-/* Copyright (c) 2015-2016. The SimGrid Team.
- * All rights reserved. */
+/* Copyright (c) 2015-2020. 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. */
#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 <vector>
namespace simgrid {
namespace xbt {
-class args {
-private:
- int argc_ = 0;
- char** argv_ = nullptr;
-public:
-
- // Main constructors
- args() {}
+template <class F> class MainFunction {
+ F code_;
+ std::shared_ptr<const std::vector<std::string>> args_;
- void assign(int argc, const char*const* 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)))
{
- 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)
+ void operator()() const
{
- this->assign(argc, argv);
+ 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());
}
+};
+
+template <class F> inline std::function<void()> wrap_main(F code, std::vector<std::string>&& args)
+{
+ return MainFunction<F>(std::move(code), std::move(args));
+}
+
+template <class F> inline std::function<void()> wrap_main(F code, int argc, const char* const 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, 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))...);
+}
+}
+
+/** Call a functional object with the values in the given tuple (from C++17)
+ *
+ * @code{.cpp}
+ * int foo(int a, bool b);
+ *
+ * auto args = std::make_tuple(1, false);
+ * int res = apply(foo, args);
+ * @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),
+ std::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<Tuple>::type>::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:
+ typedef typename std::aligned_union<0,
+ void*,
+ std::pair<void(*)(),void*>,
+ std::pair<void(whatever::*)(), whatever*>
+ >::type TaskUnion;
- char** to_argv() const
+ // Is F suitable for small buffer optimization?
+ template<class F>
+ static constexpr bool canSBO()
{
- 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;
+ return sizeof(F) <= sizeof(TaskUnion) &&
+ alignof(F) <= alignof(TaskUnion);
}
- // Free
+ static_assert(canSBO<std::reference_wrapper<whatever>>(),
+ "SBO not working for reference_wrapper");
+
+ // Call (and possibly destroy) the function:
+ typedef R (*call_function)(TaskUnion&, Args...);
+ // Destroy the function (of needed):
+ typedef void (*destroy_function)(TaskUnion&);
+ // Move the function (otherwise memcpy):
+ typedef void (*move_function)(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()
{
- for (int i = 0; i < this->argc_; i++)
- std::free(this->argv_[i]);
- std::free(this->argv_);
- this->argc_ = 0;
- this->argv_ = nullptr;
+ if (vtable_ && vtable_->destroy)
+ vtable_->destroy(buffer_);
}
- ~args() { clear(); }
- // Copy
- args(args const& that)
+public:
+ Task() = default;
+ explicit Task(std::nullptr_t) { /* Nothing to do */}
+ ~Task()
+ {
+ this->clear();
+ }
+
+ Task(Task const&) = delete;
+
+ Task(Task&& that) noexcept
{
- this->assign(that.argc(), that.argv());
+ if (that.vtable_ && that.vtable_->move)
+ that.vtable_->move(buffer_, that.buffer_);
+ else
+ std::memcpy(static_cast<void*>(&buffer_), static_cast<void*>(&that.buffer_), sizeof(buffer_));
+ vtable_ = std::move(that.vtable_);
+ that.vtable_ = nullptr;
}
- args& operator=(args const& that)
+ Task& operator=(Task const& that) = delete;
+ Task& operator=(Task&& that) noexcept
{
- this->assign(that.argc(), that.argv());
+ this->clear();
+ if (that.vtable_ && that.vtable_->move)
+ that.vtable_->move(buffer_, that.buffer_);
+ else
+ std::memcpy(static_cast<void*>(&buffer_), static_cast<void*>(&that.buffer_), sizeof(buffer_));
+ vtable_ = std::move(that.vtable_);
+ that.vtable_ = nullptr;
return *this;
}
- // Move:
- args(args&& that) : argc_(that.argc_), argv_(that.argv_)
+private:
+ template<class F>
+ typename std::enable_if<canSBO<F>()>::type
+ init(F code)
{
- that.argc_ = 0;
- that.argv_ = nullptr;
+ 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;
}
- args& operator=(args&& that)
+
+ template <class F> typename std::enable_if<not canSBO<F>()>::type init(F code)
{
- this->argc_ = that.argc_;
- this->argv_ = that.argv_;
- that.argc_ = 0;
- that.argv_ = nullptr;
- return *this;
+ 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;
}
- 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]; }
-};
+public:
+ template <class F> explicit Task(F code) { this->init(std::move(code)); }
-template<class F> inline
-std::function<void()> wrapMain(F code, std::shared_ptr<simgrid::xbt::args> args)
-{
- return [=]() {
- code(args->argc(), args->argv());
- };
-}
+ operator bool() const { return vtable_ != nullptr; }
+ bool operator!() const { return vtable_ == nullptr; }
-template<class F> inline
-std::function<void()> wrapMain(F code, simgrid::xbt::args args)
-{
- return wrapMain(std::move(code),
- std::unique_ptr<simgrid::xbt::args>(new simgrid::xbt::args(std::move(args))));
-}
+ 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> inline
-std::function<void()> wrapMain(F code, int argc, const char*const* argv)
-{
- return wrapMain(std::move(code), args(argc, argv));
-}
+template<class F, class... Args>
+class TaskImpl {
+ F code_;
+ std::tuple<Args...> args_;
+ typedef decltype(simgrid::xbt::apply(std::move(code_), std::move(args_))) result_type;
+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