/**@brief Get value given a key for storage server
* @param key
* @return value
* @return error
*/
func (ls *Libstore) iGet(key string) (string, error) {
var cli *rpc.Client
var args storageproto.GetArgs = storageproto.GetArgs{key, false, ls.Addr}
var reply storageproto.GetReply
var err error
//try cache first
if tmp, err := ls.Leases.Get(key, &args); err == nil {
reply.Value = tmp.(string)
return reply.Value, nil
}
if (ls.Flags & ALWAYS_LEASE) != 0 {
args.WantLease = true
}
//lsplog.Vlogf(0, "libstore Get %s\n", key)
cli, err = ls.GetServer(key)
if lsplog.CheckReport(1, err) {
return "", err
}
//listen on no port to accept revoke
if ls.Addr == "" {
args.WantLease = false
}
//lsplog.Vlogf(0, "Get args:%v\n", args)
err = cli.Call("StorageRPC.Get", &args, &reply)
if lsplog.CheckReport(1, err) {
return "", err
}
//lsplog.Vlogf(0, "Get reply:%v#!!\n", reply)
//fmt.Printf("Get reply granted:%v#!#\n", reply.Lease.Granted)
if reply.Lease.Granted {
ls.Leases.LeaseGranted(key, reply.Value, reply.Lease)
}
if reply.Status != storageproto.OK {
return "", MakeErr("Get()", reply.Status)
}
return reply.Value, nil
}
func (pc *ProxyCounter) GetList(args *storageproto.GetArgs, reply *storageproto.GetListReply) error {
if pc.override {
reply.Status = pc.overrideStatus
return pc.overrideErr
}
byteCount := len(args.Key)
if args.WantLease {
atomic.AddUint32(&pc.leaseRequestCount, 1)
}
if pc.disableLease {
args.WantLease = false
}
err := pc.srv.Call("StorageRPC.GetList", args, reply)
for _, s := range reply.Value {
byteCount += len(s)
}
if reply.Lease.Granted {
if pc.overrideLeaseSeconds > 0 {
reply.Lease.ValidSeconds = pc.overrideLeaseSeconds
}
atomic.AddUint32(&pc.leaseGrantedCount, 1)
}
atomic.AddUint32(&pc.rpcCount, 1)
atomic.AddUint32(&pc.byteCount, uint32(byteCount))
return err
}
func (ls *Libstore) checkWhetherLeaseNeeded(args *storageproto.GetArgs, key string) {
if ls.flags == ALWAYS_LEASE {
args.WantLease = true
args.LeaseClient = ls.cacheCallbackHostPort
} else if ls.cacheCallbackHostPort == "" {
args.WantLease = false
} else {
ls.requestsLocker.Lock()
if ls.requests[key] == nil {
lsplog.Vlogf(3, "[checkWhetherLeaseNeeded] First requested")
req := &Request{1, time.Now().Add(time.Duration(storageproto.QUERY_CACHE_SECONDS) * time.Second)}
ls.requests[key] = req
} else {
req := ls.requests[key]
if time.Now().Before(req.ts) {
req.frequency = req.frequency + 1
if req.frequency >= storageproto.QUERY_CACHE_THRESH {
lsplog.Vlogf(3, "[checkWhetherLeaseNeeded] Going to ask for a lease")
args.LeaseClient = ls.cacheCallbackHostPort
args.WantLease = true
} else {
args.WantLease = false
}
} else {
delete(ls.requests, key)
args.WantLease = false
}
}
ls.requestsLocker.Unlock()
}
}
/**@brief given a key, get list of strings
* @param key
* @return string[]
* @return error
*/
func (ls *Libstore) iGetList(key string) ([]string, error) {
var cli *rpc.Client
var args storageproto.GetArgs = storageproto.GetArgs{key, false, ls.Addr}
var reply storageproto.GetListReply
var err error
//try cache first
if tmp, err := ls.Leases.Get(key, &args); err == nil {
reply.Value = tmp.([]string)
return reply.Value, nil
}
if (ls.Flags & ALWAYS_LEASE) != 0 {
args.WantLease = true
}
cli, err = ls.GetServer(key)
if lsplog.CheckReport(1, err) {
return nil, err
}
//lsplog.Vlogf(0, "GetList args %v", args)
