2021-07-21 09:01:02 +00:00
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package batch
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import (
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"context"
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"sync"
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)
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type Option = func(b *Batch)
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type Result struct {
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Value interface{}
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Err error
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}
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type Error struct {
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Key string
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Err error
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}
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func WithConcurrencyNum(n int) Option {
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return func(b *Batch) {
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q := make(chan struct{}, n)
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for i := 0; i < n; i++ {
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q <- struct{}{}
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}
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b.queue = q
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}
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}
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// Batch similar to errgroup, but can control the maximum number of concurrent
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type Batch struct {
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result map[string]Result
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queue chan struct{}
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wg sync.WaitGroup
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mux sync.Mutex
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err *Error
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once sync.Once
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cancel func()
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}
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func (b *Batch) Go(key string, fn func() (interface{}, error)) {
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b.wg.Add(1)
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go func() {
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defer b.wg.Done()
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if b.queue != nil {
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<-b.queue
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defer func() {
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b.queue <- struct{}{}
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}()
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}
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value, err := fn()
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if err != nil {
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b.once.Do(func() {
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b.err = &Error{key, err}
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if b.cancel != nil {
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b.cancel()
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}
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})
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}
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ret := Result{value, err}
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b.mux.Lock()
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defer b.mux.Unlock()
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b.result[key] = ret
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}()
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}
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func (b *Batch) Wait() *Error {
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b.wg.Wait()
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if b.cancel != nil {
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b.cancel()
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}
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return b.err
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}
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func (b *Batch) WaitAndGetResult() (map[string]Result, *Error) {
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err := b.Wait()
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return b.Result(), err
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}
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func (b *Batch) Result() map[string]Result {
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b.mux.Lock()
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defer b.mux.Unlock()
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copy := map[string]Result{}
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for k, v := range b.result {
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copy[k] = v
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}
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return copy
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}
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2021-07-22 16:30:23 +00:00
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func New(ctx context.Context, opts ...Option) (*Batch, context.Context) {
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ctx, cancel := context.WithCancel(ctx)
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2021-07-21 09:01:02 +00:00
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b := &Batch{
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result: map[string]Result{},
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}
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for _, o := range opts {
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o(b)
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}
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b.cancel = cancel
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return b, ctx
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}
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