threads.cc

   1 #include <stdlib.h>
   2
   3 #include "libthreads.h"
   4 #include "schedule.h"
   5 #include "common.h"
   6 #include "threads_internal.h"
   7
   8 /* global "model" object */
   9 #include "model.h"
  10
  11 #define STACK_SIZE (1024 * 1024)
  12
  13 static void *stack_allocate(size_t size)
  14 {
  15         return malloc(size);
  16 }
  17
  18 static void stack_free(void *stack)
  19 {
  20         free(stack);
  21 }
  22
  23 Thread *thread_current(void)
  24 {
  25         return model->scheduler->get_current_thread();
  26 }
  27
  28 int Thread::create_context()
  29 {
  30         int ret;
  31
  32         ret = getcontext(&context);
  33         if (ret)
  34                 return ret;
  35
  36         /* start_routine == NULL means this is our initial context */
  37         if (!start_routine)
  38                 return 0;
  39
  40         /* Initialize new managed context */
  41         stack = stack_allocate(STACK_SIZE);
  42         context.uc_stack.ss_sp = stack;
  43         context.uc_stack.ss_size = STACK_SIZE;
  44         context.uc_stack.ss_flags = 0;
  45         context.uc_link = &model->system_thread->context;
  46         makecontext(&context, start_routine, 1, arg);
  47
  48         return 0;
  49 }
  50
  51 int Thread::swap(Thread *t)
  52 {
  53         return swapcontext(&this->context, &t->context);
  54 }
  55
  56 void Thread::dispose()
  57 {
  58         DEBUG("completed thread %d\n", thread_current()->get_id());
  59         state = THREAD_COMPLETED;
  60         stack_free(stack);
  61 }
  62
  63 Thread::Thread(thrd_t *t, void (*func)(), void *a) {
  64         int ret;
  65
  66         user_thread = t;
  67         start_routine = func;
  68         arg = a;
  69
  70         /* Initialize state */
  71         ret = create_context();
  72         if (ret)
  73                 printf("Error in create_context\n");
  74
  75         state = THREAD_CREATED;
  76         model->assign_id(this);
  77         model->scheduler->add_thread(this);
  78 }
  79
  80 Thread::Thread(thrd_t *t) {
  81         /* system thread */
  82         user_thread = t;
  83         state = THREAD_CREATED;
  84         model->assign_id(this);
  85         create_context();
  86         model->add_system_thread(this);
  87 }
  88
  89 thread_id_t Thread::get_id()
  90 {
  91         return thrd_to_id(*user_thread);
  92 }
  93
  94 /*
  95  * Return 1 if found next thread, 0 otherwise
  96  */
  97 static int thread_system_next(void)
  98 {
  99         Thread *curr, *next;
 100
 101         curr = thread_current();
 102         model->check_current_action();
 103         if (curr) {
 104                 if (curr->get_state() == THREAD_READY)
 105                         model->scheduler->add_thread(curr);
 106                 else if (curr->get_state() == THREAD_RUNNING)
 107                         /* Stopped while running; i.e., completed */
 108                         curr->dispose();
 109                 else
 110                         DEBUG("ERROR: current thread in unexpected state??\n");
 111         }
 112         next = model->scheduler->next_thread();
 113         if (next)
 114                 next->set_state(THREAD_RUNNING);
 115         DEBUG("(%d, %d)\n", curr ? curr->get_id() : -1, next ? next->get_id() : -1);
 116         if (!next)
 117                 return 1;
 118         return model->system_thread->swap(next);
 119 }
 120
 121 static void thread_wait_finish(void)
 122 {
 123
 124         DBG();
 125
 126         while (!thread_system_next());
 127 }
 128
 129 /*
 130  * Main system function
 131  */
 132 int main()
 133 {
 134         thrd_t user_thread, main_thread;
 135         Thread *th;
 136
 137         model = new ModelChecker();
 138
 139         th = new Thread(&main_thread);
 140
 141         /* Start user program */
 142         thrd_create(&user_thread, &user_main, NULL);
 143
 144         /* Wait for all threads to complete */
 145         thread_wait_finish();
 146
 147         model->print_trace();
 148         delete th;
 149         delete model;
 150
 151         DEBUG("Exiting\n");
 152         return 0;
 153 }