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         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         return enabled[id_to_int(t->get_id())];
  47 }
  48
  49 void Scheduler::update_sleep_set(Node *n) {
  50         enabled_type_t *enabled_array=n->get_enabled_array();
  51         for(int i=0;i<enabled_len;i++) {
  52                 if (enabled_array[i]==THREAD_SLEEP_SET) {
  53                         enabled[i]=THREAD_SLEEP_SET;
  54                 }
  55         }
  56 }
  57
  58 /**
  59  * Add a Thread to the sleep set.
  60  * @param t The Thread to add
  61  */
  62 void Scheduler::add_sleep(Thread *t)
  63 {
  64         DEBUG("thread %d\n", id_to_int(t->get_id()));
  65         set_enabled(t, THREAD_SLEEP_SET);
  66 }
  67
  68 /**
  69  * Remove a Thread from the sleep set.
  70  * @param t The Thread to remove
  71  */
  72 void Scheduler::remove_sleep(Thread *t)
  73 {
  74         DEBUG("thread %d\n", id_to_int(t->get_id()));
  75         set_enabled(t, THREAD_ENABLED);
  76 }
  77
  78 /**
  79  * Add a Thread to the scheduler's ready list.
  80  * @param t The Thread to add
  81  */
  82 void Scheduler::add_thread(Thread *t)
  83 {
  84         DEBUG("thread %d\n", id_to_int(t->get_id()));
  85         ASSERT(!t->is_model_thread());
  86         set_enabled(t, THREAD_ENABLED);
  87 }
  88
  89 /**
  90  * Remove a given Thread from the scheduler.
  91  * @param t The Thread to remove
  92  */
  93 void Scheduler::remove_thread(Thread *t)
  94 {
  95         if (current == t)
  96                 current = NULL;
  97         set_enabled(t, THREAD_DISABLED);
  98 }
  99
 100 /**
 101  * Prevent a Thread from being scheduled. The sleeping Thread should be
 102  * re-awoken via Scheduler::wake.
 103  * @param thread The Thread that should sleep
 104  */
 105 void Scheduler::sleep(Thread *t)
 106 {
 107         set_enabled(t, THREAD_DISABLED);
 108         t->set_state(THREAD_BLOCKED);
 109 }
 110
 111 /**
 112  * Wake a Thread up that was previously waiting (see Scheduler::wait)
 113  * @param t The Thread to wake up
 114  */
 115 void Scheduler::wake(Thread *t)
 116 {
 117         ASSERT(!t->is_model_thread());
 118         set_enabled(t, THREAD_DISABLED);
 119         t->set_state(THREAD_READY);
 120 }
 121
 122 /**
 123  * Select a Thread. This implementation defaults to round-robin, if a
 124  * thread is not already provided.
 125  *
 126  * @param t Thread to run, if chosen by an external entity (e.g.,
 127  * ModelChecker). May be NULL to indicate no external choice.
 128  * @return The next Thread to run
 129  */
 130 Thread * Scheduler::next_thread(Thread *t)
 131 {
 132         if ( t == NULL ) {
 133                 int old_curr_thread = curr_thread_index;
 134                 while(true) {
 135                         curr_thread_index = (curr_thread_index+1) % enabled_len;
 136                         if (enabled[curr_thread_index]==THREAD_ENABLED) {
 137                                 t = model->get_thread(int_to_id(curr_thread_index));
 138                                 break;
 139                         }
 140                         if (curr_thread_index == old_curr_thread) {
 141                                 print();
 142                                 return NULL;
 143                         }
 144                 }
 145         } else if (t->is_model_thread()) {
 146                 /* model-checker threads never run */
 147                 t = NULL;
 148         } else {
 149                 curr_thread_index = id_to_int(t->get_id());
 150         }
 151
 152         current = t;
 153         print();
 154         return t;
 155 }
 156
 157 /**
 158  * @return The currently-running Thread
 159  */
 160 Thread * Scheduler::get_current_thread() const
 161 {
 162         ASSERT(!current || !current->is_model_thread());
 163         return current;
 164 }
 165
 166 /**
 167  * Print debugging information about the current state of the scheduler. Only
 168  * prints something if debugging is enabled.
 169  */
 170 void Scheduler::print() const
 171 {
 172         if (current)
 173                 DEBUG("Current thread: %d\n", id_to_int(current->get_id()));
 174         else
 175                 DEBUG("No current thread\n");
 176 }