84 lines
1.9 KiB
Go
84 lines
1.9 KiB
Go
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// Copyright 2020-2021 Buf Technologies, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package thread
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import (
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"runtime"
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"sync"
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"go.uber.org/multierr"
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)
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var (
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globalParallelism = runtime.NumCPU()
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globalLock sync.RWMutex
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)
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// Parallelism returns the current parellism.
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//
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// This defaults to the number of CPUs.
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func Parallelism() int {
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globalLock.RLock()
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parallelism := globalParallelism
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globalLock.RUnlock()
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return parallelism
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}
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// SetParallelism sets the parallelism.
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//
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// If parallelism < 1, this sets the parallelism to 1.
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func SetParallelism(parallelism int) {
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if parallelism < 1 {
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parallelism = 1
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}
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globalLock.Lock()
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globalParallelism = parallelism
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globalLock.Unlock()
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}
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// Parallelize runs the jobs in parallel.
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//
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// A max of Parallelism jobs will be run at once.
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// Returns the combined error from the jobs.
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func Parallelize(jobs ...func() error) error {
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switch len(jobs) {
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case 0:
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return nil
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case 1:
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return jobs[0]()
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default:
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semaphoreC := make(chan struct{}, Parallelism())
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var retErr error
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var wg sync.WaitGroup
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var lock sync.Mutex
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for _, job := range jobs {
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job := job
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wg.Add(1)
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semaphoreC <- struct{}{}
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go func() {
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if err := job(); err != nil {
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lock.Lock()
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retErr = multierr.Append(retErr, err)
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lock.Unlock()
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}
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<-semaphoreC
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wg.Done()
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}()
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}
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wg.Wait()
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return retErr
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}
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}
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