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         if (enabled_status == THREAD_DISABLED)
  33                 model->check_promises_thread_disabled();
  34 }
  35
  36 /**
  37  * @brief Check if a Thread is currently enabled
  38  *
  39  * Check if a Thread is currently enabled. "Enabled" includes both
  40  * THREAD_ENABLED and THREAD_SLEEP_SET.
  41  * @param t The Thread to check
  42  * @return True if the Thread is currently enabled
  43  */
  44 bool Scheduler::is_enabled(Thread *t) const
  45 {
  46         return is_enabled(t->get_id());
  47 }
  48
  49 /**
  50  * @brief Check if a Thread is currently enabled
  51  *
  52  * Check if a Thread is currently enabled. "Enabled" includes both
  53  * THREAD_ENABLED and THREAD_SLEEP_SET.
  54  * @param tid The ID of the Thread to check
  55  * @return True if the Thread is currently enabled
  56  */
  57 bool Scheduler::is_enabled(thread_id_t tid) const
  58 {
  59         int i = id_to_int(tid);
  60         return (i >= enabled_len) ? false : (enabled[i] != THREAD_DISABLED);
  61 }
  62
  63 enabled_type_t Scheduler::get_enabled(Thread *t) {
  64         int id = id_to_int(t->get_id());
  65         ASSERT(id<enabled_len);
  66         return enabled[id];
  67 }
  68
  69 void Scheduler::update_sleep_set(Node *n) {
  70         enabled_type_t *enabled_array=n->get_enabled_array();
  71         for(int i=0;i<enabled_len;i++) {
  72                 if (enabled_array[i]==THREAD_SLEEP_SET) {
  73                         enabled[i]=THREAD_SLEEP_SET;
  74                 }
  75         }
  76 }
  77
  78 /**
  79  * Add a Thread to the sleep set.
  80  * @param t The Thread to add
  81  */
  82 void Scheduler::add_sleep(Thread *t)
  83 {
  84         DEBUG("thread %d\n", id_to_int(t->get_id()));
  85         set_enabled(t, THREAD_SLEEP_SET);
  86 }
  87
  88 /**
  89  * Remove a Thread from the sleep set.
  90  * @param t The Thread to remove
  91  */
  92 void Scheduler::remove_sleep(Thread *t)
  93 {
  94         DEBUG("thread %d\n", id_to_int(t->get_id()));
  95         set_enabled(t, THREAD_ENABLED);
  96 }
  97
  98 /**
  99  * Add a Thread to the scheduler's ready list.
 100  * @param t The Thread to add
 101  */
 102 void Scheduler::add_thread(Thread *t)
 103 {
 104         DEBUG("thread %d\n", id_to_int(t->get_id()));
 105         ASSERT(!t->is_model_thread());
 106         set_enabled(t, THREAD_ENABLED);
 107 }
 108
 109 /**
 110  * Remove a given Thread from the scheduler.
 111  * @param t The Thread to remove
 112  */
 113 void Scheduler::remove_thread(Thread *t)
 114 {
 115         if (current == t)
 116                 current = NULL;
 117         set_enabled(t, THREAD_DISABLED);
 118 }
 119
 120 /**
 121  * Prevent a Thread from being scheduled. The sleeping Thread should be
 122  * re-awoken via Scheduler::wake.
 123  * @param thread The Thread that should sleep
 124  */
 125 void Scheduler::sleep(Thread *t)
 126 {
 127         set_enabled(t, THREAD_DISABLED);
 128         t->set_state(THREAD_BLOCKED);
 129 }
 130
 131 /**
 132  * Wake a Thread up that was previously waiting (see Scheduler::wait)
 133  * @param t The Thread to wake up
 134  */
 135 void Scheduler::wake(Thread *t)
 136 {
 137         ASSERT(!t->is_model_thread());
 138         set_enabled(t, THREAD_ENABLED);
 139         t->set_state(THREAD_READY);
 140 }
 141
 142 /**
 143  * Select a Thread. This implementation defaults to round-robin, if a
 144  * thread is not already provided.
 145  *
 146  * @param t Thread to run, if chosen by an external entity (e.g.,
 147  * ModelChecker). May be NULL to indicate no external choice.
 148  * @return The next Thread to run
 149  */
 150 Thread * Scheduler::next_thread(Thread *t)
 151 {
 152         if ( t == NULL ) {
 153                 int old_curr_thread = curr_thread_index;
 154                 bool have_enabled_thread_with_priority=false;
 155                 Node *n=model->get_curr_node();
 156
 157                 for(int i=0;i<enabled_len;i++) {
 158                         thread_id_t tid=int_to_id(i);
 159                         if (n->has_priority(tid)) {
 160                                 //Have a thread with priority
 161                                 if (enabled[i]!=THREAD_DISABLED)
 162                                         have_enabled_thread_with_priority=true;
 163                         }
 164                 }
 165
 166                 while(true) {
 167                         curr_thread_index = (curr_thread_index+1) % enabled_len;
 168                         thread_id_t curr_tid=int_to_id(curr_thread_index);
 169                         if (enabled[curr_thread_index]==THREAD_ENABLED&&
 170                                         (!have_enabled_thread_with_priority||n->has_priority(curr_tid))) {
 171                                 t = model->get_thread(curr_tid);
 172                                 break;
 173                         }
 174                         if (curr_thread_index == old_curr_thread) {
 175                                 print();
 176                                 return NULL;
 177                         }
 178                 }
 179         } else if (t->is_model_thread()) {
 180                 /* model-checker threads never run */
 181                 t = NULL;
 182         } else {
 183                 curr_thread_index = id_to_int(t->get_id());
 184         }
 185
 186         current = t;
 187         print();
 188         return t;
 189 }
 190
 191 /**
 192  * @return The currently-running Thread
 193  */
 194 Thread * Scheduler::get_current_thread() const
 195 {
 196         ASSERT(!current || !current->is_model_thread());
 197         return current;
 198 }
 199
 200 /**
 201  * Print debugging information about the current state of the scheduler. Only
 202  * prints something if debugging is enabled.
 203  */
 204 void Scheduler::print() const
 205 {
 206         if (current)
 207                 DEBUG("Current thread: %d\n", id_to_int(current->get_id()));
 208         else
 209                 DEBUG("No current thread\n");
 210 }