package generator
import "text/template"
var tpl = template.Must(template.New("generated").
Funcs(template.FuncMap{
"lcFirst": lcFirst,
}).
Parse(`
// Code generated by github.com/vektah/dataloaden, DO NOT EDIT.
package {{.Package}}
import (
"context"
"sync"
"time"
{{if .KeyType.ImportPath}}"{{.KeyType.ImportPath}}"{{end}}
{{if .ValType.ImportPath}}"{{.ValType.ImportPath}}"{{end}}
)
// {{.Name}}Config captures the config to create a new {{.Name}}
type {{.Name}}Config struct {
// Fetch is a method that provides the data for the loader
Fetch func(ctx context.Context, keys []{{.KeyType.String}}) ([]{{.ValType.String}}, []error)
// Wait is how long wait before sending a batch
Wait time.Duration
// MaxBatch will limit the maximum number of keys to send in one batch, 0 = not limit
MaxBatch int
}
// New{{.Name}} creates a new {{.Name}} given a fetch, wait, and maxBatch
func New{{.Name}}(config {{.Name}}Config) *{{.Name}} {
return &{{.Name}}{
fetch: config.Fetch,
wait: config.Wait,
maxBatch: config.MaxBatch,
}
}
// {{.Name}} batches and caches requests
type {{.Name}} struct {
// this method provides the data for the loader
fetch func(ctx context.Context, keys []{{.KeyType.String}}) ([]{{.ValType.String}}, []error)
// how long to done before sending a batch
wait time.Duration
// this will limit the maximum number of keys to send in one batch, 0 = no limit
maxBatch int
// INTERNAL
// lazily created cache
cache map[{{.KeyType.String}}]{{.ValType.String}}
// the current batch. keys will continue to be collected until timeout is hit,
// then everything will be sent to the fetch method and out to the listeners
batch *{{.Name|lcFirst}}Batch
// mutex to prevent races
mu sync.Mutex
}
type {{.Name|lcFirst}}Batch struct {
keys []{{.KeyType}}
data []{{.ValType.String}}
error []error
closing bool
done chan struct{}
}
// Load a {{.ValType.Name}} by key, batching and caching will be applied automatically
func (l *{{.Name}}) Load(ctx context.Context, key {{.KeyType.String}}) ({{.ValType.String}}, error) {
return l.LoadThunk(ctx, key)()
}
// LoadThunk returns a function that when called will block waiting for a {{.ValType.Name}}.
// This method should be used if you want one goroutine to make requests to many
// different data loaders without blocking until the thunk is called.
func (l *{{.Name}}) LoadThunk(ctx context.Context, key {{.KeyType.String}}) func() ({{.ValType.String}}, error) {
l.mu.Lock()
if it, ok := l.cache[key]; ok {
l.mu.Unlock()
return func() ({{.ValType.String}}, error) {
return it, nil
}
}
if l.batch == nil {
l.batch = &{{.Name|lcFirst}}Batch{done: make(chan struct{})}
}
batch := l.batch
pos := batch.keyIndex(ctx, l, key)
l.mu.Unlock()
return func() ({{.ValType.String}}, error) {
<-batch.done
var data {{.ValType.String}}
if pos < len(batch.data) {
data = batch.data[pos]
}
var err error
// its convenient to be able to return a single error for everything
if len(batch.error) == 1 {
err = batch.error[0]
} else if batch.error != nil {
err = batch.error[pos]
}
if err == nil {
l.mu.Lock()
l.unsafeSet(key, data)
l.mu.Unlock()
}
return data, err
}
}
// LoadAll fetches many keys at once. It will be broken into appropriate sized
// sub batches depending on how the loader is configured
func (l *{{.Name}}) LoadAll(ctx context.Context, keys []{{.KeyType}}) ([]{{.ValType.String}}, []error) {
results := make([]func() ({{.ValType.String}}, error), len(keys))
for i, key := range keys {
results[i] = l.LoadThunk(ctx, key)
}
{{.ValType.Name|lcFirst}}s := make([]{{.ValType.String}}, len(keys))
errors := make([]error, len(keys))
for i, thunk := range results {
{{.ValType.Name|lcFirst}}s[i], errors[i] = thunk()
}
return {{.ValType.Name|lcFirst}}s, errors
}
// LoadAllThunk returns a function that when called will block waiting for a {{.ValType.Name}}s.
