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Adding mapping cache

Browse source 
Signed-off-by: SpencerMalone <malone.spencer@gmail.com>
This commit is contained in:
SpencerMalone 2019-04-03 11:36:34 -04:00
parent 54cf241044
commit 35d1a99592
20 changed files with 1531 additions and 42 deletions
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11
README.md
View file

@ -348,6 +348,17 @@ mappings:
Possible values for `match_metric_type` are `gauge`, `counter` and `timer`.
### Mapping cache size and cache replacement polixy
There is a cache used to improve the performance of the metric mapping, that can greatly improvement performance.
The cache has a default maximum of 1000 unique statsd metric names -> prometheus metrics mappings that it can store.
This maximum can be adjust using the `statsd.cache-size` flag.
If the maximum is reached, entries are rotated using the [least recently used replacement policy](https://en.wikipedia.org/wiki/Cache_replacement_policies#Least_recently_used_(LRU)).
If you are using this exporter to reduce the cardinality of your data, a high maximum cache size can be a costly use of memory.
### Time series expiration
The `ttl` parameter can be used to define the expiration time for stale metrics.

20
exporter_test.go
View file

@ -55,7 +55,10 @@ func TestNegativeCounter(t *testing.T) {
errorCounter := errorEventStats.WithLabelValues("illegal_negative_counter")
prev := getTelemetryCounterValue(errorCounter)
ex := NewExporter(&mapper.MetricMapper{})
testMapper := mapper.MetricMapper{}
testMapper.InitCache(0)
ex := NewExporter(&testMapper)
ex.Listen(events)
updated := getTelemetryCounterValue(errorCounter)
@ -131,7 +134,7 @@ mappings:
name: "histogram_test"
`
testMapper := &mapper.MetricMapper{}
err := testMapper.InitFromYAMLString(config)
err := testMapper.InitFromYAMLString(config, 0)
if err != nil {
t.Fatalf("Config load error: %s %s", config, err)
}
@ -180,7 +183,7 @@ mappings:
name: "${1}"
`
testMapper := &mapper.MetricMapper{}
err := testMapper.InitFromYAMLString(config)
err := testMapper.InitFromYAMLString(config, 0)
if err != nil {
t.Fatalf("Config load error: %s %s", config, err)
}
@ -218,7 +221,10 @@ func TestInvalidUtf8InDatadogTagValue(t *testing.T) {
close(events)
}()
ex := NewExporter(&mapper.MetricMapper{})
testMapper := mapper.MetricMapper{}
testMapper.InitCache(0)
ex := NewExporter(&testMapper)
ex.Listen(events)
}
@ -226,7 +232,9 @@ func TestHistogramUnits(t *testing.T) {
// Start exporter with a synchronous channel
events := make(chan Events)
go func() {
ex := NewExporter(&mapper.MetricMapper{})
testMapper := mapper.MetricMapper{}
testMapper.InitCache(0)
ex := NewExporter(&testMapper)
ex.mapper.Defaults.TimerType = mapper.TimerTypeHistogram
ex.Listen(events)
}()
@ -338,7 +346,7 @@ mappings:
`
// Create mapper from config and start an Exporter with a synchronous channel
testMapper := &mapper.MetricMapper{}
err := testMapper.InitFromYAMLString(config)
err := testMapper.InitFromYAMLString(config, 0)
if err != nil {
t.Fatalf("Config load error: %s %s", config, err)
}

1
go.mod
View file

@ -7,6 +7,7 @@ require (
github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc // indirect
github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf // indirect
github.com/davecgh/go-spew v1.1.1 // indirect
github.com/hashicorp/golang-lru v0.5.1
github.com/howeyc/fsnotify v0.0.0-20151003194602-f0c08ee9c607
github.com/kr/pretty v0.1.0 // indirect
github.com/mattn/go-isatty v0.0.4 // indirect

2
go.sum
View file

@ -16,6 +16,8 @@ github.com/fsnotify/fsnotify v1.4.7 h1:IXs+QLmnXW2CcXuY+8Mzv/fWEsPGWxqefPtCP5CnV
github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM=
github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
github.com/hashicorp/golang-lru v0.5.1 h1:0hERBMJE1eitiLkihrMvRVBYAkpHzc/J3QdDN+dAcgU=
github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
github.com/howeyc/fsnotify v0.0.0-20151003194602-f0c08ee9c607 h1:+7wvV++11s0Okyl1dekihkIiCIYDz+Qk2LvxAShINU4=
github.com/howeyc/fsnotify v0.0.0-20151003194602-f0c08ee9c607/go.mod h1:41HzSPxBGeFRQKEEwgh49TRw/nKBsYZ2cF1OzPjSJsA=
github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI=

11
main.go
View file

@ -91,7 +91,7 @@ func tcpAddrFromString(addr string) *net.TCPAddr {
}
}
func watchConfig(fileName string, mapper *mapper.MetricMapper) {
func watchConfig(fileName string, mapper *mapper.MetricMapper, cacheSize int) {
watcher, err := fsnotify.NewWatcher()
if err != nil {
log.Fatal(err)
@ -106,7 +106,7 @@ func watchConfig(fileName string, mapper *mapper.MetricMapper) {
select {
case ev := <-watcher.Event:
log.Infof("Config file changed (%s), attempting reload", ev)
err = mapper.InitFromFile(fileName)
err = mapper.InitFromFile(fileName, cacheSize)
if err != nil {
log.Errorln("Error reloading config:", err)
configLoads.WithLabelValues("failure").Inc()
@ -149,6 +149,7 @@ func main() {
statsdUnixSocketMode = kingpin.Flag("statsd.unixsocket-mode", "The permission mode of the unix socket.").Default("755").String()
mappingConfig = kingpin.Flag("statsd.mapping-config", "Metric mapping configuration file name.").String()
readBuffer = kingpin.Flag("statsd.read-buffer", "Size (in bytes) of the operating system's transmit read buffer associated with the UDP or Unixgram connection. Please make sure the kernel parameters net.core.rmem_max is set to a value greater than the value specified.").Int()
cacheSize = kingpin.Flag("statsd.cache-size", "Maximum size of your metric mapping cache. Relies on least recently used replacement policy if max size is reached.").Default("1000").Int()
dumpFSMPath = kingpin.Flag("debug.dump-fsm", "The path to dump internal FSM generated for glob matching as Dot file.").Default("").String()
)
@ -247,7 +248,7 @@ func main() {
mapper := &mapper.MetricMapper{MappingsCount: mappingsCount}
if *mappingConfig != "" {
err := mapper.InitFromFile(*mappingConfig)
err := mapper.InitFromFile(*mappingConfig, *cacheSize)
if err != nil {
log.Fatal("Error loading config:", err)
}
@ -257,7 +258,9 @@ func main() {
log.Fatal("Error dumping FSM:", err)
}
}
go watchConfig(*mappingConfig, mapper)
go watchConfig(*mappingConfig, mapper, *cacheSize)
} else {
mapper.InitCache(*cacheSize)
}
exporter := NewExporter(mapper)

