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matterbridge/vendor/github.com/graph-gophers/graphql-go/internal/exec/exec.go
2022-04-01 00:23:19 +02:00

382 lines
10 KiB
Go

package exec
import (
"bytes"
"context"
"encoding/json"
"fmt"
"reflect"
"sync"
"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/internal/query"
"github.com/graph-gophers/graphql-go/log"
"github.com/graph-gophers/graphql-go/trace"
"github.com/graph-gophers/graphql-go/types"
)
type Request struct {
selected.Request
Limiter chan struct{}
Tracer trace.Tracer
Logger log.Logger
PanicHandler errors.PanicHandler
SubscribeResolverTimeout time.Duration
}
func (r *Request) handlePanic(ctx context.Context) {
if value := recover(); value != nil {
r.Logger.LogPanic(ctx, value)
r.AddError(r.PanicHandler.MakePanicError(ctx, value))
}
}
type extensionser interface {
Extensions() map[string]interface{}
}
func (r *Request) Execute(ctx context.Context, s *resolvable.Schema, op *types.OperationDefinition) ([]byte, []*errors.QueryError) {
var out bytes.Buffer
func() {
defer r.handlePanic(ctx)
sels := selected.ApplyOperation(&r.Request, s, op)
r.execSelections(ctx, sels, nil, s, s.Resolver, &out, op.Type == query.Mutation)
}()
if err := ctx.Err(); err != nil {
return nil, []*errors.QueryError{errors.Errorf("%s", err)}
}
return out.Bytes(), r.Errs
}
type fieldToExec struct {
field *selected.SchemaField
sels []selected.Selection
resolver reflect.Value
out *bytes.Buffer
}
func resolvedToNull(b *bytes.Buffer) bool {
return bytes.Equal(b.Bytes(), []byte("null"))
}
func (r *Request) execSelections(ctx context.Context, sels []selected.Selection, path *pathSegment, s *resolvable.Schema, resolver reflect.Value, out *bytes.Buffer, serially bool) {
async := !serially && selected.HasAsyncSel(sels)
var fields []*fieldToExec
collectFieldsToResolve(sels, s, resolver, &fields, make(map[string]*fieldToExec))
if async {
var wg sync.WaitGroup
wg.Add(len(fields))
for _, f := range fields {
go func(f *fieldToExec) {
defer wg.Done()
defer r.handlePanic(ctx)
f.out = new(bytes.Buffer)
execFieldSelection(ctx, r, s, f, &pathSegment{path, f.field.Alias}, true)
}(f)
}
wg.Wait()
} else {
for _, f := range fields {
f.out = new(bytes.Buffer)
execFieldSelection(ctx, r, s, f, &pathSegment{path, f.field.Alias}, true)
}
}
out.WriteByte('{')
for i, f := range fields {
// If a non-nullable child resolved to null, an error was added to the
// "errors" list in the response, so this field resolves to null.
// If this field is non-nullable, the error is propagated to its parent.
if _, ok := f.field.Type.(*types.NonNull); ok && resolvedToNull(f.out) {
out.Reset()
out.Write([]byte("null"))
return
}
if i > 0 {
out.WriteByte(',')
}
out.WriteByte('"')
out.WriteString(f.field.Alias)
out.WriteByte('"')
out.WriteByte(':')
out.Write(f.out.Bytes())
}
out.WriteByte('}')
}
func collectFieldsToResolve(sels []selected.Selection, s *resolvable.Schema, resolver reflect.Value, fields *[]*fieldToExec, fieldByAlias map[string]*fieldToExec) {
for _, sel := range sels {
switch sel := sel.(type) {
case *selected.SchemaField:
field, ok := fieldByAlias[sel.Alias]
if !ok { // validation already checked for conflict (TODO)
field = &fieldToExec{field: sel, resolver: resolver}
fieldByAlias[sel.Alias] = field
*fields = append(*fields, field)
}
field.sels = append(field.sels, sel.Sels...)
case *selected.TypenameField:
_, ok := fieldByAlias[sel.Alias]
if !ok {
res := reflect.ValueOf(typeOf(sel, resolver))
f := s.FieldTypename
f.TypeName = res.String()
sf := &selected.SchemaField{
Field: f,
Alias: sel.Alias,
FixedResult: res,
}
field := &fieldToExec{field: sf, resolver: resolver}
*fields = append(*fields, field)
fieldByAlias[sel.Alias] = field
}
case *selected.TypeAssertion:
out := resolver.Method(sel.MethodIndex).Call(nil)
if !out[1].Bool() {
continue
}
collectFieldsToResolve(sel.Sels, s, out[0], fields, fieldByAlias)
default:
panic("unreachable")
}
}
}
func typeOf(tf *selected.TypenameField, resolver reflect.Value) string {
if len(tf.TypeAssertions) == 0 {
return tf.Name
}
for name, a := range tf.TypeAssertions {
out := resolver.Method(a.MethodIndex).Call(nil)
if out[1].Bool() {
return name
}
}
return ""
}
func execFieldSelection(ctx context.Context, r *Request, s *resolvable.Schema, f *fieldToExec, path *pathSegment, applyLimiter bool) {
if applyLimiter {
r.Limiter <- struct{}{}
}
var result reflect.Value
var err *errors.QueryError
traceCtx, finish := r.Tracer.TraceField(ctx, f.field.TraceLabel, f.field.TypeName, f.field.Name, !f.field.Async, f.field.Args)
defer func() {
finish(err)
}()
err = func() (err *errors.QueryError) {
defer func() {
if panicValue := recover(); panicValue != nil {
r.Logger.LogPanic(ctx, panicValue)
err = r.PanicHandler.MakePanicError(ctx, panicValue)
err.Path = path.toSlice()
}
}()
if f.field.FixedResult.IsValid() {
result = f.field.FixedResult
return nil
}
if err := traceCtx.Err(); err != nil {
return errors.Errorf("%s", err) // don't execute any more resolvers if context got cancelled
}
res := f.resolver
if f.field.UseMethodResolver() {
var in []reflect.Value
if f.field.HasContext {
in = append(in, reflect.ValueOf(traceCtx))
}
if f.field.ArgsPacker != nil {
in = append(in, f.field.PackedArgs)
}
callOut := res.Method(f.field.MethodIndex).Call(in)
result = callOut[0]
if f.field.HasError && !callOut[1].IsNil() {
resolverErr := callOut[1].Interface().(error)
err := errors.Errorf("%s", resolverErr)
err.Path = path.toSlice()
err.ResolverError = resolverErr
if ex, ok := callOut[1].Interface().(extensionser); ok {
err.Extensions = ex.Extensions()
}
return err
}
} else {
// TODO extract out unwrapping ptr logic to a common place
if res.Kind() == reflect.Ptr {
res = res.Elem()
}
result = res.FieldByIndex(f.field.FieldIndex)
}
return nil
}()
if applyLimiter {
<-r.Limiter
}
if err != nil {
// If an error occurred while resolving a field, it should be treated as though the field
// returned null, and an error must be added to the "errors" list in the response.