// This method should be used if you want one goroutine to make requests to many
// different data loaders without blocking until the thunk is called.
func (l *{{.Name}}) LoadAllThunk(ctx context.Context, keys []{{.KeyType}}) (func() ([]{{.ValType.String}}, []error)) {
results := make([]func() ({{.ValType.String}}, error), len(keys))
for i, key := range keys {
results[i] = l.LoadThunk(ctx, key)
}
return func() ([]{{.ValType.String}}, []error) {
{{.ValType.Name|lcFirst}}s := make([]{{.ValType.String}}, len(keys))
errors := make([]error, len(keys))
for i, thunk := range results {
{{.ValType.Name|lcFirst}}s[i], errors[i] = thunk()
}
return {{.ValType.Name|lcFirst}}s, errors
}
}
// Prime the cache with the provided key and value. If the key already exists, no change is made
// and false is returned.
// (To forcefully prime the cache, clear the key first with loader.clear(key).prime(key, value).)
func (l *{{.Name}}) Prime(key {{.KeyType}}, value {{.ValType.String}}) bool {
l.mu.Lock()
var found bool
if _, found = l.cache[key]; !found {
{{- if .ValType.IsPtr }}
// make a copy when writing to the cache, its easy to pass a pointer in from a loop var
// and end up with the whole cache pointing to the same value.
cpy := *value
l.unsafeSet(key, &cpy)
{{- else if .ValType.IsSlice }}
// make a copy when writing to the cache, its easy to pass a pointer in from a loop var
// and end up with the whole cache pointing to the same value.
cpy := make({{.ValType.String}}, len(value))
copy(cpy, value)
l.unsafeSet(key, cpy)
{{- else }}
l.unsafeSet(key, value)
{{- end }}
}
l.mu.Unlock()
return !found
}
// Clear the value at key from the cache, if it exists
func (l *{{.Name}}) Clear(key {{.KeyType}}) {
l.mu.Lock()
delete(l.cache, key)
l.mu.Unlock()
}
func (l *{{.Name}}) unsafeSet(key {{.KeyType}}, value {{.ValType.String}}) {
if l.cache == nil {
l.cache = map[{{.KeyType}}]{{.ValType.String}}{}
}
l.cache[key] = value
}
// keyIndex will return the location of the key in the batch, if its not found
// it will add the key to the batch
func (b *{{.Name|lcFirst}}Batch) keyIndex(ctx context.Context, l *{{.Name}}, key {{.KeyType}}) int {
for i, existingKey := range b.keys {
if key == existingKey {
return i
}
}
pos := len(b.keys)
b.keys = append(b.keys, key)
if pos == 0 {
go b.startTimer(ctx, l)
}
if l.maxBatch != 0 && pos >= l.maxBatch-1 {
if !b.closing {
b.closing = true
l.batch = nil
go b.end(ctx, l)
}
}
return pos
}
func (b *{{.Name|lcFirst}}Batch) startTimer(ctx context.Context, l *{{.Name}}) {
time.Sleep(l.wait)
l.mu.Lock()
// we must have hit a batch limit and are already finalizing this batch
if b.closing {
l.mu.Unlock()
return
}
l.batch = nil
l.mu.Unlock()
b.end(ctx, l)
}
func (b *{{.Name|lcFirst}}Batch) end(ctx context.Context, l *{{.Name}}) {
b.data, b.error = l.fetch(ctx, b.keys)
close(b.done)
}
`))
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent