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exec.go
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exec.go
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package exec
import (
"context"
"fmt"
"log"
"reflect"
"runtime"
"strings"
"sync"
"github.com/opentracing/opentracing-go"
"github.com/opentracing/opentracing-go/ext"
"github.com/neelance/graphql-go/errors"
"github.com/neelance/graphql-go/internal/common"
"github.com/neelance/graphql-go/internal/query"
"github.com/neelance/graphql-go/internal/schema"
)
type Exec struct {
queryExec iExec
mutationExec iExec
schema *schema.Schema
resolver reflect.Value
}
func Make(s *schema.Schema, resolver interface{}) (*Exec, error) {
e := &Exec{
schema: s,
resolver: reflect.ValueOf(resolver),
}
if t, ok := s.EntryPoints["query"]; ok {
var err error
e.queryExec, err = makeWithType(s, t, resolver)
if err != nil {
return nil, err
}
}
if t, ok := s.EntryPoints["mutation"]; ok {
var err error
e.mutationExec, err = makeWithType(s, t, resolver)
if err != nil {
return nil, err
}
}
return e, nil
}
type typeRefMapKey struct {
s common.Type
r reflect.Type
}
type typeRef struct {
targets []*iExec
exec iExec
}
func makeWithType(s *schema.Schema, t common.Type, resolver interface{}) (iExec, error) {
m := make(map[typeRefMapKey]*typeRef)
var e iExec
if err := makeExec(&e, s, t, reflect.TypeOf(resolver), m); err != nil {
return nil, err
}
for _, ref := range m {
for _, target := range ref.targets {
*target = ref.exec
}
}
return e, nil
}
func makeExec(target *iExec, s *schema.Schema, t common.Type, resolverType reflect.Type, typeRefMap map[typeRefMapKey]*typeRef) error {
k := typeRefMapKey{t, resolverType}
ref, ok := typeRefMap[k]
if !ok {
ref = &typeRef{}
typeRefMap[k] = ref
var err error
ref.exec, err = makeExec2(s, t, resolverType, typeRefMap)
if err != nil {
return err
}
}
ref.targets = append(ref.targets, target)
return nil
}
func makeExec2(s *schema.Schema, t common.Type, resolverType reflect.Type, typeRefMap map[typeRefMapKey]*typeRef) (iExec, error) {
var nonNull bool
t, nonNull = unwrapNonNull(t)
if !nonNull {
if resolverType.Kind() != reflect.Ptr && resolverType.Kind() != reflect.Interface {
return nil, fmt.Errorf("%s is not a pointer or interface", resolverType)
}
}
switch t := t.(type) {
case *scalar:
if !nonNull {
resolverType = resolverType.Elem()
}
scalarType := t.reflectType
if resolverType != scalarType {
return nil, fmt.Errorf("expected %s, got %s", scalarType, resolverType)
}
return &scalarExec{}, nil
case *schema.Object:
fields, err := makeFieldExecs(s, t.Name, t.Fields, resolverType, typeRefMap)
if err != nil {
return nil, err
}
return &objectExec{
name: t.Name,
fields: fields,
isConcrete: true,
nonNull: nonNull,
}, nil
case *schema.Interface:
fields, err := makeFieldExecs(s, t.Name, t.Fields, resolverType, typeRefMap)
if err != nil {
return nil, err
}
typeAssertions, err := makeTypeAssertions(s, t.Name, t.PossibleTypes, resolverType, typeRefMap)
if err != nil {
return nil, err
}
return &objectExec{
name: t.Name,
fields: fields,
typeAssertions: typeAssertions,
nonNull: nonNull,
}, nil
case *schema.Union:
typeAssertions, err := makeTypeAssertions(s, t.Name, t.PossibleTypes, resolverType, typeRefMap)
if err != nil {
return nil, err
}
return &objectExec{
name: t.Name,
typeAssertions: typeAssertions,
nonNull: nonNull,
}, nil
case *schema.Enum:
return &scalarExec{}, nil
case *common.List:
if !nonNull {
resolverType = resolverType.Elem()
}
if resolverType.Kind() != reflect.Slice {
return nil, fmt.Errorf("%s is not a slice", resolverType)
}
e := &listExec{nonNull: nonNull}
