/
executor.go
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/
executor.go
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// Copyright Istio Authors
//
// 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 forwarder
import (
"context"
"fmt"
"github.com/hashicorp/go-multierror"
"go.uber.org/atomic"
"golang.org/x/sync/semaphore"
)
const (
maxConcurrencyPerForward = 20
)
type executor struct {
totalRequests *atomic.Uint64
activeRequests *atomic.Uint64
stopCh chan struct{}
}
func newExecutor() *executor {
e := &executor{
totalRequests: atomic.NewUint64(0),
activeRequests: atomic.NewUint64(0),
stopCh: make(chan struct{}),
}
return e
}
func (e *executor) ActiveRequests() uint64 {
return e.activeRequests.Load()
}
// NewGroup creates a new group of tasks that can be managed collectively.
// Parallelism is limited by the global maxConcurrency of the executor.
func (e *executor) NewGroup() *execGroup {
return &execGroup{
e: e,
sem: semaphore.NewWeighted(int64(maxConcurrencyPerForward)),
}
}
type execGroup struct {
e *executor
g multierror.Group
sem *semaphore.Weighted
}
// Go runs the given work function asynchronously.
func (g *execGroup) Go(ctx context.Context, work func() error) {
g.g.Go(func() error {
g.e.totalRequests.Inc()
g.e.activeRequests.Inc()
defer g.e.activeRequests.Dec()
// Acquire the group concurrency semaphore.
if err := g.sem.Acquire(ctx, 1); err != nil {
return fmt.Errorf("request set timed out: %v", err)
}
defer g.sem.Release(1)
return work()
})
}
func (g *execGroup) Wait() *multierror.Error {
return g.g.Wait()
}
func (e *executor) Close() {
close(e.stopCh)
}