X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/f20fe8a11db9e893dbf55a03d4cf6132bdc4c65c..e71a2a302d28430dc1bfee906f842f5f3d0fa3ce:/include/xbt/functional.hpp

diff --git a/include/xbt/functional.hpp b/include/xbt/functional.hpp
index 537ba8f9dc..4f5ca2ce32 100644
--- a/include/xbt/functional.hpp
+++ b/include/xbt/functional.hpp
@@ -1,5 +1,4 @@
-/* Copyright (c) 2015-2016. The SimGrid Team.
- * All rights reserved.                                                     */
+/* Copyright (c) 2015-2021. The SimGrid Team. All rights reserved.          */
 
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
@@ -7,121 +6,60 @@
 #ifndef XBT_FUNCTIONAL_HPP
 #define XBT_FUNCTIONAL_HPP
 
+#include <xbt/sysdep.h>
+
+#include <cstddef>
 #include <cstdlib>
+#include <cstring>
 
+#include <algorithm>
+#include <array>
 #include <exception>
 #include <functional>
-#include <future>
+#include <memory>
+#include <string>
+#include <tuple>
+#include <type_traits>
 #include <utility>
-
-#include <xbt/sysdep.h>
-#include <xbt/utility.hpp>
+#include <vector>
 
 namespace simgrid {
 namespace xbt {
 
-class args {
-private:
-  int argc_ = 0;
-  char** argv_ = nullptr;
-public:
+template <class F> class MainFunction {
+  F code_;
+  std::shared_ptr<const std::vector<std::string>> args_;
 
-  // Main constructors
-  args() {}
-
-  void assign(int argc, const char*const* argv)
-  {
-    clear();
-    char** new_argv = xbt_new(char*,argc + 1);
-    for (int i = 0; i < argc; i++)
-      new_argv[i] = xbt_strdup(argv[i]);
-    new_argv[argc] = nullptr;
-    this->argc_ = argc;
-    this->argv_ = new_argv;
-  }
-  args(int argc, const char*const* argv)
-  {
-    this->assign(argc, argv);
-  }
-
-  char** to_argv() const
-  {
-    const int argc = argc_;
-    char** argv = xbt_new(char*, argc + 1);
-    for (int i=0; i< argc; i++)
-      argv[i] = xbt_strdup(argv_[i]);
-    argv[argc] = nullptr;
-    return argv;
-  }
-
-  // Free
-  void clear()
-  {
-    for (int i = 0; i < this->argc_; i++)
-      std::free(this->argv_[i]);
-    std::free(this->argv_);
-    this->argc_ = 0;
-    this->argv_ = nullptr;
-  }
-  ~args() { clear(); }
-
-  // Copy
-  args(args const& that)
-  {
-    this->assign(that.argc(), that.argv());
-  }
-  args& operator=(args const& that)
-  {
-    this->assign(that.argc(), that.argv());
-    return *this;
-  }
-
-  // Move:
-  args(args&& that) : argc_(that.argc_), argv_(that.argv_)
+public:
+  MainFunction(F code, std::vector<std::string>&& args)
+      : code_(std::move(code)), args_(std::make_shared<const std::vector<std::string>>(std::move(args)))
   {
-    that.argc_ = 0;
-    that.argv_ = nullptr;
   }
-  args& operator=(args&& that)
+  void operator()() const
   {
-    this->argc_ = that.argc_;
-    this->argv_ = that.argv_;
-    that.argc_ = 0;
-    that.argv_ = nullptr;
-    return *this;
+    const int argc                = args_->size();
+    std::vector<std::string> args = *args_;
+    std::vector<char*> argv(args.size() + 1); // argv[argc] is nullptr
+    std::transform(begin(args), end(args), begin(argv), [](std::string& s) { return &s.front(); });
+    code_(argc, argv.data());
   }
-
-  int    argc()            const { return argc_; }
-  char** argv()                  { return argv_; }
-  const char*const* argv() const { return argv_; }
-  char* operator[](std::size_t i) { return argv_[i]; }
 };
 
-template<class F> inline
-std::function<void()> wrapMain(F code, std::shared_ptr<simgrid::xbt::args> args)
-{
-  return [=]() {
-    code(args->argc(), args->argv());
-  };
-}
-
-template<class F> inline
-std::function<void()> wrapMain(F code, simgrid::xbt::args args)
+template <class F> inline std::function<void()> wrap_main(F code, std::vector<std::string>&& args)
 {
-  return wrapMain(std::move(code),
-    std::unique_ptr<simgrid::xbt::args>(new simgrid::xbt::args(std::move(args))));
+  return MainFunction<F>(std::move(code), std::move(args));
 }
 
