Update dependencies (#1784)

vendor/github.com/graph-gophers/graphql-go/internal/exec/subscribe.go

@@ -0,0 +1,179 @@
+package exec
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"time"
+
+	"github.com/graph-gophers/graphql-go/errors"
+	"github.com/graph-gophers/graphql-go/internal/exec/resolvable"
+	"github.com/graph-gophers/graphql-go/internal/exec/selected"
+	"github.com/graph-gophers/graphql-go/types"
+)
+
+type Response struct {
+	Data   json.RawMessage
+	Errors []*errors.QueryError
+}
+
+func (r *Request) Subscribe(ctx context.Context, s *resolvable.Schema, op *types.OperationDefinition) <-chan *Response {
+	var result reflect.Value
+	var f *fieldToExec
+	var err *errors.QueryError
+	func() {
+		defer r.handlePanic(ctx)
+
+		sels := selected.ApplyOperation(&r.Request, s, op)
+		var fields []*fieldToExec
+		collectFieldsToResolve(sels, s, s.Resolver, &fields, make(map[string]*fieldToExec))
+
+		// TODO: move this check into validation.Validate
+		if len(fields) != 1 {
+			err = errors.Errorf("%s", "can subscribe to at most one subscription at a time")
+			return
+		}
+		f = fields[0]
+
+		var in []reflect.Value
+		if f.field.HasContext {
+			in = append(in, reflect.ValueOf(ctx))
+		}
+		if f.field.ArgsPacker != nil {
+			in = append(in, f.field.PackedArgs)
+		}
+		callOut := f.resolver.Method(f.field.MethodIndex).Call(in)
+		result = callOut[0]
+
+		if f.field.HasError && !callOut[1].IsNil() {
+			switch resolverErr := callOut[1].Interface().(type) {
+			case *errors.QueryError:
+				err = resolverErr
+			case error:
+				err = errors.Errorf("%s", resolverErr)
+				err.ResolverError = resolverErr
+			default:
+				panic(fmt.Errorf("can only deal with *QueryError and error types, got %T", resolverErr))
+			}
+		}
+	}()
+
+	// Handles the case where the locally executed func above panicked
+	if len(r.Request.Errs) > 0 {
+		return sendAndReturnClosed(&Response{Errors: r.Request.Errs})
+	}
+
+	if f == nil {
+		return sendAndReturnClosed(&Response{Errors: []*errors.QueryError{err}})
+	}
+
+	if err != nil {
+		if _, nonNullChild := f.field.Type.(*types.NonNull); nonNullChild {
+			return sendAndReturnClosed(&Response{Errors: []*errors.QueryError{err}})
+		}
+		return sendAndReturnClosed(&Response{Data: []byte(fmt.Sprintf(`{"%s":null}`, f.field.Alias)), Errors: []*errors.QueryError{err}})
+	}
+
+	if ctxErr := ctx.Err(); ctxErr != nil {
+		return sendAndReturnClosed(&Response{Errors: []*errors.QueryError{errors.Errorf("%s", ctxErr)}})
+	}
+
+	c := make(chan *Response)
+	// TODO: handle resolver nil channel better?
+	if result.IsZero() {
+		close(c)
+		return c
+	}
+
+	go func() {
+		for {
+			// Check subscription context
+			chosen, resp, ok := reflect.Select([]reflect.SelectCase{
+				{
+					Dir:  reflect.SelectRecv,
+					Chan: reflect.ValueOf(ctx.Done()),
+				},
+				{
+					Dir:  reflect.SelectRecv,
+					Chan: result,
+				},
+			})
+			switch chosen {
+			// subscription context done
+			case 0:
+				close(c)
+				return
+			// upstream received
+			case 1:
+				// upstream closed
+				if !ok {
+					close(c)
+					return
+				}
+
+				subR := &Request{
+					Request: selected.Request{
+						Doc:    r.Request.Doc,
+						Vars:   r.Request.Vars,
+						Schema: r.Request.Schema,
+					},
+					Limiter: r.Limiter,
+					Tracer:  r.Tracer,
+					Logger:  r.Logger,
+				}
+				var out bytes.Buffer
+				func() {
+					timeout := r.SubscribeResolverTimeout
+					if timeout == 0 {
+						timeout = time.Second
+					}
+
+					subCtx, cancel := context.WithTimeout(ctx, timeout)
+					defer cancel()
+
+					// resolve response
+					func() {
+						defer subR.handlePanic(subCtx)
+
+						var buf bytes.Buffer
+						subR.execSelectionSet(subCtx, f.sels, f.field.Type, &pathSegment{nil, f.field.Alias}, s, resp, &buf)
+
+						propagateChildError := false
+						if _, nonNullChild := f.field.Type.(*types.NonNull); nonNullChild && resolvedToNull(&buf) {
+							propagateChildError = true
+						}
+
+						if !propagateChildError {
+							out.WriteString(fmt.Sprintf(`{"%s":`, f.field.Alias))
+							out.Write(buf.Bytes())
+							out.WriteString(`}`)
+						}
+					}()
+
+					if err := subCtx.Err(); err != nil {
+						c <- &Response{Errors: []*errors.QueryError{errors.Errorf("%s", err)}}
+						return
+					}
+
+					// Send response within timeout
+					// TODO: maybe block until sent?
+					select {
+					case <-subCtx.Done():
+					case c <- &Response{Data: out.Bytes(), Errors: subR.Errs}:
+					}
+				}()
+			}
+		}
+	}()
+
+	return c
+}
+
+func sendAndReturnClosed(resp *Response) chan *Response {
+	c := make(chan *Response, 1)
+	c <- resp
+	close(c)
+	return c
+}