From a5d07ee51f980942a794300636c018d0da1da5b1 Mon Sep 17 00:00:00 2001
From: Ryan Ernst <ryan@iernst.net>
Date: Wed, 20 Sep 2023 06:15:04 -0700
Subject: [PATCH] Make transport and index versions easier to extend (#99688)

When overriding transport and index versions, it is difficult to decide
whether a version constant in serverless should be returned, or the
latest version constant from serverless should be used, since the latest
from serverless is not available. This commit adjust the version
extension methods to pass in the latest serverless version constants. It
also tweaks module and method visibility for a helper method needed.
---
 server/src/main/java/module-info.java                  |  6 +++++-
 .../main/java/org/elasticsearch/TransportVersion.java  |  2 +-
 .../main/java/org/elasticsearch/TransportVersions.java |  2 +-
 .../java/org/elasticsearch/index/IndexVersion.java     |  2 +-
 .../org/elasticsearch/internal/VersionExtension.java   | 10 ++++++----
 5 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/server/src/main/java/module-info.java b/server/src/main/java/module-info.java
index 472707babf155..95749784afc45 100644
--- a/server/src/main/java/module-info.java
+++ b/server/src/main/java/module-info.java
@@ -279,7 +279,11 @@
     exports org.elasticsearch.indices.recovery.plan;
     exports org.elasticsearch.indices.store;
     exports org.elasticsearch.ingest;
-    exports org.elasticsearch.internal to org.elasticsearch.serverless.version, org.elasticsearch.serverless.buildinfo;
+    exports org.elasticsearch.internal
+        to
+            org.elasticsearch.serverless.version,
+            org.elasticsearch.serverless.buildinfo,
+            org.elasticsearch.serverless.constants;
     exports org.elasticsearch.lucene.analysis.miscellaneous;
     exports org.elasticsearch.lucene.grouping;
     exports org.elasticsearch.lucene.queries;
diff --git a/server/src/main/java/org/elasticsearch/TransportVersion.java b/server/src/main/java/org/elasticsearch/TransportVersion.java
index 2aae6befb673a..92bb88f16385d 100644
--- a/server/src/main/java/org/elasticsearch/TransportVersion.java
+++ b/server/src/main/java/org/elasticsearch/TransportVersion.java
@@ -115,7 +115,7 @@ private static TransportVersion findCurrent() {
             if (versionExtension == null) {
                 return TransportVersions.LATEST_DEFINED;
             }
-            var version = versionExtension.getCurrentTransportVersion();
+            var version = versionExtension.getCurrentTransportVersion(TransportVersions.LATEST_DEFINED);
             assert version.onOrAfter(TransportVersions.LATEST_DEFINED);
             return version;
         }
diff --git a/server/src/main/java/org/elasticsearch/TransportVersions.java b/server/src/main/java/org/elasticsearch/TransportVersions.java
index d9c0bc59c06f9..5c28fa17b7b3e 100644
--- a/server/src/main/java/org/elasticsearch/TransportVersions.java
+++ b/server/src/main/java/org/elasticsearch/TransportVersions.java
@@ -217,7 +217,7 @@ static TransportVersion def(int id) {
         IDS = null;
     }
 
-    static NavigableMap<Integer, TransportVersion> getAllVersionIds(Class<?> cls) {
+    public static NavigableMap<Integer, TransportVersion> getAllVersionIds(Class<?> cls) {
         Map<Integer, String> versionIdFields = new HashMap<>();
         NavigableMap<Integer, TransportVersion> builder = new TreeMap<>();
 
diff --git a/server/src/main/java/org/elasticsearch/index/IndexVersion.java b/server/src/main/java/org/elasticsearch/index/IndexVersion.java
index 49e2172b2f4b2..1cb03574afd86 100644
--- a/server/src/main/java/org/elasticsearch/index/IndexVersion.java
+++ b/server/src/main/java/org/elasticsearch/index/IndexVersion.java
@@ -160,7 +160,7 @@ private static IndexVersion findCurrent() {
             if (versionExtension == null) {
                 return LATEST_DEFINED;
             }
-            var version = versionExtension.getCurrentIndexVersion();
+            var version = versionExtension.getCurrentIndexVersion(LATEST_DEFINED);
 
             assert version.onOrAfter(LATEST_DEFINED);
             assert version.luceneVersion.equals(Version.LATEST)
diff --git a/server/src/main/java/org/elasticsearch/internal/VersionExtension.java b/server/src/main/java/org/elasticsearch/internal/VersionExtension.java
index 83974b3b65158..9c1b515df4043 100644
--- a/server/src/main/java/org/elasticsearch/internal/VersionExtension.java
+++ b/server/src/main/java/org/elasticsearch/internal/VersionExtension.java
@@ -18,14 +18,16 @@ public interface VersionExtension {
     /**
      * Returns the {@link TransportVersion} that Elasticsearch should use.
      * <p>
-     * This must be at least equal to the latest version found in {@link TransportVersion} V_* constants.
+     * This must be at least as high as the given fallback.
+     * @param fallback The latest transport version from server
      */
-    TransportVersion getCurrentTransportVersion();
+    TransportVersion getCurrentTransportVersion(TransportVersion fallback);
 
     /**
      * Returns the {@link IndexVersion} that Elasticsearch should use.
      * <p>
-     * This must be at least equal to the latest version found in {@link IndexVersion} V_* constants.
+     * This must be at least as high as the given fallback.
+     * @param fallback The latest index version from server
      */
-    IndexVersion getCurrentIndexVersion();
+    IndexVersion getCurrentIndexVersion(IndexVersion fallback);
 }