package org.bukkit.craftbukkit.scheduler;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.PriorityQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import java.util.logging.Level;
import co.aikar.timings.MinecraftTimings; // Paper
import com.destroystokyo.paper.ServerSchedulerReportingWrapper;
import com.destroystokyo.paper.event.server.ServerExceptionEvent;
import com.destroystokyo.paper.exception.ServerSchedulerException;
import org.apache.commons.lang3.Validate;
import org.bukkit.plugin.IllegalPluginAccessException;
import org.bukkit.plugin.Plugin;
import org.bukkit.scheduler.BukkitRunnable;
import org.bukkit.scheduler.BukkitScheduler;
import org.bukkit.scheduler.BukkitTask;
import org.bukkit.scheduler.BukkitWorker;
/**
* The fundamental concepts for this implementation:
* <li>Main thread owns {@link #head} and {@link #currentTick}, but it may be read from any thread</li>
* <li>Main thread exclusively controls {@link #temp} and {@link #pending}.
* They are never to be accessed outside of the main thread; alternatives exist to prevent locking.</li>
* <li>{@link #head} to {@link #tail} act as a linked list/queue, with 1 consumer and infinite producers.
* Adding to the tail is atomic and very efficient; utility method is {@link #handle(CraftTask, long)} or {@link #addTask(CraftTask)}. </li>
* <li>Changing the period on a task is delicate.
* Any future task needs to notify waiting threads.
* Async tasks must be synchronized to make sure that any thread that's finishing will remove itself from {@link #runners}.
* Another utility method is provided for this, {@link #cancelTask(int)}</li>
* <li>{@link #runners} provides a moderately up-to-date view of active tasks.
* If the linked head to tail set is read, all remaining tasks that were active at the time execution started will be located in runners.</li>
* <li>Async tasks are responsible for removing themselves from runners</li>
* <li>Sync tasks are only to be removed from runners on the main thread when coupled with a removal from pending and temp.</li>
* <li>Most of the design in this scheduler relies on queuing special tasks to perform any data changes on the main thread.
* When executed from inside a synchronous method, the scheduler will be updated before next execution by virtue of the frequent {@link #parsePending()} calls.</li>
*/
public class CraftScheduler implements BukkitScheduler {
/**
* Counter for IDs. Order doesn't matter, only uniqueness.
*/
private final AtomicInteger ids = new AtomicInteger(1);
/**
* Current head of linked-list. This reference is always stale, {@link CraftTask#next} is the live reference.
*/
private volatile CraftTask head = new CraftTask();
/**
* Tail of a linked-list. AtomicReference only matters when adding to queue
*/
private final AtomicReference<CraftTask> tail = new AtomicReference<CraftTask>(head);
/**
* Main thread logic only
*/
private final PriorityQueue<CraftTask> pending = new PriorityQueue<CraftTask>(10,
new Comparator<CraftTask>() {
public int compare(final CraftTask o1, final CraftTask o2) {
int value = (int) (o1.getNextRun() - o2.getNextRun());
// If the tasks should run on the same tick they should be run FIFO
return value != 0 ? value : o1.getTaskId() - o2.getTaskId();
}
});
/**
* Main thread logic only
*/
private final List<CraftTask> temp = new ArrayList<CraftTask>();
/**
* These are tasks that are currently active. It's provided for 'viewing' the current state.
