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// Copyright 2023 LiveKit, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package utils
import (
"runtime"
"sync"
"go.uber.org/atomic"
)
// ParallelExec will executes the given function with each element of vals, if len(vals) >= parallelThreshold,
// will execute them in parallel, with the given step size. So fn must be thread-safe.
func ParallelExec[T any](vals []T, parallelThreshold, step uint64, fn func(T)) {
if uint64(len(vals)) < parallelThreshold {
for _, v := range vals {
fn(v)
}
return
}
// parallel - enables much more efficient multi-core utilization
start := atomic.NewUint64(0)
end := uint64(len(vals))
var wg sync.WaitGroup
numCPU := runtime.NumCPU()
if numCPU > len(vals) {
numCPU = len(vals)
}
wg.Add(numCPU)
for p := 0; p < numCPU; p++ {
go func() {
defer wg.Done()
for {
n := start.Add(step)
if n >= end+step {
return
}
for i := n - step; i < n && i < end; i++ {
fn(vals[i])
}
}
}()
}
wg.Wait()
}