package com.alvazan.orm.layer9z.spi.db.cassandra;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import com.alvazan.orm.api.z8spi.BatchListener;
import com.alvazan.orm.api.z8spi.action.IndexColumn;
import com.alvazan.orm.api.z8spi.conv.Precondition;
import com.alvazan.orm.api.z8spi.iter.AbstractCursor;
import com.netflix.astyanax.connectionpool.OperationResult;
import com.netflix.astyanax.model.Column;
import com.netflix.astyanax.model.ColumnList;
public class CursorOfFutures extends AbstractCursor<IndexColumn> {
private StartQueryListener columnSliceCb;
private BatchListener batchListener;
private Iterator<Future<OperationResult<ColumnList<byte[]>>>> theOneBatch;
private boolean needToGetBatch;
private ListIterator<Column<byte[]>> cachedLastCols;
public CursorOfFutures(StartQueryListener l, BatchListener listener) {
Precondition.check(l,"l");
this.columnSliceCb = l;
this.batchListener = listener;
beforeFirst();
}
@Override
public String toString() {
return "CursorOfFutures["+theOneBatch+"]";
}
@Override
public void beforeFirst() {
needToGetBatch = true;
}
@Override
public void afterLast() {
needToGetBatch = true;
}
@Override
public Holder<IndexColumn> nextImpl() {
if(batchListener != null)
batchListener.beforeFetchingNextBatch();
loadBatchIfNeeded();
if(cachedLastCols != null && cachedLastCols.hasNext()) {
Column<byte[]> col = cachedLastCols.next();
IndexColumn indexedCol = CursorColumnSlice.convertToIndexCol(col, null);
return new Holder<IndexColumn>(indexedCol);
}
while(true) {
if(!theOneBatch.hasNext())
return null;
Future<OperationResult<ColumnList<byte[]>>> future = theOneBatch.next();
OperationResult<ColumnList<byte[]>> results = get(future);
ColumnList<byte[]> columnList = results.getResult();
cachedLastCols = new OurColumnListIterator(columnList);
if(cachedLastCols.hasNext()) {
Column<byte[]> col = cachedLastCols.next();
IndexColumn indexCol = CursorColumnSlice.convertToIndexCol(col, null);
if(batchListener != null)
batchListener.afterFetchingNextBatch(columnList.size());
return new Holder<IndexColumn>(indexCol);
}
}
}
@Override
public Holder<IndexColumn> previousImpl() {
if(batchListener != null)
batchListener.beforeFetchingNextBatch();
loadBatchIfNeeded();
if(cachedLastCols != null && cachedLastCols.hasPrevious()) {
Column<byte[]> col = cachedLastCols.previous();
IndexColumn indexedCol = CursorColumnSlice.convertToIndexCol(col, null);
return new Holder<IndexColumn>(indexedCol);
}
while(true) {
if(!theOneBatch.hasNext())
return null;
Future<OperationResult<ColumnList<byte[]>>> future = theOneBatch.next();
OperationResult<ColumnList<byte[]>> results = get(future);
ColumnList<byte[]> columnList = results.getResult();
cachedLastCols = new OurColumnListIterator(columnList);
while(cachedLastCols.hasNext())cachedLastCols.next();
if(cachedLastCols.hasPrevious()) {
Column<byte[]> col = cachedLastCols.previous();
IndexColumn indexCol = CursorColumnSlice.convertToIndexCol(col, null);
if(batchListener != null)
batchListener.afterFetchingNextBatch(columnList.size());
return new Holder<IndexColumn>(indexCol);
}
}
}
private void loadBatchIfNeeded() {
if(needToGetBatch) {
theOneBatch = columnSliceCb.start().iterator();
needToGetBatch = false;
}
}
private OperationResult<ColumnList<byte[]>> get(Future<OperationResult<ColumnList<byte[]>>> f) {
try {
return (OperationResult<ColumnList<byte[]>>) f.get();
} catch (InterruptedException e) {
throw new RuntimeException(e);
} catch (ExecutionException e) {
throw new RuntimeException(e);
}
}
}