X-Git-Url: http://plrg.eecs.uci.edu/git/?p=cdsspec-compiler.git;a=blobdiff_plain;f=threads.cc;h=a0bc02970aa9ff71c6e8e1a04f6565d52b6db43a;hp=0ed7bdcabc084eabf0755c8df098b724d3c023c4;hb=741d3d1160343d8545a783a2d05d3d0562b1c737;hpb=c441974826572b713174c571104bdf9bd37c018b diff --git a/threads.cc b/threads.cc index 0ed7bdc..a0bc029 100644 --- a/threads.cc +++ b/threads.cc @@ -1,36 +1,67 @@ -/* -*- Mode: C; indent-tabs-mode: t -*- */ +/** @file threads.cc + * @brief Thread functions. + */ -#include "libthreads.h" +#include + +#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 userMalloc(size); + return snapshot_malloc(size); } +/** Free a stack for a terminated thread. */ static void stack_free(void *stack) { - userFree(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(); } -/* This method just gets around makecontext not being 64-bit clean */ +/** + * 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(); -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; @@ -45,56 +76,154 @@ 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); + 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); + t->set_state(THREAD_READY); + return model_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); + t->set_state(THREAD_RUNNING); + return model_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()); - state = THREAD_COMPLETED; - if (stack) - stack_free(stack); - } + ASSERT(!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) { - 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; - parent = thread_current(); + user_thread->priv = this; } +/** Destructor */ Thread::~Thread() { - complete(); - model->remove_thread(this); + 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; } + +/** + * Set a thread's THREAD_* state (@see thread_state) + * @param s The state to enter + */ +void Thread::set_state(thread_state s) +{ + ASSERT(s == THREAD_COMPLETED || state != THREAD_COMPLETED); + state = s; +} + +/** + * 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 +{ + 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; +} + +/** + * 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 + */ +bool Thread::is_waiting_on(const Thread *t) const +{ + Thread *wait; + for (wait = waiting_on(); wait != NULL; wait = wait->waiting_on()) + if (wait == t) + return true; + return false; +}