42
pkg/mapper/mapper.go
View file

@ -20,6 +20,7 @@ import (
"sync"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/common/log"
"github.com/prometheus/statsd_exporter/pkg/mapper/fsm"
yaml "gopkg.in/yaml.v2"
"time"
@ -49,7 +50,8 @@ type MetricMapper struct {
FSM *fsm.FSM
doFSM bool
doRegex bool
mutex sync.Mutex
cache MetricMapperCache
mutex sync.RWMutex
MappingsCount prometheus.Gauge
}
@ -83,7 +85,7 @@ var defaultQuantiles = []metricObjective{
{Quantile: 0.99, Error: 0.001},
}
func (m *MetricMapper) InitFromYAMLString(fileContents string) error {
func (m *MetricMapper) InitFromYAMLString(fileContents string, cacheSize int) error {
var n MetricMapper
if err := yaml.Unmarshal([]byte(fileContents), &n); err != nil {
@ -189,6 +191,8 @@ func (m *MetricMapper) InitFromYAMLString(fileContents string) error {
m.Defaults = n.Defaults
m.Mappings = n.Mappings
m.InitCache(cacheSize)
if n.doFSM {
var mappings []string
for _, mapping := range n.Mappings {
@ -206,19 +210,37 @@ func (m *MetricMapper) InitFromYAMLString(fileContents string) error {
if m.MappingsCount != nil {
m.MappingsCount.Set(float64(len(n.Mappings)))
}
return nil
}
func (m *MetricMapper) InitFromFile(fileName string) error {
func (m *MetricMapper) InitFromFile(fileName string, cacheSize int) error {
mappingStr, err := ioutil.ReadFile(fileName)
if err != nil {
return err
}
return m.InitFromYAMLString(string(mappingStr))
return m.InitFromYAMLString(string(mappingStr), cacheSize)
}
func (m *MetricMapper) InitCache(cacheSize int) {
if cacheSize == 0 {
m.cache = NewMetricMapperNoopCache()
} else {
cache, err := NewMetricMapperCache(cacheSize)
if err != nil {
log.Fatalf("Unable to setup metric cache. Caused by: %s", err)
}
m.cache = cache
}
}
func (m *MetricMapper) GetMapping(statsdMetric string, statsdMetricType MetricType) (*MetricMapping, prometheus.Labels, bool) {
m.mutex.RLock()
defer m.mutex.RUnlock()
result, cached := m.cache.Get(statsdMetric)
if cached {
return result.Mapping, result.Labels, result.Matched
}
// glob matching
if m.doFSM {
finalState, captures := m.FSM.GetMapping(statsdMetric, string(statsdMetricType))
@ -230,17 +252,18 @@ func (m *MetricMapper) GetMapping(statsdMetric string, statsdMetricType MetricTy
for index, formatter := range result.labelFormatters {
labels[result.labelKeys[index]] = formatter.Format(captures)
}
m.cache.AddMatch(statsdMetric, result, labels)
return result, labels, true
} else if !m.doRegex {
// if there's no regex match type, return immediately
m.cache.AddMiss(statsdMetric)
return nil, nil, false
}
}
// regex matching
m.mutex.Lock()
defer m.mutex.Unlock()
for _, mapping := range m.Mappings {
// if a rule don't have regex matching type, the regex field is unset
if mapping.regex == nil {
@ -268,8 +291,11 @@ func (m *MetricMapper) GetMapping(statsdMetric string, statsdMetricType MetricTy
labels[label] = string(value)
}
m.cache.AddMatch(statsdMetric, &mapping, labels)
return &mapping, labels, true
}
m.cache.AddMiss(statsdMetric)
return nil, nil, false
}

153
pkg/mapper/mapper_benchmark_test.go
View file

@ -104,7 +104,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -168,7 +168,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -239,7 +239,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -303,7 +303,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -330,7 +330,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -358,7 +358,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -384,7 +384,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -411,7 +411,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -437,7 +437,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -464,7 +464,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -501,7 +501,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -539,7 +539,7 @@ mappings:
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -560,7 +560,28 @@ mappings:` + duplicateRules(100, ruleTemplateSingleMatchGlob)
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
b.ResetTimer()
for j := 0; j < b.N; j++ {
for _, metric := range mappings {
mapper.GetMapping(metric, MetricTypeCounter)
}
}
}
func BenchmarkGlob10RulesCached(b *testing.B) {
config := `---
mappings:` + duplicateRules(100, ruleTemplateSingleMatchGlob)
mappings := []string{
"metric100.a",
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config, 1000)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -583,7 +604,30 @@ mappings:` + duplicateRules(10, ruleTemplateSingleMatchRegex)
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
b.ResetTimer()
for j := 0; j < b.N; j++ {
for _, metric := range mappings {
mapper.GetMapping(metric, MetricTypeCounter)
}
}
}
func BenchmarkRegex10RulesAverageCached(b *testing.B) {
config := `---
defaults:
match_type: regex
mappings:` + duplicateRules(10, ruleTemplateSingleMatchRegex)
mappings := []string{
"metric5.a",
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config, 1000)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -604,7 +648,28 @@ mappings:` + duplicateRules(100, ruleTemplateSingleMatchGlob)
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
b.ResetTimer()
for j := 0; j < b.N; j++ {
for _, metric := range mappings {
mapper.GetMapping(metric, MetricTypeCounter)
}
}
}
func BenchmarkGlob100RulesCached(b *testing.B) {
config := `---
mappings:` + duplicateRules(100, ruleTemplateSingleMatchGlob)
mappings := []string{
"metric100.a",
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config, 1000)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -625,7 +690,7 @@ mappings:` + duplicateRules(100, ruleTemplateSingleMatchGlob)
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -648,7 +713,7 @@ mappings:` + duplicateRules(100, ruleTemplateSingleMatchGlob)
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -671,7 +736,7 @@ mappings:` + duplicateRules(100, ruleTemplateSingleMatchRegex)
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -694,7 +759,7 @@ mappings:` + duplicateRules(100, ruleTemplateSingleMatchRegex)
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -715,7 +780,28 @@ mappings:` + duplicateRules(100, ruleTemplateMultipleMatchGlob)
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
b.ResetTimer()
for j := 0; j < b.N; j++ {
for _, metric := range mappings {
mapper.GetMapping(metric, MetricTypeCounter)
}
}
}
func BenchmarkGlob100RulesMultipleCapturesCached(b *testing.B) {
config := `---
mappings:` + duplicateRules(100, ruleTemplateMultipleMatchGlob)
mappings := []string{
"metric50.a.b.c.d.e.f.g.h.i.j.k.l",
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config, 1000)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -738,7 +824,7 @@ mappings:` + duplicateRules(100, ruleTemplateMultipleMatchRegex)
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
@ -761,7 +847,30 @@ mappings:` + duplicateRules(100, ruleTemplateMultipleMatchRegex)
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config)
err := mapper.InitFromYAMLString(config, 0)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}
b.ResetTimer()
for j := 0; j < b.N; j++ {
for _, metric := range mappings {
mapper.GetMapping(metric, MetricTypeCounter)
}
}
}
func BenchmarkRegex100RulesMultipleCapturesWorstCached(b *testing.B) {
config := `---
defaults:
match_type: regex
mappings:` + duplicateRules(100, ruleTemplateMultipleMatchRegex)
mappings := []string{
"metric100.a.b.c.d.e.f.g.h.i.j.k.l",
}
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(config, 1000)
if err != nil {
b.Fatalf("Config load error: %s %s", config, err)
}

