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->get_system_context();
  46         makecontext(&context, start_routine, 1, arg);
  47
  48         return 0;
  49 }
  50
  51 int Thread::swap(Thread *t, ucontext_t *ctxt)
  52 {
  53         return swapcontext(&t->context, ctxt);
  54 }
  55
  56 int Thread::swap(ucontext_t *ctxt, Thread *t)
  57 {
  58         return swapcontext(ctxt, &t->context);
  59 }
  60
  61 void Thread::complete()
  62 {
  63         if (state != THREAD_COMPLETED) {
  64                 DEBUG("completed thread %d\n", get_id());
  65                 state = THREAD_COMPLETED;
  66                 if (stack)
  67                         stack_free(stack);
  68         }
  69 }
  70
  71 void * Thread::operator new(size_t size) {
  72         return userMalloc(size);
  73 }
  74
  75 void Thread::operator delete(void *ptr) {
  76         userFree(ptr);
  77 }
  78
  79 Thread::Thread(thrd_t *t, void (*func)(), void *a) {
  80         int ret;
  81
  82         user_thread = t;
  83         start_routine = func;
  84         arg = a;
  85
  86         /* Initialize state */
  87         ret = create_context();
  88         if (ret)
  89                 printf("Error in create_context\n");
  90
  91         state = THREAD_CREATED;
  92         id = model->get_next_id();
  93         *user_thread = id;
  94 }
  95
  96 Thread::Thread(thrd_t *t) {
  97         /* system thread */
  98         user_thread = t;
  99         start_routine = NULL;
 100         arg = NULL;
 101
 102         create_context();
 103         stack = NULL;
 104         state = THREAD_CREATED;
 105         id = model->get_next_id();
 106         *user_thread = id;
 107         model->set_system_context(&context);
 108 }
 109
 110 Thread::~Thread()
 111 {
 112         complete();
 113         model->remove_thread(this);
 114 }
 115
 116 thread_id_t Thread::get_id()
 117 {
 118         return id;
 119 }
 120
 121 /*
 122  * Return 1 if found next thread, 0 otherwise
 123  */
 124 static int thread_system_next(void)
 125 {
 126         Thread *curr, *next;
 127
 128         curr = thread_current();
 129         if (curr) {
 130                 if (curr->get_state() == THREAD_READY) {
 131                         model->check_current_action();
 132                         model->scheduler->add_thread(curr);
 133                 } else if (curr->get_state() == THREAD_RUNNING)
 134                         /* Stopped while running; i.e., completed */
 135                         curr->complete();
 136                 else
 137                         DEBUG("ERROR: current thread in unexpected state??\n");
 138         }
 139         next = model->scheduler->next_thread();
 140         if (next)
 141                 next->set_state(THREAD_RUNNING);
 142         DEBUG("(%d, %d)\n", curr ? curr->get_id() : -1, next ? next->get_id() : -1);
 143         if (!next)
 144                 return 1;
 145         return Thread::swap(model->get_system_context(), next);
 146 }
 147
 148 static void thread_wait_finish(void)
 149 {
 150
 151         DBG();
 152
 153         while (!thread_system_next());
 154 }
 155
 156 /*
 157  * Main system function
 158  */
 159 int main()
 160 {
 161         thrd_t user_thread;
 162         ucontext_t main_context;
 163
 164         model = new ModelChecker();
 165
 166         if (getcontext(&main_context))
 167                 return 1;
 168
 169         model->set_system_context(&main_context);
 170
 171         do {
 172                 /* Start user program */
 173                 thrd_create(&user_thread, &user_main, NULL);
 174
 175                 /* Wait for all threads to complete */
 176                 thread_wait_finish();
 177         } while (model->next_execution());
 178
 179         delete model;
 180
 181         DEBUG("Exiting\n");
 182         return 0;
 183 }