err = cli.Call("StorageRPC.GetList", &args, &reply)
if lsplog.CheckReport(1, err) {
return nil, err
}
//lsplog.Vlogf(0, "GetList reply %v", reply)
if reply.Lease.Granted {
ls.Leases.LeaseGranted(key, reply.Value, reply.Lease)
}
if reply.Status != storageproto.OK {
return nil, MakeErr("GetList()", reply.Status)
}
return reply.Value, nil
}
/**@brief Get is the most important function for cache, it will first clear all
* the expire entries, and then fetch the cache content or add the count
* of wantlease flag
* @param key
* @param GetArgs
* @return interface{}(string or []string)
* @return error
*/
func (cache *Cache) Get(
key string, args *storageproto.GetArgs) (interface{}, error) {
var entry *Entry
var valid bool
var data interface{}
//fmt.Printf("Cache get: %s\n", key)
cache.Lock.Lock()
cache.ClearExpired()
entry, valid = cache.Map[key]
if !valid {
entry = new(Entry)
entry.Queries = list.New()
entry.Queries.PushBack(time.Now())
//fmt.Printf("Cache entry: %+v\n", *entry)
//fmt.Printf("Queries: %+v\n", entry.Queries)
cache.Map[key] = entry
cache.Lock.Unlock()
return "", lsplog.MakeErr("Not found.")
}
if entry.Granted {
data = entry.Data
cache.Lock.Unlock()
//fmt.Printf("Already in Cache %s->%v\n", key, data)
return data, nil
}
entry.Queries.PushBack(time.Now())
//fmt.Printf("Cache entry: %v\n", *entry)
if entry.Queries.Len() > storageproto.QUERY_CACHE_THRESH {
//fmt.Printf("QUERY_CACHE_THRESH reached. Asking for lease.\n")
args.WantLease = true
}
cache.Lock.Unlock()
return "", lsplog.MakeErr("Not in cache")
}
func (ss *Storageserver) GetList(args *storageproto.GetArgs, reply *storageproto.GetListReply) error {
//fmt.Println("called getList")
//fmt.Printf("key: %v\n", args.Key)
rightServer := ss.checkServer(args.Key)
if rightServer == false {
reply.Status = storageproto.EWRONGSERVER
return nil
}
<-ss.leaseMapM
leaseInfo, exists := ss.leaseMap[args.Key]
ss.leaseMapM <- 1
if exists == true {
list := *leaseInfo.ClientKeys
for i := 0; i < len(list); i++ {
if list[i] == args.LeaseClient {
args.WantLease = false
}
}
}
if args.WantLease == true {
//grant lease
//is there any reason to not grant it?
reply.Lease.Granted = true
reply.Lease.ValidSeconds = storageproto.LEASE_SECONDS
if exists == true {
<-leaseInfo.Mutex
*leaseInfo.ClientKeys = append(*leaseInfo.ClientKeys, args.LeaseClient)
leaseInfo.Mutex <- 1
// fmt.Printf("**GETLIST added %v to %v lease list\n", args.LeaseClient, args.Key)
ss.PrintLeaseMap()
} else {
keys := []string{}
keys = append(keys, args.LeaseClient)
<-ss.leaseMapM
mutex := make(chan int, 1)
mutex <- 1
ss.leaseMap[args.Key] = &LeaseInfo{Mutex: mutex, ClientKeys: &keys}
ss.leaseMapM <- 1
// fmt.Printf("**GETLIST added %v to %v lease list\n", args.LeaseClient, args.Key)
ss.PrintLeaseMap()
}
<-ss.clientLeaseMapM
leaseExpiration := time.Now().Add((storageproto.LEASE_SECONDS + storageproto.LEASE_GUARD_SECONDS) * time.Second).UnixNano()
ss.clientLeaseMap[args.LeaseClient+"@"+args.Key] = leaseExpiration
ss.clientLeaseMapM <- 1
} else {
reply.Lease.Granted = false
reply.Lease.ValidSeconds = 0
}
<-ss.listMapM
list, ok := ss.listMap[args.Key]
ss.listMapM <- 1
if ok != true {
reply.Status = storageproto.EITEMNOTFOUND
reply.Value = []string{}
} else {
reply.Status = storageproto.OK
reply.Value = list
}
return nil
}
