X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/347996b4a10c4e8579080692afa60e0afb88b60a..fcf33975379cd050a6d70b94ae7857910dd01217:/include/simgrid/simix.hpp

diff --git a/include/simgrid/simix.hpp b/include/simgrid/simix.hpp
index fb3fd5aa5d..9e3ec63a77 100644
--- a/include/simgrid/simix.hpp
+++ b/include/simgrid/simix.hpp
@@ -1,4 +1,4 @@
-/* Copyright (c) 2007-2010, 2012-2015. The SimGrid Team.
+/* Copyright (c) 2007-2022. The SimGrid Team.
  * All rights reserved.                                                     */
 
 /* This program is free software; you can redistribute it and/or modify it
@@ -7,235 +7,117 @@
 #ifndef SIMGRID_SIMIX_HPP
 #define SIMGRID_SIMIX_HPP
 
-#include <cstddef>
+#include <simgrid/s4u/Actor.hpp>
+#include <xbt/promise.hpp>
+#include <xbt/signal.hpp>
 
 #include <string>
-#include <utility>
-#include <memory>
-#include <functional>
-#include <future>
-#include <type_traits>
+#include <unordered_map>
 
-#include <xbt/function_types.h>
-#include <simgrid/simix.h>
-
-XBT_PUBLIC(void) simcall_run_kernel(std::function<void()> const& code);
+XBT_PUBLIC void simcall_run_answered(std::function<void()> const& code,
+                                     simgrid::kernel::actor::SimcallObserver* observer);
+XBT_PUBLIC void simcall_run_blocking(std::function<void()> const& code,
+                                     simgrid::kernel::actor::SimcallObserver* observer);
+XBT_PUBLIC void simcall_run_object_access(std::function<void()> const& code,
+                                          simgrid::kernel::actor::ObjectAccessSimcallItem* item);
 
 namespace simgrid {
-namespace simix {
-
-/** Fulfill a promise by executing a given code */
-template<class R, class F>
-void fulfill_promise(std::promise<R>& promise, F&& code)
-{
-  try {
-    promise.set_value(std::forward<F>(code)());
-  }
-  catch(...) {
-    promise.set_exception(std::current_exception());
-  }
-}
+namespace kernel {
+namespace actor {
 
-/** Fulfill a promise by executing a given code
+/** Execute some code in kernel context on behalf of the user code.
  *
- *  This is a special version for `std::promise<void>` because the default
- *  version does not compile in this case.
- */
-template<class F>
-void fulfill_promise(std::promise<void>& promise, F&& code)
-{
-  try {
-    std::forward<F>(code)();
-    promise.set_value();
-  }
-  catch(...) {
-    promise.set_exception(std::current_exception());
-  }
-}
-
-/** Execute some code in the kernel/maestro
+ * Every modification of the environment must be protected this way: every setter, constructor and similar.
+ * Getters don't have to be protected this way, and setters may use the simcall_object_access() variant (see below).
+ *
+ * This allows deterministic parallel simulation without any locking, even if almost nobody uses parallel simulation in
+ * SimGrid. More interestingly it makes every modification of the simulated world observable by the model-checker,
+ * allowing the whole MC business.
  *
- *  This can be used to enforce mutual exclusion with other simcall.
- *  More importantly, this enforces a deterministic/reproducible ordering
- *  of the operation with respect to other simcalls.
+ * It is highly inspired from the syscalls in a regular operating system, allowing the user code to get some specific
+ * code executed in the kernel context. But here, there is almost no security involved. Parameters get checked for
+ * finiteness but that's all. The main goal remain to ensure reproducible ordering of uncomparable events (in
+ * [parallel] simulation) and observability of events (in model-checking).
+ *
+ * The code passed as argument is supposed to terminate at the exact same simulated timestamp.
+ * Do not use it if your code may block waiting for a subsequent event, e.g. if you lock a mutex,
+ * you may need to wait for that mutex to be unlocked by its current owner.
+ * Potentially blocking simcall must be issued using simcall_blocking(), right below in this file.
  */
-template<class F>
-typename std::result_of<F()>::type kernel(F&& code)
+template <class F> typename std::result_of_t<F()> simcall_answered(F&& code, SimcallObserver* observer = nullptr)
 {
   // If we are in the maestro, we take the fast path and execute the
-  // code directly without simcall mashalling/unmarshalling/dispatch:
-  if (SIMIX_is_maestro())
+  // code directly without simcall marshalling/unmarshalling/dispatch:
+  if (s4u::Actor::is_maestro())
     return std::forward<F>(code)();
 
