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)
26 /** Return the currently executing thread. */
27 Thread * thread_current(void)
30 return model->get_current_thread();
34 * Provides a startup wrapper for each thread, allowing some initial
35 * model-checking data to be recorded. This method also gets around makecontext
36 * not being 64-bit clean
37 * @todo We should make the START event always immediately follow the
38 * CREATE event, so we don't get redundant traces...
42 Thread * curr_thread = thread_current();
44 /* Add dummy "start" action, just to create a first clock vector */
45 model->switch_to_master(new ModelAction(THREAD_START, std::memory_order_seq_cst, curr_thread));
47 /* Call the actual thread function */
48 curr_thread->start_routine(curr_thread->arg);
50 /* Finish thread properly */
51 model->switch_to_master(new ModelAction(THREAD_FINISH, std::memory_order_seq_cst, curr_thread));
55 * Create a thread context for a new thread so we can use
56 * setcontext/getcontext/swapcontext to swap it out.
57 * @return 0 on success; otherwise, non-zero error condition
59 int Thread::create_context()
63 ret = getcontext(&context);
67 /* Initialize new managed context */
68 stack = stack_allocate(STACK_SIZE);
69 context.uc_stack.ss_sp = stack;
70 context.uc_stack.ss_size = STACK_SIZE;
71 context.uc_stack.ss_flags = 0;
72 context.uc_link = model->get_system_context();
73 makecontext(&context, thread_startup, 0);
79 * Swaps the current context to another thread of execution. This form switches
80 * from a user Thread to a system context.
81 * @param t Thread representing the currently-running thread. The current
82 * context is saved here.
83 * @param ctxt Context to which we will swap. Must hold a valid system context.
84 * @return Does not return, unless we return to Thread t's context. See
85 * swapcontext(3) (returns 0 for success, -1 for failure).
87 int Thread::swap(Thread *t, ucontext_t *ctxt)
89 return swapcontext(&t->context, ctxt);
93 * Swaps the current context to another thread of execution. This form switches
94 * from a system context to a user Thread.
95 * @param ctxt System context variable to which to save the current context.
96 * @param t Thread to which we will swap. Must hold a valid user context.
97 * @return Does not return, unless we return to the system context (ctxt). See
98 * swapcontext(3) (returns 0 for success, -1 for failure).
100 int Thread::swap(ucontext_t *ctxt, Thread *t)
102 return swapcontext(ctxt, &t->context);
106 /** Terminate a thread and free its stack. */
107 void Thread::complete()
109 if (!is_complete()) {
110 DEBUG("completed thread %d\n", id_to_int(get_id()));
111 state = THREAD_COMPLETED;
118 * @brief Construct a new model-checker Thread
120 * A model-checker Thread is used for accounting purposes only. It will never
121 * have its own stack, and it should never be inserted into the Scheduler.
123 * @param tid The thread ID to assign
125 Thread::Thread(thread_id_t tid) :
134 state(THREAD_READY), /* Thread is always ready? */
139 memset(&context, 0, sizeof(context));
143 * Construct a new thread.
144 * @param t The thread identifier of the newly created thread.
145 * @param func The function that the thread will call.
146 * @param a The parameter to pass to this function.
148 Thread::Thread(thrd_t *t, void (*func)(void *), void *a) :
154 state(THREAD_CREATED),
156 last_action_val(VALUE_NONE),
161 /* Initialize state */
162 ret = create_context();
164 printf("Error in create_context\n");
166 id = model->get_next_id();
168 parent = thread_current();
175 model->remove_thread(this);
178 /** @return The thread_id_t corresponding to this Thread object. */
179 thread_id_t Thread::get_id()