101
pkg/mapper/mapper_cache.go Normal file
View file

@ -0,0 +1,101 @@
// Copyright 2019 The Prometheus 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 mapper
import (
"github.com/hashicorp/golang-lru"
"github.com/prometheus/client_golang/prometheus"
)
var (
cacheLength = prometheus.NewGauge(
prometheus.GaugeOpts{
Name: "statsd_exporter_cache_length",
Help: "The count of unique metrics currently cached.",
},
)
)
type MetricMapperCacheResult struct {
Mapping *MetricMapping
Matched bool
Labels prometheus.Labels
}
type MetricMapperCache interface {
Get(metricString string) (*MetricMapperCacheResult, bool)
AddMatch(metricString string, mapping *MetricMapping, labels prometheus.Labels)
AddMiss(metricString string)
}
type MetricMapperLRUCache struct {
MetricMapperCache
cache *lru.Cache
}
type MetricMapperNoopCache struct {
MetricMapperCache
}
func NewMetricMapperCache(size int) (*MetricMapperLRUCache, error) {
cacheLength.Set(0)
cache, err := lru.New(size)
if err != nil {
return &MetricMapperLRUCache{}, err
}
return &MetricMapperLRUCache{cache: cache}, nil
}
func (m *MetricMapperLRUCache) Get(metricString string) (*MetricMapperCacheResult, bool) {
if result, ok := m.cache.Get(metricString); ok {
return result.(*MetricMapperCacheResult), true
} else {
return nil, false
}
}
func (m *MetricMapperLRUCache) AddMatch(metricString string, mapping *MetricMapping, labels prometheus.Labels) {
go m.trackCacheLength()
m.cache.Add(metricString, &MetricMapperCacheResult{Mapping: mapping, Matched: true, Labels: labels})
}
func (m *MetricMapperLRUCache) AddMiss(metricString string) {
go m.trackCacheLength()
m.cache.Add(metricString, &MetricMapperCacheResult{Matched: false})
}
func (m *MetricMapperLRUCache) trackCacheLength() {
cacheLength.Set(float64(m.cache.Len()))
}
func NewMetricMapperNoopCache() *MetricMapperNoopCache {
cacheLength.Set(0)
return &MetricMapperNoopCache{}
}
func (m *MetricMapperNoopCache) Get(metricString string) (*MetricMapperCacheResult, bool) {
return nil, false
}
func (m *MetricMapperNoopCache) AddMatch(metricString string, mapping *MetricMapping, labels prometheus.Labels) {
return
}
func (m *MetricMapperNoopCache) AddMiss(metricString string) {
return
}
func init() {
prometheus.MustRegister(cacheLength)
}

4
pkg/mapper/mapper_test.go
View file

@ -669,7 +669,7 @@ mappings:
mapper := MetricMapper{}
for i, scenario := range scenarios {
err := mapper.InitFromYAMLString(scenario.config)
err := mapper.InitFromYAMLString(scenario.config, 0)
if err != nil && !scenario.configBad {
t.Fatalf("%d. Config load error: %s %s", i, scenario.config, err)
}
@ -769,7 +769,7 @@ mappings:
for i, scenario := range scenarios {
mapper := MetricMapper{}
err := mapper.InitFromYAMLString(scenario.config)
err := mapper.InitFromYAMLString(scenario.config, 0)
if err != nil && !scenario.configBad {
t.Fatalf("%d. Config load error: %s %s", i, scenario.config, err)
}

23
vendor/github.com/hashicorp/golang-lru/.gitignore generated vendored Normal file
View file

@ -0,0 +1,23 @@
# Compiled Object files, Static and Dynamic libs (Shared Objects)
*.o
*.a
*.so
# Folders
_obj
_test
# Architecture specific extensions/prefixes
*.[568vq]
[568vq].out
*.cgo1.go
*.cgo2.c
_cgo_defun.c
_cgo_gotypes.go
_cgo_export.*
_testmain.go
*.exe
*.test

223
vendor/github.com/hashicorp/golang-lru/2q.go generated vendored Normal file
View file

