/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.cassandra.db;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.*;
import com.google.common.collect.Iterators;
import org.apache.cassandra.config.CFMetaData;
import org.apache.cassandra.config.ColumnDefinition;
import org.apache.cassandra.db.rows.*;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;
/**
* Represents the selection of multiple range of rows within a partition.
* <p>
* A {@code Slices} is basically a list of {@code Slice}, though those are guaranteed to be non-overlapping
* and always in clustering order.
*/
public abstract class Slices implements Iterable<Slice>
{
public static final Serializer serializer = new Serializer();
/** Slices selecting all the rows of a partition. */
public static final Slices ALL = new SelectAllSlices();
/** Slices selecting no rows in a partition. */
public static final Slices NONE = new SelectNoSlices();
protected Slices()
{
}
/**
* Creates a {@code Slices} object that contains a single slice.
*
* @param comparator the comparator for the table {@code slice} is a slice of.
* @param slice the single slice that the return object should contains.
*
* @return the newly created {@code Slices} object.
*/
public static Slices with(ClusteringComparator comparator, Slice slice)
{
if (slice.start() == Slice.Bound.BOTTOM && slice.end() == Slice.Bound.TOP)
return Slices.ALL;
assert comparator.compare(slice.start(), slice.end()) <= 0;
return new ArrayBackedSlices(comparator, new Slice[]{ slice });
}
/**
* Whether the slices has a lower bound, that is whether it's first slice start is {@code Slice.BOTTOM}.
*
* @return whether the slices has a lower bound.
*/
public abstract boolean hasLowerBound();
/**
* Whether the slices has an upper bound, that is whether it's last slice end is {@code Slice.TOP}.
*
* @return whether the slices has an upper bound.
*/
public abstract boolean hasUpperBound();
/**
* The number of slice this object contains.
*
* @return the number of slice this object contains.
*/
public abstract int size();
/**
* Returns the ith slice of this {@code Slices} object.
*
* @return the ith slice of this object.
*/
public abstract Slice get(int i);
/**
* Returns slices for continuing the paging of those slices given the last returned clustering prefix.
*
* @param comparator the comparator for the table this is a filter for.
* @param lastReturned the last clustering that was returned for the query we are paging for. The
* resulting slices will be such that only results coming stricly after {@code lastReturned} are returned
* (where coming after means "greater than" if {@code !reversed} and "lesser than" otherwise).
* @param inclusive whether or not we want to include the {@code lastReturned} in the newly returned page of results.
* @param reversed whether the query we're paging for is reversed or not.
*
* @return new slices that select results coming after {@code lastReturned}.
*/
public abstract Slices forPaging(ClusteringComparator comparator, Clustering lastReturned, boolean inclusive, boolean reversed);
/**
* An object that allows to test whether rows are selected by this {@code Slices} objects assuming those rows
* are tested in clustering order.
*
* @param reversed if true, the rows passed to the returned object will be assumed to be in reversed clustering
* order, otherwise they should be in clustering order.
*
* @return an object that tests for selection of rows by this {@code Slices} object.
*/
public abstract InOrderTester inOrderTester(boolean reversed);
/**
* Whether a given clustering (row) is selected by this {@code Slices} object.
*
* @param clustering the clustering to test for selection.
*
* @return whether a given clustering (row) is selected by this {@code Slices} object.
*/
public abstract boolean selects(Clustering clustering);
/**
* Given the per-clustering column minimum and maximum value a sstable contains, whether or not this slices potentially
* intersects that sstable or not.
*
* @param minClusteringValues the smallest values for each clustering column that a sstable contains.
* @param maxClusteringValues the biggest values for each clustering column that a sstable contains.
*
* @return whether the slices might intersects with the sstable having {@code minClusteringValues} and
* {@code maxClusteringValues}.
*/
public abstract boolean intersects(List<ByteBuffer> minClusteringValues, List<ByteBuffer> maxClusteringValues);
/**
* Given a sliceable row iterator, returns a row iterator that only return rows selected by the slice of
* this {@code Slices} object.
*
* @param iter the sliceable iterator to filter.
*
* @return an iterator that only returns the rows (or rather Unfiltered) of {@code iter} that are selected by those slices.
