mirror of
https://github.com/go-gitea/gitea
synced 2024-12-25 23:04:45 +01:00
88 lines
2.3 KiB
Go
88 lines
2.3 KiB
Go
// Copyright (c) 2015 Couchbase, Inc.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package index
|
|
|
|
import (
|
|
"sync"
|
|
)
|
|
|
|
type FieldCache struct {
|
|
fieldIndexes map[string]uint16
|
|
indexFields []string
|
|
lastFieldIndex int
|
|
mutex sync.RWMutex
|
|
}
|
|
|
|
func NewFieldCache() *FieldCache {
|
|
return &FieldCache{
|
|
fieldIndexes: make(map[string]uint16),
|
|
lastFieldIndex: -1,
|
|
}
|
|
}
|
|
|
|
func (f *FieldCache) AddExisting(field string, index uint16) {
|
|
f.mutex.Lock()
|
|
f.addLOCKED(field, index)
|
|
f.mutex.Unlock()
|
|
}
|
|
|
|
func (f *FieldCache) addLOCKED(field string, index uint16) uint16 {
|
|
f.fieldIndexes[field] = index
|
|
if len(f.indexFields) < int(index)+1 {
|
|
prevIndexFields := f.indexFields
|
|
f.indexFields = make([]string, int(index)+16)
|
|
copy(f.indexFields, prevIndexFields)
|
|
}
|
|
f.indexFields[int(index)] = field
|
|
if int(index) > f.lastFieldIndex {
|
|
f.lastFieldIndex = int(index)
|
|
}
|
|
return index
|
|
}
|
|
|
|
// FieldNamed returns the index of the field, and whether or not it existed
|
|
// before this call. if createIfMissing is true, and new field index is assigned
|
|
// but the second return value will still be false
|
|
func (f *FieldCache) FieldNamed(field string, createIfMissing bool) (uint16, bool) {
|
|
f.mutex.RLock()
|
|
if index, ok := f.fieldIndexes[field]; ok {
|
|
f.mutex.RUnlock()
|
|
return index, true
|
|
} else if !createIfMissing {
|
|
f.mutex.RUnlock()
|
|
return 0, false
|
|
}
|
|
// trade read lock for write lock
|
|
f.mutex.RUnlock()
|
|
f.mutex.Lock()
|
|
// need to check again with write lock
|
|
if index, ok := f.fieldIndexes[field]; ok {
|
|
f.mutex.Unlock()
|
|
return index, true
|
|
}
|
|
// assign next field id
|
|
index := f.addLOCKED(field, uint16(f.lastFieldIndex+1))
|
|
f.mutex.Unlock()
|
|
return index, false
|
|
}
|
|
|
|
func (f *FieldCache) FieldIndexed(index uint16) (field string) {
|
|
f.mutex.RLock()
|
|
if int(index) < len(f.indexFields) {
|
|
field = f.indexFields[int(index)]
|
|
}
|
|
f.mutex.RUnlock()
|
|
return field
|
|
}
|