Tidy up Store#trimUnsafeCommits (#47062)

This change removes unused parameters and simplifies the logic.

server/src/main/java/org/elasticsearch/index/engine/InternalEngine.java

@@ -88,7 +88,6 @@
 import org.elasticsearch.index.shard.ElasticsearchMergePolicy;
 import org.elasticsearch.index.shard.ShardId;
 import org.elasticsearch.index.store.FsDirectoryFactory;
-import org.elasticsearch.index.store.Store;
 import org.elasticsearch.index.translog.Translog;
 import org.elasticsearch.index.translog.TranslogConfig;
 import org.elasticsearch.index.translog.TranslogCorruptedException;
@@ -98,7 +97,6 @@
 
 import java.io.Closeable;
 import java.io.IOException;
-import java.nio.file.Path;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
@@ -203,7 +201,7 @@ public InternalEngine(EngineConfig engineConfig) {
             mergeScheduler = scheduler = new EngineMergeScheduler(engineConfig.getShardId(), engineConfig.getIndexSettings());
             throttle = new IndexThrottle();
             try {
-                trimUnsafeCommits(engineConfig);
+                store.trimUnsafeCommits(config().getTranslogConfig().getTranslogPath());
                 translog = openTranslog(engineConfig, translogDeletionPolicy, engineConfig.getGlobalCheckpointSupplier(),
                     seqNo -> {
                         final LocalCheckpointTracker tracker = getLocalCheckpointTracker();
@@ -2806,15 +2804,6 @@ private boolean assertMaxSeqNoOfUpdatesIsAdvanced(Term id, long seqNo, boolean a
         return true;
     }
 
-    private static void trimUnsafeCommits(EngineConfig engineConfig) throws IOException {
-        final Store store = engineConfig.getStore();
-        final String translogUUID = store.readLastCommittedSegmentsInfo().getUserData().get(Translog.TRANSLOG_UUID_KEY);
-        final Path translogPath = engineConfig.getTranslogConfig().getTranslogPath();
-        final long globalCheckpoint = Translog.readGlobalCheckpoint(translogPath, translogUUID);
-        final long minRetainedTranslogGen = Translog.readMinTranslogGeneration(translogPath, translogUUID);
-        store.trimUnsafeCommits(globalCheckpoint, minRetainedTranslogGen, engineConfig.getIndexSettings().getIndexVersionCreated());
-    }
-
     /**
      * Restores the live version map and local checkpoint of this engine using documents (including soft-deleted)
      * after the local checkpoint in the safe commit. This step ensures the live version map and checkpoint tracker

server/src/main/java/org/elasticsearch/index/store/Store.java

@@ -1501,31 +1501,17 @@ public void associateIndexWithNewTranslog(final String translogUUID) throws IOEx
      * commit on the replica will cause exception as the new last commit c3 will have recovery_translog_gen=1. The recovery
      * translog generation of a commit is calculated based on the current local checkpoint. The local checkpoint of c3 is 1
      * while the local checkpoint of c2 is 2.
-     * <p>
-     * 3. Commit without translog can be used in recovery. An old index, which was created before multiple-commits is introduced
-     * (v6.2), may not have a safe commit. If that index has a snapshotted commit without translog and an unsafe commit,
-     * the policy can consider the snapshotted commit as a safe commit for recovery even the commit does not have translog.
      */
-    public void trimUnsafeCommits(final long lastSyncedGlobalCheckpoint, final long minRetainedTranslogGen,
-                                  final org.elasticsearch.Version indexVersionCreated) throws IOException {
+    public void trimUnsafeCommits(final Path translogPath) throws IOException {
         metadataLock.writeLock().lock();
         try {
             final List<IndexCommit> existingCommits = DirectoryReader.listCommits(directory);
-            if (existingCommits.isEmpty()) {
-                throw new IllegalArgumentException("No index found to trim");
-            }
-            final IndexCommit lastIndexCommitCommit = existingCommits.get(existingCommits.size() - 1);
-            final String translogUUID = lastIndexCommitCommit.getUserData().get(Translog.TRANSLOG_UUID_KEY);
-            final IndexCommit startingIndexCommit;
-            // TODO: Asserts the starting commit is a safe commit once peer-recovery sets global checkpoint.
-            startingIndexCommit = CombinedDeletionPolicy.findSafeCommitPoint(existingCommits, lastSyncedGlobalCheckpoint);
-
-            if (translogUUID.equals(startingIndexCommit.getUserData().get(Translog.TRANSLOG_UUID_KEY)) == false) {
-                throw new IllegalStateException("starting commit translog uuid ["
-                    + startingIndexCommit.getUserData().get(Translog.TRANSLOG_UUID_KEY) + "] is not equal to last commit's translog uuid ["
-                    + translogUUID + "]");
-            }
-            if (startingIndexCommit.equals(lastIndexCommitCommit) == false) {
+            assert existingCommits.isEmpty() == false;
+            final IndexCommit lastIndexCommit = existingCommits.get(existingCommits.size() - 1);
+            final String translogUUID = lastIndexCommit.getUserData().get(Translog.TRANSLOG_UUID_KEY);
+            final long lastSyncedGlobalCheckpoint = Translog.readGlobalCheckpoint(translogPath, translogUUID);
+            final IndexCommit startingIndexCommit = CombinedDeletionPolicy.findSafeCommitPoint(existingCommits, lastSyncedGlobalCheckpoint);
+            if (startingIndexCommit.equals(lastIndexCommit) == false) {
                 try (IndexWriter writer = newAppendingIndexWriter(directory, startingIndexCommit)) {
                     // this achieves two things:
                     // - by committing a new commit based on the starting commit, it make sure the starting commit will be opened

server/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java

@@ -5260,7 +5260,7 @@ public void testTrimUnsafeCommits() throws Exception {
                 minTranslogGen = engine.getTranslog().getMinFileGeneration();
             }
 
-            store.trimUnsafeCommits(globalCheckpoint.get(), minTranslogGen,config.getIndexSettings().getIndexVersionCreated());
+            store.trimUnsafeCommits(config.getTranslogConfig().getTranslogPath());
             long safeMaxSeqNo =
                 commitMaxSeqNo.stream().filter(s -> s <= globalCheckpoint.get())
                     .reduce((s1, s2) -> s2) // get the last one.