github.com/matrixorigin/matrixone@v0.7.0/pkg/vm/engine/tae/logtail/service/stacker.go (about)

     1  // Copyright 2021 Matrix Origin
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //	http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package service
    16  
    17  import (
    18  	"sync"
    19  	"sync/atomic"
    20  
    21  	"github.com/matrixorigin/matrixone/pkg/pb/api"
    22  )
    23  
    24  // TableStacker registers table repeatedly.
    25  type TableStacker struct {
    26  	sync.RWMutex
    27  	tables map[TableID]*tableInfo
    28  }
    29  
    30  func NewTableStacker() *TableStacker {
    31  	return &TableStacker{
    32  		tables: make(map[TableID]*tableInfo),
    33  	}
    34  }
    35  
    36  // ListTable takes a snapshot for all registered tables.
    37  func (s *TableStacker) ListTable() []tableInfo {
    38  	s.RLock()
    39  	defer s.RUnlock()
    40  
    41  	list := make([]tableInfo, 0, len(s.tables))
    42  	for _, info := range s.tables {
    43  		list = append(list, *info)
    44  	}
    45  	return list
    46  }
    47  
    48  // Register registers subscribed table.
    49  func (s *TableStacker) Register(id TableID, table api.TableID) {
    50  	s.Lock()
    51  	defer s.Unlock()
    52  
    53  	if _, ok := s.tables[id]; !ok {
    54  		s.tables[id] = newTableInfo(id, table)
    55  	}
    56  	s.tables[id].Ref()
    57  }
    58  
    59  // Unregister decreases reference count for tables.
    60  func (s *TableStacker) Unregister(ids ...TableID) {
    61  	s.Lock()
    62  	defer s.Unlock()
    63  
    64  	for _, id := range ids {
    65  		info, ok := s.tables[id]
    66  		if !ok {
    67  			continue
    68  		}
    69  		if info.Deref() == 0 {
    70  			delete(s.tables, id)
    71  		}
    72  	}
    73  }
    74  
    75  // tableInfo maintains a table's reference counter.
    76  type tableInfo struct {
    77  	rc    int32
    78  	id    TableID
    79  	table api.TableID
    80  }
    81  
    82  func newTableInfo(id TableID, table api.TableID) *tableInfo {
    83  	return &tableInfo{
    84  		rc:    0,
    85  		id:    id,
    86  		table: table,
    87  	}
    88  }
    89  
    90  // Ref increases reference count.
    91  func (t *tableInfo) Ref() int32 {
    92  	return atomic.AddInt32(&t.rc, 1)
    93  }
    94  
    95  // Deref decreases reference count.
    96  func (t *tableInfo) Deref() int32 {
    97  	return atomic.AddInt32(&t.rc, -1)
    98  }