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cache.go
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cache.go
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// Copyright 2023 LY Corporation
//
// 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 token
import (
"fmt"
"strconv"
"strings"
"sync"
"time"
"unsafe"
"github.com/AthenZ/k8s-athenz-sia/v3/third_party/log"
"github.com/prometheus/client_golang/prometheus"
)
type TokenCache interface {
Store(k CacheKey, t Token)
Load(k CacheKey) Token
Range(func(k CacheKey, t Token) error) error
Keys() []CacheKey
Size() int64
Len() int
Clear()
}
type CacheKey struct {
Domain string
MaxExpiry int
MinExpiry int
ProxyForPrincipal string
Role string
}
// UniqueId returns a unique id of this token,
// ensuring that the id stays unique with Athenz naming rules.
// Athenz domain naming rule: "[a-zA-Z0-9_][a-zA-Z0-9_-]*")
// Athenz role naming rule: "[a-zA-Z0-9_][a-zA-Z0-9_-]*"
// and therefore delimiter "|" is used to separate domain and role for uniqueness.
func (k CacheKey) UniqueId(tokenType string) string {
d := "|" // delimiter; using not allowed character for domain/role
return strings.Join([]string{tokenType, k.Domain, k.Role, strconv.Itoa(k.MaxExpiry), strconv.Itoa(k.MinExpiry), k.ProxyForPrincipal}, d)
}
// String returns CacheKey's information in a string format, usually for logging purpose.
func (k CacheKey) String() string {
return fmt.Sprintf("{%s:role.%s,%s,%d,%d}", k.Domain, k.Role, k.ProxyForPrincipal, k.MinExpiry, k.MaxExpiry)
}
func (k CacheKey) Size() uint {
structSize := uint(unsafe.Sizeof(k))
// unsafe.Sizeof() ONLY count the string struct, need to count the actual string block explicitly
stringSize := len(k.Domain) + len(k.ProxyForPrincipal) + len(k.Role)
return structSize + uint(stringSize)
}
type LockedTokenCache struct {
cache map[CacheKey]Token
lock sync.RWMutex
// memoryUsage is the estimated number of bytes used by the cache.
memoryUsage int64
// tokenType is the type of token stored in the cache.
tokenType string
// namespace is the k8s namespace where the SIA is running.
namespace string
// podName is the k8s pod name where the SIA is running.
podName string
}
func NewLockedTokenCache(tokenType, namespace, podName string) *LockedTokenCache {
return &LockedTokenCache{
cache: make(map[CacheKey]Token),
memoryUsage: 0,
tokenType: tokenType,
namespace: namespace,
podName: podName,
}
}
func (c *LockedTokenCache) Store(k CacheKey, t Token) {
c.lock.Lock()
defer c.lock.Unlock()
oldToken, ok := c.cache[k]
c.cache[k] = t
// update cache memory usage
if ok {
// convert unsigned to signed to allow negative result
c.memoryUsage += int64(t.Size()) - int64(oldToken.Size())
} else {
c.memoryUsage += int64(t.Size() + k.Size())
}
}
func (c *LockedTokenCache) Load(k CacheKey) Token {
c.lock.RLock()
defer c.lock.RUnlock()
return c.cache[k]
}
func (c *LockedTokenCache) Range(f func(k CacheKey, t Token) error) error {
c.lock.RLock()
defer c.lock.RUnlock()
for key, token := range c.cache {
err := f(key, token)
if err != nil {
return err
}
}
return nil
}
func (c *LockedTokenCache) Keys() []CacheKey {
c.lock.RLock()
defer c.lock.RUnlock()
r := make([]CacheKey, 0, len(c.cache))
c.Range(func(k CacheKey, t Token) error {
r = append(r, k)
return nil
})
return r
}
func (c *LockedTokenCache) Size() int64 {
// structSize := uint(unsafe.Sizeof(*c)) // should equal to the following sizes
