X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=threads.cc;h=dc2db2d9bfefcab57458035f3f4bc815b75b5fc5;hb=8c795e46244df91bf9f5ad65b6268767dec054fc;hp=cc939318938170da4712191ab7ea7bd20e78140b;hpb=b01017897db7a4000d3f6f024e0b3800d0f10790;p=model-checker.git diff --git a/threads.cc b/threads.cc index cc93931..dc2db2d 100644 --- a/threads.cc +++ b/threads.cc @@ -1,30 +1,61 @@ -#include +/** @file threads.cc + * @brief Thread functions. + */ + +#include -#include "libthreads.h" -#include "schedule.h" +#include #include "common.h" -#include "threads.h" +#include "threads-model.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; @@ -39,128 +70,113 @@ int Thread::create_context() context.uc_stack.ss_size = STACK_SIZE; context.uc_stack.ss_flags = 0; context.uc_link = model->get_system_context(); - makecontext(&context, start_routine, 1, arg); + makecontext(&context, thread_startup, 0); return 0; } +/** + * 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(&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); } } -void * Thread::operator new(size_t size) { - return userMalloc(size); -} - -void Thread::operator delete(void *ptr) { - userFree(ptr); +/** + * @brief Construct a new model-checker Thread + * + * A model-checker Thread is used for accounting purposes only. It will never + * have its own stack, and it should never be inserted into the Scheduler. + * + * @param tid The thread ID to assign + */ +Thread::Thread(thread_id_t tid) : + parent(NULL), + creation(NULL), + pending(NULL), + start_routine(NULL), + arg(NULL), + stack(NULL), + user_thread(NULL), + id(tid), + state(THREAD_READY), /* Thread is always ready? */ + wait_list(), + last_action_val(0), + model_thread(true) +{ + memset(&context, 0, sizeof(context)); } -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; 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(); - if (curr) { - if (curr->get_state() == THREAD_READY) { - model->check_current_action(); - model->scheduler->add_thread(curr); - } else if (curr->get_state() == THREAD_RUNNING) - /* Stopped while running; i.e., completed */ - curr->complete(); - else - ASSERT(false); - } - 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 Thread::swap(model->get_system_context(), next); -} - -static void thread_wait_finish(void) -{ - - DBG(); - - while (!thread_system_next()); -} - -/* - * Main system function - */ -int main() -{ - thrd_t user_thread; - ucontext_t main_context; - - model = new ModelChecker(); - - if (getcontext(&main_context)) - return 1; - - model->set_system_context(&main_context); - - do { - /* Start user program */ - model->add_thread(new Thread(&user_thread, &user_main, NULL)); - - /* Wait for all threads to complete */ - thread_wait_finish(); - } while (model->next_execution()); - - delete model; - - DEBUG("Exiting\n"); - return 0; -}