+#include <string.h>
+#include <stdlib.h>
+
#include "threads.h"
#include "schedule.h"
#include "common.h"
#include "model.h"
+/** Constructor */
+Scheduler::Scheduler() :
+ is_enabled(NULL),
+ enabled_len(0),
+ curr_thread_index(0),
+ current(NULL)
+{
+}
+
+void Scheduler::set_enabled(Thread *t, bool enabled_status) {
+ int threadid=id_to_int(t->get_id());
+ if (threadid>=enabled_len) {
+ bool * new_enabled=(bool *)malloc(sizeof(bool)*(threadid+1));
+ memset(&new_enabled[enabled_len], 0, (threadid+1-enabled_len)*sizeof(bool));
+ if (is_enabled != NULL) {
+ memcpy(new_enabled, is_enabled, enabled_len*sizeof(bool));
+ free(is_enabled);
+ }
+ is_enabled=new_enabled;
+ enabled_len=threadid+1;
+ }
+ is_enabled[threadid]=enabled_status;
+}
+
+/**
+ * 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);
+ set_enabled(t, true);
}
+/**
+ * Remove a given Thread from the scheduler.
+ * @param t The Thread to remove
+ */
void Scheduler::remove_thread(Thread *t)
{
if (current == t)
current = NULL;
- else
- readyList.remove(t);
+ set_enabled(t, false);
}
-Thread * Scheduler::next_thread(void)
+/**
+ * Prevent a Thread from being scheduled. The sleeping Thread should be
+ * re-awoken via Scheduler::wake.
+ * @param thread The Thread that should sleep
+ */
+void Scheduler::sleep(Thread *t)
{
- Thread *t = model->schedule_next_thread();
+ set_enabled(t, false);
+ t->set_state(THREAD_BLOCKED);
+}
+
+/**
+ * Wake a Thread up that was previously waiting (see Scheduler::wait)
+ * @param t The Thread to wake up
+ */
+void Scheduler::wake(Thread *t)
+{
+ set_enabled(t, true);
+ t->set_state(THREAD_READY);
+}
- if (t != NULL) {
- current = t;
- readyList.remove(t);
- } else if (readyList.empty()) {
- t = NULL;
+/**
+ * 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.
+ * @return The next Thread to run
+ */
+Thread * Scheduler::next_thread(Thread *t)
+{
+ if ( t == NULL ) {
+ int old_curr_thread = curr_thread_index;
+ while(true) {
+ curr_thread_index = (curr_thread_index+1) % enabled_len;
+ if (is_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 {
- t = readyList.front();
- current = t;
- readyList.pop_front();
+ curr_thread_index = id_to_int(t->get_id());
}
+ current = t;
print();
-
return t;
}
-Thread * Scheduler::get_current_thread(void)
+/**
+ * @return The currently-running Thread
+ */
+Thread * Scheduler::get_current_thread() const
{
return current;
}
-void Scheduler::print()
+/**
+ * Print debugging information about the current state of the scheduler. Only
+ * prints something if debugging is enabled.
+ */
+void Scheduler::print() const
{
if (current)
- printf("Current thread: %d\n", current->get_id());
+ DEBUG("Current thread: %d\n", current->get_id());
else
- printf("No current thread\n");
- printf("Num. threads in ready list: %ld\n", readyList.size());
-
- std::list<Thread *>::iterator it;
- for (it = readyList.begin(); it != readyList.end(); it++)
- printf("In ready list: thread %d\n", (*it)->get_id());
+ DEBUG("No current thread\n");
}