1 /* Copyright (c) 2007-2023. 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. */
8 #include "simgrid/Exception.hpp"
9 #include "simgrid/s4u/Host.hpp"
10 #include "src/kernel/activity/CommImpl.hpp"
11 #include "src/kernel/context/Context.hpp"
12 #include "src/sthread/sthread.h"
13 #include "src/surf/surf_interface.hpp"
17 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(ker_context, kernel, "Context switching mechanism");
19 namespace simgrid::kernel::context {
21 static e_xbt_parmap_mode_t parallel_synchronization_mode = XBT_PARMAP_DEFAULT;
22 static int parallel_contexts = 1;
26 /** @brief Returns whether some parallel threads are used for the user contexts. */
29 return parallel_contexts > 1;
33 * @brief Returns the number of parallel threads used for the user contexts.
34 * @return the number of threads (1 means no parallelism)
38 return parallel_contexts;
42 * @brief Sets the number of parallel threads to use for the user contexts.
44 * This function should be called before initializing SIMIX.
45 * A value of 1 means no parallelism (1 thread only).
46 * If the value is greater than 1, the thread support must be enabled.
48 * @param nb_threads the number of threads to use
50 void set_nthreads(int nb_threads)
52 if (nb_threads <= 0) {
53 nb_threads = std::thread::hardware_concurrency();
54 XBT_INFO("Auto-setting contexts/nthreads to %d", nb_threads);
56 parallel_contexts = nb_threads;
60 * @brief Sets the synchronization mode to use when actors are run in parallel.
61 * @param mode how to synchronize threads if actors are run in parallel
63 void set_parallel_mode(e_xbt_parmap_mode_t mode)
65 parallel_synchronization_mode = mode;
69 * @brief Returns the synchronization mode used when actors are run in parallel.
70 * @return how threads are synchronized if actors are run in parallel
72 e_xbt_parmap_mode_t get_parallel_mode()
74 return parallel_synchronization_mode;
77 ContextFactory::~ContextFactory() = default;
79 thread_local Context* Context::current_context_ = nullptr;
81 /* Install or disable alternate signal stack, for SIGSEGV handler. */
82 int Context::install_sigsegv_stack(stack_t* old_stack, bool enable)
84 static std::vector<unsigned char> sigsegv_stack(SIGSTKSZ);
86 stack.ss_sp = sigsegv_stack.data();
87 stack.ss_size = sigsegv_stack.size();
88 stack.ss_flags = enable ? 0 : SS_DISABLE;
89 return sigaltstack(&stack, old_stack);
92 Context* Context::self()
94 return current_context_;
96 void Context::set_current(Context* self)
98 current_context_ = self;
101 void Context::declare_context(std::size_t size)
103 /* Store the address of the stack in heap to compare it apart of heap comparison */
104 MC_ignore_heap(this, size);
107 Context* ContextFactory::attach(actor::ActorImpl*)
109 xbt_die("Cannot attach with this ContextFactory.\n"
110 "Try using --cfg=contexts/factory:thread instead.\n");
113 Context* ContextFactory::create_maestro(std::function<void()>&&, actor::ActorImpl*)
115 xbt_die("Cannot create_maestro with this ContextFactory.\n"
116 "Try using --cfg=contexts/factory:thread instead.\n");
119 Context::Context(std::function<void()>&& code, actor::ActorImpl* actor, bool maestro)
120 : code_(std::move(code)), actor_(actor), is_maestro_(maestro)
122 /* If we are creating maestro, we should set it as the current context */
130 set_current(nullptr);
135 this->actor_->cleanup_from_self();
137 throw ForcefulKillException(); // clean RAII variables with the dedicated exception
139 AttachContext::~AttachContext() = default;
141 } // namespace simgrid::kernel::context