/*
* 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.drill.exec.physical.impl.xsort.managed;
import java.util.Queue;
import javax.inject.Named;
import org.apache.drill.exec.exception.SchemaChangeException;
import org.apache.drill.exec.memory.BaseAllocator;
import org.apache.drill.exec.memory.BufferAllocator;
import org.apache.drill.exec.ops.FragmentContext;
import org.apache.drill.exec.record.RecordBatch;
import org.apache.drill.exec.record.VectorContainer;
import org.apache.drill.exec.record.selection.SelectionVector4;
import org.apache.hadoop.util.IndexedSortable;
import com.google.common.base.Preconditions;
import com.google.common.collect.Queues;
import io.netty.buffer.DrillBuf;
public abstract class MSortTemplate implements MSorter, IndexedSortable {
// private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(MSortTemplate.class);
private SelectionVector4 vector4;
private SelectionVector4 aux;
@SuppressWarnings("unused")
private long compares;
/**
* Holds offsets into the SV4 of the start of each batch
* (sorted run.)
*/
private Queue<Integer> runStarts = Queues.newLinkedBlockingQueue();
private FragmentContext context;
/**
* Controls the maximum size of batches exposed to downstream
*/
private int desiredRecordBatchCount;
@Override
public void setup(final FragmentContext context, final BufferAllocator allocator, final SelectionVector4 vector4,
final VectorContainer hyperBatch, int outputBatchSize) throws SchemaChangeException{
// we pass in the local hyperBatch since that is where we'll be reading data.
Preconditions.checkNotNull(vector4);
this.vector4 = vector4.createNewWrapperCurrent();
this.context = context;
vector4.clear();
doSetup(context, hyperBatch, null);
// Populate the queue with the offset in the SV4 of each
// batch. Note that this is expensive as it requires a scan
// of all items to be sorted: potentially millions.
runStarts.add(0);
int batch = 0;
final int totalCount = this.vector4.getTotalCount();
for (int i = 0; i < totalCount; i++) {
final int newBatch = this.vector4.get(i) >>> 16;
if (newBatch == batch) {
continue;
} else if (newBatch == batch + 1) {
runStarts.add(i);
batch = newBatch;
} else {
throw new UnsupportedOperationException(String.format("Missing batch. batch: %d newBatch: %d", batch, newBatch));
}
}
// Create a temporary SV4 to hold the merged results.
@SuppressWarnings("resource")
final DrillBuf drillBuf = allocator.buffer(4 * totalCount);
desiredRecordBatchCount = Math.min(outputBatchSize, Character.MAX_VALUE);
desiredRecordBatchCount = Math.min(desiredRecordBatchCount, totalCount);
aux = new SelectionVector4(drillBuf, totalCount, desiredRecordBatchCount);
}
/**
* For given recordCount how much memory does MSorter needs for its own purpose. This is used in
* ExternalSortBatch to make decisions about whether to spill or not.
*
* @param recordCount
* @return
*/
public static long memoryNeeded(final int recordCount) {
// We need 4 bytes (SV4) for each record.
// The memory allocator will round this to the next
// power of 2.
return BaseAllocator.nextPowerOfTwo(recordCount * 4);
}
/**
* Given two regions within the selection vector 4 (a left and a right), merge
* the two regions to produce a combined output region in the auxiliary
* selection vector.
*
* @param leftStart
* @param rightStart
* @param rightEnd
* @param outStart
* @return
*/
protected int merge(final int leftStart, final int rightStart, final int rightEnd, final int outStart) {
int l = leftStart;
int r = rightStart;
int o = outStart;
while (l < rightStart && r < rightEnd) {
if (compare(l, r) <= 0) {
aux.set(o++, vector4.get(l++));
} else {
aux.set(o++, vector4.get(r++));
}
}
while (l < rightStart) {
aux.set(o++, vector4.get(l++));
}
while (r < rightEnd) {
aux.set(o++, vector4.get(r++));
}
assert o == outStart + (rightEnd - leftStart);
return o;
}
@Override
public SelectionVector4 getSV4() {
return vector4;
}
/**
* Sort (really, merge) a set of pre-sorted runs to produce a combined
* result set. Merging is done in the selection vector, record data does
* not move.
* <p>
* Runs are merge pairwise in multiple passes, providing performance
* of O(n * m * log(n)), where n = number of runs, m = number of records
* per run.
*/
@Override
public void sort(final VectorContainer container) {
while (runStarts.size() > 1) {
final int totalCount = this.vector4.getTotalCount();
// check if we're cancelled/failed recently
if (!context.shouldContinue()) {
return; }
int outIndex = 0;
final Queue<Integer> newRunStarts = Queues.newLinkedBlockingQueue();
newRunStarts.add(outIndex);
final int size = runStarts.size();
for (int i = 0; i < size / 2; i++) {
final int left = runStarts.poll();
final int right = runStarts.poll();
Integer end = runStarts.peek();
if (end == null) {
end = totalCount;
}
outIndex = merge(left, right, end, outIndex);
if (outIndex < vector4.getTotalCount()) {
newRunStarts.add(outIndex);
}
}
if (outIndex < totalCount) {
copyRun(outIndex, totalCount);
}
@SuppressWarnings("resource")
final SelectionVector4 tmp = aux.createNewWrapperCurrent(desiredRecordBatchCount);
aux.clear();
aux = vector4.createNewWrapperCurrent(desiredRecordBatchCount);
vector4.clear();
vector4 = tmp.createNewWrapperCurrent(desiredRecordBatchCount);
tmp.clear();
runStarts = newRunStarts;
}
aux.clear();
}
private void copyRun(final int start, final int end) {
for (int i = start; i < end; i++) {
aux.set(i, vector4.get(i));
}
}
@Override
public void swap(final int sv0, final int sv1) {
final int tmp = vector4.get(sv0);
vector4.set(sv0, vector4.get(sv1));
vector4.set(sv1, tmp);
}
@Override
public int compare(final int leftIndex, final int rightIndex) {
final int sv1 = vector4.get(leftIndex);
final int sv2 = vector4.get(rightIndex);
compares++;
try {
return doEval(sv1, sv2);
} catch (SchemaChangeException e) {
throw new IllegalStateException(e);
}
}
@Override
public void clear() {
if(vector4 != null) {
vector4.clear();
}
if(aux != null) {
aux.clear();
}
}
public abstract void doSetup(@Named("context") FragmentContext context, @Named("incoming") VectorContainer incoming, @Named("outgoing") RecordBatch outgoing) throws SchemaChangeException;
public abstract int doEval(@Named("leftIndex") int leftIndex, @Named("rightIndex") int rightIndex) throws SchemaChangeException;
}