*/
private final ConcurrentHashMap<Integer, CraftTask> runners = new ConcurrentHashMap<Integer, CraftTask>();
private volatile int currentTick = -1;
private final Executor executor = Executors.newCachedThreadPool(new com.google.common.util.concurrent.ThreadFactoryBuilder().setNameFormat("Craft Scheduler Thread - %1$d").build()); // Spigot
//private CraftAsyncDebugger debugHead = new CraftAsyncDebugger(-1, null, null) {@Override StringBuilder debugTo(StringBuilder string) {return string;}}; // Paper
//private CraftAsyncDebugger debugTail = debugHead; // Paper
private static final int RECENT_TICKS;
static {
RECENT_TICKS = 30;
}
public int scheduleSyncDelayedTask(final Plugin plugin, final Runnable task) {
return this.scheduleSyncDelayedTask(plugin, task, 0l);
}
public BukkitTask runTask(Plugin plugin, Runnable runnable) {
return runTaskLater(plugin, runnable, 0l);
}
@Deprecated
public int scheduleAsyncDelayedTask(final Plugin plugin, final Runnable task) {
return this.scheduleAsyncDelayedTask(plugin, task, 0l);
}
public BukkitTask runTaskAsynchronously(Plugin plugin, Runnable runnable) {
return runTaskLaterAsynchronously(plugin, runnable, 0l);
}
public int scheduleSyncDelayedTask(final Plugin plugin, final Runnable task, final long delay) {
return this.scheduleSyncRepeatingTask(plugin, task, delay, -1l);
}
public BukkitTask runTaskLater(Plugin plugin, Runnable runnable, long delay) {
return runTaskTimer(plugin, runnable, delay, -1l);
}
@Deprecated
public int scheduleAsyncDelayedTask(final Plugin plugin, final Runnable task, final long delay) {
return this.scheduleAsyncRepeatingTask(plugin, task, delay, -1l);
}
public BukkitTask runTaskLaterAsynchronously(Plugin plugin, Runnable runnable, long delay) {
return runTaskTimerAsynchronously(plugin, runnable, delay, -1l);
}
public int scheduleSyncRepeatingTask(final Plugin plugin, final Runnable runnable, long delay, long period) {
return runTaskTimer(plugin, runnable, delay, period).getTaskId();
}
public BukkitTask runTaskTimer(Plugin plugin, Runnable runnable, long delay, long period) {
validate(plugin, runnable);
if (delay < 0l) {
delay = 0;
}
if (period == 0l) {
period = 1l;
} else if (period < -1l) {
period = -1l;
}
return handle(new CraftTask(plugin, runnable, nextId(), period), delay);
}
@Deprecated
public int scheduleAsyncRepeatingTask(final Plugin plugin, final Runnable runnable, long delay, long period) {
return runTaskTimerAsynchronously(plugin, runnable, delay, period).getTaskId();
}
public BukkitTask runTaskTimerAsynchronously(Plugin plugin, Runnable runnable, long delay, long period) {
validate(plugin, runnable);
if (delay < 0l) {
delay = 0;
}
if (period == 0l) {
period = 1l;
} else if (period < -1l) {
period = -1l;
}
return handle(new CraftAsyncTask(runners, plugin, runnable, nextId(), period), delay);
}
public <T> Future<T> callSyncMethod(final Plugin plugin, final Callable<T> task) {
validate(plugin, task);
final CraftFuture<T> future = new CraftFuture<T>(task, plugin, nextId());
handle(future, 0l);
return future;
}
public void cancelTask(final int taskId) {
if (taskId <= 0) {
return;
}
CraftTask task = runners.get(taskId);
if (task != null) {
task.cancel0();
}
task = new CraftTask(
new Runnable() {
public void run() {
if (!check(CraftScheduler.this.temp)) {
check(CraftScheduler.this.pending);
}
}
private boolean check(final Iterable<CraftTask> collection) {
final Iterator<CraftTask> tasks = collection.iterator();
while (tasks.hasNext()) {
final CraftTask task = tasks.next();
if (task.getTaskId() == taskId) {
task.cancel0();
tasks.remove();
if (task.isSync()) {
runners.remove(taskId);
}
return true;
}
}
return false;
}}){{this.timings=co.aikar.timings.MinecraftTimings.getCancelTasksTimer();}}; // Paper
handle(task, 0l);