if err := makeExec(&e.elem, s, t.OfType, resolverType.Elem(), typeRefMap); err != nil {
return nil, err
}
return e, nil
default:
panic("invalid type")
}
}
var contextType = reflect.TypeOf((*context.Context)(nil)).Elem()
var errorType = reflect.TypeOf((*error)(nil)).Elem()
func makeFieldExecs(s *schema.Schema, typeName string, fields map[string]*schema.Field, resolverType reflect.Type, typeRefMap map[typeRefMapKey]*typeRef) (map[string]*fieldExec, error) {
methodHasReceiver := resolverType.Kind() != reflect.Interface
fieldExecs := make(map[string]*fieldExec)
for name, f := range fields {
methodIndex := findMethod(resolverType, name)
if methodIndex == -1 {
return nil, fmt.Errorf("%s does not resolve %q: missing method for field %q", resolverType, typeName, name)
}
m := resolverType.Method(methodIndex)
fe, err := makeFieldExec(s, f, m, methodIndex, methodHasReceiver, typeRefMap)
if err != nil {
return nil, fmt.Errorf("method %q of %s: %s", m.Name, resolverType, err)
}
fieldExecs[name] = fe
}
return fieldExecs, nil
}
func makeFieldExec(s *schema.Schema, f *schema.Field, m reflect.Method, methodIndex int, methodHasReceiver bool, typeRefMap map[typeRefMapKey]*typeRef) (*fieldExec, error) {
in := make([]reflect.Type, m.Type.NumIn())
for i := range in {
in[i] = m.Type.In(i)
}
if methodHasReceiver {
in = in[1:] // first parameter is receiver
}
hasContext := len(in) > 0 && in[0] == contextType
if hasContext {
in = in[1:]
}
var argsPacker *structPacker
if len(f.Args.Fields) > 0 {
if len(in) == 0 {
return nil, fmt.Errorf("must have parameter for field arguments")
}
var err error
argsPacker, err = makeStructPacker(s, &f.Args, in[0])
if err != nil {
return nil, err
}
in = in[1:]
}
if len(in) > 0 {
return nil, fmt.Errorf("too many parameters")
}
if m.Type.NumOut() > 2 {
return nil, fmt.Errorf("too many return values")
}
hasError := m.Type.NumOut() == 2
if hasError {
if m.Type.Out(1) != errorType {
return nil, fmt.Errorf(`must have "error" as its second return value`)
}
}
fe := &fieldExec{
field: f,
methodIndex: methodIndex,
hasContext: hasContext,
argsPacker: argsPacker,
hasError: hasError,
}
if err := makeExec(&fe.valueExec, s, f.Type, m.Type.Out(0), typeRefMap); err != nil {
return nil, err
}
return fe, nil
}
func makeStructPacker(s *schema.Schema, obj *common.InputMap, typ reflect.Type) (*structPacker, error) {
if typ.Kind() != reflect.Ptr || typ.Elem().Kind() != reflect.Struct {
return nil, fmt.Errorf("expected pointer to struct, got %s", typ)
}
structType := typ.Elem()
var fields []*structPackerField
defaultStruct := reflect.New(structType).Elem()
for _, f := range obj.Fields {
fe := &structPackerField{
name: f.Name,
}
sf, ok := structType.FieldByNameFunc(func(n string) bool { return strings.EqualFold(n, f.Name) })
if !ok {
return nil, fmt.Errorf("missing argument %q", f.Name)
}
fe.fieldIndex = sf.Index
ft, nonNull := unwrapNonNull(f.Type)
if f.Default != nil {
nonNull = true
}
expectType := func(got, want reflect.Type) error {
if got != want {
return fmt.Errorf("%q has wrong type, expected %s", sf.Name, want)
}
return nil
}
switch ft := ft.(type) {
case *scalar:
want := ft.reflectType
if !nonNull {
want = reflect.PtrTo(want)
}
if err := expectType(sf.Type, want); err != nil {
return nil, err
}
fe.fieldPacker = &valuePacker{
nonNull: nonNull,
}
case *schema.Enum:
want := reflect.TypeOf("string")
if !nonNull {
want = reflect.PtrTo(want)
}
if err := expectType(sf.Type, want); err != nil {
return nil, err
}
fe.fieldPacker = &valuePacker{
nonNull: nonNull,
}
case *schema.InputObject:
e, err := makeStructPacker(s, &ft.InputMap, sf.Type)
if err != nil {
