Plugin remapping

Co-authored-by: Nassim Jahnke <nassim@njahnke.dev>

paper-server/src/main/java/io/papermc/paper/util/AtomicFiles.java

@@ -0,0 +1,96 @@
+package io.papermc.paper.util;
+
+import java.io.IOException;
+import java.nio.file.AccessDeniedException;
+import java.nio.file.AtomicMoveNotSupportedException;
+import java.nio.file.CopyOption;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.Consumer;
+import org.spongepowered.configurate.util.CheckedConsumer;
+
+// Stripped down version of https://github.com/jpenilla/squaremap/blob/7d7994b4096e5fc61364ea2d87e9aa4e14edf5c6/common/src/main/java/xyz/jpenilla/squaremap/common/util/FileUtil.java
+public final class AtomicFiles {
+
+    private AtomicFiles() {
+    }
+
+    public static void atomicWrite(final Path path, final CheckedConsumer<Path, IOException> op) throws IOException {
+        final Path tmp = tempFile(path);
+
+        try {
+            op.accept(tmp);
+            atomicMove(tmp, path, true);
+        } catch (final IOException ex) {
+            try {
+                Files.deleteIfExists(tmp);
+            } catch (final IOException ex1) {
+                ex.addSuppressed(ex1);
+            }
+            throw ex;
+        }
+    }
+
+    private static Path tempFile(final Path path) {
+        return path.resolveSibling("." + System.nanoTime() + "-" + ThreadLocalRandom.current().nextInt() + "-" + path.getFileName().toString() + ".tmp");    }
+
+    @SuppressWarnings("BusyWait") // not busy waiting
+    public static void atomicMove(final Path from, final Path to, final boolean replaceExisting) throws IOException {
+        final int maxRetries = 2;
+
+        try {
+            atomicMoveIfPossible(from, to, replaceExisting);
+        } catch (final AccessDeniedException ex) {
+            // Sometimes because of file locking this will fail... Let's just try again and hope for the best
+            // Thanks Windows!
+            int retries = 1;
+            while (true) {
+                try {
+                    // Pause for a bit
+                    Thread.sleep(10L * retries);
+                    atomicMoveIfPossible(from, to, replaceExisting);
+                    break; // success
+                } catch (final AccessDeniedException ex1) {
+                    ex.addSuppressed(ex1);
+                    if (retries == maxRetries) {
+                        throw ex;
+                    }
+                } catch (final InterruptedException interruptedException) {
+                    ex.addSuppressed(interruptedException);
+                    Thread.currentThread().interrupt();
+                    throw ex;
+                }
+                ++retries;
+            }
+        }
+    }
+
+    private static void atomicMoveIfPossible(final Path from, final Path to, final boolean replaceExisting) throws IOException {
+        final CopyOption[] options = replaceExisting
+            ? new CopyOption[]{StandardCopyOption.ATOMIC_MOVE, StandardCopyOption.REPLACE_EXISTING}
+            : new CopyOption[]{StandardCopyOption.ATOMIC_MOVE};
+
+        try {
+            Files.move(from, to, options);
+        } catch (final AtomicMoveNotSupportedException ex) {
+            Files.move(from, to, replaceExisting ? new CopyOption[]{StandardCopyOption.REPLACE_EXISTING} : new CopyOption[]{});
+        }
+    }
+
+    private static <T, X extends Throwable> Consumer<T> sneaky(final CheckedConsumer<T, X> consumer) {
+        return t -> {
+            try {
+                consumer.accept(t);
+            } catch (final Throwable thr) {
+                rethrow(thr);
+            }
+        };
+    }
+
+    @SuppressWarnings("unchecked")
+    private static <X extends Throwable> RuntimeException rethrow(final Throwable t) throws X {
+        throw (X) t;
+    }
+}

paper-server/src/main/java/io/papermc/paper/util/Hashing.java

@@ -0,0 +1,50 @@
+package io.papermc.paper.util;
+
+import com.google.common.hash.HashCode;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Locale;
+import org.apache.commons.io.IOUtils;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.framework.qual.DefaultQualifier;
+
+@DefaultQualifier(NonNull.class)
+public final class Hashing {
+    private Hashing() {
+    }
+
+    /**
+     * Hash the provided {@link InputStream} using SHA-256. Stream will be closed.
+     *
+     * @param stream input stream
+     * @return SHA-256 hash string
+     */
+    public static String sha256(final InputStream stream) {
+        try (stream) {
+            return com.google.common.hash.Hashing.sha256().hashBytes(IOUtils.toByteArray(stream)).toString().toUpperCase(Locale.ROOT);
+        } catch (final IOException ex) {
+            throw new RuntimeException("Failed to take hash of InputStream", ex);
+        }
+    }
+
+    /**
+     * Hash the provided file using SHA-256.
+     *
+     * @param file file
+     * @return SHA-256 hash string
+     */
+    public static String sha256(final Path file) {
+        if (!Files.isRegularFile(file)) {
+            throw new IllegalArgumentException("'" + file + "' is not a regular file!");
+        }
+        final HashCode hash;
+        try {
+            hash = com.google.common.io.Files.asByteSource(file.toFile()).hash(com.google.common.hash.Hashing.sha256());
+        } catch (final IOException ex) {
+            throw new RuntimeException("Failed to take hash of file '" + file + "'", ex);
+        }
+        return hash.toString().toUpperCase(Locale.ROOT);
+    }
+}

