schedule.cc

   1 #include <string.h>
   2 #include <stdlib.h>
   3
   4 #include "threads.h"
   5 #include "schedule.h"
   6 #include "common.h"
   7 #include "model.h"
   8 #include "nodestack.h"
   9
  10 /** Constructor */
  11 Scheduler::Scheduler() :
  12         is_enabled(NULL),
  13         enabled_len(0),
  14         curr_thread_index(0),
  15         current(NULL)
  16 {
  17 }
  18
  19 void Scheduler::set_enabled(Thread *t, enabled_type_t enabled_status) {
  20         int threadid=id_to_int(t->get_id());
  21         if (threadid>=enabled_len) {
  22                 enabled_type_t *new_enabled = (enabled_type_t *)snapshot_malloc(sizeof(enabled_type_t) * (threadid + 1));
  23                 memset(&new_enabled[enabled_len], 0, (threadid+1-enabled_len)*sizeof(enabled_type_t));
  24                 if (is_enabled != NULL) {
  25                         memcpy(new_enabled, is_enabled, enabled_len*sizeof(enabled_type_t));
  26                         snapshot_free(is_enabled);
  27                 }
  28                 is_enabled=new_enabled;
  29                 enabled_len=threadid+1;
  30         }
  31         is_enabled[threadid]=enabled_status;
  32 }
  33
  34 enabled_type_t Scheduler::get_enabled(Thread *t) {
  35         return is_enabled[id_to_int(t->get_id())];
  36 }
  37
  38 void Scheduler::update_sleep_set(Node *n) {
  39         enabled_type_t *enabled_array=n->get_enabled_array();
  40         for(int i=0;i<enabled_len;i++) {
  41                 if (enabled_array[i]==THREAD_SLEEP_SET) {
  42                         is_enabled[i]=THREAD_SLEEP_SET;
  43                 }
  44         }
  45 }
  46
  47 /**
  48  * Add a Thread to the sleep set.
  49  * @param t The Thread to add
  50  */
  51 void Scheduler::add_sleep(Thread *t)
  52 {
  53         DEBUG("thread %d\n", id_to_int(t->get_id()));
  54         set_enabled(t, THREAD_SLEEP_SET);
  55 }
  56
  57 /**
  58  * Remove a Thread from the sleep set.
  59  * @param t The Thread to remove
  60  */
  61 void Scheduler::remove_sleep(Thread *t)
  62 {
  63         DEBUG("thread %d\n", id_to_int(t->get_id()));
  64         set_enabled(t, THREAD_ENABLED);
  65 }
  66
  67 /**
  68  * Add a Thread to the scheduler's ready list.
  69  * @param t The Thread to add
  70  */
  71 void Scheduler::add_thread(Thread *t)
  72 {
  73         DEBUG("thread %d\n", id_to_int(t->get_id()));
  74         set_enabled(t, THREAD_ENABLED);
  75 }
  76
  77 /**
  78  * Remove a given Thread from the scheduler.
  79  * @param t The Thread to remove
  80  */
  81 void Scheduler::remove_thread(Thread *t)
  82 {
  83         if (current == t)
  84                 current = NULL;
  85         set_enabled(t, THREAD_DISABLED);
  86 }
  87
  88 /**
  89  * Prevent a Thread from being scheduled. The sleeping Thread should be
  90  * re-awoken via Scheduler::wake.
  91  * @param thread The Thread that should sleep
  92  */
  93 void Scheduler::sleep(Thread *t)
  94 {
  95         set_enabled(t, THREAD_DISABLED);
  96         t->set_state(THREAD_BLOCKED);
  97 }
  98
  99 /**
 100  * Wake a Thread up that was previously waiting (see Scheduler::wait)
 101  * @param t The Thread to wake up
 102  */
 103 void Scheduler::wake(Thread *t)
 104 {
 105         set_enabled(t, THREAD_DISABLED);
 106         t->set_state(THREAD_READY);
 107 }
 108
 109 /**
 110  * Select a Thread. This implementation defaults to round-robin, if a
 111  * thread is not already provided.
 112  *
 113  * @param t Thread to run, if chosen by an external entity (e.g.,
 114  * ModelChecker). May be NULL to indicate no external choice.
 115  * @return The next Thread to run
 116  */
 117 Thread * Scheduler::next_thread(Thread *t)
 118 {
 119         if ( t == NULL ) {
 120                 int old_curr_thread = curr_thread_index;
 121                 while(true) {
 122                         curr_thread_index = (curr_thread_index+1) % enabled_len;
 123                         if (is_enabled[curr_thread_index]==THREAD_ENABLED) {
 124                                 t = model->get_thread(int_to_id(curr_thread_index));
 125                                 break;
 126                         }
 127                         if (curr_thread_index == old_curr_thread) {
 128                                 print();
 129                                 return NULL;
 130                         }
 131                 }
 132         } else {
 133                 curr_thread_index = id_to_int(t->get_id());
 134         }
 135
 136         current = t;
 137         print();
 138         return t;
 139 }
 140
 141 /**
 142  * @return The currently-running Thread
 143  */
 144 Thread * Scheduler::get_current_thread() const
 145 {
 146         return current;
 147 }
 148
 149 /**
 150  * Print debugging information about the current state of the scheduler. Only
 151  * prints something if debugging is enabled.
 152  */
 153 void Scheduler::print() const
 154 {
 155         if (current)
 156                 DEBUG("Current thread: %d\n", id_to_int(current->get_id()));
 157         else
 158                 DEBUG("No current thread\n");
 159 }