Implement optimized compression for Java 11+

Using the fact that the Java Deflater/Inflater API now supports
ByteBuffers as of Java 11, we can provide performance benefits equivalent
to the Velocity 1.0.x native compression on servers running Java 11+ on
non-macOS and non-Linux platforms (such as Windows).

native/src/main/java/com/velocitypowered/natives/Native.java

@@ -1,5 +1,7 @@
 package com.velocitypowered.natives;
 
+import com.velocitypowered.natives.util.BufferPreference;
+
 public interface Native {
-  boolean isNative();
+  BufferPreference preferredBufferType();
 }

native/src/main/java/com/velocitypowered/natives/compression/Java11VelocityCompressor.java

@@ -0,0 +1,133 @@
+package com.velocitypowered.natives.compression;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkState;
+import static com.velocitypowered.natives.compression.CompressorUtils.ZLIB_BUFFER_SIZE;
+import static com.velocitypowered.natives.compression.CompressorUtils.ensureMaxSize;
+
+import com.velocitypowered.natives.util.BufferPreference;
+import io.netty.buffer.ByteBuf;
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.nio.ByteBuffer;
+import java.util.zip.DataFormatException;
+import java.util.zip.Deflater;
+import java.util.zip.Inflater;
+
+public class Java11VelocityCompressor implements VelocityCompressor {
+
+  public static final VelocityCompressorFactory FACTORY = Java11VelocityCompressor::new;
+
+  // The use of MethodHandle is intentional. Velocity targets Java 8, and these methods don't exist
+  // in Java 8. This was also the most performant solution I could find, only slightly slower than a
+  // direct method call without long warmup times, requiring bytecode generation through ASM, or
+  // other stuff.
+  private static final MethodHandle DEFLATE_SET_INPUT;
+  private static final MethodHandle INFLATE_SET_INPUT;
+  private static final MethodHandle DEFLATE_CALL;
+  private static final MethodHandle INFLATE_CALL;
+
+  static {
+    try {
+      DEFLATE_SET_INPUT = MethodHandles.lookup().findVirtual(Deflater.class, "setInput",
+          MethodType.methodType(void.class, ByteBuffer.class));
+      INFLATE_SET_INPUT = MethodHandles.lookup().findVirtual(Inflater.class, "setInput",
+          MethodType.methodType(void.class, ByteBuffer.class));
+
+      DEFLATE_CALL = MethodHandles.lookup().findVirtual(Deflater.class, "deflate",
+          MethodType.methodType(int.class, ByteBuffer.class));
+      INFLATE_CALL = MethodHandles.lookup().findVirtual(Inflater.class, "inflate",
+          MethodType.methodType(int.class, ByteBuffer.class));
+    } catch (NoSuchMethodException | IllegalAccessException e) {
+      throw new AssertionError("Can't use Java 11 compressor on your version of Java");
+    }
+  }
+
+  private final Deflater deflater;
+  private final Inflater inflater;
+  private boolean disposed = false;
+
+  private Java11VelocityCompressor(int level) {
+    this.deflater = new Deflater(level);
+    this.inflater = new Inflater();
+  }
+
+  @Override
+  public void inflate(ByteBuf source, ByteBuf destination, int max) throws DataFormatException {
+    ensureNotDisposed();
+
+    // We (probably) can't nicely deal with >=1 buffer nicely, so let's scream loudly.
+    checkArgument(source.nioBufferCount() == 1, "source has multiple backing buffers");
+    checkArgument(destination.nioBufferCount() == 1, "destination has multiple backing buffers");
+
+    try {
+      int origIdx = source.readerIndex();
+      INFLATE_SET_INPUT.invokeExact(inflater, source.nioBuffer());
+
+      while (!inflater.finished() && inflater.getBytesRead() < source.readableBytes()) {
+        if (!destination.isWritable()) {
+          ensureMaxSize(destination, max);
+          destination.ensureWritable(ZLIB_BUFFER_SIZE);
+        }
+
+        ByteBuffer destNioBuf = destination.nioBuffer(destination.writerIndex(),
+            destination.writableBytes());
+        int produced = (int) INFLATE_CALL.invokeExact(inflater, destNioBuf);
+        source.readerIndex(origIdx + inflater.getTotalIn());
+        destination.writerIndex(destination.writerIndex() + produced);
+      }
+
+      inflater.reset();
+    } catch (Throwable e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  @Override
+  public void deflate(ByteBuf source, ByteBuf destination) throws DataFormatException {
+    ensureNotDisposed();
+
+    // We (probably) can't nicely deal with >=1 buffer nicely, so let's scream loudly.
+    checkArgument(source.nioBufferCount() == 1, "source has multiple backing buffers");
+    checkArgument(destination.nioBufferCount() == 1, "destination has multiple backing buffers");
+
+    try {
+      int origIdx = source.readerIndex();
+      DEFLATE_SET_INPUT.invokeExact(deflater, source.nioBuffer());
+      deflater.finish();
+
+      while (!deflater.finished()) {
+        if (!destination.isWritable()) {
+          destination.ensureWritable(ZLIB_BUFFER_SIZE);
+        }
+
+        ByteBuffer destNioBuf = destination.nioBuffer(destination.writerIndex(),
+            destination.writableBytes());
+        int produced = (int) DEFLATE_CALL.invokeExact(deflater, destNioBuf);
+        source.readerIndex(origIdx + deflater.getTotalIn());
+        destination.writerIndex(destination.writerIndex() + produced);
+      }
+
+      deflater.reset();
+    } catch (Throwable e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  @Override
+  public void dispose() {
+    disposed = true;
+    deflater.end();
+    inflater.end();
+  }
+
+  private void ensureNotDisposed() {
+    checkState(!disposed, "Object already disposed");
+  }
+
+  @Override
+  public BufferPreference preferredBufferType() {
+    return BufferPreference.DIRECT_PREFERRED;
+  }
+}

