open-consul/agent/consul/multilimiter/multilimiter.go

281 lines
6.9 KiB
Go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package multilimiter
import (
"bytes"
"context"
"sync"
"sync/atomic"
"time"
radix "github.com/hashicorp/go-immutable-radix"
"golang.org/x/time/rate"
)
var _ RateLimiter = &MultiLimiter{}
const separator = "♣"
func Key(keys ...[]byte) KeyType {
return bytes.Join(keys, []byte(separator))
}
// RateLimiter is the interface implemented by MultiLimiter
//
//go:generate mockery --name RateLimiter --inpackage --filename mock_RateLimiter.go
type RateLimiter interface {
Run(ctx context.Context)
Allow(entity LimitedEntity) bool
UpdateConfig(c LimiterConfig, prefix []byte)
DeleteConfig(prefix []byte)
}
type limiterWithKey struct {
l *Limiter
k []byte
t time.Time
}
// MultiLimiter implement RateLimiter interface and represent a set of rate limiters
// specific to different LimitedEntities and queried by a LimitedEntities.Key()
type MultiLimiter struct {
limiters *atomic.Pointer[radix.Tree]
limitersConfigs *atomic.Pointer[radix.Tree]
defaultConfig *atomic.Pointer[Config]
limiterCh chan *limiterWithKey
configsLock sync.Mutex
once sync.Once
}
type KeyType = []byte
// LimitedEntity is an interface used by MultiLimiter.Allow to determine
// which rate limiter to use to allow the request
type LimitedEntity interface {
Key() KeyType
}
// Limiter define a limiter to be part of the MultiLimiter structure
type Limiter struct {
limiter *rate.Limiter
lastAccess atomic.Int64
}
// LimiterConfig is a Limiter configuration
type LimiterConfig struct {
Rate rate.Limit
Burst int
}
// Config is a MultiLimiter configuration
type Config struct {
ReconcileCheckLimit time.Duration
ReconcileCheckInterval time.Duration
}
// UpdateConfig will update the MultiLimiter Config
// which will cascade to all the Limiter(s) LimiterConfig
func (m *MultiLimiter) UpdateConfig(c LimiterConfig, prefix []byte) {
m.updateConfig(&c, prefix)
}
// DeleteConfig will delete the MultiLimiter Config
// which will cascade to all the Limiter(s) LimiterConfig
func (m *MultiLimiter) DeleteConfig(prefix []byte) {
m.updateConfig(nil, prefix)
}
// NewMultiLimiter create a new MultiLimiter
func NewMultiLimiter(c Config) *MultiLimiter {
limiters := atomic.Pointer[radix.Tree]{}
configs := atomic.Pointer[radix.Tree]{}
config := atomic.Pointer[Config]{}
config.Store(&c)
limiters.Store(radix.New())
configs.Store(radix.New())
if c.ReconcileCheckLimit == 0 {
c.ReconcileCheckLimit = 30 * time.Millisecond
}
if c.ReconcileCheckInterval == 0 {
c.ReconcileCheckLimit = 1 * time.Second
}
chLimiter := make(chan *limiterWithKey, 100)
m := &MultiLimiter{limiters: &limiters, defaultConfig: &config, limitersConfigs: &configs, limiterCh: chLimiter}
return m
}
// Run the cleanup routine to remove old entries of Limiters based on ReconcileCheckLimit and ReconcileCheckInterval.
