/*
* Copyright DataStax, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.datastax.oss.driver.internal.core.cql;
import com.datastax.oss.driver.api.core.cql.AsyncResultSet;
import com.datastax.oss.driver.api.core.cql.ColumnDefinitions;
import com.datastax.oss.driver.api.core.cql.ExecutionInfo;
import com.datastax.oss.driver.api.core.cql.ResultSet;
import com.datastax.oss.driver.api.core.cql.Row;
import com.datastax.oss.driver.internal.core.util.CountingIterator;
import com.datastax.oss.driver.internal.core.util.concurrent.BlockingOperation;
import com.datastax.oss.driver.internal.core.util.concurrent.CompletableFutures;
import edu.umd.cs.findbugs.annotations.NonNull;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import net.jcip.annotations.NotThreadSafe;
@NotThreadSafe
public class MultiPageResultSet implements ResultSet {
private final RowIterator iterator;
private final List<ExecutionInfo> executionInfos = new ArrayList<>();
private ColumnDefinitions columnDefinitions;
public MultiPageResultSet(@NonNull AsyncResultSet firstPage) {
assert firstPage.hasMorePages();
this.iterator = new RowIterator(firstPage);
this.executionInfos.add(firstPage.getExecutionInfo());
this.columnDefinitions = firstPage.getColumnDefinitions();
}
@NonNull
@Override
public ColumnDefinitions getColumnDefinitions() {
return columnDefinitions;
}
@NonNull
@Override
public List<ExecutionInfo> getExecutionInfos() {
return executionInfos;
}
@Override
public boolean isFullyFetched() {
return iterator.isFullyFetched();
}
@Override
public int getAvailableWithoutFetching() {
return iterator.remaining();
}
@NonNull
@Override
public Iterator<Row> iterator() {
return iterator;
}
@Override
public boolean wasApplied() {
return iterator.wasApplied();
}
private class RowIterator extends CountingIterator<Row> {
private AsyncResultSet currentPage;
private Iterator<Row> currentRows;
private RowIterator(AsyncResultSet firstPage) {
super(firstPage.remaining());
this.currentPage = firstPage;
this.currentRows = firstPage.currentPage().iterator();
}
@Override
protected Row computeNext() {
maybeMoveToNextPage();
return currentRows.hasNext() ? currentRows.next() : endOfData();
}
private void maybeMoveToNextPage() {
if (!currentRows.hasNext() && currentPage.hasMorePages()) {
BlockingOperation.checkNotDriverThread();
AsyncResultSet nextPage =
CompletableFutures.getUninterruptibly(currentPage.fetchNextPage());
currentPage = nextPage;
remaining += nextPage.remaining();
currentRows = nextPage.currentPage().iterator();
executionInfos.add(nextPage.getExecutionInfo());
// The definitions can change from page to page if this result set was built from a bound
// 'SELECT *', and the schema was altered.
columnDefinitions = nextPage.getColumnDefinitions();
}
}
private boolean isFullyFetched() {
return !currentPage.hasMorePages();
}
private boolean wasApplied() {
return currentPage.wasApplied();
}
}
}