SERVER-68461 Persist the result of the doCompactOperation in the Pre61Compatible compaction coordinator

3 files changed, 51 insertions, 1 deletions

diff --git a/src/mongo/db/s/compact_structured_encryption_data_coordinator.cpp b/src/mongo/db/s/compact_structured_encryption_data_coordinator.cpp
index 836dde1bf79..bbf34ba008f 100644
--- a/src/mongo/db/s/compact_structured_encryption_data_coordinator.cpp
+++ b/src/mongo/db/s/compact_structured_encryption_data_coordinator.cpp
@@ -213,6 +213,39 @@ boost::optional<BSONObj> CompactStructuredEncryptionDataCoordinator::reportForCu
     return bob.obj();
 }
 
+// TODO: SERVER-68373 remove once 7.0 becomes last LTS
+void CompactStructuredEncryptionDataCoordinator::_enterPhase(const Phase& newPhase) {
+    // Before 6.1, this coordinator persists the result of the doCompactOperation()
+    // by reusing the compactionTokens field to store the _response BSON.
+    // If newPhase is kDropTempCollection, this override of _enterPhase performs this
+    // replacement on the in-memory state document (_doc), before calling the base _enterPhase()
+    // which persists _doc to disk. In the event that updating the persisted document fails,
+    // the replaced compaction tokens are restored in _doc.
+    using Base = RecoverableShardingDDLCoordinator<CompactStructuredEncryptionDataState,
+                                                   CompactStructuredEncryptionDataPhaseEnum>;
+    bool useOverload = _isPre61Compatible() && (newPhase == Phase::kDropTempCollection);
+
+    if (useOverload) {
+        BSONObj compactionTokensCopy;
+        {
+            stdx::lock_guard lg(_docMutex);
+            compactionTokensCopy = _doc.getCompactionTokens().getOwned();
+            _doc.setCompactionTokens(_response->toBSON());
+        }
+
+        try {
+            Base::_enterPhase(newPhase);
+        } catch (...) {
+            // on error, restore the compaction tokens
+            stdx::lock_guard lg(_docMutex);
+            _doc.setCompactionTokens(std::move(compactionTokensCopy));
+            throw;
+        }
+    } else {
+        Base::_enterPhase(newPhase);
+    }
+}
+
 ExecutorFuture<void> CompactStructuredEncryptionDataCoordinator::_runImpl(
     std::shared_ptr<executor::ScopedTaskExecutor> executor,
     const CancellationToken& token) noexcept {
@@ -236,7 +269,21 @@ ExecutorFuture<void> CompactStructuredEncryptionDataCoordinator::_runImpl(
             if (!_isPre61Compatible()) {
                 invariant(_doc.getResponse());
                 _response = *_doc.getResponse();
+            } else {
+                try {
+                    // restore the response that was stored in the compactionTokens field
+                    IDLParserContext ctxt("response");
+                    _response = CompactStructuredEncryptionDataCommandReply::parse(
+                        ctxt, _doc.getCompactionTokens());
+                } catch (...) {
+                    LOGV2_ERROR(6846101,
+                                "Failed to parse response from "
+                                "CompactStructuredEncryptionDataState document",
+                                "response"_attr = _doc.getCompactionTokens());
+                    // ignore for compatibility with 6.0.0
+                }
             }
+
             doDropOperation(_doc);
             if (MONGO_unlikely(fleCompactHangAfterDropTempCollection.shouldFail())) {
                 LOGV2(6790902, "Hanging due to fleCompactHangAfterDropTempCollection fail point");
diff --git a/src/mongo/db/s/compact_structured_encryption_data_coordinator.h b/src/mongo/db/s/compact_structured_encryption_data_coordinator.h
index bb0667add70..3b8c9ad2a9e 100644
--- a/src/mongo/db/s/compact_structured_encryption_data_coordinator.h
+++ b/src/mongo/db/s/compact_structured_encryption_data_coordinator.h
@@ -79,6 +79,9 @@ private:
             DDLCoordinatorTypeEnum::kCompactStructuredEncryptionDataPre61Compatible;
     }
 
+    // TODO SERVER-68373 remove once 7.0 becomes last LTS
+    void _enterPhase(const Phase& newPhase) override;
+
 private:
     boost::optional<CompactStructuredEncryptionDataCommandReply> _response;
     bool _skipCompact{false};
diff --git a/src/mongo/db/s/sharding_ddl_coordinator.h b/src/mongo/db/s/sharding_ddl_coordinator.h
index ecbd0980a41..d8eaad0139d 100644
--- a/src/mongo/db/s/sharding_ddl_coordinator.h
+++ b/src/mongo/db/s/sharding_ddl_coordinator.h
@@ -271,7 +271,7 @@ protected:
         };
     }
 
-    void _enterPhase(const Phase& newPhase) {
+    virtual void _enterPhase(const Phase& newPhase) {
         auto newDoc = [&] {
             stdx::lock_guard lk{_docMutex};
             return _doc;