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(const 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(const Thread *t) const
  64 {
  65         int id = id_to_int(t->get_id());
  66         ASSERT(id < enabled_len);
  67         return enabled[id];
  68 }
  69
  70 void Scheduler::update_sleep_set(Node *n) {
  71         enabled_type_t *enabled_array=n->get_enabled_array();
  72         for(int i=0;i<enabled_len;i++) {
  73                 if (enabled_array[i]==THREAD_SLEEP_SET) {
  74                         enabled[i]=THREAD_SLEEP_SET;
  75                 }
  76         }
  77 }
  78
  79 /**
  80  * Add a Thread to the sleep set.
  81  * @param t The Thread to add
  82  */
  83 void Scheduler::add_sleep(Thread *t)
  84 {
  85         DEBUG("thread %d\n", id_to_int(t->get_id()));
  86         set_enabled(t, THREAD_SLEEP_SET);
  87 }
  88
  89 /**
  90  * Remove a Thread from the sleep set.
  91  * @param t The Thread to remove
  92  */
  93 void Scheduler::remove_sleep(Thread *t)
  94 {
  95         DEBUG("thread %d\n", id_to_int(t->get_id()));
  96         set_enabled(t, THREAD_ENABLED);
  97 }
  98
  99 /**
 100  * Add a Thread to the scheduler's ready list.
 101  * @param t The Thread to add
 102  */
 103 void Scheduler::add_thread(Thread *t)
 104 {
 105         DEBUG("thread %d\n", id_to_int(t->get_id()));
 106         ASSERT(!t->is_model_thread());
 107         set_enabled(t, THREAD_ENABLED);
 108 }
 109
 110 /**
 111  * Remove a given Thread from the scheduler.
 112  * @param t The Thread to remove
 113  */
 114 void Scheduler::remove_thread(Thread *t)
 115 {
 116         if (current == t)
 117                 current = NULL;
 118         set_enabled(t, THREAD_DISABLED);
 119 }
 120
 121 /**
 122  * Prevent a Thread from being scheduled. The sleeping Thread should be
 123  * re-awoken via Scheduler::wake.
 124  * @param thread The Thread that should sleep
 125  */
 126 void Scheduler::sleep(Thread *t)
 127 {
 128         set_enabled(t, THREAD_DISABLED);
 129         t->set_state(THREAD_BLOCKED);
 130 }
 131
 132 /**
 133  * Wake a Thread up that was previously waiting (see Scheduler::wait)
 134  * @param t The Thread to wake up
 135  */
 136 void Scheduler::wake(Thread *t)
 137 {
 138         ASSERT(!t->is_model_thread());
 139         set_enabled(t, THREAD_ENABLED);
 140         t->set_state(THREAD_READY);
 141 }
 142
 143 /**
 144  * Select a Thread. This implementation defaults to round-robin, if a
 145  * thread is not already provided.
 146  *
 147  * @param t Thread to run, if chosen by an external entity (e.g.,
 148  * ModelChecker). May be NULL to indicate no external choice.
 149  * @return The next Thread to run
 150  */
 151 Thread * Scheduler::next_thread(Thread *t)
 152 {
 153         if ( t == NULL ) {
 154                 int old_curr_thread = curr_thread_index;
 155                 bool have_enabled_thread_with_priority=false;
 156                 Node *n=model->get_curr_node();
 157
 158                 for(int i=0;i<enabled_len;i++) {
 159                         thread_id_t tid=int_to_id(i);
 160                         if (n->has_priority(tid)) {
 161                                 //Have a thread with priority
 162                                 if (enabled[i]!=THREAD_DISABLED)
 163                                         have_enabled_thread_with_priority=true;
 164                         }
 165                 }
 166
 167                 while(true) {
 168                         curr_thread_index = (curr_thread_index+1) % enabled_len;
 169                         thread_id_t curr_tid=int_to_id(curr_thread_index);
 170                         if (enabled[curr_thread_index]==THREAD_ENABLED&&
 171                                         (!have_enabled_thread_with_priority||n->has_priority(curr_tid))) {
 172                                 t = model->get_thread(curr_tid);
 173                                 break;
 174                         }
 175                         if (curr_thread_index == old_curr_thread) {
 176                                 print();
 177                                 return NULL;
 178                         }
 179                 }
 180         } else if (t->is_model_thread()) {
 181                 /* model-checker threads never run */
 182                 t = NULL;
 183         } else {
 184                 curr_thread_index = id_to_int(t->get_id());
 185         }
 186
 187         current = t;
 188         print();
 189         return t;
 190 }
 191
 192 /**
 193  * @return The currently-running Thread
 194  */
 195 Thread * Scheduler::get_current_thread() const
 196 {
 197         ASSERT(!current || !current->is_model_thread());
 198         return current;
 199 }
 200
 201 /**
 202  * Print debugging information about the current state of the scheduler. Only
 203  * prints something if debugging is enabled.
 204  */
 205 void Scheduler::print() const
 206 {
 207         if (current)
 208                 DEBUG("Current thread: %d\n", id_to_int(current->get_id()));
 209         else
 210                 DEBUG("No current thread\n");
 211 }