e1d46e6973
It turns out that this is actually useful to limit the number of open files. Fixes https://github.com/tweag/gomod2nix/issues/50.
75 lines
1.1 KiB
Go
75 lines
1.1 KiB
Go
package lib
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import (
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"sync"
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)
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// ParallellExecutor - Execute callback functions in parallell
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type ParallellExecutor struct {
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errChan chan error
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wg *sync.WaitGroup
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mux *sync.Mutex
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guard chan struct{}
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// Error returned by Wait(), cached for other Wait() invocations
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err error
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done bool
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}
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func NewParallellExecutor(maxWorkers int) *ParallellExecutor {
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return &ParallellExecutor{
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errChan: make(chan error),
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mux: new(sync.Mutex),
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wg: new(sync.WaitGroup),
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guard: make(chan struct{}, maxWorkers),
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err: nil,
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done: false,
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}
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}
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func (e *ParallellExecutor) Add(fn func() error) {
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e.wg.Add(1)
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e.guard <- struct{}{} // Block until a worker is available
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go func() {
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defer e.wg.Done()
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defer func() {
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<-e.guard
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}()
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err := fn()
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if err != nil {
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e.errChan <- err
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}
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}()
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}
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func (e *ParallellExecutor) Wait() error {
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e.mux.Lock()
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defer e.mux.Unlock()
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if e.done {
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return e.err
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}
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var err error
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// Ensure channel is closed
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go func() {
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e.wg.Wait()
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close(e.errChan)
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}()
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for err = range e.errChan {
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if err != nil {
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break
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}
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}
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e.done = true
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e.err = err
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return err
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}
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