@ -0,0 +1,223 @@
package lru
import (
"fmt"
"sync"
"github.com/hashicorp/golang-lru/simplelru"
)
const (
// Default2QRecentRatio is the ratio of the 2Q cache dedicated
// to recently added entries that have only been accessed once.
Default2QRecentRatio = 0.25
// Default2QGhostEntries is the default ratio of ghost
// entries kept to track entries recently evicted
Default2QGhostEntries = 0.50
)
// TwoQueueCache is a thread-safe fixed size 2Q cache.
// 2Q is an enhancement over the standard LRU cache
// in that it tracks both frequently and recently used
// entries separately. This avoids a burst in access to new
// entries from evicting frequently used entries. It adds some
// additional tracking overhead to the standard LRU cache, and is
// computationally about 2x the cost, and adds some metadata over
// head. The ARCCache is similar, but does not require setting any
// parameters.
type TwoQueueCache struct {
size int
recentSize int
recent simplelru.LRUCache
frequent simplelru.LRUCache
recentEvict simplelru.LRUCache
lock sync.RWMutex
}
// New2Q creates a new TwoQueueCache using the default
// values for the parameters.
func New2Q(size int) (*TwoQueueCache, error) {
return New2QParams(size, Default2QRecentRatio, Default2QGhostEntries)
}
// New2QParams creates a new TwoQueueCache using the provided
// parameter values.
func New2QParams(size int, recentRatio float64, ghostRatio float64) (*TwoQueueCache, error) {
if size <= 0 {
return nil, fmt.Errorf("invalid size")
}
if recentRatio < 0.0 || recentRatio > 1.0 {
return nil, fmt.Errorf("invalid recent ratio")
}
if ghostRatio < 0.0 || ghostRatio > 1.0 {
return nil, fmt.Errorf("invalid ghost ratio")
}
// Determine the sub-sizes
recentSize := int(float64(size) * recentRatio)
evictSize := int(float64(size) * ghostRatio)
// Allocate the LRUs
recent, err := simplelru.NewLRU(size, nil)
if err != nil {
return nil, err
}
frequent, err := simplelru.NewLRU(size, nil)
if err != nil {
return nil, err
}
recentEvict, err := simplelru.NewLRU(evictSize, nil)
if err != nil {
return nil, err
}
// Initialize the cache
c := &TwoQueueCache{
size: size,
recentSize: recentSize,
recent: recent,
frequent: frequent,
recentEvict: recentEvict,
}
return c, nil
}
// Get looks up a key's value from the cache.
func (c *TwoQueueCache) Get(key interface{}) (value interface{}, ok bool) {
c.lock.Lock()
defer c.lock.Unlock()
// Check if this is a frequent value
if val, ok := c.frequent.Get(key); ok {
return val, ok
}
// If the value is contained in recent, then we
// promote it to frequent
if val, ok := c.recent.Peek(key); ok {
c.recent.Remove(key)
c.frequent.Add(key, val)
return val, ok
}
// No hit
return nil, false
}
// Add adds a value to the cache.
func (c *TwoQueueCache) Add(key, value interface{}) {
c.lock.Lock()
defer c.lock.Unlock()
// Check if the value is frequently used already,
// and just update the value
if c.frequent.Contains(key) {
c.frequent.Add(key, value)
return
}
// Check if the value is recently used, and promote
// the value into the frequent list
if c.recent.Contains(key) {
c.recent.Remove(key)
c.frequent.Add(key, value)
return
}
// If the value was recently evicted, add it to the
// frequently used list
if c.recentEvict.Contains(key) {
c.ensureSpace(true)
c.recentEvict.Remove(key)
c.frequent.Add(key, value)
return
}
// Add to the recently seen list
c.ensureSpace(false)
c.recent.Add(key, value)
return
}
// ensureSpace is used to ensure we have space in the cache
func (c *TwoQueueCache) ensureSpace(recentEvict bool) {
// If we have space, nothing to do
recentLen := c.recent.Len()
freqLen := c.frequent.Len()
if recentLen+freqLen < c.size {
return
}
// If the recent buffer is larger than
// the target, evict from there
if recentLen > 0 && (recentLen > c.recentSize || (recentLen == c.recentSize && !recentEvict)) {
k, _, _ := c.recent.RemoveOldest()
c.recentEvict.Add(k, nil)
return
}
// Remove from the frequent list otherwise
c.frequent.RemoveOldest()
}
// Len returns the number of items in the cache.
func (c *TwoQueueCache) Len() int {
c.lock.RLock()
defer c.lock.RUnlock()
return c.recent.Len() + c.frequent.Len()
}
// Keys returns a slice of the keys in the cache.
// The frequently used keys are first in the returned slice.
func (c *TwoQueueCache) Keys() []interface{} {
c.lock.RLock()
defer c.lock.RUnlock()
k1 := c.frequent.Keys()
k2 := c.recent.Keys()
return append(k1, k2...)
}
// Remove removes the provided key from the cache.
func (c *TwoQueueCache) Remove(key interface{}) {
c.lock.Lock()
defer c.lock.Unlock()
if c.frequent.Remove(key) {
return
}
if c.recent.Remove(key) {
return
}
if c.recentEvict.Remove(key) {
return
}
}
// Purge is used to completely clear the cache.
func (c *TwoQueueCache) Purge() {
c.lock.Lock()
defer c.lock.Unlock()
c.recent.Purge()
c.frequent.Purge()
c.recentEvict.Purge()
}
// Contains is used to check if the cache contains a key
// without updating recency or frequency.
func (c *TwoQueueCache) Contains(key interface{}) bool {
c.lock.RLock()
defer c.lock.RUnlock()
return c.frequent.Contains(key) || c.recent.Contains(key)
}
// Peek is used to inspect the cache value of a key
// without updating recency or frequency.
func (c *TwoQueueCache) Peek(key interface{}) (value interface{}, ok bool) {
c.lock.RLock()
defer c.lock.RUnlock()
if val, ok := c.frequent.Peek(key); ok {
return val, ok
}
return c.recent.Peek(key)
}

