH__LAUNCH__H__INCLUDED
+#endif // DASH__LAUNCH_POLICY_H__INCLUDED
diff --git a/dash/include/dash/algorithm/Copy.h b/dash/include/dash/algorithm/Copy.h
index 77e85ae9d..cfed4646d 100644
--- a/dash/include/dash/algorithm/Copy.h
+++ b/dash/include/dash/algorithm/Copy.h
@@ -49,7 +49,7 @@ namespace dash {
  * \ingroup  DashAlgorithms
  */
 template <
-  typename ValueType,
+  class ValueType,
   class InputIt,
   class OutputIt >
 OutputIt copy(
@@ -58,23 +58,28 @@ OutputIt copy(
   OutputIt out_first);
 
 /**
- * Asynchronous variant of \c dash::copy.
+ * Asynchronous or deferred execution of \c dash::copy.
  * Copies the elements in the range, defined by \c [in_first, in_last), to
  * another range beginning at \c out_first.
  *
  * In terms of data distribution, source and destination ranges passed to
- * \c dash::copy can be local (\c *ValueType) or global (\c GlobIter<ValueType>).
+ * \c dash::copy can be
+ *
+ * - local (\c *ValueType)
+ * - or global (\c GlobIter<ValueType>)
  *
- * For a blocking variant of \c dash::copy_async, see \c dash::copy.
+ * For a blocking variant, see \c dash::copy without launch policy parameter.
  *
  * Example:
  *
  * \code
  *     // Start asynchronous copying
  *     dash::Future<T*> fut_dest_end =
- *       dash::copy_async(array_a.block(0).begin(),
- *                        array_a.block(0).end(),
- *                        local_array);
+ *       dash::copy(
+ *         dash::launch::async,
+ *         array_a.block(0).begin(),
+ *         array_a.block(0).end(),
+ *         local_array);
  *     // Overlapping computation here
  *     // ...
  *     // Wait for completion of asynchronous copying:
@@ -88,12 +93,14 @@ OutputIt copy(
  * \ingroup  DashAlgorithms
  */
 template <
-  typename ValueType,
+  class ExecutionPolicy,
+  class ValueType,
   class GlobInputIt >
-dash::Future<ValueType *> copy_async(
-  InputIt  in_first,
-  InputIt  in_last,
-  OutputIt out_first);
+dash::Future<ValueType *> copy(
+  ExecutionPolicy && policy,
+  InputIt            in_first,
+  InputIt            in_last,
+  OutputIt           out_first);
 
 #else // DOXYGEN
 
@@ -1028,15 +1035,14 @@ ValueType * copy(
 template <
   typename ValueType,
   class GlobOutputIt >
-dash::Future<GlobOutputIt> copy_async(
+constexpr dash::Future<GlobOutputIt> copy_async(
   ValueType    * in_first,
   ValueType    * in_last,
   GlobOutputIt   out_first)
 {
-  auto fut = dash::internal::copy_async_impl(in_first,
-                                             in_last,
-                                             out_first);
-  return fut;
+  return dash::internal::copy_async_impl(in_first,
+                                         in_last,
+                                         out_first);
 }
 
 /**
diff --git a/dash/include/libdash.h b/dash/include/libdash.h
index a8af19ddf..9ad6d0f8d 100644
--- a/dash/include/libdash.h
+++ b/dash/include/libdash.h
@@ -33,17 +33,26 @@ namespace dash {
 
 #include <dash/Onesided.h>
 
+#include <dash/Future.h>
+#include <dash/Execution.h>
 #include <dash/LaunchPolicy.h>
 
+#include <dash/Atomic.h>
+
 #include <dash/Container.h>
+#include <dash/Array.h>
+#include <dash/Matrix.h>
+#include <dash/List.h>
+#include <dash/UnorderedMap.h>
+
+#include <dash/Pattern.h>
+
 #include <dash/Shared.h>
 #include <dash/SharedCounter.h>
+
 #include <dash/Exception.h>
 #include <dash/Algorithm.h>
 #include <dash/Allocator.h>
-#include <dash/Atomic.h>
-
-#include <dash/Pattern.h>
 
 #include <dash/util/BenchmarkParams.h>
 #include <dash/util/Config.h>
@@ -63,6 +72,4 @@ namespace dash {
 #include <dash/internal/Math.h>
 #include <dash/internal/Logging.h>
 
-#include <dash/tools/PatternVisualizer.h>
-
 #endif // DASH__LIBDASH_H_