/
pbs.go
219 lines (192 loc) · 4.5 KB
/
pbs.go
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package pbs
import (
"os"
"goprotobuf.googlecode.com/hg/proto"
"crypto/sha256"
"encoding/hex"
)
type DataStore interface{
Put(key string, data []byte) (err os.Error)
Get(key string) (data []byte, err os.Error)
Delete(key string) (err os.Error)
}
type PBSStorage interface{
Put(value interface{}) (key string, err os.Error)
Get(key string, value interface{}) (err os.Error)
Delete(key string) (err os.Error)
Expire(key string) (err os.Error)
}
type MemoryElem struct{
data []byte
nextLRU string
prevLRU string
}
type MemoryStore struct{
kvstore map[string] *MemoryElem
mruKey string
lruKey string
maxBytes int64
}
type DiskStore struct{
filename string
maxBytes int64
}
type NetworkStore struct{
hostname string
maxBytes int64
}
type PBSDataStore struct{
keys map[string] *PBSDataStore
datastore DataStore
next *PBSDataStore
prev *PBSDataStore
}
func DoMarshalling(value interface{}) (key string, data []byte, err os.Error) {
data, err = proto.Marshal(value)
if err == nil {
h := sha256.New()
nr, err := h.Write([]byte(data))
if err == nil && nr == len([]byte(data)) {
key = hex.EncodeToString(h.Sum())
}
}
return
}
func NewPBSDataStore(stores []DataStore) *PBSDataStore {
ds := new(PBSDataStore)
ds.prev = nil
ds.datastore = stores[0]
ds.keys = make(map[string] *PBSDataStore)
prev := ds
for _, store := range stores[1:] {
ns := new(PBSDataStore)
prev.next = ns
ns.prev = prev
ns.datastore = store
prev = ns
}
return ds
}
func (ds *PBSDataStore) Put(value interface{}) (key string, err os.Error) {
t_key, data, err := DoMarshalling(value)
if err == nil && ds.keys[t_key] == nil {
err = ds.datastore.Put(t_key, data)
if err == nil {
ds.keys[t_key] = ds
key = t_key
}
}
return
}
func (ds *PBSDataStore) Get(key string, value interface{}) (err os.Error) {
if ds.keys[key] != nil {
data, err := ds.datastore.Get(key)
if err == nil {
err = proto.Unmarshal(data, value)
}
}
return
}
func (ds *PBSDataStore) Delete(key string) (err os.Error) {
return
}
func (ds *PBSDataStore) Push(key string) (err os.Error) {
return
}
func (ds *PBSDataStore) Pull(key string) (err os.Error) {
return
}
func NewMemoryStore() *MemoryStore {
ds := new(MemoryStore)
ds.kvstore = make(map[string] *MemoryElem)
ds.mruKey = ""
ds.lruKey = ""
return ds
}
func (ds *MemoryStore) Put(key string, data []byte) (err os.Error) {
if ds.kvstore[key] == nil {
if ds.mruKey == "" && ds.lruKey == "" {
ds.mruKey = key
ds.lruKey = key
elem := new(MemoryElem)
elem.data = data
elem.nextLRU = ""
elem.prevLRU = ""
ds.kvstore[key] = elem
} else if ds.kvstore[ds.mruKey] != nil && ds.kvstore[ds.mruKey].nextLRU == "" {
ds.kvstore[ds.mruKey].nextLRU = key
elem := new(MemoryElem)
elem.data = data
elem.nextLRU = ""
elem.prevLRU = ds.mruKey
ds.kvstore[key] = elem
ds.mruKey = key
} else {
err = os.NewError("Should never happen")
}
} else {
err = os.NewError("Key already exists")
}
return
}
func (ds *MemoryStore) Get(key string) (data []byte, err os.Error) {
if ds.kvstore[key] != nil {
data = ds.kvstore[key].data
if ds.mruKey != "" && ds.mruKey == key {
// Pass
}
if ds.lruKey != "" && ds.lruKey == key {
ds.lruKey = ds.kvstore[key].nextLRU
ds.kvstore[ds.mruKey].nextLRU = key
ds.kvstore[key].prevLRU = ds.mruKey
ds.mruKey = key
} else if key != "" && ds.mruKey != "" {
prev := ds.kvstore[key].prevLRU
next := ds.kvstore[key].nextLRU
if prev != "" {
ds.kvstore[prev].nextLRU = next
}
if next != "" {
ds.kvstore[next].prevLRU = prev
}
ds.kvstore[ds.mruKey].nextLRU = key
ds.kvstore[key].prevLRU = ds.mruKey
ds.mruKey = key
} else {
err = os.NewError("Key is empty")
}
} else {
err = os.NewError("Key not found")
}
return
}
func (ds *MemoryStore) Delete(key string) (err os.Error) {
if ds.kvstore[key] != nil {
if ds.lruKey == key {
ds.lruKey = ds.kvstore[key].nextLRU
ds.kvstore[ds.lruKey].prevLRU = ""
} else if ds.mruKey == key {
ds.mruKey = ds.kvstore[key].prevLRU
ds.kvstore[ds.mruKey].nextLRU = ""
} else {
prev := ds.kvstore[key].prevLRU
next := ds.kvstore[key].nextLRU
ds.kvstore[prev].nextLRU = next
ds.kvstore[next].prevLRU = prev
}
ds.kvstore[key] = nil
} else {
err = os.NewError("Key not found")
}
return
}
func NewDiskStore(filename string) *DiskStore {
ds := new(DiskStore)
ds.filename = filename
return ds
}
func NewNetworkStore(hostname string) *NetworkStore {
ds := new(NetworkStore)
ds.hostname = hostname
return ds
}