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 userMalloc(size);
  16 }
  17
  18 static void stack_free(void *stack)
  19 {
  20         userFree(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                 if (stack)
  62                         stack_free(stack);
  63         }
  64 }
  65
  66 void * Thread::operator new(size_t size) {
  67         return userMalloc(size);
  68 }
  69
  70 void Thread::operator delete(void *ptr) {
  71         userFree(ptr);
  72 }
  73
  74 Thread::Thread(thrd_t *t, void (*func)(), void *a) {
  75         int ret;
  76
  77         user_thread = t;
  78         start_routine = func;
  79         arg = a;
  80
  81         /* Initialize state */
  82         ret = create_context();
  83         if (ret)
  84                 printf("Error in create_context\n");
  85
  86         state = THREAD_CREATED;
  87         id = model->get_next_id();
  88         *user_thread = id;
  89 }
  90
  91 Thread::Thread(thrd_t *t) {
  92         /* system thread */
  93         user_thread = t;
  94         start_routine = NULL;
  95         arg = NULL;
  96
  97         create_context();
  98         stack = NULL;
  99         state = THREAD_CREATED;
 100         id = model->get_next_id();
 101         *user_thread = id;
 102         model->add_system_thread(this);
 103 }
 104
 105 Thread::~Thread()
 106 {
 107         complete();
 108         model->remove_thread(this);
 109 }
 110
 111 thread_id_t Thread::get_id()
 112 {
 113         return id;
 114 }
 115
 116 /*
 117  * Return 1 if found next thread, 0 otherwise
 118  */
 119 static int thread_system_next(void)
 120 {
 121         Thread *curr, *next;
 122
 123         curr = thread_current();
 124         model->check_current_action();
 125         if (curr) {
 126                 if (curr->get_state() == THREAD_READY)
 127                         model->scheduler->add_thread(curr);
 128                 else if (curr->get_state() == THREAD_RUNNING)
 129                         /* Stopped while running; i.e., completed */
 130                         curr->complete();
 131                 else
 132                         DEBUG("ERROR: current thread in unexpected state??\n");
 133         }
 134         next = model->scheduler->next_thread();
 135         if (next)
 136                 next->set_state(THREAD_RUNNING);
 137         DEBUG("(%d, %d)\n", curr ? curr->get_id() : -1, next ? next->get_id() : -1);
 138         if (!next)
 139                 return 1;
 140         return model->system_thread->swap(next);
 141 }
 142
 143 static void thread_wait_finish(void)
 144 {
 145
 146         DBG();
 147
 148         while (!thread_system_next());
 149 }
 150
 151 /*
 152  * Main system function
 153  */
 154 int main()
 155 {
 156         thrd_t user_thread, main_thread;
 157         Thread *th;
 158
 159         model = new ModelChecker();
 160
 161         th = new Thread(&main_thread);
 162
 163         do {
 164                 /* Start user program */
 165                 thrd_create(&user_thread, &user_main, NULL);
 166
 167                 /* Wait for all threads to complete */
 168                 thread_wait_finish();
 169         } while (model->next_execution());
 170
 171         delete th;
 172         delete model;
 173
 174         DEBUG("Exiting\n");
 175         return 0;
 176 }