schedule.cc

   1 #include <string.h>
   2 #include <stdlib.h>
   3
   4 #include "threads-model.h"
   5 #include "schedule.h"
   6 #include "common.h"
   7 #include "model.h"
   8 #include "nodestack.h"
   9
  10 /** Constructor */
  11 Scheduler::Scheduler() :
  12         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 (enabled != NULL) {
  25                         memcpy(new_enabled, enabled, enabled_len*sizeof(enabled_type_t));
  26                         snapshot_free(enabled);
  27                 }
  28                 enabled=new_enabled;
  29                 enabled_len=threadid+1;
  30         }
  31         enabled[threadid]=enabled_status;
  32 }
  33
  34 /**
  35  * @brief Check if a Thread is currently enabled
  36  * @param t The Thread to check
  37  * @return True if the Thread is currently enabled
  38  */
  39 bool Scheduler::is_enabled(Thread *t) const
  40 {
  41         int id = id_to_int(t->get_id());
  42         return (id >= enabled_len) ? false : (enabled[id] != THREAD_DISABLED);
  43 }
  44
  45 enabled_type_t Scheduler::get_enabled(Thread *t) {
  46         int id = id_to_int(t->get_id());
  47         ASSERT(id<enabled_len);
  48         return enabled[id];
  49 }
  50
  51 void Scheduler::update_sleep_set(Node *n) {
  52         enabled_type_t *enabled_array=n->get_enabled_array();
  53         for(int i=0;i<enabled_len;i++) {
  54                 if (enabled_array[i]==THREAD_SLEEP_SET) {
  55                         enabled[i]=THREAD_SLEEP_SET;
  56                 }
  57         }
  58 }
  59
  60 /**
  61  * Add a Thread to the sleep set.
  62  * @param t The Thread to add
  63  */
  64 void Scheduler::add_sleep(Thread *t)
  65 {
  66         DEBUG("thread %d\n", id_to_int(t->get_id()));
  67         set_enabled(t, THREAD_SLEEP_SET);
  68 }
  69
  70 /**
  71  * Remove a Thread from the sleep set.
  72  * @param t The Thread to remove
  73  */
  74 void Scheduler::remove_sleep(Thread *t)
  75 {
  76         DEBUG("thread %d\n", id_to_int(t->get_id()));
  77         set_enabled(t, THREAD_ENABLED);
  78 }
  79
  80 /**
  81  * Add a Thread to the scheduler's ready list.
  82  * @param t The Thread to add
  83  */
  84 void Scheduler::add_thread(Thread *t)
  85 {
  86         DEBUG("thread %d\n", id_to_int(t->get_id()));
  87         ASSERT(!t->is_model_thread());
  88         set_enabled(t, THREAD_ENABLED);
  89 }
  90
  91 /**
  92  * Remove a given Thread from the scheduler.
  93  * @param t The Thread to remove
  94  */
  95 void Scheduler::remove_thread(Thread *t)
  96 {
  97         if (current == t)
  98                 current = NULL;
  99         set_enabled(t, THREAD_DISABLED);
 100 }
 101
 102 /**
 103  * Prevent a Thread from being scheduled. The sleeping Thread should be
 104  * re-awoken via Scheduler::wake.
 105  * @param thread The Thread that should sleep
 106  */
 107 void Scheduler::sleep(Thread *t)
 108 {
 109         set_enabled(t, THREAD_DISABLED);
 110         t->set_state(THREAD_BLOCKED);
 111 }
 112
 113 /**
 114  * Wake a Thread up that was previously waiting (see Scheduler::wait)
 115  * @param t The Thread to wake up
 116  */
 117 void Scheduler::wake(Thread *t)
 118 {
 119         ASSERT(!t->is_model_thread());
 120         set_enabled(t, THREAD_ENABLED);
 121         t->set_state(THREAD_READY);
 122 }
 123
 124 /**
 125  * Select a Thread. This implementation defaults to round-robin, if a
 126  * thread is not already provided.
 127  *
 128  * @param t Thread to run, if chosen by an external entity (e.g.,
 129  * ModelChecker). May be NULL to indicate no external choice.
 130  * @return The next Thread to run
 131  */
 132 Thread * Scheduler::next_thread(Thread *t)
 133 {
 134         if ( t == NULL ) {
 135                 int old_curr_thread = curr_thread_index;
 136                 bool have_enabled_thread_with_priority=false;
 137                 Node *n=model->get_curr_node();
 138
 139                 for(int i=0;i<enabled_len;i++) {
 140                         thread_id_t tid=int_to_id(i);
 141                         if (n->has_priority(tid)) {
 142                                 //Have a thread with priority
 143                                 if (enabled[i]!=THREAD_DISABLED)
 144                                         have_enabled_thread_with_priority=true;
 145                         }
 146                 }
 147
 148                 while(true) {
 149                         curr_thread_index = (curr_thread_index+1) % enabled_len;
 150                         thread_id_t curr_tid=int_to_id(curr_thread_index);
 151                         if (enabled[curr_thread_index]==THREAD_ENABLED&&
 152                                         (!have_enabled_thread_with_priority||n->has_priority(curr_tid))) {
 153                                 t = model->get_thread(curr_tid);
 154                                 break;
 155                         }
 156                         if (curr_thread_index == old_curr_thread) {
 157                                 print();
 158                                 return NULL;
 159                         }
 160                 }
 161         } else if (t->is_model_thread()) {
 162                 /* model-checker threads never run */
 163                 t = NULL;
 164         } else {
 165                 curr_thread_index = id_to_int(t->get_id());
 166         }
 167
 168         current = t;
 169         print();
 170         return t;
 171 }
 172
 173 /**
 174  * @return The currently-running Thread
 175  */
 176 Thread * Scheduler::get_current_thread() const
 177 {
 178         ASSERT(!current || !current->is_model_thread());
 179         return current;
 180 }
 181
 182 /**
 183  * Print debugging information about the current state of the scheduler. Only
 184  * prints something if debugging is enabled.
 185  */
 186 void Scheduler::print() const
 187 {
 188         if (current)
 189                 DEBUG("Current thread: %d\n", id_to_int(current->get_id()));
 190         else
 191                 DEBUG("No current thread\n");
 192 }