GODRIVER-2539 Remove MinWireVersion < 6 Logic (mongodb#1084)

mongo/change_stream.go

@@ -287,7 +287,7 @@ func (cs *ChangeStream) executeOperation(ctx context.Context, resuming bool) err
 	// Execute the aggregate, retrying on retryable errors once (1) if retryable reads are enabled and
 	// infinitely (-1) if context is a Timeout context.
 	var retries int
-	if cs.client.retryReads && cs.wireVersion != nil && cs.wireVersion.Max >= 6 {
+	if cs.client.retryReads {
 		retries = 1
 	}
 	if internal.IsTimeoutContext(ctx) {
@@ -325,11 +325,8 @@ AggregateExecuteLoop:
 			}
 			defer conn.Close()
 
-			// If wire version is now < 6, do not retry.
+			// Update the wire version with data from the new connection.
 			cs.wireVersion = conn.Description().WireVersion
-			if cs.wireVersion == nil || cs.wireVersion.Max < 6 {
-				break AggregateExecuteLoop
-			}
 
 			// Reset deployment.
 			cs.aggregate.Deployment(cs.createOperationDeployment(server, conn))
@@ -435,10 +432,7 @@ func (cs *ChangeStream) createPipelineOptionsDoc() (bsoncore.Document, error) {
 	}
 
 	if cs.options.FullDocument != nil {
-		// Only append a default "fullDocument" field if wire version is less than 6 (3.6). Otherwise,
-		// the server will assume users want the default behavior, and "fullDocument" does not need to be
-		// specified.
-		if *cs.options.FullDocument != options.Default || (cs.wireVersion != nil && cs.wireVersion.Max < 6) {
+		if *cs.options.FullDocument != options.Default {
 			plDoc = bsoncore.AppendStringElement(plDoc, "fullDocument", string(*cs.options.FullDocument))
 		}
 	}

x/mongo/driver/operation.go

@@ -505,24 +505,6 @@ func (op Operation) Execute(ctx context.Context) error {
 		}
 
 		desc := description.SelectedServer{Server: conn.Description(), Kind: op.Deployment.Kind()}
-		if desc.WireVersion == nil || desc.WireVersion.Max < 4 {
-			switch op.Legacy {
-			case LegacyFind:
-				return op.legacyFind(ctx, (*wm)[:0], srvr, conn, desc, maxTimeMS)
-			case LegacyGetMore:
-				return op.legacyGetMore(ctx, (*wm)[:0], srvr, conn, desc)
-			case LegacyKillCursors:
-				return op.legacyKillCursors(ctx, (*wm)[:0], srvr, conn, desc)
-			}
-		}
-		if desc.WireVersion == nil || desc.WireVersion.Max < 3 {
-			switch op.Legacy {
-			case LegacyListCollections:
-				return op.legacyListCollections(ctx, (*wm)[:0], srvr, conn, desc)
-			case LegacyListIndexes:
-				return op.legacyListIndexes(ctx, (*wm)[:0], srvr, conn, desc, maxTimeMS)
-			}
-		}
 
 		if batching {
 			targetBatchSize := desc.MaxDocumentSize
@@ -830,7 +812,6 @@ func (op Operation) retryable(desc description.Server) bool {
 			return true
 		}
 		if retryWritesSupported(desc) &&
-			desc.WireVersion != nil && desc.WireVersion.Max >= 6 &&
 			op.Client != nil && !(op.Client.TransactionInProgress() || op.Client.TransactionStarting()) &&
 			writeconcern.AckWrite(op.WriteConcern) {
 			return true
@@ -839,8 +820,7 @@ func (op Operation) retryable(desc description.Server) bool {
 		if op.Client != nil && (op.Client.Committing || op.Client.Aborting) {
 			return true
 		}
-		if desc.WireVersion != nil && desc.WireVersion.Max >= 6 &&
-			(op.Client == nil || !(op.Client.TransactionInProgress() || op.Client.TransactionStarting())) {
+		if op.Client == nil || !(op.Client.TransactionInProgress() || op.Client.TransactionStarting()) {
 			return true
 		}
 	}