*/
public abstract UnfilteredRowIterator makeSliceIterator(SliceableUnfilteredRowIterator iter);
public abstract String toCQLString(CFMetaData metadata);
/**
* Checks if this <code>Slices</code> is empty.
* @return <code>true</code> if this <code>Slices</code> is empty, <code>false</code> otherwise.
*/
public final boolean isEmpty()
{
return size() == 0;
}
/**
* In simple object that allows to test the inclusion of rows in those slices assuming those rows
* are passed (to {@link #includes}) in clustering order (or reverse clustering ordered, depending
* of the argument passed to {@link #inOrderTester}).
*/
public interface InOrderTester
{
public boolean includes(Clustering value);
public boolean isDone();
}
/**
* Builder to create {@code Slices} objects.
*/
public static class Builder
{
private final ClusteringComparator comparator;
private final List<Slice> slices;
private boolean needsNormalizing;
public Builder(ClusteringComparator comparator)
{
this.comparator = comparator;
this.slices = new ArrayList<>();
}
public Builder(ClusteringComparator comparator, int initialSize)
{
this.comparator = comparator;
this.slices = new ArrayList<>(initialSize);
}
public Builder add(Slice.Bound start, Slice.Bound end)
{
return add(Slice.make(start, end));
}
public Builder add(Slice slice)
{
assert comparator.compare(slice.start(), slice.end()) <= 0;
if (slices.size() > 0 && comparator.compare(slices.get(slices.size()-1).end(), slice.start()) > 0)
needsNormalizing = true;
slices.add(slice);
return this;
}
public Builder addAll(Slices slices)
{
for (Slice slice : slices)
add(slice);
return this;
}
public int size()
{
return slices.size();
}
public Slices build()
{
if (slices.isEmpty())
return NONE;
if (slices.size() == 1 && slices.get(0) == Slice.ALL)
return ALL;
List<Slice> normalized = needsNormalizing
? normalize(slices)
: slices;
return new ArrayBackedSlices(comparator, normalized.toArray(new Slice[normalized.size()]));
}
/**
* Given an array of slices (potentially overlapping and in any order) and return an equivalent array
* of non-overlapping slices in clustering order.
*
* @param slices an array of slices. This may be modified by this method.
* @return the smallest possible array of non-overlapping slices in clustering order. If the original
* slices are already non-overlapping and in comparator order, this may or may not return the provided slices
* directly.
*/
private List<Slice> normalize(List<Slice> slices)
{
if (slices.size() <= 1)
return slices;
Collections.sort(slices, new Comparator<Slice>()
{
@Override
public int compare(Slice s1, Slice s2)
{
int c = comparator.compare(s1.start(), s2.start());
if (c != 0)
return c;
return comparator.compare(s1.end(), s2.end());
}
});
List<Slice> slicesCopy = new ArrayList<>(slices.size());
Slice last = slices.get(0);
for (int i = 1; i < slices.size(); i++)
{
Slice s2 = slices.get(i);
boolean includesStart = last.includes(comparator, s2.start());
boolean includesFinish = last.includes(comparator, s2.end());
if (includesStart && includesFinish)
continue;
if (!includesStart && !includesFinish)
{
slicesCopy.add(last);
last = s2;
continue;
}
if (includesStart)
{
last = Slice.make(last.start(), s2.end());
continue;
}
assert !includesFinish;
}
slicesCopy.add(last);
return slicesCopy;
}
}
public static class Serializer
{
public void serialize(Slices slices, DataOutputPlus out, int version) throws IOException
{
int size = slices.size();
out.writeUnsignedVInt(size);
if (size == 0)
return;
List<AbstractType<?>> types = slices == ALL
? Collections.<AbstractType<?>>emptyList()
: ((ArrayBackedSlices)slices).comparator.subtypes();
for (Slice slice : slices)
Slice.serializer.serialize(slice, out, version, types);
}
public long serializedSize(Slices slices, int version)
{
long size = TypeSizes.sizeofUnsignedVInt(slices.size());
if (slices.size() == 0)
return size;
List<AbstractType<?>> types = slices instanceof SelectAllSlices
? Collections.<AbstractType<?>>emptyList()
: ((ArrayBackedSlices)slices).comparator.subtypes();
for (Slice slice : slices)
size += Slice.serializer.serializedSize(slice, version, types);
return size;
}
public Slices deserialize(DataInputPlus in, int version, CFMetaData metadata) throws IOException
{
int size = (int)in.readUnsignedVInt();
if (size == 0)
return NONE;
Slice[] slices = new Slice[size];
for (int i = 0; i < size; i++)
slices[i] = Slice.serializer.deserialize(in, version, metadata.comparator.subtypes());
if (size == 1 && slices[0].start() == Slice.Bound.BOTTOM && slices[0].end() == Slice.Bound.TOP)
return ALL;
return new ArrayBackedSlices(metadata.comparator, slices);
}
}
/**
* Simple {@code Slices} implementation that stores its slices in an array.
