-#include <stdlib.h>
+/** @file threads.cc
+ * @brief Thread functions.
+ */
#include "libthreads.h"
-#include "schedule.h"
#include "common.h"
#include "threads.h"
/* global "model" object */
#include "model.h"
-#define STACK_SIZE (1024 * 1024)
-
+/** Allocate a stack for a new thread. */
static void * stack_allocate(size_t size)
{
- return userMalloc(size);
+ return snapshot_malloc(size);
}
+/** Free a stack for a terminated thread. */
static void stack_free(void *stack)
{
- userFree(stack);
+ snapshot_free(stack);
}
+/** Return the currently executing thread. */
Thread * thread_current(void)
{
- return model->scheduler->get_current_thread();
+ ASSERT(model);
+ return model->get_current_thread();
+}
+
+/**
+ * Provides a startup wrapper for each thread, allowing some initial
+ * model-checking data to be recorded. This method also gets around makecontext
+ * not being 64-bit clean
+ * @todo We should make the START event always immediately follow the
+ * CREATE event, so we don't get redundant traces...
+ */
+void thread_startup()
+{
+ Thread * curr_thread = thread_current();
+
+ /* Add dummy "start" action, just to create a first clock vector */
+ model->switch_to_master(new ModelAction(THREAD_START, std::memory_order_seq_cst, curr_thread));
+
+ /* Call the actual thread function */
+ curr_thread->start_routine(curr_thread->arg);
+
+ /* Finish thread properly */
+ model->switch_to_master(new ModelAction(THREAD_FINISH, std::memory_order_seq_cst, curr_thread));
}
+/**
+ * Create a thread context for a new thread so we can use
+ * setcontext/getcontext/swapcontext to swap it out.
+ * @return 0 on success; otherwise, non-zero error condition
+ */
int Thread::create_context()
{
int ret;
if (ret)
return ret;
- /* start_routine == NULL means this is our initial context */
- if (!start_routine)
- return 0;
-
/* Initialize new managed context */
stack = stack_allocate(STACK_SIZE);
context.uc_stack.ss_sp = stack;
context.uc_stack.ss_size = STACK_SIZE;
context.uc_stack.ss_flags = 0;
- context.uc_link = &model->system_thread->context;
- makecontext(&context, start_routine, 1, arg);
+ context.uc_link = model->get_system_context();
+ makecontext(&context, thread_startup, 0);
return 0;
}
-int Thread::swap(Thread *t)
+/**
+ * Swaps the current context to another thread of execution. This form switches
+ * from a user Thread to a system context.
+ * @param t Thread representing the currently-running thread. The current
+ * context is saved here.
+ * @param ctxt Context to which we will swap. Must hold a valid system context.
+ * @return Does not return, unless we return to Thread t's context. See
+ * swapcontext(3) (returns 0 for success, -1 for failure).
+ */
+int Thread::swap(Thread *t, ucontext_t *ctxt)
{
- return swapcontext(&this->context, &t->context);
+ return swapcontext(&t->context, ctxt);
}
+/**
+ * Swaps the current context to another thread of execution. This form switches
+ * from a system context to a user Thread.
+ * @param ctxt System context variable to which to save the current context.
+ * @param t Thread to which we will swap. Must hold a valid user context.
+ * @return Does not return, unless we return to the system context (ctxt). See
+ * swapcontext(3) (returns 0 for success, -1 for failure).
+ */
+int Thread::swap(ucontext_t *ctxt, Thread *t)
+{
+ return swapcontext(ctxt, &t->context);
+}
+
+
+/** Terminate a thread and free its stack. */
void Thread::complete()
{
- if (state != THREAD_COMPLETED) {
- DEBUG("completed thread %d\n", get_id());
+ if (!is_complete()) {
+ DEBUG("completed thread %d\n", id_to_int(get_id()));
state = THREAD_COMPLETED;
if (stack)
stack_free(stack);
}
}
-Thread::Thread(thrd_t *t, void (*func)(), void *a) {
+/**
+ * Construct a new thread.
+ * @param t The thread identifier of the newly created thread.
+ * @param func The function that the thread will call.
+ * @param a The parameter to pass to this function.
+ */
+Thread::Thread(thrd_t *t, void (*func)(void *), void *a) :
+ creation(NULL),
+ pending(NULL),
+ start_routine(func),
+ arg(a),
+ user_thread(t),
+ state(THREAD_CREATED),
+ wait_list(),
+ last_action_val(VALUE_NONE),
+ model_thread(false)
+{
int ret;
- user_thread = t;
- start_routine = func;
- arg = a;
-
/* Initialize state */
ret = create_context();
if (ret)
printf("Error in create_context\n");
- state = THREAD_CREATED;
- id = model->get_next_id();
- *user_thread = id;
-}
-
-Thread::Thread(thrd_t *t) {
- /* system thread */
- user_thread = t;
- start_routine = NULL;
- arg = NULL;
-
- create_context();
- stack = NULL;
- state = THREAD_CREATED;
id = model->get_next_id();
*user_thread = id;
- model->add_system_thread(this);
+ parent = thread_current();
}
+/** Destructor */
Thread::~Thread()
{
complete();
model->remove_thread(this);
}
+/** @return The thread_id_t corresponding to this Thread object. */
thread_id_t Thread::get_id()
{
return id;
}
-
-/*
- * Return 1 if found next thread, 0 otherwise
- */
-static int thread_system_next(void)
-{
- Thread *curr, *next;
-
- curr = thread_current();
- model->check_current_action();
- if (curr) {
- if (curr->get_state() == THREAD_READY)
- model->scheduler->add_thread(curr);
- else if (curr->get_state() == THREAD_RUNNING)
- /* Stopped while running; i.e., completed */
- curr->complete();
- else
- DEBUG("ERROR: current thread in unexpected state??\n");
- }
- next = model->scheduler->next_thread();
- if (next)
- next->set_state(THREAD_RUNNING);
- DEBUG("(%d, %d)\n", curr ? curr->get_id() : -1, next ? next->get_id() : -1);
- if (!next)
- return 1;
- return model->system_thread->swap(next);
-}
-
-static void thread_wait_finish(void)
-{
-
- DBG();
-
- while (!thread_system_next());
-}
-
-/*
- * Main system function
- */
-int main()
-{
- thrd_t user_thread, main_thread;
- Thread *th;
-
- model = new ModelChecker();
-
- th = new Thread(&main_thread);
-
- do {
- /* Start user program */
- thrd_create(&user_thread, &user_main, NULL);
-
- /* Wait for all threads to complete */
- thread_wait_finish();
- } while (model->next_execution());
-
- delete th;
- delete model;
-
- DEBUG("Exiting\n");
- return 0;
-}
projects / c11tester.git / blobdiff