for (CraftTask taskPending = head.getNext(); taskPending != null; taskPending = taskPending.getNext()) {
if (taskPending == task) {
return;
}
if (taskPending.getTaskId() == taskId) {
taskPending.cancel0();
}
}
}
public void cancelTasks(final Plugin plugin) {
Validate.notNull(plugin, "Cannot cancel tasks of null plugin");
final CraftTask task = new CraftTask(
new Runnable() {
public void run() {
check(CraftScheduler.this.pending);
check(CraftScheduler.this.temp);
}
void check(final Iterable<CraftTask> collection) {
final Iterator<CraftTask> tasks = collection.iterator();
while (tasks.hasNext()) {
final CraftTask task = tasks.next();
if (task.getOwner().equals(plugin)) {
task.cancel0();
tasks.remove();
if (task.isSync()) {
runners.remove(task.getTaskId());
}
}
}
}
}){{this.timings=co.aikar.timings.MinecraftTimings.getCancelTasksTimer(plugin);}}; // Paper
handle(task, 0l);
for (CraftTask taskPending = head.getNext(); taskPending != null; taskPending = taskPending.getNext()) {
if (taskPending == task) {
return;
}
if (taskPending.getTaskId() != -1 && taskPending.getOwner().equals(plugin)) {
taskPending.cancel0();
}
}
for (CraftTask runner : runners.values()) {
if (runner.getOwner().equals(plugin)) {
runner.cancel0();
}
}
}
public void cancelAllTasks() {
final CraftTask task = new CraftTask(
new Runnable() {
public void run() {
Iterator<CraftTask> it = CraftScheduler.this.runners.values().iterator();
while (it.hasNext()) {
CraftTask task = it.next();
task.cancel0();
if (task.isSync()) {
it.remove();
}
}
CraftScheduler.this.pending.clear();
CraftScheduler.this.temp.clear();
}
}){{this.timings=co.aikar.timings.MinecraftTimings.getCancelTasksTimer();}}; // Paper
handle(task, 0l);
for (CraftTask taskPending = head.getNext(); taskPending != null; taskPending = taskPending.getNext()) {
if (taskPending == task) {
break;
}
taskPending.cancel0();
}
for (CraftTask runner : runners.values()) {
runner.cancel0();
}
}
public boolean isCurrentlyRunning(final int taskId) {
final CraftTask task = runners.get(taskId);
if (task == null || task.isSync()) {
return false;
}
final CraftAsyncTask asyncTask = (CraftAsyncTask) task;
synchronized (asyncTask.getWorkers()) {
return asyncTask.getWorkers().isEmpty();
}
}
public boolean isQueued(final int taskId) {
if (taskId <= 0) {
return false;
}
for (CraftTask task = head.getNext(); task != null; task = task.getNext()) {
if (task.getTaskId() == taskId) {
return task.getPeriod() >= -1l; // The task will run
}
}
CraftTask task = runners.get(taskId);
return task != null && task.getPeriod() >= -1l;
}
public List<BukkitWorker> getActiveWorkers() {
final ArrayList<BukkitWorker> workers = new ArrayList<BukkitWorker>();
for (final CraftTask taskObj : runners.values()) {
// Iterator will be a best-effort (may fail to grab very new values) if called from an async thread
if (taskObj.isSync()) {
continue;
}
final CraftAsyncTask task = (CraftAsyncTask) taskObj;
synchronized (task.getWorkers()) {
// This will never have an issue with stale threads; it's state-safe
workers.addAll(task.getWorkers());
}
}
return workers;
}
public List<BukkitTask> getPendingTasks() {
final ArrayList<CraftTask> truePending = new ArrayList<CraftTask>();
for (CraftTask task = head.getNext(); task != null; task = task.getNext()) {
if (task.getTaskId() != -1) {
// -1 is special code
truePending.add(task);
}
}
final ArrayList<BukkitTask> pending = new ArrayList<BukkitTask>();
for (CraftTask task : runners.values()) {
if (task.getPeriod() >= -1l) {
pending.add(task);
}
}
for (final CraftTask task : truePending) {
if (task.getPeriod() >= -1l && !pending.contains(task)) {
pending.add(task);
}
}
return pending;
}
/**
* This method is designed to never block or wait for locks; an immediate execution of all current tasks.