*/
private static class ArrayBackedSlices extends Slices
{
private final ClusteringComparator comparator;
private final Slice[] slices;
private ArrayBackedSlices(ClusteringComparator comparator, Slice[] slices)
{
this.comparator = comparator;
this.slices = slices;
}
public int size()
{
return slices.length;
}
public boolean hasLowerBound()
{
return slices[0].start().size() != 0;
}
public boolean hasUpperBound()
{
return slices[slices.length - 1].end().size() != 0;
}
public Slice get(int i)
{
return slices[i];
}
public boolean selects(Clustering clustering)
{
for (int i = 0; i < slices.length; i++)
{
Slice slice = slices[i];
if (comparator.compare(clustering, slice.start()) < 0)
return false;
if (comparator.compare(clustering, slice.end()) <= 0)
return true;
}
return false;
}
public InOrderTester inOrderTester(boolean reversed)
{
return reversed ? new InReverseOrderTester() : new InForwardOrderTester();
}
public Slices forPaging(ClusteringComparator comparator, Clustering lastReturned, boolean inclusive, boolean reversed)
{
return reversed ? forReversePaging(comparator, lastReturned, inclusive) : forForwardPaging(comparator, lastReturned, inclusive);
}
private Slices forForwardPaging(ClusteringComparator comparator, Clustering lastReturned, boolean inclusive)
{
for (int i = 0; i < slices.length; i++)
{
Slice slice = slices[i];
Slice newSlice = slice.forPaging(comparator, lastReturned, inclusive, false);
if (newSlice == null)
continue;
if (slice == newSlice && i == 0)
return this;
ArrayBackedSlices newSlices = new ArrayBackedSlices(comparator, Arrays.copyOfRange(slices, i, slices.length));
newSlices.slices[0] = newSlice;
return newSlices;
}
return Slices.NONE;
}
private Slices forReversePaging(ClusteringComparator comparator, Clustering lastReturned, boolean inclusive)
{
for (int i = slices.length - 1; i >= 0; i--)
{
Slice slice = slices[i];
Slice newSlice = slice.forPaging(comparator, lastReturned, inclusive, true);
if (newSlice == null)
continue;
if (slice == newSlice && i == slices.length - 1)
return this;
ArrayBackedSlices newSlices = new ArrayBackedSlices(comparator, Arrays.copyOfRange(slices, 0, i + 1));
newSlices.slices[i] = newSlice;
return newSlices;
}
return Slices.NONE;
}
public boolean intersects(List<ByteBuffer> minClusteringValues, List<ByteBuffer> maxClusteringValues)
{
for (Slice slice : this)
{
if (slice.intersects(comparator, minClusteringValues, maxClusteringValues))
return true;
}
return false;
}
public UnfilteredRowIterator makeSliceIterator(final SliceableUnfilteredRowIterator iter)
{
return new WrappingUnfilteredRowIterator(iter)
{
private int nextSlice = iter.isReverseOrder() ? slices.length - 1 : 0;
private Iterator<Unfiltered> currentSliceIterator = Collections.emptyIterator();
private Unfiltered next;
@Override
public boolean hasNext()
{
prepareNext();
return next != null;
}
@Override
public Unfiltered next()
{
prepareNext();
Unfiltered toReturn = next;
next = null;
return toReturn;
}
private boolean hasMoreSlice()
{
return isReverseOrder()
? nextSlice >= 0
: nextSlice < slices.length;
}
private Slice popNextSlice()
{
return slices[isReverseOrder() ? nextSlice-- : nextSlice++];
}
private void prepareNext()
{
if (next != null)
return;
while (true)
{
if (currentSliceIterator.hasNext())
{
next = currentSliceIterator.next();
return;
}
if (!hasMoreSlice())
return;
currentSliceIterator = iter.slice(popNextSlice());
}
}
};
}
public Iterator<Slice> iterator()
{
return Iterators.forArray(slices);
}
private class InForwardOrderTester implements InOrderTester
{
private int idx;
private boolean inSlice;
public boolean includes(Clustering value)
{
while (idx < slices.length)
{
if (!inSlice)
{
int cmp = comparator.compare(value, slices[idx].start());
// value < start
if (cmp < 0)
return false;
inSlice = true;
if (cmp == 0)
return true;
}
// Here, start < value and inSlice
if (comparator.compare(value, slices[idx].end()) <= 0)
return true;
++idx;
inSlice = false;
}
return false;
}
public boolean isDone()
{
return idx >= slices.length;
}
}
private class InReverseOrderTester implements InOrderTester
{
private int idx;
private boolean inSlice;
public InReverseOrderTester()
{
this.idx = slices.length - 1;
}
public boolean includes(Clustering value)
{
while (idx >= 0)
{
if (!inSlice)
{
int cmp = comparator.compare(slices[idx].end(), value);
// value > end
if (cmp > 0)
return false;
inSlice = true;
if (cmp == 0)
return true;
}
// Here, value <= end and inSlice
if (comparator.compare(slices[idx].start(), value) <= 0)
return true;
--idx;
inSlice = false;
}
return false;
}
public boolean isDone()
{
return idx < 0;
}
}
@Override
public String toString()
{
StringBuilder sb = new StringBuilder();
sb.append("{");
for (int i = 0; i < slices.length; i++)
{
if (i > 0)
sb.append(", ");
sb.append(slices[i].toString(comparator));
}
return sb.append("}").toString();
}
public String toCQLString(CFMetaData metadata)
{
StringBuilder sb = new StringBuilder();
// In CQL, condition are expressed by column, so first group things that way,
// i.e. for each column, we create a list of what each slice contains on that column
int clusteringSize = metadata.clusteringColumns().size();
List<List<ComponentOfSlice>> columnComponents = new ArrayList<>(clusteringSize);
for (int i = 0; i < clusteringSize; i++)
{
List<ComponentOfSlice> perSlice = new ArrayList<>();
columnComponents.add(perSlice);
for (int j = 0; j < slices.length; j++)
{
ComponentOfSlice c = ComponentOfSlice.fromSlice(i, slices[j]);
if (c != null)
perSlice.add(c);
}
}
boolean needAnd = false;
for (int i = 0; i < clusteringSize; i++)
{
ColumnDefinition column = metadata.clusteringColumns().get(i);
List<ComponentOfSlice> componentInfo = columnComponents.get(i);
if (componentInfo.isEmpty())
break;
// For a given column, there is only 3 cases that CQL currently generates:
// 1) every slice are EQ with the same value, it's a simple '=' relation.
// 2) every slice are EQ but with different values, it's a IN relation.
// 3) every slice aren't EQ but have the same values, we have inequality relations.
// Note that this doesn't cover everything that ReadCommand can express, but
// as it's all that CQL support for now, we'll ignore other cases (which would then
// display a bogus query but that's not the end of the world).
// TODO: we should improve this at some point.
ComponentOfSlice first = componentInfo.get(0);
if (first.isEQ())
{
if (needAnd)
sb.append(" AND ");
needAnd = true;
sb.append(column.name);
Set<ByteBuffer> values = new LinkedHashSet<>();
for (int j = 0; j < componentInfo.size(); j++)
values.add(componentInfo.get(j).startValue);
if (values.size() == 1)
{
sb.append(" = ").append(column.type.getString(first.startValue));
}
else
{
sb.append(" IN (");
int j = 0;
for (ByteBuffer value : values)
sb.append(j++ == 0 ? "" : ", ").append(column.type.getString(value));
sb.append(")");
}
}
else
{
// As said above, we assume (without checking) that this means all ComponentOfSlice for this column
// are the same, so we only bother about the first.
