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tidb/statistics/handle/cache/internal/inner.go
2023-07-10 10:47:12 +00:00

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// Copyright 2023 PingCAP, 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 internal
import (
"github.com/pingcap/tidb/statistics"
)
// StatsCacheInner is the interface to manage the statsCache, it can be implemented by map, lru cache or other structures.
// TODO: this cache shouldn't be aware of *statistics.Table, e.g.
// 1. change Put(int64, *stats.Table) to Put(k, v interface{}, vMem int64).
// 2. remove XXXByQuery methods.
// 3. remove remove the Version method.
type StatsCacheInner interface {
// GetByQuery retrieves cache triggered by a query. Usually used in LRU.
// TODO: merge this method with Get.
GetByQuery(int64) (*statistics.Table, bool)
// Get gets the cache.
Get(int64) (*statistics.Table, bool)
// PutByQuery puts a cache triggered by a query. Usually used in LRU.
// TODO: merge this method with Put.
PutByQuery(int64, *statistics.Table)
// Put puts a cache.
Put(int64, *statistics.Table)
// Del deletes a cache.
Del(int64)
// Cost returns the memory usage of the cache.
Cost() int64
// Values returns the values of the cache.
Values() []*statistics.Table
// Len returns the length of the cache.
Len() int
// Copy returns a copy of the cache
Copy() StatsCacheInner
// SetCapacity sets the capacity of the cache
SetCapacity(int64)
// Front returns the front element's owner tableID, only used for test
// TODO: this method is mainly for test, remove it in the future.
Front() int64
}