diff options
Diffstat (limited to 'src/main/java/com/amazon/carbonado/qe')
6 files changed, 94 insertions, 1 deletions
diff --git a/src/main/java/com/amazon/carbonado/qe/AbstractQuery.java b/src/main/java/com/amazon/carbonado/qe/AbstractQuery.java index 7639348..767b039 100644 --- a/src/main/java/com/amazon/carbonado/qe/AbstractQuery.java +++ b/src/main/java/com/amazon/carbonado/qe/AbstractQuery.java @@ -129,4 +129,26 @@ public abstract class AbstractQuery<S extends Storable> implements Query<S>, App @Override
public abstract boolean equals(Object obj);
+
+ /**
+ * Called by sliced fetch to ensure that arguments are valid.
+ *
+ * @return false if from is 0 and to is null
+ * @throws IllegalArgumentException if arguments are invalid
+ * @since 1.2
+ */
+ protected boolean checkSliceArguments(long from, Long to) {
+ if (from < 0) {
+ throw new IllegalArgumentException("Slice from is negative: " + from);
+ }
+ if (to == null) {
+ if (from == 0) {
+ return false;
+ }
+ } else if (from > to) {
+ throw new IllegalArgumentException
+ ("Slice from is more than to: " + from + " > " + to);
+ }
+ return true;
+ }
}
diff --git a/src/main/java/com/amazon/carbonado/qe/AbstractQueryExecutor.java b/src/main/java/com/amazon/carbonado/qe/AbstractQueryExecutor.java index dc67fc1..8a8a127 100644 --- a/src/main/java/com/amazon/carbonado/qe/AbstractQueryExecutor.java +++ b/src/main/java/com/amazon/carbonado/qe/AbstractQueryExecutor.java @@ -24,6 +24,9 @@ import com.amazon.carbonado.Cursor; import com.amazon.carbonado.FetchException;
import com.amazon.carbonado.Storable;
+import com.amazon.carbonado.cursor.LimitCursor;
+import com.amazon.carbonado.cursor.SkipCursor;
+
import com.amazon.carbonado.filter.FilterValues;
/**
@@ -37,7 +40,25 @@ public abstract class AbstractQueryExecutor<S extends Storable> implements Query }
/**
- * Counts results by opening a cursor and skipping entries.
+ * Produces a slice via skip and limit cursors. Subclasses are encouraged
+ * to override with a more efficient implementation.
+ *
+ * @since 1.2
+ */
+ public Cursor<S> fetch(FilterValues<S> values, long from, Long to) throws FetchException {
+ Cursor<S> cursor = fetch(values);
+ if (from > 0) {
+ cursor = new SkipCursor<S>(cursor, from);
+ }
+ if (to != null) {
+ cursor = new LimitCursor<S>(cursor, to - from);
+ }
+ return cursor;
+ }
+
+ /**
+ * Counts results by opening a cursor and skipping entries. Subclasses are
+ * encouraged to override with a more efficient implementation.
*/
public long count(FilterValues<S> values) throws FetchException {
Cursor<S> cursor = fetch(values);
diff --git a/src/main/java/com/amazon/carbonado/qe/DelegatedQueryExecutor.java b/src/main/java/com/amazon/carbonado/qe/DelegatedQueryExecutor.java index b4bc0a3..3ec209d 100644 --- a/src/main/java/com/amazon/carbonado/qe/DelegatedQueryExecutor.java +++ b/src/main/java/com/amazon/carbonado/qe/DelegatedQueryExecutor.java @@ -95,6 +95,10 @@ public class DelegatedQueryExecutor<S extends Storable> implements QueryExecutor return applyFilterValues(values).fetch();
}
+ public Cursor<S> fetch(FilterValues<S> values, long from, Long to) throws FetchException {
+ return applyFilterValues(values).fetch(from, to);
+ }
+
public long count(FilterValues<S> values) throws FetchException {
return applyFilterValues(values).count();
}
diff --git a/src/main/java/com/amazon/carbonado/qe/EmptyQuery.java b/src/main/java/com/amazon/carbonado/qe/EmptyQuery.java index f3d54f5..9754019 100644 --- a/src/main/java/com/amazon/carbonado/qe/EmptyQuery.java +++ b/src/main/java/com/amazon/carbonado/qe/EmptyQuery.java @@ -215,11 +215,27 @@ public final class EmptyQuery<S extends Storable> extends AbstractQuery<S> { /**
* Always returns an {@link EmptyCursor}.
