GODRIVER-3145 Don't retry on context timeout or cancellation. (#1598)

Author: matthewdale

mongo/integration/client_test.go

@@ -768,6 +768,77 @@ func TestClient(t *testing.T) {
 				"expected 'OP_MSG' OpCode in wire message, got %q", pair.Sent.OpCode.String())
 		}
 	})
+
+	opts := mtest.NewOptions().
+		// Blocking failpoints don't work on pre-4.2 and sharded clusters.
+		Topologies(mtest.Single, mtest.ReplicaSet).
+		MinServerVersion("4.2").
+		// Expliticly enable retryable reads and retryable writes.
+		ClientOptions(options.Client().SetRetryReads(true).SetRetryWrites(true))
+	mt.RunOpts("operations don't retry after a context timeout", opts, func(mt *mtest.T) {
+		testCases := []struct {
+			desc      string
+			operation func(context.Context, *mongo.Collection) error
+		}{
+			{
+				desc: "read op",
+				operation: func(ctx context.Context, coll *mongo.Collection) error {
+					return coll.FindOne(ctx, bson.D{}).Err()
+				},
+			},
+			{
+				desc: "write op",
+				operation: func(ctx context.Context, coll *mongo.Collection) error {
+					_, err := coll.InsertOne(ctx, bson.D{})
+					return err
+				},
+			},
+		}
+
+		for _, tc := range testCases {
+			mt.Run(tc.desc, func(mt *mtest.T) {
+				_, err := mt.Coll.InsertOne(context.Background(), bson.D{})
+				require.NoError(mt, err)
+
+				mt.SetFailPoint(mtest.FailPoint{
+					ConfigureFailPoint: "failCommand",
+					Mode:               "alwaysOn",
+					Data: mtest.FailPointData{
+						FailCommands:    []string{"find", "insert"},
+						BlockConnection: true,
+						BlockTimeMS:     500,
+					},
+				})
+
+				mt.ClearEvents()
+
+				for i := 0; i < 50; i++ {
+					// Run 50 operations, each with a timeout of 50ms. Expect
+					// them to all return a timeout error because the failpoint
+					// blocks find operations for 500ms. Run 50 to increase the
+					// probability that an operation will time out in a way that
+					// can cause a retry.
+					ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
+					err = tc.operation(ctx, mt.Coll)
+					cancel()
+					assert.ErrorIs(mt, err, context.DeadlineExceeded)
+					assert.True(mt, mongo.IsTimeout(err), "expected mongo.IsTimeout(err) to be true")
+
+					// Assert that each operation reported exactly one command
+					// started events, which means the operation did not retry
+					// after the context timeout.
+					evts := mt.GetAllStartedEvents()
+					require.Len(mt,
+						mt.GetAllStartedEvents(),
+						1,
+						"expected exactly 1 command started event per operation, but got %d after %d iterations",
+						len(evts),
+						i)
+					mt.ClearEvents()
+				}
+			})
+		}
+	})
 }
 
 func TestClient_BSONOptions(t *testing.T) {

x/mongo/driver/operation.go

@@ -622,6 +622,13 @@ func (op Operation) Execute(ctx context.Context) error {
 		}
 	}()
 	for {
+		// If we're starting a retry and the the error from the previous try was
+		// a context canceled or deadline exceeded error, stop retrying and
+		// return that error.
+		if errors.Is(prevErr, context.Canceled) || errors.Is(prevErr, context.DeadlineExceeded) {
+			return prevErr
+		}
+
 		requestID := wiremessage.NextRequestID()
 
 		// If the server or connection are nil, try to select a new server and get a new connection.