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Improve thread safety of viewer iterator (forEach is recommended instead)

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Signed-off-by: TheMode <themode@outlook.fr>
This commit is contained in:
TheMode 2021-12-09 17:26:27 +01:00
parent 61995e1b0c
commit ac4210d7d7
1 changed files with 5 additions and 59 deletions
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64
src/main/java/net/minestom/server/utils/ViewEngine.java
View File

@ -10,10 +10,7 @@ import org.jetbrains.annotations.ApiStatus;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import java.util.AbstractSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.*;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.function.Consumer;
@ -211,10 +208,12 @@ public final class ViewEngine {
}
final class SetImpl extends AbstractSet<Player> {
private static final Object[] EMPTY = new Object[0];
@Override
public @NotNull Iterator<Player> iterator() {
synchronized (mutex) {
return new It();
return Arrays.asList(toArray(Player[]::new)).iterator();
}
}
@ -291,14 +290,12 @@ public final class ViewEngine {
}
}
private static final Object[] EMPTY = new Object[0];
@Override
public @NotNull Object @NotNull [] toArray() {
synchronized (mutex) {
final int size = size();
if (size == 0) return EMPTY;
Object[] array = new Object[size];
Player[] array = new Player[size];
AtomicInteger index = new AtomicInteger();
forEach(player -> array[index.getAndIncrement()] = player);
assert index.get() == size;
@ -320,56 +317,5 @@ public final class ViewEngine {
return array;
}
}
final class It implements Iterator<Player> {
private Iterator<Player> current = ViewEngine.this.manualViewers.iterator();
private boolean autoIterator = false; // True if the current iterator comes from the auto-viewable references
private int index;
private Player next;
@Override
public boolean hasNext() {
synchronized (mutex) {
return next != null || (next = findNext()) != null;
}
}
@Override
public Player next() {
synchronized (mutex) {
if (next == null) return findNext();
final Player temp = this.next;
this.next = null;
return temp;
}
}
private Player findNext() {
Player result;
if ((result = nextValidEntry(current)) != null) return result;
this.autoIterator = true;
final var references = viewableOption.references;
if (references == null || !viewableOption.isAuto()) return null;
for (int i = index + 1; i < references.size(); i++) {
final List<Player> players = references.get(i);
Iterator<Player> iterator = players.iterator();
if ((result = nextValidEntry(iterator)) != null) {
this.current = iterator;
this.index = i;
return result;
}
}
return null;
}
private Player nextValidEntry(Iterator<Player> iterator) {
while (iterator.hasNext()) {
final Player player = iterator.next();
if (autoIterator ? validAutoViewer(player) : player != entity)
return player;
}
return null;
}
}
}
}