-template<class F> inline
-std::function<void()> wrapMain(F code, int argc, const char*const* argv)
+template <class F> inline std::function<void()> wrap_main(F code, int argc, const char* const argv[])
 {
-  return wrapMain(std::move(code), args(argc, argv));
+  std::vector<std::string> args(argv, argv + argc);
+  return MainFunction<F>(std::move(code), std::move(args));
 }
 
 namespace bits {
 template <class F, class Tuple, std::size_t... I>
-constexpr auto apply(F&& f, Tuple&& t, simgrid::xbt::index_sequence<I...>)
-  -> decltype(std::forward<F>(f)(std::get<I>(std::forward<Tuple>(t))...))
+constexpr auto apply(F&& f, Tuple&& t, std::index_sequence<I...>)
+    -> decltype(std::forward<F>(f)(std::get<I>(std::forward<Tuple>(t))...))
 {
   return std::forward<F>(f)(std::get<I>(std::forward<Tuple>(t))...);
 }
@@ -134,26 +72,195 @@ constexpr auto apply(F&& f, Tuple&& t, simgrid::xbt::index_sequence<I...>)
  *
  *  auto args = std::make_tuple(1, false);
  *  int res = apply(foo, args);
- *  @encode
+ *  @endcode
  **/
 template <class F, class Tuple>
-constexpr auto apply(F&& f, Tuple&& t)
-  -> decltype(simgrid::xbt::bits::apply(
-    std::forward<F>(f),
-    std::forward<Tuple>(t),
-    simgrid::xbt::make_index_sequence<
-      std::tuple_size<typename std::decay<Tuple>::type>::value
-    >()))
+constexpr auto apply(F&& f, Tuple&& t) -> decltype(
+    simgrid::xbt::bits::apply(std::forward<F>(f), std::forward<Tuple>(t),
+                              std::make_index_sequence<std::tuple_size<typename std::decay_t<Tuple>>::value>()))
 {
-  return simgrid::xbt::bits::apply(
-    std::forward<F>(f),
-    std::forward<Tuple>(t),
-    simgrid::xbt::make_index_sequence<
-      std::tuple_size<typename std::decay<Tuple>::type>::value
-    >());
+  return simgrid::xbt::bits::apply(std::forward<F>(f), std::forward<Tuple>(t),
+                                   std::make_index_sequence<std::tuple_size<typename std::decay_t<Tuple>>::value>());
 }
 