native/src/main/java/com/velocitypowered/natives/compression/JavaVelocityCompressor.java

@@ -4,6 +4,7 @@ import static com.velocitypowered.natives.compression.CompressorUtils.ZLIB_BUFFE
 import static com.velocitypowered.natives.compression.CompressorUtils.ensureMaxSize;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.natives.util.BufferPreference;
 import io.netty.buffer.ByteBuf;
 import java.util.zip.DataFormatException;
 import java.util.zip.Deflater;
@@ -77,7 +78,7 @@ public class JavaVelocityCompressor implements VelocityCompressor {
   }
 
   @Override
-  public boolean isNative() {
-    return false;
+  public BufferPreference preferredBufferType() {
+    return BufferPreference.HEAP_PREFERRED;
   }
 }

native/src/main/java/com/velocitypowered/natives/compression/NativeVelocityCompressor.java

@@ -4,6 +4,7 @@ import static com.velocitypowered.natives.compression.CompressorUtils.ZLIB_BUFFE
 import static com.velocitypowered.natives.compression.CompressorUtils.ensureMaxSize;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.natives.util.BufferPreference;
 import io.netty.buffer.ByteBuf;
 import java.util.zip.DataFormatException;
 
@@ -82,7 +83,7 @@ public class NativeVelocityCompressor implements VelocityCompressor {
   }
 
   @Override
-  public boolean isNative() {
-    return true;
+  public BufferPreference preferredBufferType() {
+    return BufferPreference.DIRECT_REQUIRED;
   }
 }

native/src/main/java/com/velocitypowered/natives/encryption/JavaVelocityCipher.java

@@ -1,6 +1,7 @@
 package com.velocitypowered.natives.encryption;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.natives.util.BufferPreference;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
 import io.netty.channel.ChannelHandlerContext;
@@ -88,7 +89,7 @@ public class JavaVelocityCipher implements VelocityCipher {
   }
 
   @Override
-  public boolean isNative() {
-    return false;
+  public BufferPreference preferredBufferType() {
+    return BufferPreference.HEAP_PREFERRED;
   }
 }

native/src/main/java/com/velocitypowered/natives/encryption/NativeVelocityCipher.java

@@ -1,6 +1,7 @@
 package com.velocitypowered.natives.encryption;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.natives.util.BufferPreference;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 import java.security.GeneralSecurityException;
@@ -81,7 +82,7 @@ public class NativeVelocityCipher implements VelocityCipher {
   }
 
   @Override
-  public boolean isNative() {
-    return true;
+  public BufferPreference preferredBufferType() {
+    return BufferPreference.DIRECT_REQUIRED;
   }
 }

native/src/main/java/com/velocitypowered/natives/util/BufferPreference.java

@@ -0,0 +1,16 @@
+package com.velocitypowered.natives.util;
+
+public enum BufferPreference {
+  /**
+   * A heap buffer is preferred (but not required).
+   */
+  HEAP_PREFERRED,
+  /**
+   * A direct buffer is preferred (but not required).
+   */
+  DIRECT_PREFERRED,
+  /**
+   * A direct buffer is required.
+   */
+  DIRECT_REQUIRED
+}