*/
public void mainThreadHeartbeat(final int currentTick) {
this.currentTick = currentTick;
final List<CraftTask> temp = this.temp;
parsePending();
while (isReady(currentTick)) {
final CraftTask task = pending.remove();
if (task.getPeriod() < -1l) {
if (task.isSync()) {
runners.remove(task.getTaskId(), task);
}
parsePending();
continue;
}
if (task.isSync()) {
try {
task.run();
} catch (final Throwable throwable) {
// Paper start
String msg = String.format(
"Task #%s for %s generated an exception",
task.getTaskId(),
task.getOwner().getDescription().getFullName());
task.getOwner().getLogger().log(
Level.WARNING,
msg,
throwable);
task.getOwner().getServer().getPluginManager().callEvent(
new ServerExceptionEvent(new ServerSchedulerException(msg, throwable, task))
);
// Paper end
}
parsePending();
} else {
//debugTail = debugTail.setNext(new CraftAsyncDebugger(currentTick + RECENT_TICKS, task.getOwner(), task.getTaskClass())); // Paper
executor.execute(new ServerSchedulerReportingWrapper(task)); // Paper
// We don't need to parse pending
// (async tasks must live with race-conditions if they attempt to cancel between these few lines of code)
}
final long period = task.getPeriod(); // State consistency
if (period > 0) {
task.setNextRun(currentTick + period);
temp.add(task);
} else if (task.isSync()) {
runners.remove(task.getTaskId());
}
}
MinecraftTimings.bukkitSchedulerFinishTimer.startTiming();
pending.addAll(temp);
temp.clear();
MinecraftTimings.bukkitSchedulerFinishTimer.stopTiming();
//debugHead = debugHead.getNextHead(currentTick); // Paper
}
private void addTask(final CraftTask task) {
final AtomicReference<CraftTask> tail = this.tail;
CraftTask tailTask = tail.get();
while (!tail.compareAndSet(tailTask, task)) {
tailTask = tail.get();
}
tailTask.setNext(task);
}
private CraftTask handle(final CraftTask task, final long delay) {
task.setNextRun(currentTick + delay);
addTask(task);
return task;
}
private static void validate(final Plugin plugin, final Object task) {
Validate.notNull(plugin, "Plugin cannot be null");
Validate.notNull(task, "Task cannot be null");
if (!plugin.isEnabled()) {
throw new IllegalPluginAccessException("Plugin attempted to register task while disabled");
}
}
private int nextId() {
return ids.incrementAndGet();
}
private void parsePending() {
MinecraftTimings.bukkitSchedulerPendingTimer.startTiming();
CraftTask head = this.head;
CraftTask task = head.getNext();
CraftTask lastTask = head;
for (; task != null; task = (lastTask = task).getNext()) {
if (task.getTaskId() == -1) {
task.run();
} else if (task.getPeriod() >= -1l) {
pending.add(task);
runners.put(task.getTaskId(), task);
}
}
// We split this because of the way things are ordered for all of the async calls in CraftScheduler
// (it prevents race-conditions)
for (task = head; task != lastTask; task = head) {
head = task.getNext();
task.setNext(null);
}
this.head = lastTask;
MinecraftTimings.bukkitSchedulerPendingTimer.stopTiming();
}
private boolean isReady(final int currentTick) {
return !pending.isEmpty() && pending.peek().getNextRun() <= currentTick;
}
@Override
public String toString() {
// Paper start
return "";
/*
int debugTick = currentTick;
StringBuilder string = new StringBuilder("Recent tasks from ").append(debugTick - RECENT_TICKS).append('-').append(debugTick).append('{');
debugHead.debugTo(string);
return string.append('}').toString();
*/
// Paper end
}
@Deprecated
@Override
public int scheduleSyncDelayedTask(Plugin plugin, BukkitRunnable task, long delay) {
return scheduleSyncDelayedTask(plugin, (Runnable) task, delay);
}
@Deprecated
@Override
public int scheduleSyncDelayedTask(Plugin plugin, BukkitRunnable task) {
return scheduleSyncDelayedTask(plugin, (Runnable) task);
}
@Deprecated
@Override
public int scheduleSyncRepeatingTask(Plugin plugin, BukkitRunnable task, long delay, long period) {
return scheduleSyncRepeatingTask(plugin, (Runnable) task, delay, period);
}
@Deprecated
@Override
public BukkitTask runTask(Plugin plugin, BukkitRunnable task) throws IllegalArgumentException {
return runTask(plugin, (Runnable) task);
}
@Deprecated
@Override
public BukkitTask runTaskAsynchronously(Plugin plugin, BukkitRunnable task) throws IllegalArgumentException {
return runTaskAsynchronously(plugin, (Runnable) task);
}
@Deprecated
@Override
public BukkitTask runTaskLater(Plugin plugin, BukkitRunnable task, long delay) throws IllegalArgumentException {
return runTaskLater(plugin, (Runnable) task, delay);
}
@Deprecated
@Override
public BukkitTask runTaskLaterAsynchronously(Plugin plugin, BukkitRunnable task, long delay) throws IllegalArgumentException {
return runTaskLaterAsynchronously(plugin, (Runnable) task, delay);
}
@Deprecated
@Override
public BukkitTask runTaskTimer(Plugin plugin, BukkitRunnable task, long delay, long period) throws IllegalArgumentException {
return runTaskTimer(plugin, (Runnable) task, delay, period);
}
@Deprecated
@Override
public BukkitTask runTaskTimerAsynchronously(Plugin plugin, BukkitRunnable task, long delay, long period) throws IllegalArgumentException {
return runTaskTimerAsynchronously(plugin, (Runnable) task, delay, period);
}
}