-}
+template<class T> class Task;
+
+/** Type-erased run-once task
+ *
+ *  * Like std::function but callable only once.
+ *    However, it works with move-only types.
+ *
+ *  * Like std::packaged_task<> but without the shared state.
+ */
+template<class R, class... Args>
+class Task<R(Args...)> {
+  // Placeholder for some class type:
+  struct whatever {};
+
+  // Union used for storage:
+  using TaskUnion =
+      typename std::aligned_union_t<0, void*, std::pair<void (*)(), void*>, std::pair<void (whatever::*)(), whatever*>>;
+
+  // Is F suitable for small buffer optimization?
+  template<class F>
+  static constexpr bool canSBO()
+  {
+    return sizeof(F) <= sizeof(TaskUnion) &&
+      alignof(F) <= alignof(TaskUnion);
+  }
+
+  static_assert(canSBO<std::reference_wrapper<whatever>>(),
+    "SBO not working for reference_wrapper");
+
+  // Call (and possibly destroy) the function:
+  using call_function = R (*)(TaskUnion&, Args...);
+  // Destroy the function (of needed):
+  using destroy_function = void (*)(TaskUnion&);
+  // Move the function (otherwise memcpy):
+  using move_function = void (*)(TaskUnion& dest, TaskUnion& src);
+
+  // Vtable of functions for manipulating whatever is in the TaskUnion:
+  struct TaskVtable {
+    call_function call;
+    destroy_function destroy;
+    move_function move;
+  };
+
+  TaskUnion buffer_;
+  const TaskVtable* vtable_ = nullptr;
+
+  void clear()
+  {
+    if (vtable_ && vtable_->destroy)
+      vtable_->destroy(buffer_);
+  }
+
+public:
+  Task() = default;
+  explicit Task(std::nullptr_t) { /* Nothing to do */}
+  ~Task()
+  {
+    this->clear();
+  }
+
+  Task(Task const&) = delete;
+
+  Task(Task&& that) noexcept
+  {
+    if (that.vtable_ && that.vtable_->move)
+      that.vtable_->move(buffer_, that.buffer_);
+    else
+      std::memcpy(&buffer_, &that.buffer_, sizeof(buffer_));
+    vtable_      = std::move(that.vtable_);
+    that.vtable_ = nullptr;
+  }
+  Task& operator=(Task const& that) = delete;
+  Task& operator=(Task&& that) noexcept
+  {
+    this->clear();
+    if (that.vtable_ && that.vtable_->move)
+      that.vtable_->move(buffer_, that.buffer_);
+    else
+      std::memcpy(&buffer_, &that.buffer_, sizeof(buffer_));
+    vtable_      = std::move(that.vtable_);
+    that.vtable_ = nullptr;
+    return *this;
+  }
+
+private:
+  template <class F> typename std::enable_if_t<canSBO<F>()> init(F code)
+  {
+    const static TaskVtable vtable {
+      // Call:
+      [](TaskUnion& buffer, Args... args) {
+        auto* src = reinterpret_cast<F*>(&buffer);
+        F code = std::move(*src);
+        src->~F();
+        // NOTE: std::forward<Args>(args)... is correct.
+        return code(std::forward<Args>(args)...);
+      },
+      // Destroy:
+      std::is_trivially_destructible<F>::value ?
+      static_cast<destroy_function>(nullptr) :
+      [](TaskUnion& buffer) {
+        auto* code = reinterpret_cast<F*>(&buffer);
+        code->~F();
+      },
+      // Move:
+      [](TaskUnion& dst, TaskUnion& src) {
+        auto* src_code = reinterpret_cast<F*>(&src);
+        auto* dst_code = reinterpret_cast<F*>(&dst);
+        new(dst_code) F(std::move(*src_code));
+        src_code->~F();
+      }
+    };
+    new(&buffer_) F(std::move(code));
+    vtable_ = &vtable;
+  }
+
+  template <class F> typename std::enable_if_t<not canSBO<F>()> init(F code)
+  {
+    const static TaskVtable vtable {
+      // Call:
+      [](TaskUnion& buffer, Args... args) {
+        // Delete F when we go out of scope:
+        std::unique_ptr<F> code(*reinterpret_cast<F**>(&buffer));
+        // NOTE: std::forward<Args>(args)... is correct.
+        return (*code)(std::forward<Args>(args)...);
+      },
+      // Destroy:
+      [](TaskUnion& buffer) {
+        F* code = *reinterpret_cast<F**>(&buffer);
+        delete code;
+      },
+      // Move:
+      nullptr
+    };
+    *reinterpret_cast<F**>(&buffer_) = new F(std::move(code));
+    vtable_ = &vtable;
+  }
+
+public:
+  template <class F> explicit Task(F code) { this->init(std::move(code)); }
+
+  operator bool() const { return vtable_ != nullptr; }
+  bool operator!() const { return vtable_ == nullptr; }
+
+  R operator()(Args... args)
+  {
+    if (vtable_ == nullptr)
+      throw std::bad_function_call();
+    const TaskVtable* vtable = vtable_;
+    vtable_ = nullptr;
+    // NOTE: std::forward<Args>(args)... is correct.
+    // see C++ [func.wrap.func.inv] for an example
+    return vtable->call(buffer_, std::forward<Args>(args)...);
+  }
+};
+
+template<class F, class... Args>
+class TaskImpl {
+  F code_;
+  std::tuple<Args...> args_;
+  using result_type = decltype(simgrid::xbt::apply(std::move(code_), std::move(args_)));
+
+public:
+  TaskImpl(F code, std::tuple<Args...> args) :
+    code_(std::move(code)),
+    args_(std::move(args))
+  {}
+  result_type operator()()
+  {
+    return simgrid::xbt::apply(std::move(code_), std::move(args_));
+  }
+};
+
+template <class F, class... Args> auto make_task(F code, Args... args) -> Task<decltype(code(std::move(args)...))()>
+{
+  TaskImpl<F, Args...> task(std::move(code), std::make_tuple(std::move(args)...));
+  return Task<decltype(code(std::move(args)...))()>(std::move(task));
 }
 
+} // namespace xbt
+} // namespace simgrid
 #endif