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// Copyright 2016 The etcd 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 etcdserver
import (
"sync"
pb "go.etcd.io/etcd/api/v3/etcdserverpb"
humanize "github.com/dustin/go-humanize"
"go.uber.org/zap"
)
const (
// DefaultQuotaBytes is the number of bytes the backend Size may
// consume before exceeding the space quota.
DefaultQuotaBytes = int64(2 * 1024 * 1024 * 1024) // 2GB
// MaxQuotaBytes is the maximum number of bytes suggested for a backend
// quota. A larger quota may lead to degraded performance.
MaxQuotaBytes = int64(8 * 1024 * 1024 * 1024) // 8GB
)
// Quota represents an arbitrary quota against arbitrary requests. Each request
// costs some charge; if there is not enough remaining charge, then there are
// too few resources available within the quota to apply the request.
type Quota interface {
// Available judges whether the given request fits within the quota.
Available(req interface{}) bool
// Cost computes the charge against the quota for a given request.
Cost(req interface{}) int
// Remaining is the amount of charge left for the quota.
Remaining() int64
}
type passthroughQuota struct{}
func (*passthroughQuota) Available(interface{}) bool { return true }
func (*passthroughQuota) Cost(interface{}) int { return 0 }
func (*passthroughQuota) Remaining() int64 { return 1 }
type backendQuota struct {
s *EtcdServer
maxBackendBytes int64
}
const (
// leaseOverhead is an estimate for the cost of storing a lease
leaseOverhead = 64
// kvOverhead is an estimate for the cost of storing a key's metadata
kvOverhead = 256
)
var (
// only log once
quotaLogOnce sync.Once
DefaultQuotaSize = humanize.Bytes(uint64(DefaultQuotaBytes))
maxQuotaSize = humanize.Bytes(uint64(MaxQuotaBytes))
)
// NewBackendQuota creates a quota layer with the given storage limit.
func NewBackendQuota(s *EtcdServer, name string) Quota {
lg := s.Logger()
quotaBackendBytes.Set(float64(s.Cfg.QuotaBackendBytes))
if s.Cfg.QuotaBackendBytes < 0 {
// disable quotas if negative
quotaLogOnce.Do(func() {
lg.Info(
"disabled backend quota",
zap.String("quota-name", name),
zap.Int64("quota-size-bytes", s.Cfg.QuotaBackendBytes),
)
})
return &passthroughQuota{}
}
if s.Cfg.QuotaBackendBytes == 0 {
// use default size if no quota size given
quotaLogOnce.Do(func() {
if lg != nil {
lg.Info(
"enabled backend quota with default value",
zap.String("quota-name", name),
zap.Int64("quota-size-bytes", DefaultQuotaBytes),
zap.String("quota-size", DefaultQuotaSize),
)
}
})
quotaBackendBytes.Set(float64(DefaultQuotaBytes))
return &backendQuota{s, DefaultQuotaBytes}
}
quotaLogOnce.Do(func() {
if s.Cfg.QuotaBackendBytes > MaxQuotaBytes {
lg.Warn(
"quota exceeds the maximum value",
zap.String("quota-name", name),
zap.Int64("quota-size-bytes", s.Cfg.QuotaBackendBytes),
zap.String("quota-size", humanize.Bytes(uint64(s.Cfg.QuotaBackendBytes))),
zap.Int64("quota-maximum-size-bytes", MaxQuotaBytes),
zap.String("quota-maximum-size", maxQuotaSize),
)
}
lg.Info(
"enabled backend quota",
zap.String("quota-name", name),
zap.Int64("quota-size-bytes", s.Cfg.QuotaBackendBytes),
zap.String("quota-size", humanize.Bytes(uint64(s.Cfg.QuotaBackendBytes))),
)
})
return &backendQuota{s, s.Cfg.QuotaBackendBytes}
}
func (b *backendQuota) Available(v interface{}) bool {
cost := b.Cost(v)
// if there are no mutating requests, it's safe to pass through
if cost == 0 {
return true
}
// TODO: maybe optimize backend.Size()
return b.s.Backend().Size()+int64(cost) < b.maxBackendBytes
}
func (b *backendQuota) Cost(v interface{}) int {
switch r := v.(type) {
case *pb.PutRequest:
return costPut(r)
case *pb.TxnRequest:
return costTxn(r)
case *pb.LeaseGrantRequest:
return leaseOverhead
default:
panic("unexpected cost")
}
}
func costPut(r *pb.PutRequest) int { return kvOverhead + len(r.Key) + len(r.Value) }
func costTxnReq(u *pb.RequestOp) int {
r := u.GetRequestPut()
if r == nil {
return 0
}
return costPut(r)
}
func costTxn(r *pb.TxnRequest) int {
sizeSuccess := 0
for _, u := range r.Success {
sizeSuccess += costTxnReq(u)
}
sizeFailure := 0
for _, u := range r.Failure {
sizeFailure += costTxnReq(u)
}
if sizeFailure > sizeSuccess {
return sizeFailure
}
return sizeSuccess
}
func (b *backendQuota) Remaining() int64 {
return b.maxBackendBytes - b.s.Backend().Size()
}
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