if (first.startValue != null)
{
if (needAnd)
sb.append(" AND ");
needAnd = true;
sb.append(column.name).append(first.startInclusive ? " >= " : " > ").append(column.type.getString(first.startValue));
}
if (first.endValue != null)
{
if (needAnd)
sb.append(" AND ");
needAnd = true;
sb.append(column.name).append(first.endInclusive ? " <= " : " < ").append(column.type.getString(first.endValue));
}
}
}
return sb.toString();
}
// An somewhat adhoc utility class only used by toCQLString
private static class ComponentOfSlice
{
public final boolean startInclusive;
public final ByteBuffer startValue;
public final boolean endInclusive;
public final ByteBuffer endValue;
private ComponentOfSlice(boolean startInclusive, ByteBuffer startValue, boolean endInclusive, ByteBuffer endValue)
{
this.startInclusive = startInclusive;
this.startValue = startValue;
this.endInclusive = endInclusive;
this.endValue = endValue;
}
public static ComponentOfSlice fromSlice(int component, Slice slice)
{
Slice.Bound start = slice.start();
Slice.Bound end = slice.end();
if (component >= start.size() && component >= end.size())
return null;
boolean startInclusive = true, endInclusive = true;
ByteBuffer startValue = null, endValue = null;
if (component < start.size())
{
startInclusive = start.isInclusive();
startValue = start.get(component);
}
if (component < end.size())
{
endInclusive = end.isInclusive();
endValue = end.get(component);
}
return new ComponentOfSlice(startInclusive, startValue, endInclusive, endValue);
}
public boolean isEQ()
{
return startValue.equals(endValue);
}
}
}
/**
* Specialized implementation of {@code Slices} that selects all rows.
* <p>
* This is equivalent to having the single {@code Slice.ALL} slice, but is somewhat more effecient.
*/
private static class SelectAllSlices extends Slices
{
private static final InOrderTester trivialTester = new InOrderTester()
{
public boolean includes(Clustering value)
{
return true;
}
public boolean isDone()
{
return false;
}
};
public int size()
{
return 1;
}
public Slice get(int i)
{
return Slice.ALL;
}
public boolean hasLowerBound()
{
return false;
}
public boolean hasUpperBound()
{
return false;
}
public boolean selects(Clustering clustering)
{
return true;
}
public Slices forPaging(ClusteringComparator comparator, Clustering lastReturned, boolean inclusive, boolean reversed)
{
return new ArrayBackedSlices(comparator, new Slice[]{ Slice.ALL.forPaging(comparator, lastReturned, inclusive, reversed) });
}
public InOrderTester inOrderTester(boolean reversed)
{
return trivialTester;
}
public boolean intersects(List<ByteBuffer> minClusteringValues, List<ByteBuffer> maxClusteringValues)
{
return true;
}
public UnfilteredRowIterator makeSliceIterator(SliceableUnfilteredRowIterator iter)
{
return iter;
}
public Iterator<Slice> iterator()
{
return Iterators.singletonIterator(Slice.ALL);
}
@Override
public String toString()
{
return "ALL";
}
public String toCQLString(CFMetaData metadata)
{
return "";
}
}
/**
* Specialized implementation of {@code Slices} that selects no rows.
*/
private static class SelectNoSlices extends Slices
{
private static final InOrderTester trivialTester = new InOrderTester()
{
public boolean includes(Clustering value)
{
return false;
}
public boolean isDone()
{
return true;
}
};
public int size()
{
return 0;
}
public Slice get(int i)
{
throw new UnsupportedOperationException();
}
public boolean hasLowerBound()
{
return false;
}
public boolean hasUpperBound()
{
return false;
}
public Slices forPaging(ClusteringComparator comparator, Clustering lastReturned, boolean inclusive, boolean reversed)
{
return this;
}
public boolean selects(Clustering clustering)
{
return false;
}
public InOrderTester inOrderTester(boolean reversed)
{
return trivialTester;
}
public boolean intersects(List<ByteBuffer> minClusteringValues, List<ByteBuffer> maxClusteringValues)
{
return false;
}
public UnfilteredRowIterator makeSliceIterator(SliceableUnfilteredRowIterator iter)
{
return UnfilteredRowIterators.noRowsIterator(iter.metadata(), iter.partitionKey(), iter.staticRow(),
iter.partitionLevelDeletion(), iter.isReverseOrder());
}
public Iterator<Slice> iterator()
{
return Iterators.emptyIterator();
}
@Override
public String toString()
{
return "NONE";
}
public String toCQLString(CFMetaData metadata)
{
return "";
}
}
}