*/
+ public Cursor<S> fetch(long from, Long to) {
+ checkSliceArguments(from, to);
+ return EmptyCursor.the();
+ }
+
+ /**
+ * Always returns an {@link EmptyCursor}.
+ */
public Cursor<S> fetchAfter(S start) {
return EmptyCursor.the();
}
/**
+ * Always returns an {@link EmptyCursor}.
+ */
+ public Cursor<S> fetchAfter(S start, long from, Long to) {
+ checkSliceArguments(from, to);
+ return EmptyCursor.the();
+ }
+
+ /**
* Always throws {@link PersistNoneException}.
*/
public void deleteOne() throws PersistNoneException {
diff --git a/src/main/java/com/amazon/carbonado/qe/QueryExecutor.java b/src/main/java/com/amazon/carbonado/qe/QueryExecutor.java index b0ab801..6b5a864 100644 --- a/src/main/java/com/amazon/carbonado/qe/QueryExecutor.java +++ b/src/main/java/com/amazon/carbonado/qe/QueryExecutor.java @@ -46,6 +46,13 @@ public interface QueryExecutor<S extends Storable> { Cursor<S> fetch(FilterValues<S> values) throws FetchException;
/**
+ * Returns a new cursor using the given filter values and slice.
+ *
+ * @since 1.2
+ */
+ Cursor<S> fetch(FilterValues<S> values, long from, Long to) throws FetchException;
+
+ /**
* Counts the query results using the given filter values.
*/
long count(FilterValues<S> values) throws FetchException;
diff --git a/src/main/java/com/amazon/carbonado/qe/StandardQuery.java b/src/main/java/com/amazon/carbonado/qe/StandardQuery.java index 5596c32..10fdf43 100644 --- a/src/main/java/com/amazon/carbonado/qe/StandardQuery.java +++ b/src/main/java/com/amazon/carbonado/qe/StandardQuery.java @@ -217,6 +217,18 @@ public abstract class StandardQuery<S extends Storable> extends AbstractQuery<S> }
}
+ public Cursor<S> fetch(long from, Long to) throws FetchException {
+ if (!checkSliceArguments(from, to)) {
+ return fetch();
+ }
+ try {
+ QueryHints hints = QueryHints.emptyHints().with(QueryHint.CONSUME_SLICE);
+ return executorFactory().executor(mFilter, mOrdering, hints).fetch(mValues, from, to);
+ } catch (RepositoryException e) {
+ throw e.toFetchException();
+ }
+ }
+
public Cursor<S> fetchAfter(S start) throws FetchException {
OrderingList<S> orderings;
if (start == null || (orderings = mOrdering).size() == 0) {
@@ -225,6 +237,17 @@ public abstract class StandardQuery<S extends Storable> extends AbstractQuery<S> return buildAfter(start, orderings).fetch();
}
+ public Cursor<S> fetchAfter(S start, long from, Long to) throws FetchException {
+ if (!checkSliceArguments(from, to)) {
+ return fetchAfter(start);
+ }
+ OrderingList<S> orderings;
+ if (start == null || (orderings = mOrdering).size() == 0) {
+ return fetch(from, to);
+ }
+ return buildAfter(start, orderings).fetch(from, to);
+ }
+
private Query<S> buildAfter(S start, OrderingList<S> orderings) throws FetchException {
Class<S> storableType = getStorableType();
Filter<S> orderFilter = Filter.getClosedFilter(storableType);
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