362
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Mozilla Public License, version 2.0
1. Definitions
1.1. "Contributor"
means each individual or legal entity that creates, contributes to the
creation of, or owns Covered Software.
1.2. "Contributor Version"
means the combination of the Contributions of others (if any) used by a
Contributor and that particular Contributor's Contribution.
1.3. "Contribution"
means Covered Software of a particular Contributor.
1.4. "Covered Software"
means Source Code Form to which the initial Contributor has attached the
notice in Exhibit A, the Executable Form of such Source Code Form, and
Modifications of such Source Code Form, in each case including portions
thereof.
1.5. "Incompatible With Secondary Licenses"
means
a. that the initial Contributor has attached the notice described in
Exhibit B to the Covered Software; or
b. that the Covered Software was made available under the terms of
version 1.1 or earlier of the License, but not also under the terms of
a Secondary License.
1.6. "Executable Form"
means any form of the work other than Source Code Form.
1.7. "Larger Work"
means a work that combines Covered Software with other material, in a
separate file or files, that is not Covered Software.
1.8. "License"
means this document.
1.9. "Licensable"
means having the right to grant, to the maximum extent possible, whether
at the time of the initial grant or subsequently, any and all of the
rights conveyed by this License.
1.10. "Modifications"
means any of the following:
a. any file in Source Code Form that results from an addition to,
deletion from, or modification of the contents of Covered Software; or
b. any new file in Source Code Form that contains any Covered Software.
1.11. "Patent Claims" of a Contributor
means any patent claim(s), including without limitation, method,
process, and apparatus claims, in any patent Licensable by such
Contributor that would be infringed, but for the grant of the License,
by the making, using, selling, offering for sale, having made, import,
or transfer of either its Contributions or its Contributor Version.
1.12. "Secondary License"
means either the GNU General Public License, Version 2.0, the GNU Lesser
General Public License, Version 2.1, the GNU Affero General Public
License, Version 3.0, or any later versions of those licenses.
1.13. "Source Code Form"
means the form of the work preferred for making modifications.
1.14. "You" (or "Your")
means an individual or a legal entity exercising rights under this
License. For legal entities, "You" includes any entity that controls, is
controlled by, or is under common control with You. For purposes of this
definition, "control" means (a) the power, direct or indirect, to cause
the direction or management of such entity, whether by contract or
otherwise, or (b) ownership of more than fifty percent (50%) of the
outstanding shares or beneficial ownership of such entity.
2. License Grants and Conditions
2.1. Grants
Each Contributor hereby grants You a world-wide, royalty-free,
non-exclusive license:
a. under intellectual property rights (other than patent or trademark)
Licensable by such Contributor to use, reproduce, make available,
modify, display, perform, distribute, and otherwise exploit its
Contributions, either on an unmodified basis, with Modifications, or
as part of a Larger Work; and
b. under Patent Claims of such Contributor to make, use, sell, offer for
sale, have made, import, and otherwise transfer either its
Contributions or its Contributor Version.
2.2. Effective Date
The licenses granted in Section 2.1 with respect to any Contribution
become effective for each Contribution on the date the Contributor first
distributes such Contribution.
2.3. Limitations on Grant Scope
The licenses granted in this Section 2 are the only rights granted under
this License. No additional rights or licenses will be implied from the
distribution or licensing of Covered Software under this License.
Notwithstanding Section 2.1(b) above, no patent license is granted by a
Contributor:
a. for any code that a Contributor has removed from Covered Software; or
b. for infringements caused by: (i) Your and any other third party's
modifications of Covered Software, or (ii) the combination of its
Contributions with other software (except as part of its Contributor
Version); or
c. under Patent Claims infringed by Covered Software in the absence of
its Contributions.
This License does not grant any rights in the trademarks, service marks,
or logos of any Contributor (except as may be necessary to comply with
the notice requirements in Section 3.4).
2.4. Subsequent Licenses
No Contributor makes additional grants as a result of Your choice to
distribute the Covered Software under a subsequent version of this
License (see Section 10.2) or under the terms of a Secondary License (if
permitted under the terms of Section 3.3).
2.5. Representation
Each Contributor represents that the Contributor believes its
Contributions are its original creation(s) or it has sufficient rights to
grant the rights to its Contributions conveyed by this License.
2.6. Fair Use
This License is not intended to limit any rights You have under
applicable copyright doctrines of fair use, fair dealing, or other
equivalents.
2.7. Conditions
Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted in
Section 2.1.
3. Responsibilities
3.1. Distribution of Source Form
All distribution of Covered Software in Source Code Form, including any
Modifications that You create or to which You contribute, must be under
the terms of this License. You must inform recipients that the Source
Code Form of the Covered Software is governed by the terms of this
License, and how they can obtain a copy of this License. You may not
attempt to alter or restrict the recipients' rights in the Source Code
Form.
3.2. Distribution of Executable Form
If You distribute Covered Software in Executable Form then:
a. such Covered Software must also be made available in Source Code Form,
as described in Section 3.1, and You must inform recipients of the
Executable Form how they can obtain a copy of such Source Code Form by
reasonable means in a timely manner, at a charge no more than the cost
of distribution to the recipient; and
b. You may distribute such Executable Form under the terms of this
License, or sublicense it under different terms, provided that the
license for the Executable Form does not attempt to limit or alter the
recipients' rights in the Source Code Form under this License.
3.3. Distribution of a Larger Work
You may create and distribute a Larger Work under terms of Your choice,
provided that You also comply with the requirements of this License for
the Covered Software. If the Larger Work is a combination of Covered
Software with a work governed by one or more Secondary Licenses, and the
Covered Software is not Incompatible With Secondary Licenses, this
License permits You to additionally distribute such Covered Software
under the terms of such Secondary License(s), so that the recipient of
the Larger Work may, at their option, further distribute the Covered
Software under the terms of either this License or such Secondary
License(s).
3.4. Notices
You may not remove or alter the substance of any license notices
(including copyright notices, patent notices, disclaimers of warranty, or
