func (ds *DiskStore) Put(name string, vn IVnode, r io.Reader) (written int64, err os.Error) {
written = 0
dir_path, full_path, err := ds.buildBlobPath(vn, name)
if err != nil {
return
}
err = os.MkdirAll(dir_path, 0700)
if err != nil {
return
}
_, err = os.Stat(full_path)
if err == nil {
// blob with same name exists.
// means we are done.
// TODO: check to verify size of the blobs are same
// and log that we tried to add existing blob.
l4g.Info("Blob already exists at %s", full_path)
return
}
f, err := os.Create(full_path)
defer f.Close()
if err != nil {
return
}
written, err = io.Copy(f, r)
return
}
func serve(configs *ConfigOpts) os.Error {
ks := NewKeySpace(configs.ZkRootNode, configs.ZkHosts, 5e6)
ks.Connect()
rs := &SimpleRep{N: configs.ReplicationFactor}
ls := NewDiskStore(configs.RootDir)
rsf := &RemoteStoreFactory{}
b := NewBlobStore(ks, rs, ls, rsf, configs.Port)
rpc.Register(b)
rpc.HandleHTTP()
addr := fmt.Sprintf(":%d", configs.Port)
l4g.Info("Serving on %s", addr)
http.ListenAndServe(addr, nil)
return nil
}
func (k *KeySpace) Connect() os.Error {
zk, session, err := gozk.Init(k.zkServers, k.zkTimeout)
if err != nil {
return os.NewError("Couldn't connect: " + err.String())
}
event := <-session
if event.State != gozk.STATE_CONNECTED {
return os.NewError("Couldn't connect to zookeeper\n")
}
k.zk = zk
stat, err := k.zk.Exists(k.zkRoot)
if stat == nil {
path, err := k.zk.Create(k.zkRoot, "root", 0, gozk.WorldACL(gozk.PERM_ALL))
if err != nil {
l4g.Info("Created root node: %s\n", path)
}
}
return nil
}
func (b *BlobStore) Get(key *string, w io.Writer) os.Error {
// get replica list
// TODO: remove servers that aren't currently up.
// If we are in the replica list:
// return data
// if data not available locally, get data from other replicas
// (readrepair: store locally so next time we can field the request)
// If not on us:
// hit one of the replicas for data, it will find and return data.
vnodes, err := b.ks.GetVnodes()
if err != nil {
return err
}
replicas, err := b.rs.Replicas(*key, vnodes)
if err != nil {
return err
}
copyLocally := false
var local_vnode_idx int
for i, replica := range replicas {
// look for a local one first.
if isLocalVnode(replica) {
// this code assumes that there is only one matching local vnode.
// i.e that replicas aren't on the same server.
l4g.Debug("Key should be on local vnode: %s", replica)
_, err = b.ls.Get(*key, replica, w)
if err != nil {
// err is assumed to be coz data was missing.
// so, copy it locally once we get it.
l4g.Debug("Key not found on local vnode. Will read repair vode %s for key: %s", replica, *key)
copyLocally = true
local_vnode_idx = i
} else {
// if no errors getting data locally,
// we are done
//TODO: verify data:
//if hash doesn't match, get it from another replica.
l4g.Debug("Found data for key %s locally.", *key)
return nil
}
}
}
// the fact that we are here means data wasn't found locally.
// if copyLocally is true, it means that we should store
// the data locally coz it should have been here.
var local_vnode IVnode
if copyLocally {
//remove local vnode from list so it isn't tried again.
local_vnode = replicas[local_vnode_idx]
replicas = append(replicas[:local_vnode_idx], replicas[local_vnode_idx+1:]...)
}
l4g.Debug("Data for key %s not found locally. Trying other replicas.", *key)
for _, replica := range replicas {
err = b.getRemoteBlob(key, replica, w)
if err == nil {
l4g.Debug("Got data for key %s from remote: %s", *key, replica.String())
if copyLocally {
l4g.Debug("ReadRepair: Copying key %s to local vnode: %s", *key, local_vnode.String())
// go b.ls.Put(blob, *key, local_vnode)
l4g.Error("ReadRepaid not implemented")
}
return nil
} else {
l4g.Info("Couldnt get key %s from remote replica %s. Error: %s", *key, replica, err.String())
}
}
return os.NewError("Could not get from any of the replicas")
}
