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