-  // If we are in the application, pass the code to the maestro which is
+  // If we are in the application, pass the code to the maestro which
   // executes it for us and reports the result. We use a std::future which
   // conveniently handles the success/failure value for us.
-  typedef typename std::result_of<F()>::type R;
-  std::promise<R> promise;
-  simcall_run_kernel([&]{
-    xbt_assert(SIMIX_is_maestro(), "Not in maestro");
-    fulfill_promise(promise, std::forward<F>(code));
-  });
-  return promise.get_future().get();
+  using R = typename std::result_of_t<F()>;
+  simgrid::xbt::Result<R> result;
+  simcall_run_answered([&result, &code] { simgrid::xbt::fulfill_promise(result, std::forward<F>(code)); }, observer);
+  return result.get();
 }
 
-class args {
-private:
-  int argc_;
-  char** argv_;
-public:
-
-  // Main constructors
-  args() : argc_(0), argv_(nullptr) {}
-  args(int argc, char** argv) : argc_(argc), argv_(argv) {}
-
-  // Free
-  void clear()
-  {
-    for (int i = 0; i < this->argc_; i++)
-      free(this->argv_[i]);
-    free(this->argv_);
-    this->argc_ = 0;
-    this->argv_ = nullptr;
-  }
-  ~args() { clear(); }
-
-  // Copy
-  args(args const& that) = delete;
-  args& operator=(args const& that) = delete;
-
-  // Move:
-  args(args&& that) : argc_(that.argc_), argv_(that.argv_)
-  {
-    that.argc_ = 0;
-    that.argv_ = nullptr;
-  }
-  args& operator=(args&& that)
-  {
-    this->argc_ = that.argc_;
-    this->argv_ = that.argv_;
-    that.argc_ = 0;
-    that.argv_ = nullptr;
-    return *this;
-  }
-
-  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]; }
-};
-
-inline
-std::function<void()> wrap_main(xbt_main_func_t code, int argc, char **argv)
+/** Use a setter on the `item` object. That's a simcall only if running in parallel or with MC activated.
+ *
+ * Simulation without MC and without parallelism (contexts/nthreads=1) will not pay the price of a simcall for an
+ * harmless setter. When running in parallel, you want your write access to be done in a mutual exclusion way, while the
+ * getters can still occure out of order.
+ *
+ * When running in MC, you want to make this access visible to the checker. Actually in this case, it's not visible from
+ * the checker (and thus still use a fast track) if the setter is called from the actor that created the object.
+ */
+template <class F> typename std::result_of_t<F()> simcall_object_access(ObjectAccessSimcallItem* item, F&& code)
 {
-  if (code) {
-    auto arg = std::make_shared<simgrid::simix::args>(argc, argv);
-    return [=]() {
-      code(arg->argc(), arg->argv());
-    };
-  }
-  // TODO, we should free argv
-  else return std::function<void()>();
-}
-
-class Context;
-class ContextFactory;
-
-XBT_PUBLIC_CLASS ContextFactory {
-private:
-  std::string name_;
-public:
-
-  ContextFactory(std::string name) : name_(std::move(name)) {}
-  virtual ~ContextFactory();
-  virtual Context* create_context(std::function<void()> code,
-    void_pfn_smxprocess_t cleanup, smx_process_t process) = 0;
-
-  // Optional methods for attaching main() as a context:
-
-  /** Creates a context from the current context of execution
-   *
-   *  This will not work on all implementation of `ContextFactory`.
-   */
-  virtual Context* attach(void_pfn_smxprocess_t cleanup_func, smx_process_t process);
-  virtual Context* create_maestro(std::function<void()> code, smx_process_t process);
-
-  virtual void run_all() = 0;
-  virtual Context* self();
-  std::string const& name() const
-  {
-    return name_;
-  }
-private:
-  void declare_context(void* T, std::size_t size);
-protected:
-  template<class T, class... Args>
-  T* new_context(Args&&... args)
-  {
-    T* context = new T(std::forward<Args>(args)...);
-    this->declare_context(context, sizeof(T));
-    return context;
-  }
-};
-
-XBT_PUBLIC_CLASS Context {
-private:
-  std::function<void()> code_;
-  void_pfn_smxprocess_t cleanup_func_ = nullptr;
-  smx_process_t process_ = nullptr;
-public:
-  bool iwannadie;
-public:
-  Context(std::function<void()> code,
-          void_pfn_smxprocess_t cleanup_func,
-          smx_process_t process);
-  void operator()()
-  {
-    code_();
-  }
-  bool has_code() const
-  {
-    return (bool) code_;
-  }
-  smx_process_t process()
-  {
-    return this->process_;
-  }
-  void set_cleanup(void_pfn_smxprocess_t cleanup)
-  {
-    cleanup_func_ = cleanup;
-  }
-
-  // Virtual methods
-  virtual ~Context();
-  virtual void stop();
-  virtual void suspend() = 0;
-};
-
-XBT_PUBLIC_CLASS AttachContext : public Context {
-public:
-
-  AttachContext(std::function<void()> code,
-          void_pfn_smxprocess_t cleanup_func,
-          smx_process_t process)
-    : Context(std::move(code), cleanup_func, process)
-  {}
-
-  ~AttachContext();
+  // If we are in the maestro, we take the fast path and execute the code directly
+  if (simgrid::s4u::Actor::is_maestro())
+    return std::forward<F>(code)();
 