native/src/main/java/com/velocitypowered/natives/util/MoreByteBufUtils.java

@@ -20,9 +20,8 @@ public class MoreByteBufUtils {
    * @return a buffer compatible with the native
    */
   public static ByteBuf ensureCompatible(ByteBufAllocator alloc, Native nativeStuff, ByteBuf buf) {
-    if (!nativeStuff.isNative() || buf.hasMemoryAddress()) {
-      // Will always work in either case. JNI code demands a memory address, and if we have a Java
-      // fallback, it uses byte arrays in all cases.
+    if (nativeStuff.preferredBufferType() != BufferPreference.DIRECT_REQUIRED
+        || buf.hasMemoryAddress()) {
       return buf.retain();
     }
 
@@ -41,7 +40,8 @@ public class MoreByteBufUtils {
    * @return a buffer compatible with the native
    */
   public static ByteBuf preferredBuffer(ByteBufAllocator alloc, Native nativeStuff) {
-    return nativeStuff.isNative() ? alloc.directBuffer() : alloc.heapBuffer();
+    return nativeStuff.preferredBufferType() != BufferPreference.HEAP_PREFERRED
+        ? alloc.directBuffer() : alloc.heapBuffer();
   }
 
   /**
@@ -55,7 +55,7 @@ public class MoreByteBufUtils {
    */
   public static ByteBuf preferredBuffer(ByteBufAllocator alloc, Native nativeStuff,
       int initialCapacity) {
-    return nativeStuff.isNative() ? alloc.directBuffer(initialCapacity) : alloc
-        .heapBuffer(initialCapacity);
+    return nativeStuff.preferredBufferType() != BufferPreference.HEAP_PREFERRED
+        ? alloc.directBuffer(initialCapacity) : alloc.heapBuffer(initialCapacity);
   }
 }

native/src/main/java/com/velocitypowered/natives/util/NativeCodeLoader.java

@@ -15,7 +15,7 @@ public final class NativeCodeLoader<T> implements Supplier<T> {
 
   @Override
   public T get() {
-    return selected.object;
+    return selected.constructed;
   }
 
   private static <T> Variant<T> getVariant(List<Variant<T>> variants) {
@@ -38,9 +38,14 @@ public final class NativeCodeLoader<T> implements Supplier<T> {
     private Status status;
     private final Runnable setup;
     private final String name;
-    private final T object;
+    private final Supplier<T> object;
+    private T constructed;
 
     Variant(BooleanSupplier possiblyAvailable, Runnable setup, String name, T object) {
+      this(possiblyAvailable, setup, name, () -> object);
+    }
+
+    Variant(BooleanSupplier possiblyAvailable, Runnable setup, String name, Supplier<T> object) {
       this.status =
           possiblyAvailable.getAsBoolean() ? Status.POSSIBLY_AVAILABLE : Status.NOT_AVAILABLE;
       this.setup = setup;
@@ -57,6 +62,7 @@ public final class NativeCodeLoader<T> implements Supplier<T> {
       if (status == Status.POSSIBLY_AVAILABLE) {
         try {
           setup.run();
+          constructed = object.get();
           status = Status.SETUP;
         } catch (Exception e) {
           status = Status.SETUP_FAILURE;
@@ -64,7 +70,7 @@ public final class NativeCodeLoader<T> implements Supplier<T> {
         }
       }
 
-      return object;
+      return constructed;
     }
   }
 

native/src/main/java/com/velocitypowered/natives/util/NativeConstraints.java

@@ -6,6 +6,7 @@ import java.util.function.BooleanSupplier;
 
 public class NativeConstraints {
   private static final boolean NATIVES_ENABLED = !Boolean.getBoolean("velocity.natives-disabled");
+  private static final boolean IS_AMD64;
   private static final boolean CAN_GET_MEMORYADDRESS;
 
   static {
@@ -15,19 +16,28 @@ public class NativeConstraints {
     } finally {
       test.release();
     }
+
+    String osArch = System.getProperty("os.arch", "");
+    // HotSpot on Intel macOS prefers x86_64, but OpenJ9 on macOS and HotSpot/OpenJ9 elsewhere
+    // give amd64.
+    IS_AMD64 = osArch.equals("amd64") || osArch.equals("x86_64");
   }
 
   static final BooleanSupplier MACOS = () -> {
     return NATIVES_ENABLED
         && CAN_GET_MEMORYADDRESS
         && System.getProperty("os.name", "").equalsIgnoreCase("Mac OS X")
-        && System.getProperty("os.arch", "").equals("x86_64");
+        && IS_AMD64;
   };
 
