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         /* Initialize new managed context */
  37         stack = stack_allocate(STACK_SIZE);
  38         context.uc_stack.ss_sp = stack;
  39         context.uc_stack.ss_size = STACK_SIZE;
  40         context.uc_stack.ss_flags = 0;
  41         context.uc_link = model->get_system_context();
  42         makecontext(&context, start_routine, 1, arg);
  43
  44         return 0;
  45 }
  46
  47 int Thread::swap(Thread *t, ucontext_t *ctxt)
  48 {
  49         return swapcontext(&t->context, ctxt);
  50 }
  51
  52 int Thread::swap(ucontext_t *ctxt, Thread *t)
  53 {
  54         return swapcontext(ctxt, &t->context);
  55 }
  56
  57 void Thread::complete()
  58 {
  59         if (state != THREAD_COMPLETED) {
  60                 DEBUG("completed thread %d\n", get_id());
  61                 state = THREAD_COMPLETED;
  62                 if (stack)
  63                         stack_free(stack);
  64         }
  65 }
  66
  67 void * Thread::operator new(size_t size) {
  68         return userMalloc(size);
  69 }
  70
  71 void Thread::operator delete(void *ptr) {
  72         userFree(ptr);
  73 }
  74
  75 Thread::Thread(thrd_t *t, void (*func)(), void *a) {
  76         int ret;
  77
  78         user_thread = t;
  79         start_routine = func;
  80         arg = a;
  81
  82         /* Initialize state */
  83         ret = create_context();
  84         if (ret)
  85                 printf("Error in create_context\n");
  86
  87         state = THREAD_CREATED;
  88         id = model->get_next_id();
  89         *user_thread = id;
  90         parent = thread_current();
  91 }
  92
  93 Thread::~Thread()
  94 {
  95         complete();
  96         model->remove_thread(this);
  97 }
  98
  99 thread_id_t Thread::get_id()
 100 {
 101         return id;
 102 }
 103
 104 /*
 105  * Return 1 if found next thread, 0 otherwise
 106  */
 107 static int thread_system_next(void)
 108 {
 109         Thread *curr, *next;
 110
 111         curr = thread_current();
 112         if (curr) {
 113                 if (curr->get_state() == THREAD_READY) {
 114                         model->check_current_action();
 115                         model->scheduler->add_thread(curr);
 116                 } else if (curr->get_state() == THREAD_RUNNING)
 117                         /* Stopped while running; i.e., completed */
 118                         curr->complete();
 119                 else
 120                         ASSERT(false);
 121         }
 122         next = model->scheduler->next_thread();
 123         if (next)
 124                 next->set_state(THREAD_RUNNING);
 125         DEBUG("(%d, %d)\n", curr ? curr->get_id() : -1, next ? next->get_id() : -1);
 126         if (!next)
 127                 return 1;
 128         return Thread::swap(model->get_system_context(), next);
 129 }
 130
 131 static void thread_wait_finish(void)
 132 {
 133
 134         DBG();
 135
 136         while (!thread_system_next());
 137 }
 138
 139 /*
 140  * Main system function
 141  */
 142 int main()
 143 {
 144         thrd_t user_thread;
 145         ucontext_t main_context;
 146
 147         model = new ModelChecker();
 148
 149         if (getcontext(&main_context))
 150                 return 1;
 151
 152         model->set_system_context(&main_context);
 153
 154         do {
 155                 /* Start user program */
 156                 model->add_thread(new Thread(&user_thread, &user_main, NULL));
 157
 158                 /* Wait for all threads to complete */
 159                 thread_wait_finish();
 160         } while (model->next_execution());
 161
 162         delete model;
 163
 164         DEBUG("Exiting\n");
 165         return 0;
 166 }