// Copyright 2022 The Dawn & Tint Authors
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//  1. Redistributions of source code must retain the above copyright notice, this
//     list of conditions and the following disclaimer.
//
//  2. Redistributions in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
//     and/or other materials provided with the distribution.
//
//  3. Neither the name of the copyright holder nor the names of its
//     contributors may be used to endorse or promote products derived from
//     this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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package utils

import "sync"

// RunConcurrent calls fn on numRoutines separate go routines.
// RunConcurrent will return on the first error returned, leaving the other go
// routines to complete.
func RunConcurrent(numRoutines int, fn func() error) error {
	errs := make(chan error, numRoutines)
	wg := sync.WaitGroup{}
	wg.Add(numRoutines)
	for i := 0; i < numRoutines; i++ {
		go func() {
			defer wg.Done()
			errs <- fn()
		}()
	}
	go func() {
		wg.Wait()
		close(errs)
	}()
	for err := range errs {
		if err != nil {
			return err
		}
	}
	return nil
}