Remove RowAccumulator related code (#1400)

The alternative to ArrayList has never been used in Vert.x 4.
We can get rid of it in Vert.x 5.

Signed-off-by: Thomas Segismont <[email protected]>

Author: tsegismont

vertx-sql-client/pom.xml

@@ -62,58 +62,6 @@
       <type>test-jar</type>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>org.openjdk.jmh</groupId>
-      <artifactId>jmh-core</artifactId>
-      <version>${jmh.version}</version>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
-      <groupId>org.openjdk.jmh</groupId>
-      <artifactId>jmh-generator-annprocess</artifactId>
-      <version>${jmh.version}</version>
-      <scope>test</scope>
-    </dependency>
   </dependencies>
 
-  <profiles>
-    <profile>
-      <id>benchmarks</id>
-      <build>
-        <plugins>
-          <plugin>
-            <artifactId>maven-assembly-plugin</artifactId>
-            <executions>
-              <execution>
-                <id>assemble-benchmarks</id>
-                <phase>package</phase>
-                <goals>
-                  <goal>single</goal>
-                </goals>
-                <configuration>
-                  <archive>
-                    <manifest>
-                      <mainClass>org.openjdk.jmh.Main</mainClass>
-                    </manifest>
-                  </archive>
-                  <descriptors>
-                    <descriptor>src/test/assembly/benchmarks.xml</descriptor>
-                  </descriptors>
-                </configuration>
-              </execution>
-            </executions>
-          </plugin>
-        </plugins>
-      </build>
-      <dependencies>
-        <dependency>
-          <groupId>org.openjdk.jmh</groupId>
-          <artifactId>jmh-generator-annprocess</artifactId>
-          <version>${jmh.version}</version>
-          <scope>test</scope>
-        </dependency>
-      </dependencies>
-    </profile>
-  </profiles>
-
 </project>

vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/RowSetImpl.java

@@ -19,10 +19,11 @@
 import io.vertx.sqlclient.Row;
 import io.vertx.sqlclient.RowIterator;
 import io.vertx.sqlclient.RowSet;
-import io.vertx.sqlclient.impl.accumulator.ArrayListRowAccumulator;
-import io.vertx.sqlclient.impl.accumulator.RowAccumulator;
 
-import java.util.NoSuchElementException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
 import java.util.function.Function;
 import java.util.stream.Collector;
 
@@ -38,9 +39,7 @@ class RowSetImpl<R> extends SqlResultBase<RowSet<R>> implements RowSet<R> {
   static <U> Collector<Row, RowSetImpl<U>, RowSet<U>> collector(Function<Row, U> mapper) {
     return Collector.of(
       RowSetImpl::new,
-      (set, row) -> {
-        set.add(mapper.apply(row));
-      },
+      (set, row) -> set.add(mapper.apply(row)),
       (set1, set2) -> null, // Shall not be invoked as this is sequential
       (set) -> set
     );
@@ -52,65 +51,38 @@ static <U> Function<RowSet<U>, RowSetImpl<U>> factory() {
     return rs -> (RowSetImpl<U>) rs;
   }
 
-  private R firstRow;
-  private RowAccumulator<R> rowAccumulator;
+  private List<R> rowAccumulator = Collections.emptyList();
 
   @Override
   public RowSet<R> value() {
     return this;
   }
 
   private void add(R row) {
-    if (rowAccumulator != null) {
-      rowAccumulator.accept(row);
-    } else if (firstRow != null) {
-      rowAccumulator = new ArrayListRowAccumulator<>();
-      rowAccumulator.accept(firstRow);
-      rowAccumulator.accept(row);
-      firstRow = null;
-    } else {
-      firstRow = row;
+    if (rowAccumulator.isEmpty()) {
+      rowAccumulator = new ArrayList<>();
     }
+    rowAccumulator.add(row);
   }
 
   @Override
   public RowIterator<R> iterator() {
-    return rowAccumulator != null ? rowAccumulator.iterator() : SingletonRowIterator.createFor(firstRow);
+    Iterator<R> iter = rowAccumulator.iterator();
+    return new RowIterator<R>() {
+      @Override
+      public boolean hasNext() {
+        return iter.hasNext();
+      }
+
+      @Override
+      public R next() {
+        return iter.next();
+      }
+    };
   }
 
   @Override
   public RowSetImpl<R> next() {
     return (RowSetImpl<R>) super.next();
   }
-
-  private static final class SingletonRowIterator<ROW> implements RowIterator<ROW> {
-
-    static final SingletonRowIterator<Object> EMPTY_INSTANCE = new SingletonRowIterator<>(null);
-
-    ROW row;
-
-    SingletonRowIterator(ROW row) {
-      this.row = row;
-    }
-
-    @SuppressWarnings("unchecked")
-    static <X> SingletonRowIterator<X> createFor(X row) {
-      return row != null ? new SingletonRowIterator<>(row) : (SingletonRowIterator<X>) EMPTY_INSTANCE;
-    }
-
-    @Override
-    public boolean hasNext() {
-      return row != null;
-    }
-
-    @Override
-    public ROW next() {
-      if (row != null) {
-        ROW res = row;
-        row = null;
-        return res;
-      }
-      throw new NoSuchElementException();
-    }
-  }
 }