return nil, err
}
fe.fieldPacker = e
default:
panic("TODO")
}
if f.Default != nil {
defaultValue, err := coerceValue(nil, f.Type, f.Default)
if err != nil {
return nil, err
}
defaultStruct.FieldByIndex(fe.fieldIndex).Set(fe.fieldPacker.pack(defaultValue))
}
fields = append(fields, fe)
}
return &structPacker{
structType: structType,
defaultStruct: defaultStruct,
fields: fields,
}, nil
}
func makeTypeAssertions(s *schema.Schema, typeName string, impls []*schema.Object, resolverType reflect.Type, typeRefMap map[typeRefMapKey]*typeRef) (map[string]*typeAssertExec, error) {
typeAssertions := make(map[string]*typeAssertExec)
for _, impl := range impls {
methodIndex := findMethod(resolverType, "to"+impl.Name)
if methodIndex == -1 {
return nil, fmt.Errorf("%s does not resolve %q: missing method %q to convert to %q", resolverType, typeName, "to"+impl.Name, impl.Name)
}
a := &typeAssertExec{
methodIndex: methodIndex,
}
if err := makeExec(&a.typeExec, s, impl, resolverType.Method(methodIndex).Type.Out(0), typeRefMap); err != nil {
return nil, err
}
typeAssertions[impl.Name] = a
}
return typeAssertions, nil
}
func findMethod(t reflect.Type, name string) int {
for i := 0; i < t.NumMethod(); i++ {
if strings.EqualFold(name, t.Method(i).Name) {
return i
}
}
return -1
}
type request struct {
doc *query.Document
vars map[string]interface{}
schema *schema.Schema
mu sync.Mutex
errs []*errors.QueryError
}
func (r *request) addError(err *errors.QueryError) {
r.mu.Lock()
r.errs = append(r.errs, err)
r.mu.Unlock()
}
func (r *request) handlePanic() {
if err := recover(); err != nil {
execErr := errors.Errorf("graphql: panic occured: %v", err)
r.addError(execErr)
const size = 64 << 10
buf := make([]byte, size)
buf = buf[:runtime.Stack(buf, false)]
log.Printf("%s\n%s", execErr, buf)
}
}
func ExecuteRequest(ctx context.Context, e *Exec, document *query.Document, operationName string, variables map[string]interface{}) (interface{}, []*errors.QueryError) {
op, err := getOperation(document, operationName)
if err != nil {
return nil, []*errors.QueryError{errors.Errorf("%s", err)}
}
coercedVariables, err := coerceMap(nil, &op.Vars, variables)
if err != nil {
return nil, []*errors.QueryError{errors.Errorf("%s", err)}
}
r := &request{
doc: document,
vars: coercedVariables,
schema: e.schema,
}
var opExec iExec
var serially bool
switch op.Type {
case query.Query:
opExec = e.queryExec
serially = false
case query.Mutation:
opExec = e.mutationExec
serially = true
}
data := func() interface{} {
defer r.handlePanic()
return opExec.exec(ctx, r, op.SelSet, e.resolver, serially)
}()
return data, r.errs
}
func getOperation(document *query.Document, operationName string) (*query.Operation, error) {
if len(document.Operations) == 0 {
return nil, fmt.Errorf("no operations in query document")
}
if operationName == "" {
if len(document.Operations) > 1 {
return nil, fmt.Errorf("more than one operation in query document and no operation name given")
}
for _, op := range document.Operations {
return op, nil // return the one and only operation
}
}
op, ok := document.Operations[operationName]
if !ok {
return nil, fmt.Errorf("no operation with name %q", operationName)
}
return op, nil
}
type iExec interface {
exec(ctx context.Context, r *request, selSet *query.SelectionSet, resolver reflect.Value, serially bool) interface{}
}
type scalarExec struct{}
func (e *scalarExec) exec(ctx context.Context, r *request, selSet *query.SelectionSet, resolver reflect.Value, serially bool) interface{} {
return resolver.Interface()
}
type listExec struct {
elem iExec
nonNull bool
}
