seaweedfs/go/operation/lookup.go

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package operation
import (
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"encoding/json"
"errors"
"fmt"
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"math/rand"
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"net/url"
"strings"
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"time"
"github.com/chrislusf/seaweedfs/go/util"
)
type Location struct {
Url string `json:"url,omitempty"`
PublicUrl string `json:"publicUrl,omitempty"`
}
type LookupResult struct {
VolumeId string `json:"volumeId,omitempty"`
Locations []Location `json:"locations,omitempty"`
Error string `json:"error,omitempty"`
}
func (lr *LookupResult) String() string {
return fmt.Sprintf("VolumeId:%s, Locations:%v, Error:%s", lr.VolumeId, lr.Locations, lr.Error)
}
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var (
vc VidCache // caching of volume locations, re-check if after 10 minutes
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)
func Lookup(server string, vid string) (ret *LookupResult, err error) {
locations, cache_err := vc.Get(vid)
if cache_err != nil {
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if ret, err = do_lookup(server, vid); err == nil {
vc.Set(vid, ret.Locations, 10*time.Minute)
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}
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} else {
ret = &LookupResult{VolumeId: vid, Locations: locations}
}
return
}
func do_lookup(server string, vid string) (*LookupResult, error) {
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values := make(url.Values)
values.Add("volumeId", vid)
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jsonBlob, err := util.Post("http://"+server+"/dir/lookup", values)
if err != nil {
return nil, err
}
var ret LookupResult
err = json.Unmarshal(jsonBlob, &ret)
if err != nil {
return nil, err
}
if ret.Error != "" {
return nil, errors.New(ret.Error)
}
return &ret, nil
}
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func LookupFileId(server string, fileId string) (fullUrl string, err error) {
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parts := strings.Split(fileId, ",")
if len(parts) != 2 {
return "", errors.New("Invalid fileId " + fileId)
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}
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lookup, lookupError := Lookup(server, parts[0])
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if lookupError != nil {
return "", lookupError
}
if len(lookup.Locations) == 0 {
return "", errors.New("File Not Found")
}
return "http://" + lookup.Locations[rand.Intn(len(lookup.Locations))].Url + "/" + fileId, nil
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}
// LookupVolumeIds find volume locations by cache and actual lookup
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func LookupVolumeIds(server string, vids []string) (map[string]LookupResult, error) {
ret := make(map[string]LookupResult)
var unknown_vids []string
//check vid cache first
for _, vid := range vids {
locations, cache_err := vc.Get(vid)
if cache_err == nil {
ret[vid] = LookupResult{VolumeId: vid, Locations: locations}
} else {
unknown_vids = append(unknown_vids, vid)
}
}
//return success if all volume ids are known
if len(unknown_vids) == 0 {
return ret, nil
}
//only query unknown_vids
values := make(url.Values)
for _, vid := range unknown_vids {
values.Add("volumeId", vid)
}
jsonBlob, err := util.Post("http://"+server+"/vol/lookup", values)
if err != nil {
return nil, err
}
err = json.Unmarshal(jsonBlob, &ret)
if err != nil {
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return nil, errors.New(err.Error() + " " + string(jsonBlob))
}
//set newly checked vids to cache
for _, vid := range unknown_vids {
locations := ret[vid].Locations
vc.Set(vid, locations, 10*time.Minute)
}
return ret, nil
}