github.com/99designs/gqlgen@v0.17.45/graphql/fieldset.go (about)

     1  package graphql
     2  
     3  import (
     4  	"context"
     5  	"io"
     6  	"sync"
     7  )
     8  
     9  type FieldSet struct {
    10  	fields   []CollectedField
    11  	Values   []Marshaler
    12  	Invalids uint32
    13  	delayed  []delayedResult
    14  }
    15  
    16  type delayedResult struct {
    17  	i int
    18  	f func(context.Context) Marshaler
    19  }
    20  
    21  func NewFieldSet(fields []CollectedField) *FieldSet {
    22  	return &FieldSet{
    23  		fields: fields,
    24  		Values: make([]Marshaler, len(fields)),
    25  	}
    26  }
    27  
    28  func (m *FieldSet) AddField(field CollectedField) {
    29  	m.fields = append(m.fields, field)
    30  	m.Values = append(m.Values, nil)
    31  }
    32  
    33  func (m *FieldSet) Concurrently(i int, f func(context.Context) Marshaler) {
    34  	m.delayed = append(m.delayed, delayedResult{i: i, f: f})
    35  }
    36  
    37  func (m *FieldSet) Dispatch(ctx context.Context) {
    38  	if len(m.delayed) == 1 {
    39  		// only one concurrent task, no need to spawn a goroutine or deal create waitgroups
    40  		d := m.delayed[0]
    41  		m.Values[d.i] = d.f(ctx)
    42  	} else if len(m.delayed) > 1 {
    43  		// more than one concurrent task, use the main goroutine to do one, only spawn goroutines for the others
    44  
    45  		var wg sync.WaitGroup
    46  		for _, d := range m.delayed[1:] {
    47  			wg.Add(1)
    48  			go func(d delayedResult) {
    49  				defer wg.Done()
    50  				m.Values[d.i] = d.f(ctx)
    51  			}(d)
    52  		}
    53  
    54  		m.Values[m.delayed[0].i] = m.delayed[0].f(ctx)
    55  		wg.Wait()
    56  	}
    57  }
    58  
    59  func (m *FieldSet) MarshalGQL(writer io.Writer) {
    60  	writer.Write(openBrace)
    61  	for i, field := range m.fields {
    62  		if i != 0 {
    63  			writer.Write(comma)
    64  		}
    65  		writeQuotedString(writer, field.Alias)
    66  		writer.Write(colon)
    67  		m.Values[i].MarshalGQL(writer)
    68  	}
    69  	writer.Write(closeBrace)
    70  }