limitations of liability) contained within the Source Code Form of the
Covered Software, except that You may alter any license notices to the
extent required to remedy known factual inaccuracies.
3.5. Application of Additional Terms
You may choose to offer, and to charge a fee for, warranty, support,
indemnity or liability obligations to one or more recipients of Covered
Software. However, You may do so only on Your own behalf, and not on
behalf of any Contributor. You must make it absolutely clear that any
such warranty, support, indemnity, or liability obligation is offered by
You alone, and You hereby agree to indemnify every Contributor for any
liability incurred by such Contributor as a result of warranty, support,
indemnity or liability terms You offer. You may include additional
disclaimers of warranty and limitations of liability specific to any
jurisdiction.
4. Inability to Comply Due to Statute or Regulation
If it is impossible for You to comply with any of the terms of this License
with respect to some or all of the Covered Software due to statute,
judicial order, or regulation then You must: (a) comply with the terms of
this License to the maximum extent possible; and (b) describe the
limitations and the code they affect. Such description must be placed in a
text file included with all distributions of the Covered Software under
this License. Except to the extent prohibited by statute or regulation,
such description must be sufficiently detailed for a recipient of ordinary
skill to be able to understand it.
5. Termination
5.1. The rights granted under this License will terminate automatically if You
fail to comply with any of its terms. However, if You become compliant,
then the rights granted under this License from a particular Contributor
are reinstated (a) provisionally, unless and until such Contributor
explicitly and finally terminates Your grants, and (b) on an ongoing
basis, if such Contributor fails to notify You of the non-compliance by
some reasonable means prior to 60 days after You have come back into
compliance. Moreover, Your grants from a particular Contributor are
reinstated on an ongoing basis if such Contributor notifies You of the
non-compliance by some reasonable means, this is the first time You have
received notice of non-compliance with this License from such
Contributor, and You become compliant prior to 30 days after Your receipt
of the notice.
5.2. If You initiate litigation against any entity by asserting a patent
infringement claim (excluding declaratory judgment actions,
counter-claims, and cross-claims) alleging that a Contributor Version
directly or indirectly infringes any patent, then the rights granted to
You by any and all Contributors for the Covered Software under Section
2.1 of this License shall terminate.
5.3. In the event of termination under Sections 5.1 or 5.2 above, all end user
license agreements (excluding distributors and resellers) which have been
validly granted by You or Your distributors under this License prior to
termination shall survive termination.
6. Disclaimer of Warranty
Covered Software is provided under this License on an "as is" basis,
without warranty of any kind, either expressed, implied, or statutory,
including, without limitation, warranties that the Covered Software is free
of defects, merchantable, fit for a particular purpose or non-infringing.
The entire risk as to the quality and performance of the Covered Software
is with You. Should any Covered Software prove defective in any respect,
You (not any Contributor) assume the cost of any necessary servicing,
repair, or correction. This disclaimer of warranty constitutes an essential
part of this License. No use of any Covered Software is authorized under
this License except under this disclaimer.
7. Limitation of Liability
Under no circumstances and under no legal theory, whether tort (including
negligence), contract, or otherwise, shall any Contributor, or anyone who
distributes Covered Software as permitted above, be liable to You for any
direct, indirect, special, incidental, or consequential damages of any
character including, without limitation, damages for lost profits, loss of
goodwill, work stoppage, computer failure or malfunction, or any and all
other commercial damages or losses, even if such party shall have been
informed of the possibility of such damages. This limitation of liability
shall not apply to liability for death or personal injury resulting from
such party's negligence to the extent applicable law prohibits such
limitation. Some jurisdictions do not allow the exclusion or limitation of
incidental or consequential damages, so this exclusion and limitation may
not apply to You.
8. Litigation
Any litigation relating to this License may be brought only in the courts
of a jurisdiction where the defendant maintains its principal place of
business and such litigation shall be governed by laws of that
jurisdiction, without reference to its conflict-of-law provisions. Nothing
in this Section shall prevent a party's ability to bring cross-claims or
counter-claims.
9. Miscellaneous
This License represents the complete agreement concerning the subject
matter hereof. If any provision of this License is held to be
unenforceable, such provision shall be reformed only to the extent
necessary to make it enforceable. Any law or regulation which provides that
the language of a contract shall be construed against the drafter shall not
be used to construe this License against a Contributor.
10. Versions of the License
10.1. New Versions
Mozilla Foundation is the license steward. Except as provided in Section
10.3, no one other than the license steward has the right to modify or
publish new versions of this License. Each version will be given a
distinguishing version number.
10.2. Effect of New Versions
You may distribute the Covered Software under the terms of the version
of the License under which You originally received the Covered Software,
or under the terms of any subsequent version published by the license
steward.
10.3. Modified Versions
If you create software not governed by this License, and you want to
create a new license for such software, you may create and use a
modified version of this License if you rename the license and remove
any references to the name of the license steward (except to note that
such modified license differs from this License).
10.4. Distributing Source Code Form that is Incompatible With Secondary
Licenses If You choose to distribute Source Code Form that is
Incompatible With Secondary Licenses under the terms of this version of
the License, the notice described in Exhibit B of this License must be
attached.
Exhibit A - Source Code Form License Notice
This Source Code Form is subject to the
terms of the Mozilla Public License, v.
2.0. If a copy of the MPL was not
distributed with this file, You can
obtain one at
http://mozilla.org/MPL/2.0/.
If it is not possible or desirable to put the notice in a particular file,
then You may include the notice in a location (such as a LICENSE file in a
relevant directory) where a recipient would be likely to look for such a
notice.
You may add additional accurate notices of copyright ownership.
Exhibit B - "Incompatible With Secondary Licenses" Notice
This Source Code Form is "Incompatible
With Secondary Licenses", as defined by
the Mozilla Public License, v. 2.0.

