From 846aa2f8c3f1e6a691f0448d90023b1bbb5b5ada Mon Sep 17 00:00:00 2001
From: Adrien Grand <jpountz@gmail.com>
Date: Wed, 5 Jun 2024 13:41:58 +0200
Subject: [PATCH] Use `ReadAdvice#NORMAL` on files that have a forward-only
 access pattern. (#13450)

This applies to files where performing readahead could help:
 - Doc values data (`.dvd`)
 - Norms data (`.nvd`)
 - Docs and freqs in postings lists (`.doc`)
 - Points data (`.kdd`)

Other files (KNN vectors, stored fields, term vectors) keep using a `RANDOM`
advice.
---
 .../lucene/codecs/lucene90/Lucene90DocValuesProducer.java   | 6 +++++-
 .../lucene/codecs/lucene90/Lucene90NormsProducer.java       | 4 +++-
 .../apache/lucene/codecs/lucene90/Lucene90PointsReader.java | 5 ++++-
 .../lucene/codecs/lucene99/Lucene99PostingsReader.java      | 5 ++++-
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90DocValuesProducer.java b/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90DocValuesProducer.java
index f0b7b723432..16272c156b1 100644
--- a/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90DocValuesProducer.java
+++ b/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90DocValuesProducer.java
@@ -44,6 +44,7 @@ import org.apache.lucene.store.ChecksumIndexInput;
 import org.apache.lucene.store.DataInput;
 import org.apache.lucene.store.IndexInput;
 import org.apache.lucene.store.RandomAccessInput;
+import org.apache.lucene.store.ReadAdvice;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.IOUtils;
 import org.apache.lucene.util.LongValues;
@@ -106,7 +107,10 @@ final class Lucene90DocValuesProducer extends DocValuesProducer {
 
     String dataName =
         IndexFileNames.segmentFileName(state.segmentInfo.name, state.segmentSuffix, dataExtension);
-    this.data = state.directory.openInput(dataName, state.context);
+    // Doc-values have a forward-only access pattern, so pass ReadAdvice.NORMAL to perform
+    // readahead.
+    this.data =
+        state.directory.openInput(dataName, state.context.withReadAdvice(ReadAdvice.NORMAL));
     boolean success = false;
     try {
       final int version2 =
diff --git a/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90NormsProducer.java b/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90NormsProducer.java
index 0b996c5d952..4655091d57a 100644
--- a/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90NormsProducer.java
+++ b/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90NormsProducer.java
@@ -33,6 +33,7 @@ import org.apache.lucene.internal.hppc.IntObjectHashMap;
 import org.apache.lucene.store.ChecksumIndexInput;
 import org.apache.lucene.store.IndexInput;
 import org.apache.lucene.store.RandomAccessInput;
+import org.apache.lucene.store.ReadAdvice;
 import org.apache.lucene.util.IOUtils;
 
 /** Reader for {@link Lucene90NormsFormat} */
@@ -80,7 +81,8 @@ final class Lucene90NormsProducer extends NormsProducer implements Cloneable {
 
     String dataName =
         IndexFileNames.segmentFileName(state.segmentInfo.name, state.segmentSuffix, dataExtension);
-    data = state.directory.openInput(dataName, state.context);
+    // Norms have a forward-only access pattern, so pass ReadAdvice.NORMAL to perform readahead.
+    data = state.directory.openInput(dataName, state.context.withReadAdvice(ReadAdvice.NORMAL));
     boolean success = false;
     try {
       final int version2 =
diff --git a/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90PointsReader.java b/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90PointsReader.java
index 75805d798bb..d3f256cbf00 100644
--- a/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90PointsReader.java
+++ b/lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90PointsReader.java
@@ -71,7 +71,10 @@ public class Lucene90PointsReader extends PointsReader {
           readState.segmentSuffix);
       CodecUtil.retrieveChecksum(indexIn);
 
-      dataIn = readState.directory.openInput(dataFileName, readState.context);
+      // Points read whole ranges of bytes at once, so pass ReadAdvice.NORMAL to perform readahead.
+      dataIn =
+          readState.directory.openInput(
+              dataFileName, readState.context.withReadAdvice(ReadAdvice.NORMAL));
       CodecUtil.checkIndexHeader(
           dataIn,
           Lucene90PointsFormat.DATA_CODEC_NAME,
diff --git a/lucene/core/src/java/org/apache/lucene/codecs/lucene99/Lucene99PostingsReader.java b/lucene/core/src/java/org/apache/lucene/codecs/lucene99/Lucene99PostingsReader.java
index 13353c42603..846a9f307eb 100644
--- a/lucene/core/src/java/org/apache/lucene/codecs/lucene99/Lucene99PostingsReader.java
+++ b/lucene/core/src/java/org/apache/lucene/codecs/lucene99/Lucene99PostingsReader.java
@@ -41,6 +41,7 @@ import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.SlowImpactsEnum;
 import org.apache.lucene.store.DataInput;
 import org.apache.lucene.store.IndexInput;
+import org.apache.lucene.store.ReadAdvice;
 import org.apache.lucene.util.ArrayUtil;
 import org.apache.lucene.util.BitUtil;
 import org.apache.lucene.util.BytesRef;
@@ -78,7 +79,9 @@ public final class Lucene99PostingsReader extends PostingsReaderBase {
         IndexFileNames.segmentFileName(
             state.segmentInfo.name, state.segmentSuffix, Lucene99PostingsFormat.DOC_EXTENSION);
     try {
-      docIn = state.directory.openInput(docName, state.context);
+      // Postings have a forward-only access pattern, so pass ReadAdvice.NORMAL to perform
+      // readahead.
+      docIn = state.directory.openInput(docName, state.context.withReadAdvice(ReadAdvice.NORMAL));
       version =
           CodecUtil.checkIndexHeader(
               docIn,