func (e *listExec) exec(ctx context.Context, r *request, selSet *query.SelectionSet, resolver reflect.Value, serially bool) interface{} {
if !e.nonNull {
if resolver.IsNil() {
return nil
}
resolver = resolver.Elem()
}
l := make([]interface{}, resolver.Len())
var wg sync.WaitGroup
for i := range l {
wg.Add(1)
go func(i int) {
defer wg.Done()
defer r.handlePanic()
l[i] = e.elem.exec(ctx, r, selSet, resolver.Index(i), false)
}(i)
}
wg.Wait()
return l
}
type objectExec struct {
name string
fields map[string]*fieldExec
isConcrete bool
typeAssertions map[string]*typeAssertExec
nonNull bool
}
type addResultFn func(key string, value interface{})
func (e *objectExec) exec(ctx context.Context, r *request, selSet *query.SelectionSet, resolver reflect.Value, serially bool) interface{} {
if resolver.IsNil() {
if e.nonNull {
r.addError(errors.Errorf("got nil for non-null %q", e.name))
}
return nil
}
var mu sync.Mutex
results := make(map[string]interface{})
addResult := func(key string, value interface{}) {
mu.Lock()
results[key] = value
mu.Unlock()
}
e.execSelectionSet(ctx, r, selSet, resolver, addResult, serially)
return results
}
func (e *objectExec) execSelectionSet(ctx context.Context, r *request, selSet *query.SelectionSet, resolver reflect.Value, addResult addResultFn, serially bool) {
var wg sync.WaitGroup
for _, sel := range selSet.Selections {
execSel := func(f func()) {
if serially {
defer r.handlePanic()
f()
return
}
wg.Add(1)
go func() {
defer wg.Done()
defer r.handlePanic()
f()
}()
}
switch sel := sel.(type) {
case *query.Field:
if !skipByDirective(r, sel.Directives) {
f := sel
execSel(func() {
switch f.Name {
case "__typename":
if e.isConcrete {
addResult(f.Alias, e.name)
return
}
for name, a := range e.typeAssertions {
out := resolver.Method(a.methodIndex).Call(nil)
if out[1].Bool() {
addResult(f.Alias, name)
return
}
}
case "__schema":
addResult(f.Alias, introspectSchema(ctx, r, f.SelSet))
case "__type":
v, err := coerceValue(r, stringScalar, f.Arguments["name"])
if err != nil {
r.addError(errors.Errorf("%s", err))
addResult(f.Alias, nil)
return
}
addResult(f.Alias, introspectType(ctx, r, v.(string), f.SelSet))
default:
fe, ok := e.fields[f.Name]
if !ok {
panic(fmt.Errorf("%q has no field %q", e.name, f.Name)) // TODO proper error handling
}
fe.execField(ctx, r, f, resolver, addResult)
}
})
}
case *query.FragmentSpread:
if !skipByDirective(r, sel.Directives) {
fs := sel
execSel(func() {
frag, ok := r.doc.Fragments[fs.Name]
if !ok {
panic(fmt.Errorf("fragment %q not found", fs.Name)) // TODO proper error handling
}
e.execFragment(ctx, r, &frag.Fragment, resolver, addResult)
})
}
case *query.InlineFragment:
if !skipByDirective(r, sel.Directives) {
frag := sel
execSel(func() {
e.execFragment(ctx, r, &frag.Fragment, resolver, addResult)
})
}
default:
panic("invalid type")
}
}
wg.Wait()
}
func (e *objectExec) execFragment(ctx context.Context, r *request, frag *query.Fragment, resolver reflect.Value, addResult addResultFn) {
if frag.On != "" && frag.On != e.name {
a, ok := e.typeAssertions[frag.On]
if !ok {
panic(fmt.Errorf("%q does not implement %q", frag.On, e.name)) // TODO proper error handling
}
out := resolver.Method(a.methodIndex).Call(nil)
if !out[1].Bool() {
return
}
a.typeExec.(*objectExec).execSelectionSet(ctx, r, frag.SelSet, out[0], addResult, false)
return
}
e.execSelectionSet(ctx, r, frag.SelSet, resolver, addResult, false)
}
type fieldExec struct {
field *schema.Field
methodIndex int
hasContext bool
argsPacker *structPacker
hasError bool
valueExec iExec
}
func (e *fieldExec) execField(ctx context.Context, r *request, f *query.Field, resolver reflect.Value, addResult addResultFn) {
