threads: add flag for a special type of "model-checker thread"

[c11tester.git] / threads.cc

diff --git a/threads.cc b/threads.cc
index 1e2af8cbba16343349b91a90e2f87d5bd335631b..e1f74bfbd210da803259b09300ca15f5db3f964e 100644 (file)
--- a/threads.cc
+++ b/threads.cc
@@ -1,3 +1,7 @@
+/** @file threads.cc
+ *  @brief Thread functions.
+ */
+
 #include "libthreads.h"
 #include "common.h"
 #include "threads.h"
@@ -5,23 +9,51 @@
 /* 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;
@@ -36,63 +68,87 @@ 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);
-}
-
-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;