r.AddError(err)
f.out.WriteString("null")
return
}
r.execSelectionSet(traceCtx, f.sels, f.field.Type, path, s, result, f.out)
}
func (r *Request) execSelectionSet(ctx context.Context, sels []selected.Selection, typ types.Type, path *pathSegment, s *resolvable.Schema, resolver reflect.Value, out *bytes.Buffer) {
t, nonNull := unwrapNonNull(typ)
// a reflect.Value of a nil interface will show up as an Invalid value
if resolver.Kind() == reflect.Invalid || ((resolver.Kind() == reflect.Ptr || resolver.Kind() == reflect.Interface) && resolver.IsNil()) {
// If a field of a non-null type resolves to null (either because the
// function to resolve the field returned null or because an error occurred),
// add an error to the "errors" list in the response.
if nonNull {
err := errors.Errorf("graphql: got nil for non-null %q", t)
err.Path = path.toSlice()
r.AddError(err)
}
out.WriteString("null")
return
}
switch t.(type) {
case *types.ObjectTypeDefinition, *types.InterfaceTypeDefinition, *types.Union:
r.execSelections(ctx, sels, path, s, resolver, out, false)
return
}
// Any pointers or interfaces at this point should be non-nil, so we can get the actual value of them
// for serialization
if resolver.Kind() == reflect.Ptr || resolver.Kind() == reflect.Interface {
resolver = resolver.Elem()
}
switch t := t.(type) {
case *types.List:
r.execList(ctx, sels, t, path, s, resolver, out)
case *types.ScalarTypeDefinition:
v := resolver.Interface()
data, err := json.Marshal(v)
if err != nil {
panic(errors.Errorf("could not marshal %v: %s", v, err))
}
out.Write(data)
case *types.EnumTypeDefinition:
var stringer fmt.Stringer = resolver
if s, ok := resolver.Interface().(fmt.Stringer); ok {
stringer = s
}
name := stringer.String()
var valid bool
for _, v := range t.EnumValuesDefinition {
if v.EnumValue == name {
valid = true
break
}
}
if !valid {
err := errors.Errorf("Invalid value %s.\nExpected type %s, found %s.", name, t.Name, name)
err.Path = path.toSlice()
r.AddError(err)
out.WriteString("null")
return
}
out.WriteByte('"')
out.WriteString(name)
out.WriteByte('"')
default:
panic("unreachable")
}
}
func (r *Request) execList(ctx context.Context, sels []selected.Selection, typ *types.List, path *pathSegment, s *resolvable.Schema, resolver reflect.Value, out *bytes.Buffer) {
l := resolver.Len()
entryouts := make([]bytes.Buffer, l)
if selected.HasAsyncSel(sels) {
// Limit the number of concurrent goroutines spawned as it can lead to large
// memory spikes for large lists.
concurrency := cap(r.Limiter)
sem := make(chan struct{}, concurrency)
for i := 0; i < l; i++ {
sem <- struct{}{}
go func(i int) {
defer func() { <-sem }()
defer r.handlePanic(ctx)
r.execSelectionSet(ctx, sels, typ.OfType, &pathSegment{path, i}, s, resolver.Index(i), &entryouts[i])
}(i)
}
for i := 0; i < concurrency; i++ {
sem <- struct{}{}
}
} else {
for i := 0; i < l; i++ {
r.execSelectionSet(ctx, sels, typ.OfType, &pathSegment{path, i}, s, resolver.Index(i), &entryouts[i])
}
}
_, listOfNonNull := typ.OfType.(*types.NonNull)
out.WriteByte('[')
for i, entryout := range entryouts {
// If the list wraps a non-null type and one of the list elements
// resolves to null, then the entire list resolves to null.
if listOfNonNull && resolvedToNull(&entryout) {
out.Reset()
out.WriteString("null")
return
}
if i > 0 {
out.WriteByte(',')
}
out.Write(entryout.Bytes())
}
out.WriteByte(']')
}
func unwrapNonNull(t types.Type) (types.Type, bool) {
if nn, ok := t.(*types.NonNull); ok {
return nn.OfType, true
}
return t, false
}
type pathSegment struct {
parent *pathSegment
value interface{}
}
func (p *pathSegment) toSlice() []interface{} {
if p == nil {
return nil
}
return append(p.parent.toSlice(), p.value)
}