/**
* Returns the set of tasks that are startable. A startable task is currently in STATE_NEW and has
* also met all of its starting dependencies. This requires that each starting dependency must be
* in STATE_ENDED. In addition if there are any starting or ending dependencies of an task that
* are not present in the map, then hat task will never be considered startable.
*
* @param tasks Map of tasks indexed by their unique identification
* @return The set of startable tasks
*/
private <T extends Task> Set<T> getStartables(Map<Integer, T> tasks) {
Set<T> startables = new HashSet<T>();
for (T task : tasks.values()) {
// Ignore tasks that have not been started or have not been added
// to the schduler.
if (task.getState() != Task.STATE_NEW || !startDepends.containsKey(task.getTaskId())) {
continue;
}
// Check if the task has met all of its start dependencies
boolean canStart = true;
for (int id : startDepends.get(task.getTaskId())) {
if (!tasks.containsKey(id) || tasks.get(id).getState() != Task.STATE_ENDED) {
canStart = false;
break;
}
}
// In addition check that we *know* about all of this task's
// ending dependencies. We do not want to accidentally start an
// task that we can never end.
if (canStart && tasks.keySet().containsAll(endDepends.get(task.getTaskId()))) {
startables.add(task);
}
}
return startables;
}
/**
* Returns the set of tasks that are endable. An endable task is not only in STATE_ENDABLE, but
* also has met all of its ending dependencies. To meet this requirement, each ending dependency
* must be in either STATE_ENDABLE, STATE_ENDING, or STATE_ENDED.
*
* @param tasks Map of tasks indexed by their unique identification
* @return The set of endable tasks
*/
private <T extends Task> Set<T> getEndables(Map<Integer, T> tasks) {
Set<T> endables = new HashSet<T>();
for (T task : tasks.values()) {
// Ignore tasks that are not endable or have not been added to
// the scheduler.
if (task.getState() != Task.STATE_ENDABLE || !endDepends.containsKey(task.getTaskId())) {
continue;
}
// Check if the task has met all of its end dependencies
boolean canEnd = true;
for (int id : endDepends.get(task.getTaskId())) {
if (!tasks.containsKey(id) || tasks.get(id).getState() < Task.STATE_ENDABLE) {
canEnd = false;
break;
}
}
if (canEnd) {
endables.add(task);
}
}
return endables;
}
