GODRIVER-3217 Always use the manually-specified maxTimeMS on Find and…

… Aggregate.

mongo/integration/csot_test.go

@@ -455,6 +455,46 @@ func TestCSOT(t *testing.T) {
 			bsoncore.ErrElementNotFound,
 			"expected maxTimeMS BSON value to be missing, but is present")
 	})
+
+	// TODO(GODRIVER-2944): Remove this test once the "timeoutMode" option is
+	// supported.
+	mt.RunOpts("Find always sends manually-specified maxTimeMS", csotOpts, func(mt *mtest.T) {
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+
+		// Manually set a maxTimeMS on the Find and assert that it's sent with
+		// the command, even when CSOT is enabled.
+		cursor, err := mt.Coll.Find(
+			ctx,
+			bson.D{},
+			options.Find().SetMaxTime(5*time.Second))
+		require.NoError(mt, err, "Find error")
+		err = cursor.Close(context.Background())
+		require.NoError(mt, err, "Cursor.Close error")
+
+		evt := getStartedEvent(mt, "find")
+		assertMaxTimeMSIsSet(mt, evt.Command)
+	})
+
+	// TODO(GODRIVER-2944): Remove this test once the "timeoutMode" option is
+	// supported.
+	mt.RunOpts("Aggregate always sends manually-specified maxTimeMS", csotOpts, func(mt *mtest.T) {
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+
+		// Manually set a maxTimeMS on the Aggregate and assert that it's sent with
+		// the command, even when CSOT is enabled.
+		cursor, err := mt.Coll.Aggregate(
+			ctx,
+			bson.D{},
+			options.Aggregate().SetMaxTime(5*time.Second))
+		require.NoError(mt, err, "Aggregate error")
+		err = cursor.Close(context.Background())
+		require.NoError(mt, err, "Cursor.Close error")
+
+		evt := getStartedEvent(mt, "aggregate")
+		assertMaxTimeMSIsSet(mt, evt.Command)
+	})
 }
 
 func TestCSOT_errors(t *testing.T) {

x/mongo/driver/operation.go

@@ -1574,11 +1574,17 @@ func (op Operation) addClusterTime(dst []byte, desc description.SelectedServer)
 // operation's MaxTimeMS if set. If no MaxTimeMS is set on the operation, and context is
 // not a Timeout context, calculateMaxTimeMS returns 0.
 func (op Operation) calculateMaxTimeMS(ctx context.Context, mon RTTMonitor) (uint64, error) {
-	if csot.IsTimeoutContext(ctx) {
-		if op.OmitCSOTMaxTimeMS {
-			return 0, nil
-		}
-
+	// If CSOT is enabled and we're not omitting the CSOT-calculated maxTimeMS
+	// value, then calculate maxTimeMS.
+	//
+	// This allows commands that do not currently send CSOT-calculated maxTimeMS
+	// (e.g. Find and Aggregate) to still use a manually-provided maxTimeMS
+	// value.
+	//
+	// TODO(GODRIVER-2944): Remove or refactor this logic when we add the
+	// "timeoutMode" option, which will allow users to opt-in to the
+	// CSOT-calculated maxTimeMS values if that's the behavior they want.
+	if csot.IsTimeoutContext(ctx) && !op.OmitCSOTMaxTimeMS {
 		if deadline, ok := ctx.Deadline(); ok {
 			remainingTimeout := time.Until(deadline)
 			rtt90 := mon.P90()