schedule.cc

   1 #include "threads.h"
   2 #include "schedule.h"
   3 #include "common.h"
   4 #include "model.h"
   5
   6 /** Constructor */
   7 Scheduler::Scheduler() :
   8         is_enabled(NULL),
   9         enabled_len(0),
  10         curr_thread_index(0),
  11         current(NULL)
  12 {
  13 }
  14
  15 void Scheduler::set_enabled(Thread *t, bool enabled_status) {
  16         int threadid=id_to_int(t->get_id());
  17         if (threadid>=enabled_len) {
  18                 bool * new_enabled=(bool *)malloc(sizeof(bool)*(threadid+1));
  19                 memset(&new_enabled[enabled_len], 0, (threadid+1-enabled_len)*sizeof(bool));
  20                 if (is_enabled != NULL) {
  21                         memcpy(new_enabled, is_enabled, enabled_len*sizeof(bool));
  22                         free(is_enabled);
  23                 }
  24                 is_enabled=new_enabled;
  25                 enabled_len=threadid+1;
  26         }
  27         is_enabled[threadid]=enabled_status;
  28 }
  29
  30 /**
  31  * Add a Thread to the scheduler's ready list.
  32  * @param t The Thread to add
  33  */
  34 void Scheduler::add_thread(Thread *t)
  35 {
  36         DEBUG("thread %d\n", t->get_id());
  37         set_enabled(t, true);
  38 }
  39
  40 /**
  41  * Remove a given Thread from the scheduler.
  42  * @param t The Thread to remove
  43  */
  44 void Scheduler::remove_thread(Thread *t)
  45 {
  46         if (current == t)
  47                 current = NULL;
  48         set_enabled(t, false);
  49 }
  50
  51 /**
  52  * Prevent a Thread from being scheduled. The sleeping Thread should be
  53  * re-awoken via Scheduler::wake.
  54  * @param thread The Thread that should sleep
  55  */
  56 void Scheduler::sleep(Thread *t)
  57 {
  58         set_enabled(t, false);
  59         t->set_state(THREAD_BLOCKED);
  60 }
  61
  62 /**
  63  * Wake a Thread up that was previously waiting (see Scheduler::wait)
  64  * @param t The Thread to wake up
  65  */
  66 void Scheduler::wake(Thread *t)
  67 {
  68         set_enabled(t, true);
  69         t->set_state(THREAD_READY);
  70 }
  71
  72 /**
  73  * Remove one Thread from the scheduler. This implementation defaults to FIFO,
  74  * if a thread is not already provided.
  75  *
  76  * @param t Thread to run, if chosen by an external entity (e.g.,
  77  * ModelChecker). May be NULL to indicate no external choice.
  78  * @return The next Thread to run
  79  */
  80 Thread * Scheduler::next_thread(Thread *t)
  81 {
  82         if ( t == NULL ) {
  83                 int old_curr_thread = curr_thread_index;
  84                 while(true) {
  85                         curr_thread_index = (curr_thread_index+1) % enabled_len;
  86                         if (is_enabled[curr_thread_index]) {
  87                                 t = model->get_thread(int_to_id(curr_thread_index));
  88                                 break;
  89                         }
  90                         if (curr_thread_index == old_curr_thread) {
  91                                 print();
  92                                 return NULL;
  93                         }
  94                 }
  95         } else {
  96                 curr_thread_index = id_to_int(t->get_id());
  97         }
  98
  99         current = t;
 100         print();
 101         return t;
 102 }
 103
 104 /**
 105  * @return The currently-running Thread
 106  */
 107 Thread * Scheduler::get_current_thread() const
 108 {
 109         return current;
 110 }
 111
 112 /**
 113  * Print debugging information about the current state of the scheduler. Only
 114  * prints something if debugging is enabled.
 115  */
 116 void Scheduler::print() const
 117 {
 118         if (current)
 119                 DEBUG("Current thread: %d\n", current->get_id());
 120         else
 121                 DEBUG("No current thread\n");
 122 }