/
manager.go
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/
manager.go
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// Copyright 2023 Google LLC
//
// 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 localresources ensures locally executed tasks have enough resources to run.
package localresources
import (
"context"
"runtime"
"golang.org/x/sync/semaphore"
log "github.com/golang/glog"
)
// Manager is the manager of local resources.
type Manager struct {
cpus *semaphore.Weighted
ram *semaphore.Weighted
totalCPUs int64
totalRAMMBs int64
}
// NewDefaultManager retrieves a Manager with default local resources.
func NewDefaultManager() *Manager {
numCPU := int64(runtime.NumCPU())
ramMBs := TotalRAMMBs()
return NewManager(numCPU, ramMBs)
}
// NewFractionalDefaultManager retrieves a Manager with the given fraction of default local
// resources.
func NewFractionalDefaultManager(fraction float64) *Manager {
numCPU := int64(float64(runtime.NumCPU()) * fraction)
ramMBs := int64(float64(TotalRAMMBs()) * fraction)
return NewManager(numCPU, ramMBs)
}
// NewManager is used to initialize the manager with non default local resources.
func NewManager(cpus, ramMBs int64) *Manager {
return &Manager{
cpus: semaphore.NewWeighted(max(1, cpus)),
ram: semaphore.NewWeighted(max(1, ramMBs)),
totalCPUs: max(1, cpus),
totalRAMMBs: max(1, ramMBs),
}
}
// Lock locks the desired resources and returns a function to release them.
func (m *Manager) Lock(ctx context.Context, cpus, ramMBs int64) (func(), error) {
if m == nil {
return func() {}, nil
}
if cpus > m.totalCPUs || ramMBs > m.totalRAMMBs {
log.Warningf("Capping request to available system resources, cpu-max=%v(req=%v), ramMBs-max=%v(req=%v)", m.totalCPUs, cpus, m.totalRAMMBs, ramMBs)
cpus = min(cpus, m.totalCPUs)
ramMBs = min(ramMBs, m.totalRAMMBs)
}
if err := m.cpus.Acquire(ctx, cpus); err != nil {
return nil, err
}
if err := m.ram.Acquire(ctx, ramMBs); err != nil {
m.cpus.Release(cpus)
return nil, err
}
return func() {
m.cpus.Release(cpus)
m.ram.Release(ramMBs)
}, nil
}
func min(a int64, b int64) int64 {
if a < b {
return a
}
return b
}
func max(a, b int64) int64 {
if a > b {
return a
}
return b
}