schedule: do not allow model-checker thread to enter scheduler

[c11tester.git] / schedule.cc

diff --git a/schedule.cc b/schedule.cc
index cbb4957a3e4a3865730679e8e816dfb51f636324..dd35237b22232df0744e22baadaaceb54ae6affd 100644 (file)
--- a/schedule.cc
+++ b/schedule.cc
@@ -1,3 +1,6 @@
+#include <string.h>
+#include <stdlib.h>
+
 #include "threads.h"
 #include "schedule.h"
 #include "common.h"
@@ -5,18 +8,48 @@
 
 /** Constructor */
 Scheduler::Scheduler() :
+       enabled(NULL),
+       enabled_len(0),
+       curr_thread_index(0),
        current(NULL)
 {
 }
 
+void Scheduler::set_enabled(Thread *t, enabled_type_t enabled_status) {
+       int threadid=id_to_int(t->get_id());
+       if (threadid>=enabled_len) {
+               enabled_type_t *new_enabled = (enabled_type_t *)snapshot_malloc(sizeof(enabled_type_t) * (threadid + 1));
+               memset(&new_enabled[enabled_len], 0, (threadid+1-enabled_len)*sizeof(enabled_type_t));
+               if (enabled != NULL) {
+                       memcpy(new_enabled, enabled, enabled_len*sizeof(enabled_type_t));
+                       snapshot_free(enabled);
+               }
+               enabled=new_enabled;
+               enabled_len=threadid+1;
+       }
+       enabled[threadid]=enabled_status;
+}
+
+/**
+ * @brief Check if a Thread is currently enabled
+ * @param t The Thread to check
+ * @return True if the Thread is currently enabled
+ */
+bool Scheduler::is_enabled(Thread *t) const
+{
+       int id = id_to_int(t->get_id());
+       return (id >= enabled_len) ? false : (enabled[id] == THREAD_ENABLED);
+}
+
 /**
  * Add a Thread to the scheduler's ready list.
  * @param t The Thread to add
  */
 void Scheduler::add_thread(Thread *t)
 {
-       DEBUG("thread %d\n", t->get_id());
-       readyList.push_back(t);
+       DEBUG("thread %d\n", id_to_int(t->get_id()));
+       ASSERT(!t->is_model_thread());
+       set_enabled(t, THREAD_ENABLED);
 }
 
 /**
@@ -27,8 +60,7 @@ void Scheduler::remove_thread(Thread *t)
 {
        if (current == t)
                current = NULL;
-       else
-               readyList.remove(t);
+       set_enabled(t, THREAD_DISABLED);
 }
 
 /**
@@ -38,7 +70,7 @@ void Scheduler::remove_thread(Thread *t)
  */
 void Scheduler::sleep(Thread *t)
 {
-       remove_thread(t);
+       set_enabled(t, THREAD_DISABLED);
        t->set_state(THREAD_BLOCKED);
 }
 
@@ -48,13 +80,14 @@ void Scheduler::sleep(Thread *t)
  */
 void Scheduler::wake(Thread *t)
 {
-       add_thread(t);
+       ASSERT(!t->is_model_thread());
+       set_enabled(t, THREAD_DISABLED);
        t->set_state(THREAD_READY);
 }
 
 /**
- * Remove one Thread from the scheduler. This implementation defaults to FIFO,
- * if a thread is not already provided.
+ * Select a Thread. This implementation defaults to round-robin, if a
+ * thread is not already provided.
  *
  * @param t Thread to run, if chosen by an external entity (e.g.,
  * ModelChecker). May be NULL to indicate no external choice.
@@ -62,19 +95,28 @@ void Scheduler::wake(Thread *t)
  */
 Thread * Scheduler::next_thread(Thread *t)
 {
-       if (t != NULL) {
-               current = t;
-               readyList.remove(t);
-       } else if (readyList.empty()) {
+       if ( t == NULL ) {
+               int old_curr_thread = curr_thread_index;
+               while(true) {
+                       curr_thread_index = (curr_thread_index+1) % enabled_len;
+                       if (enabled[curr_thread_index]) {
+                               t = model->get_thread(int_to_id(curr_thread_index));
+                               break;
+                       }
+                       if (curr_thread_index == old_curr_thread) {
+                               print();
+                               return NULL;
+                       }
+               }
+       } else if (t->is_model_thread()) {
+               /* model-checker threads never run */
                t = NULL;
        } else {
-               t = readyList.front();
-               current = t;
-               readyList.pop_front();
+               curr_thread_index = id_to_int(t->get_id());
        }
 
+       current = t;
        print();
-
        return t;
 }
 
@@ -83,6 +125,7 @@ Thread * Scheduler::next_thread(Thread *t)
  */
 Thread * Scheduler::get_current_thread() const
 {
+       ASSERT(!current || !current->is_model_thread());
        return current;
 }
 
@@ -93,12 +136,7 @@ Thread * Scheduler::get_current_thread() const
 void Scheduler::print() const
 {
        if (current)
-               DEBUG("Current thread: %d\n", current->get_id());
+               DEBUG("Current thread: %d\n", id_to_int(current->get_id()));
        else
                DEBUG("No current thread\n");
-       DEBUG("Num. threads in ready list: %zu\n", readyList.size());
-
-       std::list<Thread *, MyAlloc< Thread * > >::const_iterator it;
-       for (it = readyList.begin(); it != readyList.end(); it++)
-               DEBUG("In ready list: thread %d\n", (*it)->get_id());
 }