Trim translog when safe commit advanced (#32967)

Since #28140 when the global checkpoint is advanced, we try to move the
safe commit forward, and clean up old index commits if possible. However,
we forget to trim unreferenced translog.

This change makes sure that we prune both old translog and index commits
when the safe commit advanced.

Relates #28140
Closes #32089

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

@@ -458,6 +458,7 @@ public void syncTranslog() throws IOException {
     private void revisitIndexDeletionPolicyOnTranslogSynced() throws IOException {
         if (combinedDeletionPolicy.hasUnreferencedCommits()) {
             indexWriter.deleteUnusedFiles();
+            translog.trimUnreferencedReaders();
         }
     }
 
@@ -1746,6 +1747,8 @@ private void releaseIndexCommit(IndexCommit snapshot) throws IOException {
         // Revisit the deletion policy if we can clean up the snapshotting commit.
         if (combinedDeletionPolicy.releaseCommit(snapshot)) {
             ensureOpen();
+            // Here we don't have to trim translog because snapshotting an index commit
+            // does not lock translog or prevents unreferenced files from trimming.
             indexWriter.deleteUnusedFiles();
         }
     }

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

@@ -4310,13 +4310,18 @@ public void testAcquireIndexCommit() throws Exception {
 
     public void testCleanUpCommitsWhenGlobalCheckpointAdvanced() throws Exception {
         IOUtils.close(engine, store);
-        store = createStore();
+        final IndexSettings indexSettings = IndexSettingsModule.newIndexSettings("test",
+            Settings.builder().put(defaultSettings.getSettings())
+                .put(IndexSettings.INDEX_TRANSLOG_RETENTION_SIZE_SETTING.getKey(), -1)
+                .put(IndexSettings.INDEX_TRANSLOG_RETENTION_AGE_SETTING.getKey(), -1).build());
         final AtomicLong globalCheckpoint = new AtomicLong(SequenceNumbers.NO_OPS_PERFORMED);
-        try (InternalEngine engine = createEngine(store, createTempDir(), globalCheckpoint::get)) {
+        try (Store store = createStore();
+             InternalEngine engine =
+                 createEngine(config(indexSettings, store, createTempDir(), newMergePolicy(), null, null, globalCheckpoint::get))) {
             final int numDocs = scaledRandomIntBetween(10, 100);
             for (int docId = 0; docId < numDocs; docId++) {
                 index(engine, docId);
-                if (frequently()) {
+                if (rarely()) {
                     engine.flush(randomBoolean(), randomBoolean());
                 }
             }
@@ -4330,6 +4335,7 @@ public void testCleanUpCommitsWhenGlobalCheckpointAdvanced() throws Exception {
             globalCheckpoint.set(randomLongBetween(engine.getLocalCheckpointTracker().getCheckpoint(), Long.MAX_VALUE));
             engine.syncTranslog();
             assertThat(DirectoryReader.listCommits(store.directory()), contains(commits.get(commits.size() - 1)));
+            assertThat(engine.estimateTranslogOperationsFromMinSeq(0L), equalTo(0));
         }
     }
 

server/src/test/java/org/elasticsearch/indices/recovery/RecoveryTests.java

@@ -43,7 +43,6 @@
 import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.index.translog.SnapshotMatchers;
 import org.elasticsearch.index.translog.Translog;
-import org.elasticsearch.test.junit.annotations.TestLogging;
 
 import java.util.HashMap;
 import java.util.List;
@@ -74,7 +73,6 @@ public void testTranslogHistoryTransferred() throws Exception {
         }
     }
 
-    @TestLogging("_root:TRACE")
     public void testRetentionPolicyChangeDuringRecovery() throws Exception {
         try (ReplicationGroup shards = createGroup(0)) {
             shards.startPrimary();