Implements Netty Thread-local object pool for Command

core/src/main/java/dev/keva/core/aof/AOFContainer.java

@@ -81,21 +81,26 @@ public void sync() throws IOException {
         bufferLock.lock();
         try {
             for (Command command : buffer) {
-                output.writeObject(command);
+                output.writeObject(command.getObjects());
             }
         } finally {
             output.flush();
+            for (Command command : buffer) {
+                command.recycle();
+            }
             buffer.clear();
             bufferLock.unlock();
         }
     }
 
     public void syncPerMutation(Command command) {
         try {
-            output.writeObject(command);
+            output.writeObject(command.getObjects());
             output.flush();
         } catch (IOException e) {
             log.error("Error writing AOF file", e);
+        } finally {
+            command.recycle();
         }
     }
 
@@ -106,8 +111,8 @@ public List<Command> read() throws IOException {
             ObjectInputStream input = new ObjectInputStream(fis);
             while (true) {
                 try {
-                    Command command = (Command) input.readObject();
-                    commands.add(command);
+                    byte[][] objects = (byte[][]) input.readObject();
+                    commands.add(Command.newInstance(objects, false));
                 } catch (EOFException e) {
                     fis.close();
                     return commands;

core/src/main/java/dev/keva/core/command/impl/key/manager/ExpirationManager.java

@@ -70,7 +70,7 @@ public void executeExpire(byte[] key) {
                 byte[][] data = new byte[2][];
                 data[0] = "delete".getBytes();
                 data[1] = key;
-                Command command = new Command(data, false);
+                Command command = Command.newInstance(data, false);
                 Lock lock = database.getLock();
                 lock.lock();
                 try {

core/src/main/java/dev/keva/core/command/mapping/CommandMapper.java

@@ -108,6 +108,11 @@ public void init() {
                                 }
                                 Object[] objects = new Object[types.length];
                                 command.toArguments(objects, types, ctx);
+                                // If not in AOF mode, then recycle(),
+                                // else, the command will be recycled in the AOF dump
+                                if (!kevaConfig.getAof()) {
+                                    command.recycle();
+                                }
                                 return (Reply<?>) method.invoke(instance, objects);
                             } finally {
                                 lock.unlock();

resp-protocol/src/main/java/dev/keva/protocol/resp/Command.java

@@ -1,25 +1,56 @@
 package dev.keva.protocol.resp;
 
 import io.netty.channel.ChannelHandlerContext;
+import io.netty.util.Recycler;
+import lombok.Getter;
 
 import java.io.Serializable;
 import java.nio.charset.StandardCharsets;
 
 public class Command implements Serializable {
     private static final byte LOWER_DIFF = 'a' - 'A';
 
-    private final Object[] objects;
+    private static final Recycler<Command> RECYCLER = new Recycler<Command>() {
+        protected Command newObject(Recycler.Handle<Command> handle) {
+            return new Command(handle);
+        }
+    };
+
+    private final Recycler.Handle<Command> handle;
+
+    @Getter
+    private byte[][] objects;
+
+    private Command(Recycler.Handle<Command> handle) {
+        this.handle = handle;
+    }
 
-    public Command(Object[] objects, boolean inline) {
+    public static Command newInstance(byte[][] objects, boolean inline) {
+        if (objects == null) {
+            throw new IllegalArgumentException("objects must not be null");
+        }
+        if (objects.length == 0) {
+            throw new IllegalArgumentException("objects must not be empty");
+        }
+
+        Command command = RECYCLER.get();
         if (inline) {
-            byte[] objs = ByteUtil.getBytes(objects[0]);
+            byte[] objs = objects[0];
             String[] strings = new String(objs, StandardCharsets.UTF_8).trim().split("\\s+");
-            objects = new Object[strings.length];
+            objects = new byte[strings.length][];
             for (int i = 0; i < strings.length; i++) {
                 objects[i] = ByteUtil.getBytes(strings[i]);
             }
         }
-        this.objects = objects;
+        command.objects = objects;
+        // LowerCase bytes
+        for (int i = 0; i < objects[0].length; i++) {
+            byte b = objects[0][i];
+            if (b >= 'A' && b <= 'Z') {
+                objects[0][i] = (byte) (b + LOWER_DIFF);
+            }
+        }
+        return command;
     }
 
     public int getLength() {
@@ -31,15 +62,7 @@ public int getLength() {
     }
 
     public byte[] getName() {
-        byte[] name = ByteUtil.getBytes(objects[0]);
-        // LowerCase bytes
-        for (int i = 0; i < name.length; i++) {
-            byte b = name[i];
-            if (b >= 'A' && b <= 'Z') {
-                name[i] = (byte) (b + LOWER_DIFF);
-            }
-        }
-        return name;
+        return objects[0];
     }
 
     public void toArguments(Object[] arguments, Class<?>[] types, ChannelHandlerContext ctx) {
@@ -60,11 +83,16 @@ public void toArguments(Object[] arguments, Class<?>[] types, ChannelHandlerCont
                 int left = isFirstVararg ? (objects.length - position - 1) : (objects.length - 1);
                 byte[][] lastArgument = new byte[left][];
                 for (int i = 0; i < left; i++) {
-                    lastArgument[i] = isFirstVararg ? (byte[]) (objects[i + position + 1]) : (byte[]) (objects[i + position]);
+                    lastArgument[i] = isFirstVararg ? objects[i + position + 1] : objects[i + position];
                 }
                 arguments[position] = lastArgument;
             }
             position++;
         }
     }
+
+    public void recycle() {
+        objects = null;
+        handle.recycle(this);
+    }
 }

resp-protocol/src/main/java/dev/keva/protocol/resp/RedisCommandDecoder.java

@@ -34,7 +34,7 @@ protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) t
                 }
             }
             try {
-                out.add(new Command(bytes, false));
+                out.add(Command.newInstance(bytes, false));
             } finally {
                 bytes = null;
                 arguments = 0;
@@ -60,7 +60,7 @@ protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) t
             b[0] = new byte[buf.readableBytes()];
             buf.getBytes(0, b[0]);
             in.skipBytes(isCRLF ? 2 : 1);
-            out.add(new Command(b, true));
+            out.add(Command.newInstance(b, true));
         }
     }
 }