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golang-lru
==========
This provides the `lru` package which implements a fixed-size
thread safe LRU cache. It is based on the cache in Groupcache.
Documentation
=============
Full docs are available on [Godoc](http://godoc.org/github.com/hashicorp/golang-lru)
Example
=======
Using the LRU is very simple:
```go
l, _ := New(128)
for i := 0; i < 256; i++ {
l.Add(i, nil)
}
if l.Len() != 128 {
panic(fmt.Sprintf("bad len: %v", l.Len()))
}
```

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package lru
import (
"sync"
"github.com/hashicorp/golang-lru/simplelru"
)
// ARCCache is a thread-safe fixed size Adaptive Replacement Cache (ARC).
// ARC is an enhancement over the standard LRU cache in that tracks both
// frequency and recency of use. This avoids a burst in access to new
// entries from evicting the frequently used older entries. It adds some
// additional tracking overhead to a standard LRU cache, computationally
// it is roughly 2x the cost, and the extra memory overhead is linear
// with the size of the cache. ARC has been patented by IBM, but is
// similar to the TwoQueueCache (2Q) which requires setting parameters.
type ARCCache struct {
size int // Size is the total capacity of the cache
p int // P is the dynamic preference towards T1 or T2
t1 simplelru.LRUCache // T1 is the LRU for recently accessed items
b1 simplelru.LRUCache // B1 is the LRU for evictions from t1
t2 simplelru.LRUCache // T2 is the LRU for frequently accessed items
b2 simplelru.LRUCache // B2 is the LRU for evictions from t2
lock sync.RWMutex
}
// NewARC creates an ARC of the given size
func NewARC(size int) (*ARCCache, error) {
// Create the sub LRUs
b1, err := simplelru.NewLRU(size, nil)
if err != nil {
return nil, err
}
b2, err := simplelru.NewLRU(size, nil)
if err != nil {
return nil, err
}
t1, err := simplelru.NewLRU(size, nil)
if err != nil {
return nil, err
}
t2, err := simplelru.NewLRU(size, nil)
if err != nil {
return nil, err
}
// Initialize the ARC
c := &ARCCache{
size: size,
p: 0,
t1: t1,
b1: b1,
t2: t2,
b2: b2,
}
return c, nil
}
// Get looks up a key's value from the cache.
func (c *ARCCache) Get(key interface{}) (value interface{}, ok bool) {
c.lock.Lock()
defer c.lock.Unlock()
// If the value is contained in T1 (recent), then
// promote it to T2 (frequent)
if val, ok := c.t1.Peek(key); ok {
c.t1.Remove(key)
c.t2.Add(key, val)
return val, ok
}
// Check if the value is contained in T2 (frequent)
if val, ok := c.t2.Get(key); ok {
return val, ok
}
// No hit
return nil, false
}
// Add adds a value to the cache.
func (c *ARCCache) Add(key, value interface{}) {
c.lock.Lock()
defer c.lock.Unlock()
// Check if the value is contained in T1 (recent), and potentially
// promote it to frequent T2
if c.t1.Contains(key) {
c.t1.Remove(key)
c.t2.Add(key, value)
return
}
// Check if the value is already in T2 (frequent) and update it
if c.t2.Contains(key) {
c.t2.Add(key, value)
return
}
// Check if this value was recently evicted as part of the
// recently used list
if c.b1.Contains(key) {
// T1 set is too small, increase P appropriately
delta := 1
b1Len := c.b1.Len()
b2Len := c.b2.Len()
if b2Len > b1Len {
delta = b2Len / b1Len
}
if c.p+delta >= c.size {
c.p = c.size
} else {
c.p += delta
}
// Potentially need to make room in the cache
if c.t1.Len()+c.t2.Len() >= c.size {
c.replace(false)
}
// Remove from B1
c.b1.Remove(key)
// Add the key to the frequently used list
c.t2.Add(key, value)
return
}
// Check if this value was recently evicted as part of the
// frequently used list
if c.b2.Contains(key) {
// T2 set is too small, decrease P appropriately
delta := 1
b1Len := c.b1.Len()
b2Len := c.b2.Len()
if b1Len > b2Len {
delta = b1Len / b2Len
}
if delta >= c.p {
c.p = 0
} else {
c.p -= delta
}
// Potentially need to make room in the cache
if c.t1.Len()+c.t2.Len() >= c.size {
c.replace(true)
}
// Remove from B2
c.b2.Remove(key)
// Add the key to the frequently used list
c.t2.Add(key, value)
return
}
// Potentially need to make room in the cache
if c.t1.Len()+c.t2.Len() >= c.size {
c.replace(false)
}
// Keep the size of the ghost buffers trim
if c.b1.Len() > c.size-c.p {
c.b1.RemoveOldest()
}
if c.b2.Len() > c.p {
c.b2.RemoveOldest()
}
// Add to the recently seen list
c.t1.Add(key, value)
return
}
// replace is used to adaptively evict from either T1 or T2
// based on the current learned value of P
func (c *ARCCache) replace(b2ContainsKey bool) {
t1Len := c.t1.Len()
if t1Len > 0 && (t1Len > c.p || (t1Len == c.p && b2ContainsKey)) {
k, _, ok := c.t1.RemoveOldest()
if ok {
c.b1.Add(k, nil)
}
} else {
k, _, ok := c.t2.RemoveOldest()
if ok {
c.b2.Add(k, nil)
}
}
}
// Len returns the number of cached entries
func (c *ARCCache) Len() int {
c.lock.RLock()
defer c.lock.RUnlock()
return c.t1.Len() + c.t2.Len()
}
// Keys returns all the cached keys
func (c *ARCCache) Keys() []interface{} {
c.lock.RLock()
defer c.lock.RUnlock()
k1 := c.t1.Keys()
k2 := c.t2.Keys()
return append(k1, k2...)
}
// Remove is used to purge a key from the cache
func (c *ARCCache) Remove(key interface{}) {
c.lock.Lock()
defer c.lock.Unlock()
if c.t1.Remove(key) {
return
}
if c.t2.Remove(key) {
return
}
if c.b1.Remove(key) {
return
}
if c.b2.Remove(key) {
return
}
}
// Purge is used to clear the cache
func (c *ARCCache) Purge() {
c.lock.Lock()
defer c.lock.Unlock()
c.t1.Purge()
c.t2.Purge()
c.b1.Purge()
c.b2.Purge()
}
// Contains is used to check if the cache contains a key
// without updating recency or frequency.
func (c *ARCCache) Contains(key interface{}) bool {
c.lock.RLock()
defer c.lock.RUnlock()
return c.t1.Contains(key) || c.t2.Contains(key)
}
// Peek is used to inspect the cache value of a key
// without updating recency or frequency.
func (c *ARCCache) Peek(key interface{}) (value interface{}, ok bool) {
c.lock.RLock()
defer c.lock.RUnlock()
if val, ok := c.t1.Peek(key); ok {
return val, ok
}
return c.t2.Peek(key)
}

21
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// Package lru provides three different LRU caches of varying sophistication.
//
// Cache is a simple LRU cache. It is based on the
// LRU implementation in groupcache:
// https://github.com/golang/groupcache/tree/master/lru
//
// TwoQueueCache tracks frequently used and recently used entries separately.
// This avoids a burst of accesses from taking out frequently used entries,
// at the cost of about 2x computational overhead and some extra bookkeeping.
//
// ARCCache is an adaptive replacement cache. It tracks recent evictions as
// well as recent usage in both the frequent and recent caches. Its
// computational overhead is comparable to TwoQueueCache, but the memory
// overhead is linear with the size of the cache.
//
// ARC has been patented by IBM, so do not use it if that is problematic for
// your program.
//
// All caches in this package take locks while operating, and are therefore
// thread-safe for consumers.
package lru

1
vendor/github.com/hashicorp/golang-lru/go.mod generated vendored Normal file
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@ -0,0 +1 @@
module github.com/hashicorp/golang-lru

116
vendor/github.com/hashicorp/golang-lru/lru.go generated vendored Normal file
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package lru
import (
"sync"
"github.com/hashicorp/golang-lru/simplelru"
)
// Cache is a thread-safe fixed size LRU cache.
type Cache struct {
lru simplelru.LRUCache
lock sync.RWMutex
}
// New creates an LRU of the given size.
func New(size int) (*Cache, error) {
return NewWithEvict(size, nil)
}
// NewWithEvict constructs a fixed size cache with the given eviction
// callback.
func NewWithEvict(size int, onEvicted func(key interface{}, value interface{})) (*Cache, error) {
lru, err := simplelru.NewLRU(size, simplelru.EvictCallback(onEvicted))
if err != nil {
return nil, err
}
c := &Cache{
lru: lru,
}
return c, nil
}
// Purge is used to completely clear the cache.
func (c *Cache) Purge() {
c.lock.Lock()
c.lru.Purge()
c.lock.Unlock()
}
// Add adds a value to the cache. Returns true if an eviction occurred.
func (c *Cache) Add(key, value interface{}) (evicted bool) {
c.lock.Lock()
evicted = c.lru.Add(key, value)
c.lock.Unlock()
return evicted
}
// Get looks up a key's value from the cache.
func (c *Cache) Get(key interface{}) (value interface{}, ok bool) {
c.lock.Lock()
value, ok = c.lru.Get(key)
c.lock.Unlock()
return value, ok
}
// Contains checks if a key is in the cache, without updating the
// recent-ness or deleting it for being stale.
func (c *Cache) Contains(key interface{}) bool {
c.lock.RLock()
containKey := c.lru.Contains(key)
c.lock.RUnlock()
return containKey
}
// Peek returns the key value (or undefined if not found) without updating
// the "recently used"-ness of the key.
func (c *Cache) Peek(key interface{}) (value interface{}, ok bool) {
c.lock.RLock()
value, ok = c.lru.Peek(key)
c.lock.RUnlock()
return value, ok
}
// ContainsOrAdd checks if a key is in the cache without updating the
// recent-ness or deleting it for being stale, and if not, adds the value.
// Returns whether found and whether an eviction occurred.
func (c *Cache) ContainsOrAdd(key, value interface{}) (ok, evicted bool) {
c.lock.Lock()
defer c.lock.Unlock()
if c.lru.Contains(key) {
return true, false
}
evicted = c.lru.Add(key, value)
return false, evicted
}
// Remove removes the provided key from the cache.
func (c *Cache) Remove(key interface{}) {
c.lock.Lock()
c.lru.Remove(key)
c.lock.Unlock()
}
// RemoveOldest removes the oldest item from the cache.
func (c *Cache) RemoveOldest() {
c.lock.Lock()
c.lru.RemoveOldest()
c.lock.Unlock()
}
// Keys returns a slice of the keys in the cache, from oldest to newest.
func (c *Cache) Keys() []interface{} {
c.lock.RLock()
keys := c.lru.Keys()
c.lock.RUnlock()
return keys
}
// Len returns the number of items in the cache.
func (c *Cache) Len() int {
c.lock.RLock()
length := c.lru.Len()
c.lock.RUnlock()
return length
}

