threads.cc

   1 #include <stdlib.h>
   2
   3 #include "libthreads.h"
   4 #include "schedule.h"
   5 #include "common.h"
   6 #include "threads.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::complete()
  57 {
  58         if (state != THREAD_COMPLETED) {
  59                 DEBUG("completed thread %d\n", get_id());
  60                 state = THREAD_COMPLETED;
  61                 stack_free(stack);
  62         }
  63 }
  64
  65 Thread::Thread(thrd_t *t, void (*func)(), void *a) {
  66         int ret;
  67
  68         user_thread = t;
  69         start_routine = func;
  70         arg = a;
  71
  72         /* Initialize state */
  73         ret = create_context();
  74         if (ret)
  75                 printf("Error in create_context\n");
  76
  77         state = THREAD_CREATED;
  78         id = model->get_next_id();
  79         *user_thread = id;
  80 }
  81
  82 Thread::Thread(thrd_t *t) {
  83         /* system thread */
  84         user_thread = t;
  85         start_routine = NULL;
  86         arg = NULL;
  87
  88         state = THREAD_CREATED;
  89         id = model->get_next_id();
  90         *user_thread = id;
  91         create_context();
  92         model->add_system_thread(this);
  93 }
  94
  95 Thread::~Thread()
  96 {
  97         complete();
  98         model->remove_thread(this);
  99 }
 100
 101 thread_id_t Thread::get_id()
 102 {
 103         return id;
 104 }
 105
 106 /*
 107  * Return 1 if found next thread, 0 otherwise
 108  */
 109 static int thread_system_next(void)
 110 {
 111         Thread *curr, *next;
 112
 113         curr = thread_current();
 114         model->check_current_action();
 115         if (curr) {
 116                 if (curr->get_state() == THREAD_READY)
 117                         model->scheduler->add_thread(curr);
 118                 else if (curr->get_state() == THREAD_RUNNING)
 119                         /* Stopped while running; i.e., completed */
 120                         curr->complete();
 121                 else
 122                         DEBUG("ERROR: current thread in unexpected state??\n");
 123         }
 124         next = model->scheduler->next_thread();
 125         if (next)
 126                 next->set_state(THREAD_RUNNING);
 127         DEBUG("(%d, %d)\n", curr ? curr->get_id() : -1, next ? next->get_id() : -1);
 128         if (!next)
 129                 return 1;
 130         return model->system_thread->swap(next);
 131 }
 132
 133 static void thread_wait_finish(void)
 134 {
 135
 136         DBG();
 137
 138         while (!thread_system_next());
 139 }
 140
 141 /*
 142  * Main system function
 143  */
 144 int main()
 145 {
 146         thrd_t user_thread, main_thread;
 147         Thread *th;
 148
 149         model = new ModelChecker();
 150
 151         th = new Thread(&main_thread);
 152
 153         do {
 154                 /* Start user program */
 155                 thrd_create(&user_thread, &user_main, NULL);
 156
 157                 /* Wait for all threads to complete */
 158                 thread_wait_finish();
 159
 160                 model->print_trace();
 161         } while (model->next_execution());
 162
 163         delete th;
 164         delete model;
 165
 166         DEBUG("Exiting\n");
 167         return 0;
 168 }