112 lines
2.3 KiB
Go
112 lines
2.3 KiB
Go
package state
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import (
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"container/list"
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"fmt"
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cmn "github.com/tendermint/tmlibs/common"
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)
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// KVCache is a cache that enforces deterministic sync order.
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type KVCache struct {
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store KVStore
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cache map[string]kvCacheValue
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keys *list.List
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logging bool
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logLines []string
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}
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type kvCacheValue struct {
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v []byte // The value of some key
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e *list.Element // The KVCache.keys element
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}
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// NOTE: If store is nil, creates a new MemKVStore
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func NewKVCache(store KVStore) *KVCache {
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if store == nil {
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store = NewMemKVStore()
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}
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return (&KVCache{
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store: store,
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}).Reset()
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}
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func (kvc *KVCache) SetLogging() {
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kvc.logging = true
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}
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func (kvc *KVCache) GetLogLines() []string {
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return kvc.logLines
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}
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func (kvc *KVCache) ClearLogLines() {
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kvc.logLines = nil
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}
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func (kvc *KVCache) Reset() *KVCache {
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kvc.cache = make(map[string]kvCacheValue)
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kvc.keys = list.New()
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return kvc
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}
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func (kvc *KVCache) Set(key []byte, value []byte) {
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if kvc.logging {
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line := fmt.Sprintf("Set %v = %v", LegibleBytes(key), LegibleBytes(value))
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kvc.logLines = append(kvc.logLines, line)
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}
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cacheValue, ok := kvc.cache[string(key)]
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if ok {
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kvc.keys.MoveToBack(cacheValue.e)
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} else {
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cacheValue.e = kvc.keys.PushBack(key)
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}
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cacheValue.v = value
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kvc.cache[string(key)] = cacheValue
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}
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func (kvc *KVCache) Get(key []byte) (value []byte) {
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cacheValue, ok := kvc.cache[string(key)]
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if ok {
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if kvc.logging {
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line := fmt.Sprintf("Get (hit) %v = %v", LegibleBytes(key), LegibleBytes(cacheValue.v))
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kvc.logLines = append(kvc.logLines, line)
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}
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return cacheValue.v
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} else {
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value := kvc.store.Get(key)
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kvc.cache[string(key)] = kvCacheValue{
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v: value,
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e: kvc.keys.PushBack(key),
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}
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if kvc.logging {
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line := fmt.Sprintf("Get (miss) %v = %v", LegibleBytes(key), LegibleBytes(value))
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kvc.logLines = append(kvc.logLines, line)
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}
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return value
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}
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}
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//Update the store with the values from the cache
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func (kvc *KVCache) Sync() {
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for e := kvc.keys.Front(); e != nil; e = e.Next() {
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key := e.Value.([]byte)
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value := kvc.cache[string(key)]
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kvc.store.Set(key, value.v)
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}
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kvc.Reset()
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}
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//----------------------------------------
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func LegibleBytes(data []byte) string {
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s := ""
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for _, b := range data {
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if 0x21 <= b && b < 0x7F {
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s += cmn.Green(string(b))
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} else {
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s += cmn.Blue(cmn.Fmt("%02X", b))
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}
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}
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return s
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}
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