X-Git-Url: http://plrg.eecs.uci.edu/git/?p=cdsspec-compiler.git;a=blobdiff_plain;f=threads.cc;h=a0bc02970aa9ff71c6e8e1a04f6565d52b6db43a;hp=4c7ac41f1849d2a18fa6ad4510df118f2d81f87d;hb=741d3d1160343d8545a783a2d05d3d0562b1c737;hpb=a9aac0d43e0e24354af4163cd3161036586f029a diff --git a/threads.cc b/threads.cc index 4c7ac41..a0bc029 100644 --- a/threads.cc +++ b/threads.cc @@ -1,30 +1,67 @@ -#include +/** @file threads.cc + * @brief Thread functions. + */ + +#include -#include "libthreads.h" -#include "schedule.h" +#include +#include #include "common.h" -#include "threads.h" +#include "threads-model.h" +#include "action.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 malloc(size); + return snapshot_malloc(size); } +/** Free a stack for a terminated thread. */ static void stack_free(void *stack) { - free(stack); + snapshot_free(stack); } +/** + * @brief Get the current Thread + * + * Must be called from a user context + * + * @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 + */ +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; @@ -33,129 +70,160 @@ int Thread::create_context() 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); + t->set_state(THREAD_READY); + return model_swapcontext(&t->context, ctxt); } -void Thread::dispose() +/** + * 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) +{ + t->set_state(THREAD_RUNNING); + return model_swapcontext(ctxt, &t->context); +} + + +/** Terminate a thread and free its stack. */ +void Thread::complete() { - DEBUG("completed thread %d\n", thread_current()->get_id()); + ASSERT(!is_complete()); + DEBUG("completed thread %d\n", id_to_int(get_id())); state = THREAD_COMPLETED; - stack_free(stack); + if (stack) + stack_free(stack); } -Thread::Thread(thrd_t *t, void (*func)(), void *a) { - int ret; +/** + * @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? */ + last_action_val(0), + model_thread(true) +{ + memset(&context, 0, sizeof(context)); +} - user_thread = t; - start_routine = func; - arg = 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(thread_id_t tid, thrd_t *t, void (*func)(void *), void *a, Thread *parent) : + parent(parent), + creation(NULL), + pending(NULL), + start_routine(func), + arg(a), + user_thread(t), + id(tid), + state(THREAD_CREATED), + last_action_val(VALUE_NONE), + model_thread(false) +{ + int ret; /* Initialize state */ ret = create_context(); if (ret) - printf("Error in create_context\n"); + model_print("Error in create_context\n"); - state = THREAD_CREATED; - id = model->get_next_id(); - *user_thread = id; - model->scheduler->add_thread(this); + user_thread->priv = this; } -Thread::Thread(thrd_t *t) { - /* system thread */ - user_thread = t; - start_routine = NULL; - arg = NULL; - - state = THREAD_CREATED; - id = model->get_next_id(); - *user_thread = id; - create_context(); - model->add_system_thread(this); +/** Destructor */ +Thread::~Thread() +{ + if (!is_complete()) + complete(); } -thread_id_t Thread::get_id() +/** @return The thread_id_t corresponding to this Thread object. */ +thread_id_t Thread::get_id() const { return id; } -/* - * Return 1 if found next thread, 0 otherwise +/** + * Set a thread's THREAD_* state (@see thread_state) + * @param s The state to enter */ -static int thread_system_next(void) +void Thread::set_state(thread_state s) { - 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->dispose(); - 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); + ASSERT(s == THREAD_COMPLETED || state != THREAD_COMPLETED); + state = s; } -static void thread_wait_finish(void) +/** + * Get the Thread that this Thread is immediately waiting on + * @return The thread we are waiting on, if any; otherwise NULL + */ +Thread * Thread::waiting_on() const { - - DBG(); - - while (!thread_system_next()); + if (!pending) + return NULL; + + if (pending->get_type() == THREAD_JOIN) + return pending->get_thread_operand(); + else if (pending->is_lock()) + return (Thread *)pending->get_mutex()->get_state()->locked; + return NULL; } -/* - * Main system function +/** + * Check if this Thread is waiting (blocking) on a given Thread, directly or + * indirectly (via a chain of waiting threads) + * + * @param t The Thread on which we may be waiting + * @return True if we are waiting on Thread t; false otherwise */ -int main() +bool Thread::is_waiting_on(const Thread *t) const { - 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(); - - model->print_trace(); - } while (model->next_execution()); - - delete th; - delete model; - - DEBUG("Exiting\n"); - return 0; + Thread *wait; + for (wait = waiting_on(); wait != NULL; wait = wait->waiting_on()) + if (wait == t) + return true; + return false; }