cacheSize := uint(unsafe.Sizeof(c.cache)) // not exact, there are hidden variables in map
lockSize := uint(unsafe.Sizeof(c.lock)) // not exact, there are hidden variables in sync.RWMutex
memSize := uint(unsafe.Sizeof(c.memoryUsage))
// estimate hidden bucket allocation by map
_, bSize := getMapBucketLenAndSize(c.cache)
return int64(cacheSize+lockSize+memSize) + c.memoryUsage + bSize
}
func (c *LockedTokenCache) Len() int {
return len(c.cache)
}
func (c *LockedTokenCache) Clear() {
c.lock.Lock()
defer c.lock.Unlock()
for t := range c.cache {
delete(c.cache, t)
// TODO: reset metrics on delete
}
c.memoryUsage = 0
}
var (
cachedTokenBytesMetric = "cached_token_bytes"
cachedTokenBytesHelp = "Number of bytes cached"
cachedTokenEntriesMetric = "cached_token_entries"
cachedTokenEntriesHelp = "Number of entries cached"
tokenExpiresInMetric = "token_expires_in_seconds"
tokenExpiresInHelp = "Indicates remaining time until the token expires"
)
func (c *LockedTokenCache) Describe(ch chan<- *prometheus.Desc) {
labelKeys := []string{"domain", "role"}
constLabels := prometheus.Labels{
"type": c.tokenType,
}
ch <- prometheus.NewDesc(cachedTokenBytesMetric, cachedTokenBytesHelp, nil, constLabels)
ch <- prometheus.NewDesc(cachedTokenEntriesMetric, cachedTokenEntriesHelp, nil, constLabels)
ch <- prometheus.NewDesc(tokenExpiresInMetric, tokenExpiresInHelp, labelKeys, constLabels)
}
func (c *LockedTokenCache) Collect(ch chan<- prometheus.Metric) {
c.lock.RLock()
defer c.lock.RUnlock()
constLabels := prometheus.Labels{
"type": c.tokenType,
}
// token cache metrics
var metric prometheus.Metric
var err error
metric, err = prometheus.NewConstMetric(
prometheus.NewDesc(cachedTokenBytesMetric, cachedTokenBytesHelp, nil, constLabels),
prometheus.GaugeValue,
float64(c.Size()),
)
if err != nil {
log.Errorf("Failed to create metric: %s", err.Error())
} else {
ch <- metric
}
metric, err = prometheus.NewConstMetric(
prometheus.NewDesc(cachedTokenEntriesMetric, cachedTokenEntriesHelp, nil, constLabels),
prometheus.GaugeValue,
float64(c.Len()),
)
if err != nil {
log.Errorf("Failed to create metric: %s", err.Error())
} else {
ch <- metric
}
// token expiry metrics
for k, t := range c.cache {
// skip placeholder token added during daemon creation
if t.Raw() == "" {
continue
}
labelKeys := []string{"domain", "role"}
labelValues := []string{k.Domain, k.Role}
if k.ProxyForPrincipal != "" {
labelKeys = append(labelKeys, "proxy_for_principal")
labelValues = append(labelValues, k.ProxyForPrincipal)
}
if k.MinExpiry != 0 {
labelKeys = append(labelKeys, "min_expiry")
labelValues = append(labelValues, fmt.Sprintf("%d", k.MinExpiry))
}
if k.MaxExpiry != 0 {
labelKeys = append(labelKeys, "max_expiry")
labelValues = append(labelValues, fmt.Sprintf("%d", k.MaxExpiry))
}
// only appends k8s_namespace as key if c.namespace exists
if c.namespace != "" {
labelKeys = append(labelKeys, "k8s_namespace")
labelValues = append(labelValues, c.namespace)
}
// only appends k8s_pod as key if c.podName exists
if c.podName != "" {
labelKeys = append(labelKeys, "k8s_pod")
labelValues = append(labelValues, c.podName)
}
metric, err := prometheus.NewConstMetric(
prometheus.NewDesc(tokenExpiresInMetric, tokenExpiresInHelp, labelKeys, constLabels),
prometheus.GaugeValue,
float64(time.Until(time.Unix(t.Expiry(), 0)).Seconds()),
labelValues...,
)
if err != nil {
log.Errorf("Failed to create metric: %s", err.Error())
continue
}
ch <- metric
}
}