161
vendor/github.com/hashicorp/golang-lru/simplelru/lru.go generated vendored Normal file
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package simplelru
import (
"container/list"
"errors"
)
// EvictCallback is used to get a callback when a cache entry is evicted
type EvictCallback func(key interface{}, value interface{})
// LRU implements a non-thread safe fixed size LRU cache
type LRU struct {
size int
evictList *list.List
items map[interface{}]*list.Element
onEvict EvictCallback
}
// entry is used to hold a value in the evictList
type entry struct {
key interface{}
value interface{}
}
// NewLRU constructs an LRU of the given size
func NewLRU(size int, onEvict EvictCallback) (*LRU, error) {
if size <= 0 {
return nil, errors.New("Must provide a positive size")
}
c := &LRU{
size: size,
evictList: list.New(),
items: make(map[interface{}]*list.Element),
onEvict: onEvict,
}
return c, nil
}
// Purge is used to completely clear the cache.
func (c *LRU) Purge() {
for k, v := range c.items {
if c.onEvict != nil {
c.onEvict(k, v.Value.(*entry).value)
}
delete(c.items, k)
}
c.evictList.Init()
}
// Add adds a value to the cache. Returns true if an eviction occurred.
func (c *LRU) Add(key, value interface{}) (evicted bool) {
// Check for existing item
if ent, ok := c.items[key]; ok {
c.evictList.MoveToFront(ent)
ent.Value.(*entry).value = value
return false
}
// Add new item
ent := &entry{key, value}
entry := c.evictList.PushFront(ent)
c.items[key] = entry
evict := c.evictList.Len() > c.size
// Verify size not exceeded
if evict {
c.removeOldest()
}
return evict
}
// Get looks up a key's value from the cache.
func (c *LRU) Get(key interface{}) (value interface{}, ok bool) {
if ent, ok := c.items[key]; ok {
c.evictList.MoveToFront(ent)
return ent.Value.(*entry).value, true
}
return
}
// Contains checks if a key is in the cache, without updating the recent-ness
// or deleting it for being stale.
func (c *LRU) Contains(key interface{}) (ok bool) {
_, ok = c.items[key]
return ok
}
// Peek returns the key value (or undefined if not found) without updating
// the "recently used"-ness of the key.
func (c *LRU) Peek(key interface{}) (value interface{}, ok bool) {
var ent *list.Element
if ent, ok = c.items[key]; ok {
return ent.Value.(*entry).value, true
}
return nil, ok
}
// Remove removes the provided key from the cache, returning if the
// key was contained.
func (c *LRU) Remove(key interface{}) (present bool) {
if ent, ok := c.items[key]; ok {
c.removeElement(ent)
return true
}
return false
}
// RemoveOldest removes the oldest item from the cache.
func (c *LRU) RemoveOldest() (key interface{}, value interface{}, ok bool) {
ent := c.evictList.Back()
if ent != nil {
c.removeElement(ent)
kv := ent.Value.(*entry)
return kv.key, kv.value, true
}
return nil, nil, false
}
// GetOldest returns the oldest entry
func (c *LRU) GetOldest() (key interface{}, value interface{}, ok bool) {
ent := c.evictList.Back()
if ent != nil {
kv := ent.Value.(*entry)
return kv.key, kv.value, true
}
return nil, nil, false
}
// Keys returns a slice of the keys in the cache, from oldest to newest.
func (c *LRU) Keys() []interface{} {
keys := make([]interface{}, len(c.items))
i := 0
for ent := c.evictList.Back(); ent != nil; ent = ent.Prev() {
keys[i] = ent.Value.(*entry).key
i++
}
return keys
}
// Len returns the number of items in the cache.
func (c *LRU) Len() int {
return c.evictList.Len()
}
// removeOldest removes the oldest item from the cache.
func (c *LRU) removeOldest() {
ent := c.evictList.Back()
if ent != nil {
c.removeElement(ent)
}
}
// removeElement is used to remove a given list element from the cache
func (c *LRU) removeElement(e *list.Element) {
c.evictList.Remove(e)
kv := e.Value.(*entry)
delete(c.items, kv.key)
if c.onEvict != nil {
c.onEvict(kv.key, kv.value)
}
}

36
vendor/github.com/hashicorp/golang-lru/simplelru/lru_interface.go generated vendored Normal file
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package simplelru
// LRUCache is the interface for simple LRU cache.
type LRUCache interface {
// Adds a value to the cache, returns true if an eviction occurred and
// updates the "recently used"-ness of the key.
Add(key, value interface{}) bool
// Returns key's value from the cache and
// updates the "recently used"-ness of the key. #value, isFound
Get(key interface{}) (value interface{}, ok bool)
// Check if a key exsists in cache without updating the recent-ness.
Contains(key interface{}) (ok bool)
// Returns key's value without updating the "recently used"-ness of the key.
Peek(key interface{}) (value interface{}, ok bool)
// Removes a key from the cache.
Remove(key interface{}) bool
// Removes the oldest entry from cache.
RemoveOldest() (interface{}, interface{}, bool)
// Returns the oldest entry from the cache. #key, value, isFound
GetOldest() (interface{}, interface{}, bool)
// Returns a slice of the keys in the cache, from oldest to newest.
Keys() []interface{}
// Returns the number of items in the cache.
Len() int
// Clear all cache entries
Purge()
}

3
vendor/modules.txt vendored
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@ -7,6 +7,9 @@ github.com/alecthomas/units
github.com/beorn7/perks/quantile
# github.com/golang/protobuf v1.2.0
github.com/golang/protobuf/proto
# github.com/hashicorp/golang-lru v0.5.1
github.com/hashicorp/golang-lru
github.com/hashicorp/golang-lru/simplelru
# github.com/howeyc/fsnotify v0.0.0-20151003194602-f0c08ee9c607
github.com/howeyc/fsnotify
# github.com/matttproud/golang_protobuf_extensions v1.0.1