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Remove delayed seek optimization. (#12815) 

I think that this optimization was introduced because `advanceShallow` may
advance skip lists and then never decode a block of postings. But actually
`IndexInput#seek` is cheap, including on `NIOFSDirectory`. So let's seek
immediately?
This commit is contained in:
Adrien Grand 2023-11-18 08:11:07 +01:00 committed by GitHub
parent 6db09131d6
commit 48e234d988
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 3 additions and 20 deletions
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23
lucene/core/src/java/org/apache/lucene/codecs/lucene99/Lucene99PostingsReader.java
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@ -1073,8 +1073,6 @@ public final class Lucene99PostingsReader extends PostingsReaderBase {
private int nextSkipDoc = -1; private int nextSkipDoc = -1;
private long seekTo = -1;
// as we read freqBuffer lazily, isFreqsRead shows if freqBuffer are read for the current block // as we read freqBuffer lazily, isFreqsRead shows if freqBuffer are read for the current block
// always true when we don't have freqBuffer (indexHasFreq=false) or don't need freqBuffer // always true when we don't have freqBuffer (indexHasFreq=false) or don't need freqBuffer
// (needsFreq=false) // (needsFreq=false)
@ -1178,7 +1176,8 @@ public final class Lucene99PostingsReader extends PostingsReaderBase {
// Force to read next block // Force to read next block
docBufferUpto = BLOCK_SIZE; docBufferUpto = BLOCK_SIZE;
accum = skipper.getDoc(); accum = skipper.getDoc();
seekTo = skipper.getDocPointer(); // delay the seek docIn.seek(skipper.getDocPointer());
isFreqsRead = true;
} }
// next time we call advance, this is used to // next time we call advance, this is used to
// foresee whether skipper is necessary. // foresee whether skipper is necessary.
@ -1198,11 +1197,6 @@ public final class Lucene99PostingsReader extends PostingsReaderBase {
@Override @Override
public int nextDoc() throws IOException { public int nextDoc() throws IOException {
if (docBufferUpto == BLOCK_SIZE) { if (docBufferUpto == BLOCK_SIZE) {
if (seekTo >= 0) {
docIn.seek(seekTo);
isFreqsRead = true; // reset isFreqsRead
seekTo = -1;
}
refillDocs(); refillDocs();
} }
return this.doc = (int) docBuffer[docBufferUpto++]; return this.doc = (int) docBuffer[docBufferUpto++];
@ -1214,11 +1208,6 @@ public final class Lucene99PostingsReader extends PostingsReaderBase {
advanceShallow(target); advanceShallow(target);
} }
if (docBufferUpto == BLOCK_SIZE) { if (docBufferUpto == BLOCK_SIZE) {
if (seekTo >= 0) {
docIn.seek(seekTo);
isFreqsRead = true; // reset isFreqsRead
seekTo = -1;
}
refillDocs(); refillDocs();
} }
@ -1307,8 +1296,6 @@ public final class Lucene99PostingsReader extends PostingsReaderBase {
private int nextSkipDoc = -1; private int nextSkipDoc = -1;
private long seekTo = -1;
public BlockImpactsPostingsEnum(FieldInfo fieldInfo, IntBlockTermState termState) public BlockImpactsPostingsEnum(FieldInfo fieldInfo, IntBlockTermState termState)
throws IOException { throws IOException {
indexHasOffsets = indexHasOffsets =
@ -1426,7 +1413,7 @@ public final class Lucene99PostingsReader extends PostingsReaderBase {
accum = skipper.getDoc(); accum = skipper.getDoc();
posPendingFP = skipper.getPosPointer(); posPendingFP = skipper.getPosPointer();
posPendingCount = skipper.getPosBufferUpto(); posPendingCount = skipper.getPosBufferUpto();
seekTo = skipper.getDocPointer(); // delay the seek docIn.seek(skipper.getDocPointer());
} }
// next time we call advance, this is used to // next time we call advance, this is used to
// foresee whether skipper is necessary. // foresee whether skipper is necessary.
@ -1452,10 +1439,6 @@ public final class Lucene99PostingsReader extends PostingsReaderBase {
advanceShallow(target); advanceShallow(target);
} }
if (docBufferUpto == BLOCK_SIZE) { if (docBufferUpto == BLOCK_SIZE) {
if (seekTo >= 0) {
docIn.seek(seekTo);
seekTo = -1;
}
refillDocs(); refillDocs();
} }