vitess.io/vitess@v0.16.2/go/pools/refresh_pool.go (about)

     1  /*
     2  Copyright 2022 The Vitess Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package pools
    18  
    19  import (
    20  	"sync"
    21  	"time"
    22  
    23  	"vitess.io/vitess/go/vt/log"
    24  )
    25  
    26  type (
    27  	// RefreshCheck is a function used to determine if a resource pool should be
    28  	// refreshed (i.e. closed and reopened)
    29  	RefreshCheck func() (bool, error)
    30  
    31  	// poolRefresh refreshes the pool by calling the RefreshCheck function.
    32  	// If the RefreshCheck returns true, the pool is closed and reopened.
    33  	poolRefresh struct {
    34  		refreshCheck    RefreshCheck
    35  		refreshInterval time.Duration
    36  		refreshTicker   *time.Ticker
    37  		refreshStop     chan struct{}
    38  		refreshWg       sync.WaitGroup
    39  
    40  		pool refreshPool
    41  	}
    42  )
    43  
    44  type refreshPool interface {
    45  	// reopen drains and reopens the connection pool
    46  	reopen()
    47  
    48  	// closeIdleResources scans the pool for idle resources and closes them.
    49  	closeIdleResources()
    50  }
    51  
    52  func newPoolRefresh(pool refreshPool, refreshCheck RefreshCheck, refreshInterval time.Duration) *poolRefresh {
    53  	if refreshCheck == nil || refreshInterval <= 0 {
    54  		return nil
    55  	}
    56  	return &poolRefresh{
    57  		pool:            pool,
    58  		refreshInterval: refreshInterval,
    59  		refreshCheck:    refreshCheck,
    60  	}
    61  }
    62  
    63  func (pr *poolRefresh) startRefreshTicker() {
    64  	if pr == nil {
    65  		return
    66  	}
    67  	pr.refreshTicker = time.NewTicker(pr.refreshInterval)
    68  	pr.refreshStop = make(chan struct{})
    69  	pr.refreshWg.Add(1)
    70  	go func() {
    71  		defer pr.refreshWg.Done()
    72  		for {
    73  			select {
    74  			case <-pr.refreshTicker.C:
    75  				val, err := pr.refreshCheck()
    76  				if err != nil {
    77  					log.Info(err)
    78  				}
    79  				if val {
    80  					go pr.pool.reopen()
    81  					return
    82  				}
    83  			case <-pr.refreshStop:
    84  				return
    85  			}
    86  		}
    87  	}()
    88  }
    89  
    90  func (pr *poolRefresh) stop() {
    91  	if pr == nil || pr.refreshTicker == nil {
    92  		return
    93  	}
    94  	pr.refreshTicker.Stop()
    95  	close(pr.refreshStop)
    96  	pr.refreshWg.Wait()
    97  }