jpountz commented on code in PR #987:
URL: https://github.com/apache/lucene/pull/987#discussion_r922672203
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/compressing/Lucene90CompressingStoredFieldsWriter.java:
##########
@@ -247,21 +249,18 @@ private void flush(boolean force) throws IOException {
writeHeader(docBase, numBufferedDocs, numStoredFields, lengths, sliced,
dirtyChunk);
// compress stored fields to fieldsStream.
- //
- // TODO: do we need to slice it since we already have the slices in the
buffer? Perhaps
- // we should use max-block-bits restriction on the buffer itself, then we
won't have to check it
- // here.
- byte[] content = bufferedDocs.toArrayCopy();
- bufferedDocs.reset();
-
if (sliced) {
- // big chunk, slice it
- for (int compressed = 0; compressed < content.length; compressed +=
chunkSize) {
- compressor.compress(
- content, compressed, Math.min(chunkSize, content.length -
compressed), fieldsStream);
+ // big chunk, slice it, using ByteBuffersDataInput ignore memory copy
+ ByteBuffersDataInput bytebuffers = bufferedDocs.toDataInput();
+ final int capacity = (int) bytebuffers.size();
+ for (int compressed = 0; compressed < capacity; compressed += chunkSize)
{
+ int l = Math.min(chunkSize, capacity - compressed);
+ ByteBuffersDataInput bbdi = bytebuffers.slice(compressed, l);
+ compressor.compress(bbdi, fieldsStream);
}
} else {
- compressor.compress(content, 0, content.length, fieldsStream);
+ ByteBuffersDataInput bytebuffers = bufferedDocs.toDataInput();
Review Comment:
Maybe move this before the `if` statement since we create `byteBuffers` the
same way on both branches?
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/compressing/Lucene90CompressingStoredFieldsWriter.java:
##########
@@ -519,7 +518,13 @@ private void
copyOneDoc(Lucene90CompressingStoredFieldsReader reader, int docID)
assert reader.getVersion() == VERSION_CURRENT;
SerializedDocument doc = reader.document(docID);
startDocument();
- bufferedDocs.copyBytes(doc.in, doc.length);
+
+ if (doc.in instanceof ByteArrayDataInput) {
+ // reuse ByteArrayDataInput to reduce memory copy
+ bufferedDocs.copyBytes((ByteArrayDataInput) doc.in, doc.length);
+ } else {
+ bufferedDocs.copyBytes(doc.in, doc.length);
+ }
Review Comment:
I think that we could avoid this `instanceof` check by overriding
`ByteBuffersDataOutput#copyBytes` to read directly into its internal buffers
when they are not direct (ie. backed by a `byte[]`)? (Maybe in a separate
change?)
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/DeflateWithPresetDictCompressionMode.java:
##########
@@ -163,12 +165,16 @@ private static class DeflateWithPresetDictCompressor
extends Compressor {
final Deflater compressor;
final BugfixDeflater_JDK8252739 deflaterBugfix;
byte[] compressed;
+ byte[] bufferDict;
+ byte[] bufferBlock;
boolean closed;
DeflateWithPresetDictCompressor(int level) {
compressor = new Deflater(level, true);
deflaterBugfix = BugfixDeflater_JDK8252739.createBugfix(compressor);
compressed = new byte[64];
+ bufferDict = BytesRef.EMPTY_BYTES;
+ bufferBlock = BytesRef.EMPTY_BYTES;
}
private void doCompress(byte[] bytes, int off, int len, DataOutput out)
throws IOException {
Review Comment:
Can we remove this one and require callers to use the ByteBuffer variant
instead?
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/DeflateWithPresetDictCompressionMode.java:
##########
@@ -199,23 +205,65 @@ private void doCompress(byte[] bytes, int off, int len,
DataOutput out) throws I
out.writeBytes(compressed, totalCount);
}
+ private void doCompress(ByteBuffer bytes, int len, DataOutput out) throws
IOException {
+ if (len == 0) {
+ out.writeVInt(0);
+ return;
+ }
+ compressor.setInput(bytes);
+ compressor.finish();
+ if (compressor.needsInput()) {
+ throw new IllegalStateException();
+ }
+
+ int totalCount = 0;
+ for (; ; ) {
+ final int count =
+ compressor.deflate(compressed, totalCount, compressed.length -
totalCount);
+ totalCount += count;
+ assert totalCount <= compressed.length;
+ if (compressor.finished()) {
+ break;
+ } else {
+ compressed = ArrayUtil.grow(compressed);
+ }
+ }
+
+ out.writeVInt(totalCount);
+ out.writeBytes(compressed, totalCount);
+ }
+
@Override
- public void compress(byte[] bytes, int off, int len, DataOutput out)
throws IOException {
+ public void compress(ByteBuffersDataInput buffersInput, DataOutput out)
throws IOException {
+ final int len = (int) (buffersInput.size() - buffersInput.position());
+ final int end = (int) buffersInput.size();
final int dictLength = len / (NUM_SUB_BLOCKS * DICT_SIZE_FACTOR);
final int blockLength = (len - dictLength + NUM_SUB_BLOCKS - 1) /
NUM_SUB_BLOCKS;
out.writeVInt(dictLength);
out.writeVInt(blockLength);
- final int end = off + len;
// Compress the dictionary first
compressor.reset();
- doCompress(bytes, off, dictLength, out);
+ bufferDict = ArrayUtil.growNoCopy(bufferDict, dictLength);
+ buffersInput.readBytes(bufferDict, 0, dictLength);
+ doCompress(bufferDict, 0, dictLength, out);
// And then sub blocks
- for (int start = off + dictLength; start < end; start += blockLength) {
+ for (int start = dictLength; start < end; start += blockLength) {
compressor.reset();
- deflaterBugfix.setDictionary(bytes, off, dictLength);
- doCompress(bytes, start, Math.min(blockLength, off + len - start),
out);
+ deflaterBugfix.setDictionary(bufferDict, 0, dictLength);
+ int l = Math.min(blockLength, len - start);
+ // if [start,start + len] stay in one ByteBuffer, we can ignore memory
copy
+ // otherwise need to copy bytes into on continuous byte array
+ ByteBuffer bb = buffersInput.sliceOne(start, l);
Review Comment:
I would prefer abstracting this at the ByteBuffersDataInput level, e.g.
maybe there could be a `ByteBuffer ByteBuffersDataInput#readBytes(int
numBytes)` API that would automatically return a view of one of its internal
buffers when the bytes are fully contained into a single buffer, and create a
fresh new ByteBuffer otherwise?
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