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package core
import (
"hash/fnv"
"sort"
"sync"
)
const NumShards = 16
type Shard struct{
Mu sync.RWMutex
Id int
Data map[string]Item
}
func (db *RedisDB) GetShard(key string)*Shard{
hash := fnv.New64a()
hash.Write([]byte(key))
val := hash.Sum64()
return db.Shards[val%NumShards]
}
func (db *RedisDB) Execute(key string, fn func(*Shard) interface{}) interface{} {
shard := db.GetShard(key)
shard.Mu.Lock()
defer shard.Mu.Unlock()
return fn(shard)
}
func (db *RedisDB) ExecuteRead(key string, fn func(*Shard) interface{}) interface{} {
shard := db.GetShard(key)
shard.Mu.RLock()
defer shard.Mu.RUnlock()
return fn(shard)
}
func ( db *RedisDB) ExecuteMulti(keys []string, fn func([]*Shard) interface{})interface{}{
if len(keys) == 1{
shard := db.GetShard(keys[0])
shard.Mu.Lock()
defer shard.Mu.Unlock()
Shards := []*Shard{shard}
return fn(Shards)
}else{
shardMap := make(map[int]*Shard)
for _, k := range keys {
shard := db.GetShard(k)
shardMap[shard.Id] = shard
}
var sortedIDs []int
for Id := range shardMap {
sortedIDs = append(sortedIDs, Id)
}
sort.Ints(sortedIDs)
for _, Id := range sortedIDs{
shardMap[Id].Mu.Lock()
}
defer func(){
for i := len(sortedIDs)-1; i >= 0; i --{
shardMap[sortedIDs[i]].Mu.Unlock()
}
}()
Shards := make([]*Shard, 0, len(shardMap))
for _, Id := range sortedIDs {
Shards = append(Shards, shardMap[Id])
}
return fn(Shards)
}
}
func ( db *RedisDB) ExecuteAll(fn func([]*Shard) interface{})interface{}{
for _, shard := range db.Shards {
shard.Mu.Lock()
}
defer func(){
for i := len(db.Shards)-1;i >= 0; i --{
db.Shards[i].Mu.Unlock()
}
}()
return fn(db.Shards)
}
func ( db *RedisDB) ExecuteReadAll(fn func([]*Shard) interface{})interface{}{
for _, shard := range db.Shards {
shard.Mu.RLock()
}
defer func(){
for i := len(db.Shards)-1;i >= 0; i --{
db.Shards[i].Mu.RUnlock()
}
}()
return fn(db.Shards)
}
func ( db *RedisDB) Lock(keys []string){
if len(keys) == 1{
shard := db.GetShard(keys[0])
shard.Mu.Lock()
}else{
shardMap := make(map[int]*Shard)
for _, k := range keys {
shard := db.GetShard(k)
shardMap[shard.Id] = shard
}
var sortedIDs []int
for Id := range shardMap {
sortedIDs = append(sortedIDs, Id)
}
sort.Ints(sortedIDs)
for _, Id := range sortedIDs{
shardMap[Id].Mu.Lock()
}
}
}
func ( db *RedisDB) Unlock(keys []string){
shardMap := make(map[int]*Shard)
for _, k := range keys {
shard := db.GetShard(k)
shardMap[shard.Id] = shard
}
var sortedIDs []int
for Id := range shardMap {
sortedIDs = append(sortedIDs, Id)
}
sort.Ints(sortedIDs)
for i := len(sortedIDs)-1; i >= 0; i --{
shardMap[sortedIDs[i]].Mu.Unlock()
}
}
|