-  /** Called by the context when it is ready to give control
-   *  to the maestro.
-   */
-  virtual void attach_start() = 0;
+  // If called from another thread, do a real simcall. It will be short-cut on need
+  using R = typename std::result_of_t<F()>;
+  simgrid::xbt::Result<R> result;
+  simcall_run_object_access([&result, &code] { simgrid::xbt::fulfill_promise(result, std::forward<F>(code)); }, item);
 
-  /** Called by the context when it has finished its job */
-  virtual void attach_stop() = 0;
-};
+  return result.get();
+}
 
-XBT_PUBLIC(void) set_maestro(std::function<void()> code);
-XBT_PUBLIC(void) create_maestro(std::function<void()> code);
+/** Execute some code (that does not return immediately) in kernel context
+ *
+ * This is very similar to simcall_answered() above, but the calling actor will not get rescheduled until
+ * actor->simcall_answer() is called explicitly.
+ *
+ * This is meant for blocking actions. For example, locking a mutex is a blocking simcall.
+ * First it's a simcall because that's obviously a modification of the world. Then, that's a blocking simcall because if
+ * the mutex happens not to be free, the actor is added to a queue of actors in the mutex. Every mutex->unlock() takes
+ * the first actor from the queue, mark it as current owner of the mutex and call actor->simcall_answer() to mark that
+ * this mutex is now unblocked and ready to run again. If the mutex is initially free, the calling actor is unblocked
+ * right away with actor->simcall_answer() once the mutex is marked as locked.
+ *
+ * If your code never calls actor->simcall_answer() itself, the actor will never return from its simcall.
+ *
+ * The return value is obtained from observer->get_result() if it exists. Otherwise void is returned.
+ */
+template <class F> void simcall_blocking(F&& code, SimcallObserver* observer = nullptr)
+{
+  xbt_assert(not s4u::Actor::is_maestro(), "Cannot execute blocking call in kernel mode");
 
-}
+  // Pass the code to the maestro which executes it for us and reports the result. We use a std::future which
+  // conveniently handles the success/failure value for us.
+  simgrid::xbt::Result<void> result;
+  simcall_run_blocking([&result, &code] { simgrid::xbt::fulfill_promise(result, std::forward<F>(code)); }, observer);
+  result.get(); // rethrow stored exception if any
 }
 
+template <class F, class Observer>
+auto simcall_blocking(F&& code, Observer* observer) -> decltype(observer->get_result())
+{
+  simcall_blocking(std::forward<F>(code), static_cast<SimcallObserver*>(observer));
+  return observer->get_result();
+}
+// compact namespaces are C++17 and this is a public header file so let's stick to C++14
+} // namespace actor
+} // namespace kernel
+} // namespace simgrid
 #endif