github.com/matrixorigin/matrixone@v0.7.0/pkg/vm/engine/tae/logstore/sm/safeq.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 sm
    16  
    17  import (
    18  	"context"
    19  	"runtime"
    20  	"sync"
    21  	"sync/atomic"
    22  
    23  	"github.com/matrixorigin/matrixone/pkg/vm/engine/tae/common"
    24  )
    25  
    26  const (
    27  	Created int32 = iota
    28  	Running
    29  	ReceiverStopped
    30  	PrepareStop
    31  	Stopped
    32  )
    33  
    34  type safeQueue struct {
    35  	queue     chan any
    36  	ctx       context.Context
    37  	cancel    context.CancelFunc
    38  	wg        sync.WaitGroup
    39  	state     atomic.Int32
    40  	pending   atomic.Int64
    41  	batchSize int
    42  	onItemsCB OnItemsCB
    43  }
    44  
    45  func NewSafeQueue(queueSize, batchSize int, onItem OnItemsCB) *safeQueue {
    46  	q := &safeQueue{
    47  		queue:     make(chan any, queueSize),
    48  		batchSize: batchSize,
    49  		onItemsCB: onItem,
    50  	}
    51  	q.state.Store(Created)
    52  	q.ctx, q.cancel = context.WithCancel(context.Background())
    53  	return q
    54  }
    55  
    56  func (q *safeQueue) Start() {
    57  	q.state.Store(Running)
    58  	q.wg.Add(1)
    59  	items := make([]any, 0, q.batchSize)
    60  	go func() {
    61  		defer q.wg.Done()
    62  		for {
    63  			select {
    64  			case <-q.ctx.Done():
    65  				return
    66  			case item := <-q.queue:
    67  				if q.onItemsCB == nil {
    68  					continue
    69  				}
    70  				items = append(items, item)
    71  			Left:
    72  				for i := 0; i < q.batchSize-1; i++ {
    73  					select {
    74  					case item = <-q.queue:
    75  						items = append(items, item)
    76  					default:
    77  						break Left
    78  					}
    79  				}
    80  				cnt := len(items)
    81  				q.onItemsCB(items...)
    82  				items = items[:0]
    83  				q.pending.Add(-1 * int64(cnt))
    84  			}
    85  		}
    86  	}()
    87  }
    88  
    89  func (q *safeQueue) Stop() {
    90  	q.stopReceiver()
    91  	q.waitStop()
    92  	close(q.queue)
    93  }
    94  
    95  func (q *safeQueue) stopReceiver() {
    96  	state := q.state.Load()
    97  	if state >= ReceiverStopped {
    98  		return
    99  	}
   100  	q.state.CompareAndSwap(state, ReceiverStopped)
   101  }
   102  
   103  func (q *safeQueue) waitStop() {
   104  	if q.state.Load() <= Running {
   105  		panic("logic error")
   106  	}
   107  	if q.state.Load() == Stopped {
   108  		return
   109  	}
   110  	if q.state.CompareAndSwap(ReceiverStopped, PrepareStop) {
   111  		for q.pending.Load() != 0 {
   112  			runtime.Gosched()
   113  		}
   114  		q.cancel()
   115  	}
   116  	q.wg.Wait()
   117  }
   118  
   119  func (q *safeQueue) Enqueue(item any) (any, error) {
   120  	if q.state.Load() != Running {
   121  		return item, common.ErrClose
   122  	}
   123  	q.pending.Add(1)
   124  	if q.state.Load() != Running {
   125  		q.pending.Add(-1)
   126  		return item, common.ErrClose
   127  	}
   128  	q.queue <- item
   129  	return item, nil
   130  }