mikemccand commented on a change in pull request #657: LUCENE-8781: FST direct
arc addressing
URL: https://github.com/apache/lucene-solr/pull/657#discussion_r280692040
##########
File path: lucene/core/src/java/org/apache/lucene/util/fst/FST.java
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@@ -865,20 +939,32 @@ public int readNextArcLabel(Arc<T> arc, BytesReader in)
throws IOException {
} else {
in.setPosition(pos);
}
+ // skip flags
+ in.readByte();
} else {
if (arc.bytesPerArc != 0) {
//System.out.println(" nextArc real array");
- // arcs are at fixed entries
- in.setPosition(arc.posArcsStart);
- in.skipBytes((1+arc.arcIdx)*arc.bytesPerArc);
+ // arcs are in an array
+ if (arc.arcIdx >= 0) {
+ in.setPosition(arc.posArcsStart);
+ // point at next arc, -1 to skip flags
+ in.skipBytes((1 + arc.arcIdx) * arc.bytesPerArc + 1);
+ } else {
+ in.setPosition(arc.nextArc);
+ byte flags = in.readByte();
+ // skip missing arcs
+ while (flag(flags, BIT_MISSING_ARC)) {
Review comment:
It would be nice (separate issue) if we could track counters of how many
"arc scans" (typically done by `seekCeil` from Lucene's terms dict) versus
"direct lookups" are done, in a typical use case ... but that's a future issue.
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