/**
* Copyright 2011-2014 Asakusa Framework Team.
*
* 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.asakusafw.runtime.directio.hadoop;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import com.asakusafw.runtime.directio.DirectInputFragment;
/**
* compute fragments.
* @since 0.2.5
* @version 0.7.0
*/
class FragmentComputer {
static final long MAX_MIN_SIZE = Long.MAX_VALUE / 8;
private final long minSize;
private final long prefSize;
private final boolean combineBlocks;
private final boolean splitBlocks;
/**
* Creates a new instance.
* @since 0.7.0
*/
public FragmentComputer() {
this(-1L, -1L, false, false);
}
/**
* Creates a new instance.
* @param minSize minimum fragment size, or {@code < 0} for restrict fragmentation
* @param prefSize preferred fragment size
* @param combineBlocks whether combines blocks
* @param splitBlocks {@code true} to split fragments
*/
public FragmentComputer(long minSize, long prefSize, boolean combineBlocks, boolean splitBlocks) {
this.minSize = Math.min(minSize, MAX_MIN_SIZE);
this.prefSize = Math.max(minSize, prefSize);
this.combineBlocks = combineBlocks;
this.splitBlocks = splitBlocks;
}
/**
* Computes fragments from blocks hint.
* @param path the target path
* @param fileSize target file size
* @param blocks block hints
* @return the computed fragments
* @throws IllegalArgumentException if some parameters were {@code null}
*/
public List<DirectInputFragment> computeFragments(String path, long fileSize, Collection<BlockInfo> blocks) {
if (path == null) {
throw new IllegalArgumentException("path must not be null"); //$NON-NLS-1$
}
if (blocks == null) {
throw new IllegalArgumentException("blocks must not be null"); //$NON-NLS-1$
}
BlockMap map = BlockMap.create(path, fileSize, blocks, combineBlocks);
List<DirectInputFragment> fragments = computeFragments(map);
return fragments;
}
private List<DirectInputFragment> computeFragments(BlockMap map) {
assert map != null;
long size = map.getFileSize();
if (canFragmentation() == false || size / 2 < minSize) {
return Collections.singletonList(map.get(0, size));
}
assert minSize > 0;
assert map.getFileSize() > minSize;
List<BlockInfo> blocks = map.getBlocks();
BitSet processed = new BitSet(blocks.size());
assert size == blocks.get(blocks.size() - 1).end;
List<DirectInputFragment> results = new ArrayList<DirectInputFragment>();
for (int index = processed.nextClearBit(0); index < blocks.size(); index = processed.nextClearBit(index + 1)) {
int lastIndex = index + 1;
BlockInfo startBlock = blocks.get(index);
assert size - startBlock.start >= minSize;
while (blocks.get(lastIndex - 1).end - startBlock.start < minSize) {
lastIndex++;
assert lastIndex <= blocks.size();
}
long rest = size - blocks.get(lastIndex - 1).end;
if (rest < minSize) {
lastIndex = blocks.size();
}
processed.set(index, lastIndex);
long start = startBlock.start;
long end = blocks.get(lastIndex - 1).end;
if (splitBlocks) {
long groupSize = end - start;
int fragmentCount = Math.max((int) (groupSize / prefSize), 1);
long eachFragmentSize = (groupSize + fragmentCount - 1) / fragmentCount;
long offset = start;
while (offset != end) {
long fragmentSize = Math.min(end - offset, eachFragmentSize);
results.add(map.get(offset, offset + fragmentSize));
offset += fragmentSize;
assert offset <= end : offset + " > " + end;
}
assert offset == end;
} else {
results.add(map.get(start, end));
}
}
assert validFragments(map, results);
return results;
}
private boolean canFragmentation() {
return minSize >= 1;
}
private boolean validFragments(BlockMap map, List<DirectInputFragment> results) {
assert map != null;
assert results != null;
Collections.sort(results, new Comparator<DirectInputFragment>() {
@Override
public int compare(DirectInputFragment o1, DirectInputFragment o2) {
long i1 = o1.getOffset();
long i2 = o2.getOffset();
if (i1 < i2) {
return -1;
}
if (i1 > i2) {
return +1;
}
return 0;
}
});
long expectedOffset = 0;
for (DirectInputFragment fragment : results) {
long offset = fragment.getOffset();
assert offset == expectedOffset : offset + " != " + expectedOffset;
expectedOffset = offset + fragment.getSize();
}
assert map.getFileSize() == expectedOffset : map.getFileSize() + " != " + expectedOffset;
return true;
}
}