2 * @brief Thread functions.
9 #include "threads-model.h"
11 /* global "model" object */
14 /** Allocate a stack for a new thread. */
15 static void * stack_allocate(size_t size)
17 return snapshot_malloc(size);
20 /** Free a stack for a terminated thread. */
21 static void stack_free(void *stack)
27 * @brief Get the current Thread
29 * Must be called from a user context
31 * @return The currently executing thread
33 Thread * thread_current(void)
36 return model->get_current_thread();
40 * Provides a startup wrapper for each thread, allowing some initial
41 * model-checking data to be recorded. This method also gets around makecontext
42 * not being 64-bit clean
46 Thread * curr_thread = thread_current();
48 /* Add dummy "start" action, just to create a first clock vector */
49 model->switch_to_master(new ModelAction(THREAD_START, std::memory_order_seq_cst, curr_thread));
51 /* Call the actual thread function */
52 curr_thread->start_routine(curr_thread->arg);
54 /* Finish thread properly */
55 model->switch_to_master(new ModelAction(THREAD_FINISH, std::memory_order_seq_cst, curr_thread));
59 * Create a thread context for a new thread so we can use
60 * setcontext/getcontext/swapcontext to swap it out.
61 * @return 0 on success; otherwise, non-zero error condition
63 int Thread::create_context()
67 ret = getcontext(&context);
71 /* Initialize new managed context */
72 stack = stack_allocate(STACK_SIZE);
73 context.uc_stack.ss_sp = stack;
74 context.uc_stack.ss_size = STACK_SIZE;
75 context.uc_stack.ss_flags = 0;
76 context.uc_link = model->get_system_context();
77 makecontext(&context, thread_startup, 0);
83 * Swaps the current context to another thread of execution. This form switches
84 * from a user Thread to a system context.
85 * @param t Thread representing the currently-running thread. The current
86 * context is saved here.
87 * @param ctxt Context to which we will swap. Must hold a valid system context.
88 * @return Does not return, unless we return to Thread t's context. See
89 * swapcontext(3) (returns 0 for success, -1 for failure).
91 int Thread::swap(Thread *t, ucontext_t *ctxt)
93 t->set_state(THREAD_READY);
94 return swapcontext(&t->context, ctxt);
98 * Swaps the current context to another thread of execution. This form switches
99 * from a system context to a user Thread.
100 * @param ctxt System context variable to which to save the current context.
101 * @param t Thread to which we will swap. Must hold a valid user context.
102 * @return Does not return, unless we return to the system context (ctxt). See
103 * swapcontext(3) (returns 0 for success, -1 for failure).
105 int Thread::swap(ucontext_t *ctxt, Thread *t)
107 t->set_state(THREAD_RUNNING);
108 return swapcontext(ctxt, &t->context);
112 /** Terminate a thread and free its stack. */
113 void Thread::complete()
115 ASSERT(!is_complete());
116 DEBUG("completed thread %d\n", id_to_int(get_id()));
117 state = THREAD_COMPLETED;
123 * @brief Construct a new model-checker Thread
125 * A model-checker Thread is used for accounting purposes only. It will never
126 * have its own stack, and it should never be inserted into the Scheduler.
128 * @param tid The thread ID to assign
130 Thread::Thread(thread_id_t tid) :
139 state(THREAD_READY), /* Thread is always ready? */
144 memset(&context, 0, sizeof(context));
148 * Construct a new thread.
149 * @param t The thread identifier of the newly created thread.
150 * @param func The function that the thread will call.
151 * @param a The parameter to pass to this function.
153 Thread::Thread(thrd_t *t, void (*func)(void *), void *a) :
159 state(THREAD_CREATED),
161 last_action_val(VALUE_NONE),
166 /* Initialize state */
167 ret = create_context();
169 model_print("Error in create_context\n");
171 id = model->get_next_id();
172 user_thread->priv = this;
173 parent = thread_current();
181 model->remove_thread(this);
184 /** @return The thread_id_t corresponding to this Thread object. */
185 thread_id_t Thread::get_id() const
191 * Set a thread's THREAD_* state (@see thread_state)
192 * @param s The state to enter
194 void Thread::set_state(thread_state s)
196 ASSERT(s == THREAD_COMPLETED || state != THREAD_COMPLETED);