Replace usage of CommandBase#handler by CommandMessage#handler

Motivation:

In the quest of removing CommandBase#handler, we are replacing its usage by CommandMessage#handler.

Hopefully we will remove it also for the Oracle implementation.

Author: vietj

vertx-db2-client/src/main/java/io/vertx/db2client/impl/DB2SocketConnection.java

@@ -93,8 +93,7 @@ protected <R> void doSchedule(CommandBase<R> cmd, Completable<R> handler) {
       if (txCmd.kind == TxCommand.Kind.BEGIN) {
         // DB2 always implicitly starts a transaction with each query, and does
         // not support the 'BEGIN' keyword. Instead we can no-op BEGIN commands
-        cmd.handler = handler;
-        cmd.complete(CommandResponse.success(txCmd.result).toAsyncResult());
+        handler.succeed(txCmd.result);
       } else {
         SimpleQueryCommand<Void> cmd2 = new SimpleQueryCommand<>(txCmd.kind.sql, false, false,
             QueryCommandBase.NULL_COLLECTOR, QueryResultHandler.NOOP_HANDLER);

vertx-db2-client/src/main/java/io/vertx/db2client/impl/codec/CommandCodec.java

@@ -34,11 +34,10 @@ public abstract class CommandCodec<R, C extends CommandBase<R>> extends CommandM
   Handler<? super CommandResponse<R>> completionHandler;
   public Throwable failure;
   public R result;
-  final C cmd;
   DB2Encoder encoder;
 
   CommandCodec(C cmd) {
-    this.cmd = cmd;
+    super(cmd);
   }
 
   @SuppressWarnings({ "rawtypes", "unchecked" })

vertx-db2-client/src/main/java/io/vertx/db2client/impl/codec/DB2Codec.java

@@ -43,7 +43,7 @@ public void channelInactive(ChannelHandlerContext ctx) throws Exception {
 
   private void clearInflightCommands(Throwable failure) {
     for (CommandCodec<?, ?> commandCodec : inflight) {
-      commandCodec.cmd.fail(failure);
+      commandCodec.fail(failure);
     }
   }
 }

vertx-db2-client/src/main/java/io/vertx/db2client/impl/codec/DB2Encoder.java

@@ -20,6 +20,7 @@
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelOutboundHandlerAdapter;
 import io.netty.channel.ChannelPromise;
+import io.vertx.core.Completable;
 import io.vertx.core.internal.logging.Logger;
 import io.vertx.core.internal.logging.LoggerFactory;
 import io.vertx.db2client.impl.DB2SocketConnection;
@@ -59,7 +60,7 @@ public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise)
   void write(CommandCodec<?, ?> msg) {
     msg.completionHandler = resp -> {
       CommandCodec<?, ?> c = inflight.poll();
-      resp.cmd = (CommandBase) c.cmd;
+      resp.handler = (Completable) c.handler;
       chctx.fireChannelRead(resp);
     };
     inflight.add(msg);

vertx-db2-client/src/main/java/io/vertx/db2client/impl/codec/InitialHandshakeCommandCodec.java

@@ -59,7 +59,7 @@ void encode(DB2Encoder encoder) {
         // -4499 = A fatal error occurred that resulted in a disconnect from the data
         // source.
         // 08001 = "The connection was unable to be established"
-        cmd.fail(new DB2Exception("The connection was closed by the database server.", SqlCode.CONNECTION_REFUSED,
+        fail(new DB2Exception("The connection was closed by the database server.", SqlCode.CONNECTION_REFUSED,
             SQLState.AUTH_DATABASE_CONNECTION_REFUSED));
       }
     });
@@ -130,7 +130,7 @@ void decodePayload(ByteBuf payload, int payloadLength) {
         break;
 
       default:
-        cmd.fail(new DB2Exception("The connection was unable to be established. Invalid connection state.", SqlCode.CONNECTION_REFUSED,
+        fail(new DB2Exception("The connection was unable to be established. Invalid connection state.", SqlCode.CONNECTION_REFUSED,
           SQLState.AUTH_DATABASE_CONNECTION_REFUSED));
         break;
 

vertx-mssql-client/src/main/java/io/vertx/mssqlclient/impl/codec/MSSQLCommandCodec.java

@@ -37,12 +37,11 @@ public abstract class MSSQLCommandCodec<R, C extends CommandBase<R>> extends Com
 
   public TdsMessageCodec tdsMessageCodec;
 
-  final C cmd;
   public MSSQLException failure;
   public R result;
 
   MSSQLCommandCodec(C cmd) {
-    this.cmd = cmd;
+    super(cmd);
   }
 
   public static MSSQLCommandCodec<?, ?> wrap(CommandBase<?> cmd) {

vertx-mssql-client/src/main/java/io/vertx/mssqlclient/impl/codec/TdsMessageCodec.java

@@ -65,7 +65,7 @@ private void fail(Throwable cause) {
   }
 
   private void fail(MSSQLCommandCodec<?, ?> codec, Throwable cause) {
-    codec.cmd.fail(cause);
+    codec.fail(cause);
   }
 
   @Override

vertx-mssql-client/src/main/java/io/vertx/mssqlclient/impl/codec/TdsMessageDecoder.java

@@ -14,6 +14,7 @@
 import io.netty.buffer.ByteBufAllocator;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
+import io.vertx.core.Completable;
 import io.vertx.sqlclient.internal.command.CommandBase;
 import io.vertx.sqlclient.internal.command.CommandResponse;
 
@@ -55,7 +56,7 @@ public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
 
   void fireCommandResponse(CommandResponse<?> commandResponse) {
     MSSQLCommandCodec<?, ?> c = tdsMessageCodec.poll();
-    commandResponse.cmd = (CommandBase) c.cmd;
+    commandResponse.handler = (Completable) c.handler;
     chctx.fireChannelRead(commandResponse);
   }
 

vertx-mysql-client/src/main/java/io/vertx/mysqlclient/impl/codec/CommandCodec.java

@@ -49,12 +49,11 @@ public abstract class CommandCodec<R, C extends CommandBase<R>> extends CommandM
 
   public Throwable failure;
   public R result;
-  final C cmd;
   MySQLEncoder encoder;
   int sequenceId;
 
   CommandCodec(C cmd) {
-    this.cmd = cmd;
+    super(cmd);
   }
 
   public static CommandCodec<?, ?> wrap(CommandBase<?> cmd) {

vertx-mysql-client/src/main/java/io/vertx/mysqlclient/impl/codec/MySQLCodec.java

@@ -78,7 +78,7 @@ private void clearInflightCommands(Throwable cause) {
   private void fail(CommandCodec<?, ?> codec, Throwable cause) {
     if (failure == null) {
       failure = cause;
-      codec.cmd.fail(cause);
+      codec.fail(cause);
     }
   }