github.com/matrixorigin/matrixone@v1.2.0/pkg/vm/engine/tae/logtail/service/waterline.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  	"fmt"
    19  	"sync"
    20  
    21  	"github.com/matrixorigin/matrixone/pkg/pb/timestamp"
    22  )
    23  
    24  // Waterliner maintains waterline for all subscribed tables.
    25  type Waterliner struct {
    26  	sync.Mutex
    27  	waterline timestamp.Timestamp
    28  }
    29  
    30  func NewWaterliner() *Waterliner {
    31  	return &Waterliner{}
    32  }
    33  
    34  // Waterline returns waterline for subscribed table.
    35  //
    36  // it would be initialized on its first call.
    37  func (w *Waterliner) Waterline() timestamp.Timestamp {
    38  	w.Lock()
    39  	defer w.Unlock()
    40  
    41  	return w.waterline
    42  }
    43  
    44  // Advance updates waterline.
    45  //
    46  // Caller should keep monotonous.
    47  func (w *Waterliner) Advance(update timestamp.Timestamp) {
    48  	w.Lock()
    49  	defer w.Unlock()
    50  
    51  	if update.Less(w.waterline) {
    52  		panic(fmt.Sprintf("timestamp rollback for waterline, current: %v, update: %v", w.waterline.String(), update.String()))
    53  	}
    54  
    55  	w.waterline = update
    56  }