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