Fix: Use Replace for manifest.

A while back* we stopped deleting the manifest document during
refurbish. The reason was that if we delete the manifest on a refurbish,
it's pretty much inevitable that every FormatDriver would need to
disconnect and reconnect, even if it were not otherwise necessary,
because the database would temporarily be in a state where the
FormatDriver cannot determine whether its local state is correct
anymore. Even a FormatDriver refurbishing to its own format, which
should not cause a disruption at all, would cause an otherwise
unnecessary reconnection cycle.

One consequence of this change was that the UPDATE operation used to
change from, say, sequoia to pando format, would simply write to the
manifest's "pando" field, leaving the manifest document in an invalid
state where it has format configurations for both sequoia and pando.

This change fixes this by using a REPLACE instead of an UPDATE.

* Commit f40bfad

bosk-mongo/src/main/java/io/vena/bosk/drivers/mongo/PandoFormatDriver.java

@@ -2,6 +2,7 @@
 
 import com.mongodb.client.MongoCursor;
 import com.mongodb.client.model.CountOptions;
+import com.mongodb.client.model.ReplaceOptions;
 import com.mongodb.client.model.UpdateOptions;
 import com.mongodb.client.model.changestream.ChangeStreamDocument;
 import com.mongodb.client.model.changestream.OperationType;
@@ -49,6 +50,7 @@
 import static com.mongodb.client.model.Projections.fields;
 import static com.mongodb.client.model.Projections.include;
 import static com.mongodb.client.model.changestream.OperationType.INSERT;
+import static com.mongodb.client.model.changestream.OperationType.REPLACE;
 import static io.vena.bosk.Path.parseParameterized;
 import static io.vena.bosk.drivers.mongo.BsonSurgeon.docSegments;
 import static io.vena.bosk.drivers.mongo.Formatter.REVISION_ZERO;
@@ -242,11 +244,10 @@ public void initializeCollection(StateAndMetadata<R> priorContents) {
 	private void writeManifest() {
 		BsonDocument doc = new BsonDocument("_id", MANIFEST_ID);
 		doc.putAll((BsonDocument) formatter.object2bsonValue(Manifest.forPando(format), Manifest.class));
-		BsonDocument update = new BsonDocument("$set", doc);
 		BsonDocument filter = new BsonDocument("_id", MANIFEST_ID);
-		UpdateOptions options = new UpdateOptions().upsert(true);
 		LOGGER.debug("| Initial manifest: {}", doc);
-		UpdateResult result = collection.updateOne(filter, update, options);
+		ReplaceOptions options = new ReplaceOptions().upsert(true);
+		UpdateResult result = collection.replaceOne(filter, doc, options);
 		LOGGER.debug("| Manifest result: {}", result);
 	}
 
@@ -447,7 +448,8 @@ private Reference<?> documentID2MainRef(String pipedPath, ChangeStreamDocument<B
 	 * so incompatible database changes don't go unnoticed.
 	 */
 	private void onManifestEvent(ChangeStreamDocument<BsonDocument> event) throws UnprocessableEventException {
-		if (event.getOperationType() == INSERT) {
+		LOGGER.debug("onManifestEvent({})", event.getOperationType().name());
+		if (event.getOperationType() == INSERT || event.getOperationType() == REPLACE) {
 			BsonDocument manifestDoc = requireNonNull(event.getFullDocument());
 			Manifest manifest;
 			try {

bosk-mongo/src/main/java/io/vena/bosk/drivers/mongo/SequoiaFormatDriver.java

@@ -2,6 +2,7 @@
 
 import com.mongodb.client.MongoCollection;
 import com.mongodb.client.MongoCursor;
+import com.mongodb.client.model.ReplaceOptions;
 import com.mongodb.client.model.UpdateOptions;
 import com.mongodb.client.model.changestream.ChangeStreamDocument;
 import com.mongodb.client.model.changestream.OperationType;
@@ -35,6 +36,7 @@
 import static com.mongodb.client.model.Projections.fields;
 import static com.mongodb.client.model.Projections.include;
 import static com.mongodb.client.model.changestream.OperationType.INSERT;
+import static com.mongodb.client.model.changestream.OperationType.REPLACE;
 import static io.vena.bosk.drivers.mongo.Formatter.REVISION_ZERO;
 import static io.vena.bosk.drivers.mongo.Formatter.dottedFieldNameOf;
 import static io.vena.bosk.drivers.mongo.Formatter.enclosingReference;
@@ -134,7 +136,8 @@ BsonState loadBsonState() throws UninitializedCollectionException {
 			BsonDocument document = cursor.next();
 			return new BsonState(
 				document.getDocument(DocumentFields.state.name(), null),
-				document.getInt64(DocumentFields.revision.name(), null), Formatter.getDiagnosticAttributesIfAny(document)
+				document.getInt64(DocumentFields.revision.name(), null),
+				Formatter.getDiagnosticAttributesIfAny(document)
 			);
 		} catch (NoSuchElementException e) {
 			throw new UninitializedCollectionException("No existing document", e);
@@ -169,11 +172,10 @@ private void writeManifest() {
 		assert settings.experimental().manifestMode() == CREATE_IF_ABSENT;
 		BsonDocument doc = new BsonDocument("_id", MANIFEST_ID);
 		doc.putAll((BsonDocument) formatter.object2bsonValue(Manifest.forSequoia(), Manifest.class));
-		BsonDocument update = new BsonDocument("$set", doc);
 		BsonDocument filter = new BsonDocument("_id", MANIFEST_ID);
-		UpdateOptions options = new UpdateOptions().upsert(true);
 		LOGGER.debug("| Initial manifest: {}", doc);
-		UpdateResult result = collection.updateOne(filter, update, options);
+		ReplaceOptions options = new ReplaceOptions().upsert(true);
+		UpdateResult result = collection.replaceOne(filter, doc, options);
 		LOGGER.debug("| Manifest result: {}", result);
 	}
 
@@ -250,7 +252,8 @@ public void onEvent(ChangeStreamDocument<BsonDocument> event) throws Unprocessab
 	 * so incompatible database changes don't go unnoticed.
 	 */
 	private void onManifestEvent(ChangeStreamDocument<BsonDocument> event) throws UnprocessableEventException {
-		if (event.getOperationType() == INSERT) {
+		LOGGER.debug("onManifestEvent({})", event.getOperationType().name());
+		if (event.getOperationType() == INSERT || event.getOperationType() == REPLACE) {
 			BsonDocument manifest = requireNonNull(event.getFullDocument());
 			manifest.remove("_id");
 			try {