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lru.go
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lru.go
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package lru
import (
json "encoding/json"
lru "github.com/hashicorp/golang-lru"
libkb "github.com/keybase/client/go/libkb"
keybase1 "github.com/keybase/client/go/protocol/keybase1"
context "golang.org/x/net/context"
"reflect"
"sync"
)
type Cache struct {
sync.Mutex
mem *lru.Cache
version int
typ reflect.Type
stats stats
}
type stats struct {
memHit int
diskHit int
diskStale int
miss int
}
func NewLRU(ctx libkb.LRUContext, sz int, version int, exampleObj interface{}) *Cache {
cache, err := lru.New(sz)
if err != nil {
ctx.GetLog().Fatalf("Bad LRU constructor: %s", err.Error())
}
return &Cache{
mem: cache,
version: version,
typ: reflect.TypeOf(exampleObj),
}
}
type diskWrapper struct {
Version int `codec:"v"`
Data string `codex:"d"`
CachedAt keybase1.Time `codec:"t"`
}
func (c *Cache) ClearMemory() {
c.mem.Purge()
}
func (c *Cache) Get(ctx context.Context, lctx libkb.LRUContext, k libkb.LRUKeyer) (interface{}, error) {
c.Lock()
defer c.Unlock()
val, ok := c.mem.Get(k.MemKey())
if ok {
c.stats.memHit++
lctx.GetVDebugLog().CLogf(ctx, libkb.VLog3, "lru(%v): mem hit", k.MemKey())
return val, nil
}
var w diskWrapper
ok, err := lctx.GetKVStore().GetInto(&w, k.DbKey())
if err != nil {
return nil, err
}
if !ok {
c.stats.miss++
lctx.GetVDebugLog().CLogf(ctx, libkb.VLog3, "lru(%v): miss", k.DbKey())
return nil, nil
}
if w.Version != c.version {
c.stats.diskStale++
lctx.GetVDebugLog().CLogf(ctx, libkb.VLog0, "lru(%v), old version: %d < %d", k.DbKey(), w.Version, c.version)
return nil, nil
}
var ret interface{}
if len(w.Data) > 0 {
tmp := reflect.New(c.typ)
ret = tmp.Interface()
err = json.Unmarshal([]byte(w.Data), ret)
if err != nil {
return nil, err
}
}
c.stats.diskHit++
lctx.GetVDebugLog().CLogf(ctx, libkb.VLog3, "lru(%v): disk hit", k.DbKey())
c.mem.Add(k.MemKey(), ret)
return ret, nil
}
func (c *Cache) Put(ctx context.Context, lctx libkb.LRUContext, k libkb.LRUKeyer, v interface{}) error {
c.Lock()
defer c.Unlock()
var data string
if v != nil {
b, err := json.Marshal(v)
if err != nil {
return err
}
data = string(b)
}
w := diskWrapper{
Version: c.version,
Data: data,
CachedAt: keybase1.ToTime(lctx.GetClock().Now()),
}
lctx.GetKVStore().PutObj(k.DbKey(), nil, w)
c.mem.Add(k.MemKey(), v)
return nil
}
var _ libkb.LRUer = (*Cache)(nil)