func (m *MultiLimiter) Run(ctx context.Context) {
m.once.Do(func() {
go func() {
cfg := m.defaultConfig.Load()
writeTimeout := cfg.ReconcileCheckInterval
limiters := m.limiters.Load()
txn := limiters.Txn()
waiter := time.NewTicker(writeTimeout)
wt := tickerWrapper{ticker: waiter}
defer waiter.Stop()
for {
if txn = m.reconcile(ctx, wt, txn, cfg.ReconcileCheckLimit); txn == nil {
return
}
}
}()
})
}
// Allow should be called by a request processor to check if the current request is Limited
// The request processor should provide a LimitedEntity that implement the right Key()
func (m *MultiLimiter) Allow(e LimitedEntity) bool {
limiters := m.limiters.Load()
l, ok := limiters.Get(e.Key())
now := time.Now()
unixNow := time.Now().UnixMilli()
if ok {
limiter := l.(*Limiter)
if limiter.limiter != nil {
limiter.lastAccess.Store(unixNow)
return limiter.limiter.Allow()
}
}
configs := m.limitersConfigs.Load()
p, _, ok := configs.Root().LongestPrefix(e.Key())
if !ok {
return true
}
var config *LimiterConfig
c, ok := configs.Get(p)
if ok && c != nil {
config = c.(*LimiterConfig)
}
limiter := &Limiter{limiter: rate.NewLimiter(config.Rate, config.Burst)}
limiter.lastAccess.Store(unixNow)
m.limiterCh <- &limiterWithKey{l: limiter, k: e.Key(), t: now}
return limiter.limiter.Allow()
}
// UpdateConfig will update the MultiLimiter Config
// which will cascade to all the Limiter(s) LimiterConfig
func (m *MultiLimiter) updateConfig(c *LimiterConfig, prefix []byte) {
m.configsLock.Lock()
defer m.configsLock.Unlock()
if prefix == nil {
prefix = []byte("")
}
configs := m.limitersConfigs.Load()
var newConfigs *radix.Tree
if c == nil {
newConfigs, _, _ = configs.Delete(prefix)
} else {
newConfigs, _, _ = configs.Insert(prefix, c)
}
m.limitersConfigs.Store(newConfigs)
}
type ticker interface {
Ticker() <-chan time.Time
}
type tickerWrapper struct {
ticker *time.Ticker
}
func (t tickerWrapper) Ticker() <-chan time.Time {
return t.ticker.C
}
func (m *MultiLimiter) reconcile(ctx context.Context, waiter ticker, txn *radix.Txn, reconcileCheckLimit time.Duration) *radix.Txn {
select {
case <-waiter.Ticker():
tree := txn.Commit()
m.limiters.Store(tree)
txn = tree.Txn()
m.cleanLimiters(time.Now(), reconcileCheckLimit, txn)
m.reconcileConfig(txn)
tree = txn.Commit()
txn = tree.Txn()
case lk := <-m.limiterCh:
v, ok := txn.Get(lk.k)
if !ok {
txn.Insert(lk.k, lk.l)
} else {
if l, ok := v.(*Limiter); ok {
l.lastAccess.Store(lk.t.Unix())
l.limiter.AllowN(lk.t, 1)
}
}
case <-ctx.Done():
return nil
}
return txn
}
func (m *MultiLimiter) reconcileConfig(txn *radix.Txn) {
iter := txn.Root().Iterator()
// make sure all limiters have the latest defaultConfig of their prefix
for k, v, ok := iter.Next(); ok; k, v, ok = iter.Next() {
pl, ok := v.(*Limiter)
if pl == nil || !ok {
continue
}
if pl.limiter == nil {
continue
}
// find the prefix for the leaf and check if the defaultConfig is up-to-date
// it's possible that the prefix is equal to the key
p, _, ok := m.limitersConfigs.Load().Root().LongestPrefix(k)
// no corresponding config found, need to delete it
if !ok {
txn.Delete(k)
continue
}
v, ok := m.limitersConfigs.Load().Get(p)
if v == nil || !ok {
continue
}
cl, ok := v.(*LimiterConfig)
if cl == nil || !ok {
continue
}
if cl.isApplied(pl.limiter) {
continue
}
limiter := Limiter{limiter: rate.NewLimiter(cl.Rate, cl.Burst)}
limiter.lastAccess.Store(pl.lastAccess.Load())
txn.Insert(k, &limiter)
}
}
func (m *MultiLimiter) cleanLimiters(now time.Time, reconcileCheckLimit time.Duration, txn *radix.Txn) {
iter := txn.Root().Iterator()
// remove all expired limiters
for k, v, ok := iter.Next(); ok; k, v, ok = iter.Next() {
t, isLimiter := v.(*Limiter)
if !isLimiter || t.limiter == nil {
continue
}
lastAccess := time.UnixMilli(t.lastAccess.Load())
if now.Sub(lastAccess) > reconcileCheckLimit {
txn.Delete(k)
}
}
}
func (lc *LimiterConfig) isApplied(l *rate.Limiter) bool {
return l.Limit() == lc.Rate && l.Burst() == lc.Burst
}