   static final BooleanSupplier LINUX = () -> {
     return NATIVES_ENABLED
         && CAN_GET_MEMORYADDRESS
         && System.getProperty("os.name", "").equalsIgnoreCase("Linux")
-        && System.getProperty("os.arch", "").equals("amd64");
+        && IS_AMD64;
+  };
+
+  static final BooleanSupplier JAVA_11 = () -> {
+    return Double.parseDouble(System.getProperty("java.specification.version")) >= 11;
   };
 }

native/src/main/java/com/velocitypowered/natives/util/Natives.java

@@ -2,6 +2,7 @@ package com.velocitypowered.natives.util;
 
 import com.google.common.collect.ImmutableList;
 import com.velocitypowered.natives.NativeSetupException;
+import com.velocitypowered.natives.compression.Java11VelocityCompressor;
 import com.velocitypowered.natives.compression.JavaVelocityCompressor;
 import com.velocitypowered.natives.compression.NativeVelocityCompressor;
 import com.velocitypowered.natives.compression.VelocityCompressorFactory;
@@ -52,6 +53,8 @@ public class Natives {
           new NativeCodeLoader.Variant<>(NativeConstraints.LINUX,
               copyAndLoadNative("/linux_x64/velocity-compress.so"), "native (Linux amd64)",
               NativeVelocityCompressor.FACTORY),
+          new NativeCodeLoader.Variant<>(NativeConstraints.JAVA_11, () -> {
+          }, "Java 11", () -> Java11VelocityCompressor.FACTORY),
           new NativeCodeLoader.Variant<>(NativeCodeLoader.ALWAYS, () -> {
           }, "Java", JavaVelocityCompressor.FACTORY)
       )

native/src/test/java/com/velocitypowered/natives/compression/VelocityCompressorTest.java

@@ -6,6 +6,7 @@ import static org.junit.jupiter.api.Assertions.fail;
 import static org.junit.jupiter.api.condition.OS.LINUX;
 import static org.junit.jupiter.api.condition.OS.MAC;
 
+import com.velocitypowered.natives.util.BufferPreference;
 import com.velocitypowered.natives.util.Natives;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
@@ -17,7 +18,9 @@ import java.util.zip.DataFormatException;
 import java.util.zip.Deflater;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledOnJre;
 import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.condition.JRE;
 
 class VelocityCompressorTest {
 
@@ -39,7 +42,7 @@ class VelocityCompressorTest {
   @EnabledOnOs({MAC, LINUX})
   void nativeIntegrityCheck() throws DataFormatException {
     VelocityCompressor compressor = Natives.compress.get().create(Deflater.DEFAULT_COMPRESSION);
-    if (compressor instanceof JavaVelocityCompressor) {
+    if (compressor.preferredBufferType() != BufferPreference.DIRECT_REQUIRED) {
       compressor.dispose();
       fail("Loaded regular compressor");
     }
@@ -60,6 +63,22 @@ class VelocityCompressorTest {
     check(compressor, () -> Unpooled.buffer(TEST_DATA.length + 32));
   }
 
+  @Test
+  @EnabledOnJre(JRE.JAVA_11)
+  void java11IntegrityCheckDirect() throws DataFormatException {
+    VelocityCompressor compressor = Java11VelocityCompressor.FACTORY
+        .create(Deflater.DEFAULT_COMPRESSION);
+    check(compressor, () -> Unpooled.directBuffer(TEST_DATA.length + 32));
+  }
+
+  @Test
+  @EnabledOnJre(JRE.JAVA_11)
+  void java11IntegrityCheckHeap() throws DataFormatException {
+    VelocityCompressor compressor = Java11VelocityCompressor.FACTORY
+        .create(Deflater.DEFAULT_COMPRESSION);
+    check(compressor, () -> Unpooled.buffer(TEST_DATA.length + 32));
+  }
+
   private void check(VelocityCompressor compressor, Supplier<ByteBuf> bufSupplier)
       throws DataFormatException {
     ByteBuf source = bufSupplier.get();

proxy/src/main/java/com/velocitypowered/proxy/util/concurrent/VelocityNettyThreadFactory.java

@@ -17,7 +17,7 @@ public class VelocityNettyThreadFactory implements ThreadFactory {
 
   @Override
   public Thread newThread(Runnable r) {
-    String name = String.format(nameFormat, threadNumber.incrementAndGet());
+    String name = String.format(nameFormat, threadNumber.getAndIncrement());
     return new FastThreadLocalThread(r, name);
   }
 }