...
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func build(im * immutablemap_string2string) Builder{
builder := &Builder{
reference: im
mutable: nil
}
return builder
}
//struct to bulid a new immutablemap according to the exist version
type Builder struct{
reference immutablemap_string2string
mutable map[string]string
}
func (bdr *Builder) maybeClone(){
if bdr.reference != nil{
bdr.mutable = make(map[string]string)
for k,v := range bdr.reference.storemap{
bdr.mutable[k] = v
}
bdr.reference = nil
}
}
func (bdr *Builder) getnamefromalias(key string) (string, bool){
bdr.maybeClone()
return bdr.mutable[key]
}
func(bdr *Builder) putalias2name(key string, val string) (string, bool){
bdr.maybeclone()
var pre string
if v,ok = bdr.mutable[key], ok{
pre = v
}else{
pre = nil
}
bdr.mutable[key] = val
return pre, ok
}
func(bdr *Builder) removealias2name(key string) (string, bool){
bdr.maybeclone()
var pre string
if v,ok = bdr.mutable[key], ok{
pre = v
delete(bdr.mutable, key)
}else{
pre = nil
}
return pre, ok
}
func (bdr *Builder) build() immutablemap_string2string{
if bdr.reference != nil{
reference := bdr.reference
bdr.reference = nil
return reference
}else{
mutable = bdr.mutable
bdr.mutable = nil
res := & immutablemap_string2string{
storemap:mutable
}
return res
}
}
func (mt * metatable) addAlias(collectionAlias string, collectionName string) (string, error){
mt.ddLock.Lock()
defer mt.ddLock.Unlock()
...
ts = getTimestamp()
tspre = mt.newestAliasTs
Bdr = build(mt.ts2alias2name[tspre])
pre,ok := Bdr.putalias2name(collectionAlias, collectionName)
if ok{
return pre, fmt.Errorf("alias already exist when add alias")
}
mt.ts2alias2name[ts] = Bdr.build()
mt.newestAliasTs = ts
...
return nil, nil
}
func (mt * metatable) dropAlias(collectionAlias string) (string, error){
mt.ddLock.Lock()
defer mt.ddLock.Unlock()
...
ts = getTimestamp()
tspre = mt.newestAliasTs
Bdr = build(mt.ts2alias2name[tspre])
pre,ok := Bdr.removealias2id(collectionAlias)
if !ok{
return nil, fmt.Errorf("alias not exist when drop alias")
}
mt.ts2alias2name[ts] = Bdr.build()
mt.newestAliasTs = ts
...
return pre, nil
}
func (mt * metatable) alterAlias(collectionAlias string, collectionName string) (string, error){
mt.ddLock.Lock()
defer mt.ddLock.Unlock()
...
ts = getTimestamp()
tspre = mt.newestAliasTs
Bdr = build(mt.ts2alias2name[tspre])
pre,ok := Bdr.putalias2name(collectionAlias, collectionName)
if !ok{
return nil, fmt.Errorf("alias not exist when alter alias")
}
mt.ts2alias2name[ts] = Bdr.build()
mt.newestAliasTs = ts
...
return pre, nil
} |