trivial := !e.hasContext && e.argsPacker == nil && !e.hasError
var span opentracing.Span
if !trivial {
span, ctx = opentracing.StartSpanFromContext(ctx, "GraphQL field: "+f.Name)
defer span.Finish()
}
result, err := e.execField2(ctx, r, f, resolver, span)
if err != nil {
r.addError(errors.Errorf("%s", err))
addResult(f.Alias, nil) // TODO handle non-nil
ext.Error.Set(span, true)
span.SetTag("errorMsg", err)
return
}
addResult(f.Alias, result)
}
func (e *fieldExec) execField2(ctx context.Context, r *request, f *query.Field, resolver reflect.Value, span opentracing.Span) (interface{}, error) {
var in []reflect.Value
if e.hasContext {
in = append(in, reflect.ValueOf(ctx))
}
if e.argsPacker != nil {
values := make(map[string]interface{})
for name, arg := range f.Arguments {
v, err := coerceValue(r, e.field.Args.Fields[name].Type, arg)
if err != nil {
return nil, err
}
values[name] = v
span.SetTag(name, v)
}
in = append(in, e.argsPacker.pack(values))
}
m := resolver.Method(e.methodIndex)
out := m.Call(in)
if e.hasError && !out[1].IsNil() {
return nil, out[1].Interface().(error)
}
return e.valueExec.exec(ctx, r, f.SelSet, out[0], false), nil
}
type typeAssertExec struct {
methodIndex int
typeExec iExec
}
func coerceMap(r *request, io *common.InputMap, m map[string]interface{}) (map[string]interface{}, error) {
coerced := make(map[string]interface{})
for _, iv := range io.Fields {
value, ok := m[iv.Name]
if !ok {
if iv.Default == nil {
return nil, errors.Errorf("missing %q", iv.Name)
}
value = iv.Default
}
c, err := coerceValue(r, iv.Type, value)
if err != nil {
return nil, err
}
coerced[iv.Name] = c
}
return coerced, nil
}
func coerceValue(r *request, typ common.Type, value interface{}) (interface{}, error) {
if v, ok := value.(common.Variable); ok {
return r.vars[string(v)], nil
}
t, _ := unwrapNonNull(typ)
switch t := t.(type) {
case *scalar:
v, err := t.coerceInput(value)
if v == nil {
return nil, fmt.Errorf("could not convert %#v (%T) to %s: %s", value, value, t.name, err)
}
return v, nil
case *schema.InputObject:
return coerceMap(r, &t.InputMap, value.(map[string]interface{}))
}
return value, nil
}
type packer interface {
pack(value interface{}) reflect.Value
}
type structPacker struct {
structType reflect.Type
defaultStruct reflect.Value
fields []*structPackerField
}
type structPackerField struct {
name string
fieldIndex []int
fieldPacker packer
}
func (e *structPacker) pack(value interface{}) reflect.Value {
values := value.(map[string]interface{})
v := reflect.New(e.structType)
v.Elem().Set(e.defaultStruct)
for _, f := range e.fields {
if value, ok := values[f.name]; ok {
fv := f.fieldPacker.pack(value)
v.Elem().FieldByIndex(f.fieldIndex).Set(fv)
}
}
return v
}
type valuePacker struct {
nonNull bool
}
func (e *valuePacker) pack(value interface{}) reflect.Value {
v := reflect.ValueOf(value)
if !e.nonNull {
p := reflect.New(v.Type())
p.Elem().Set(v)
return p
}
return v
}
func skipByDirective(r *request, d map[string]*query.Directive) bool {
if skip, ok := d["skip"]; ok {
v, err := coerceValue(r, booleanScalar, skip.Arguments["if"])
if err != nil {
r.addError(errors.Errorf("%s", err))
}
if err == nil && v.(bool) {
return true
}
}
if include, ok := d["include"]; ok {
v, err := coerceValue(r, booleanScalar, include.Arguments["if"])
if err != nil {
r.addError(errors.Errorf("%s", err))
}
if err == nil && !v.(bool) {
return true
}
}
return false
}
func unwrapNonNull(t common.Type) (common.Type, bool) {
if nn, ok := t.(*common.NonNull); ok {
return nn.OfType, true
}
return t, false
}