1 /* Copyright (c) 2016-2020. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #ifndef SIMGRID_SIMIX_BLOCKING_SIMCALL_HPP
7 #define SIMGRID_SIMIX_BLOCKING_SIMCALL_HPP
14 #include <xbt/sysdep.h>
16 #include <xbt/future.hpp>
17 #include <simgrid/kernel/future.hpp>
18 #include <simgrid/simix.h>
19 #include <simgrid/simix.hpp>
24 XBT_PUBLIC void unblock(smx_actor_t process);
26 /** Execute some code in kernel mode and wakes up the actor when
27 * the result is available.
29 * It is given a callback which is executed in the SimGrid kernel and
30 * returns a `simgrid::kernel::Future<T>`. The kernel blocks the actor
31 * until the Future is ready and:
33 * - either returns the value wrapped in the future to the actor
35 * - or raises the exception stored in the future in the actor.
37 * This can be used to implement blocking calls without adding new simcalls.
38 * One downside of this approach is that we don't have any semantic on what
39 * the actor is waiting. This might be a problem for the model-checker and
40 * we'll have to devise a way to make it work.
42 * @param code Kernel code returning a `simgrid::kernel::Future<T>`
43 * @return Value of the kernel future
44 * @exception Exception from the kernel future
46 template <class F> auto kernel_sync(F code) -> decltype(code().get())
48 typedef decltype(code().get()) T;
49 if (SIMIX_is_maestro())
50 xbt_die("Can't execute blocking call in kernel mode");
52 smx_actor_t self = SIMIX_process_self();
53 simgrid::xbt::Result<T> result;
56 [&result, self, &code] {
59 future.then_([&result, self](std::shared_ptr<simgrid::kernel::FutureState<T>> value) {
60 simgrid::xbt::set_promise(result, simgrid::kernel::Future<T>(std::move(value)));
61 simgrid::simix::unblock(self);
64 result.set_exception(std::current_exception());
65 simgrid::simix::unblock(self);
72 /** A blocking (`wait()`-based) future for SIMIX processes */
76 // TODO, simgrid::simix::when_all - wait for all future to be ready (this one is simple!)
77 // TODO, simgrid::simix::when_any - wait for any future to be ready
81 Future() { /* Nothing to do*/}
82 explicit Future(simgrid::kernel::Future<T> future) : future_(std::move(future)) {}
83 Future(Future&&) noexcept = default;
84 Future& operator=(Future&&) noexcept = default;
86 bool valid() const { return future_.valid(); }
90 throw std::future_error(std::future_errc::no_state);
91 smx_actor_t self = SIMIX_process_self();
92 simgrid::xbt::Result<T> result;
94 [this, &result, self] {
96 // When the kernel future is ready...
97 this->future_.then_([&result, self](std::shared_ptr<simgrid::kernel::FutureState<T>> value) {
98 // ... wake up the process with the result of the kernel future.
99 simgrid::xbt::set_promise(result, simgrid::kernel::Future<T>(std::move(value)));
100 simgrid::simix::unblock(self);
103 result.set_exception(std::current_exception());
104 simgrid::simix::unblock(self);
110 bool is_ready() const
113 throw std::future_error(std::future_errc::no_state);
114 return future_.is_ready();
118 // The future is ready! We don't have to wait:
119 if (this->is_ready())
121 // The future is not ready. We have to delegate to the SimGrid kernel:
122 std::exception_ptr exception;
123 smx_actor_t self = SIMIX_process_self();
124 simcall_run_blocking(
125 [this, &exception, self] {
127 // When the kernel future is ready...
128 this->future_.then_([this, self](std::shared_ptr<simgrid::kernel::FutureState<T>> value) {
129 // ...store it the simix kernel and wake up.
130 this->future_ = simgrid::kernel::Future<T>(std::move(value));
131 simgrid::simix::unblock(self);
134 exception = std::current_exception();
135 simgrid::simix::unblock(self);
142 // We wrap an event-based kernel future:
143 simgrid::kernel::Future<T> future_;
146 /** Start some asynchronous work
148 * @param code SimGrid kernel code which returns a simgrid::kernel::Future
149 * @return Actor future
151 template <class F> auto kernel_async(F code) -> Future<decltype(code().get())>
153 typedef decltype(code().get()) T;
155 // Execute the code in the kernel and get the kernel future:
156 simgrid::kernel::Future<T> future = simgrid::kernel::actor::simcall(std::move(code));
158 // Wrap the kernel future in a actor future:
159 return simgrid::simix::Future<T>(std::move(future));