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#891: Fix scheduler task ID overflow and duplication issues

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By: Phoenix616 <max@themoep.de>
This commit is contained in:
CraftBukkit/Spigot 2021-07-17 11:39:56 +10:00
parent 96ffc08c35
commit 71d4016a4d
2 changed files with 28 additions and 3 deletions
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26
paper-server/src/main/java/org/bukkit/craftbukkit/scheduler/CraftScheduler.java
View file

@ -14,6 +14,7 @@ import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;
import java.util.function.IntUnaryOperator;
import java.util.logging.Level;
import org.apache.commons.lang.Validate;
import org.bukkit.plugin.IllegalPluginAccessException;
@ -43,10 +44,24 @@ import org.bukkit.scheduler.BukkitWorker;
*/
public class CraftScheduler implements BukkitScheduler {
/**
* The start ID for the counter.
*/
private static final int START_ID = 1;
/**
* Increment the {@link #ids} field and reset it to the {@link #START_ID} if it reaches {@link Integer#MAX_VALUE}
*/
private static final IntUnaryOperator INCREMENT_IDS = previous -> {
// We reached the end, go back to the start!
if (previous == Integer.MAX_VALUE) {
return START_ID;
}
return previous + 1;
};
/**
* Counter for IDs. Order doesn't matter, only uniqueness.
*/
private final AtomicInteger ids = new AtomicInteger(1);
private final AtomicInteger ids = new AtomicInteger(START_ID);
/**
* Current head of linked-list. This reference is always stale, {@link CraftTask#next} is the live reference.
*/
@ -65,7 +80,7 @@ public class CraftScheduler implements BukkitScheduler {
int value = Long.compare(o1.getNextRun(), o2.getNextRun());
// If the tasks should run on the same tick they should be run FIFO
return value != 0 ? value : Integer.compare(o1.getTaskId(), o2.getTaskId());
return value != 0 ? value : Long.compare(o1.getCreatedAt(), o2.getCreatedAt());
}
});
/**
@ -453,7 +468,12 @@ public class CraftScheduler implements BukkitScheduler {
}
private int nextId() {
return ids.incrementAndGet();
Validate.isTrue(runners.size() < Integer.MAX_VALUE, "There are already " + Integer.MAX_VALUE + " tasks scheduled! Cannot schedule more.");
int id;
do {
id = ids.updateAndGet(INCREMENT_IDS);
} while (runners.containsKey(id)); // Avoid generating duplicate IDs
return id;
}
private void parsePending() {

5
paper-server/src/main/java/org/bukkit/craftbukkit/scheduler/CraftTask.java
View file

@ -27,6 +27,7 @@ class CraftTask implements BukkitTask, Runnable {
private final Consumer<BukkitTask> cTask;
private final Plugin plugin;
private final int id;
private final long createdAt = System.nanoTime();
CraftTask() {
this(null, null, CraftTask.NO_REPEATING, CraftTask.NO_REPEATING);
@ -79,6 +80,10 @@ class CraftTask implements BukkitTask, Runnable {
}
}
long getCreatedAt() {
return createdAt;
}
long getPeriod() {
return period;
}