paper-server/src/main/java/io/papermc/paper/util/MappingEnvironment.java

@@ -0,0 +1,65 @@
+package io.papermc.paper.util;
+
+import java.io.InputStream;
+import java.util.Objects;
+import java.util.jar.Manifest;
+import net.minecraft.world.entity.MobCategory;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.framework.qual.DefaultQualifier;
+
+@DefaultQualifier(NonNull.class)
+public final class MappingEnvironment {
+    private static final @Nullable String MAPPINGS_HASH = readMappingsHash();
+    private static final boolean REOBF = checkReobf();
+
+    private MappingEnvironment() {
+    }
+
+    public static boolean reobf() {
+        return REOBF;
+    }
+
+    public static boolean hasMappings() {
+        return MAPPINGS_HASH != null;
+    }
+
+    public static InputStream mappingsStream() {
+        return Objects.requireNonNull(mappingsStreamIfPresent(), "Missing mappings!");
+    }
+
+    public static @Nullable InputStream mappingsStreamIfPresent() {
+        return MappingEnvironment.class.getClassLoader().getResourceAsStream("META-INF/mappings/reobf.tiny");
+    }
+
+    public static String mappingsHash() {
+        return Objects.requireNonNull(MAPPINGS_HASH, "MAPPINGS_HASH");
+    }
+
+    private static @Nullable String readMappingsHash() {
+        final @Nullable Manifest manifest = JarManifests.manifest(MappingEnvironment.class);
+        if (manifest != null) {
+            final Object hash = manifest.getMainAttributes().getValue("Included-Mappings-Hash");
+            if (hash != null) {
+                return hash.toString();
+            }
+        }
+
+        final @Nullable InputStream stream = mappingsStreamIfPresent();
+        if (stream == null) {
+            return null;
+        }
+        return Hashing.sha256(stream);
+    }
+
+    @SuppressWarnings("ConstantConditions")
+    private static boolean checkReobf() {
+        final Class<?> clazz = MobCategory.class;
+        if (clazz.getSimpleName().equals("MobCategory")) {
+            return false;
+        } else if (clazz.getSimpleName().equals("EnumCreatureType")) {
+            return true;
+        }
+        throw new IllegalStateException();
+    }
+}

paper-server/src/main/java/io/papermc/paper/util/ObfHelper.java

@@ -80,10 +80,10 @@ public enum ObfHelper {
     }
 
     private static @Nullable Set<ClassMapping> loadMappingsIfPresent() {
-        try (final @Nullable InputStream mappingsInputStream = ObfHelper.class.getClassLoader().getResourceAsStream("META-INF/mappings/reobf.tiny")) {
-            if (mappingsInputStream == null) {
-                return null;
-            }
+        if (!MappingEnvironment.hasMappings()) {
+            return null;
+        }
+        try (final InputStream mappingsInputStream = MappingEnvironment.mappingsStream()) {
             final IMappingFile mappings = IMappingFile.load(mappingsInputStream); // Mappings are mojang->spigot
             final Set<ClassMapping> classes = new HashSet<>();
 

paper-server/src/main/java/io/papermc/paper/util/concurrent/ScalingThreadPool.java

@@ -0,0 +1,85 @@
+package io.papermc.paper.util.concurrent;
+
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.RejectedExecutionHandler;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Utilities for scaling thread pools.
+ *
+ * @see <a href="https://medium.com/@uditharosha/java-scale-first-executorservice-4245a63222df">Java Scale First ExecutorService — A myth or a reality</a>
+ */
+public final class ScalingThreadPool {
+    private ScalingThreadPool() {
+    }
+
+    public static RejectedExecutionHandler defaultReEnqueuePolicy() {
+        return reEnqueuePolicy(new ThreadPoolExecutor.AbortPolicy());
+    }
+
+    public static RejectedExecutionHandler reEnqueuePolicy(final RejectedExecutionHandler original) {
+        return new ReEnqueuePolicy(original);
+    }
+
+    public static <E> BlockingQueue<E> createUnboundedQueue() {
+        return new Queue<>();
+    }
+
+    public static <E> BlockingQueue<E> createQueue(final int capacity) {
+        return new Queue<>(capacity);
+    }
+
+    private static final class Queue<E> extends LinkedBlockingQueue<E> {
+        private final AtomicInteger idleThreads = new AtomicInteger(0);
+
+        private Queue() {
+            super();
+        }
+
+        private Queue(final int capacity) {
+            super(capacity);
+        }
+
+        @Override
+        public boolean offer(final E e) {
+            return this.idleThreads.get() > 0 && super.offer(e);
+        }
+
+        @Override
+        public E take() throws InterruptedException {
+            this.idleThreads.incrementAndGet();
+            try {
+                return super.take();
+            } finally {
+                this.idleThreads.decrementAndGet();
+            }
+        }
+
+        @Override
+        public E poll(final long timeout, final TimeUnit unit) throws InterruptedException {
+            this.idleThreads.incrementAndGet();
+            try {
+                return super.poll(timeout, unit);
+            } finally {
+                this.idleThreads.decrementAndGet();
+            }
+        }
+
+        @Override
+        public boolean add(final E e) {
+            return super.offer(e);
+        }
+    }
+
+    private record ReEnqueuePolicy(RejectedExecutionHandler originalHandler) implements RejectedExecutionHandler {
+        @Override
+        public void rejectedExecution(final Runnable r, final ThreadPoolExecutor executor) {
+            if (!executor.getQueue().add(r)) {
+                this.originalHandler.rejectedExecution(r, executor);
+            }
+        }
+    }
+}