github.com/matrixorigin/matrixone@v0.7.0/pkg/lockservice/waiter_queue.go (about)

     1  // Copyright 2023 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 lockservice
    16  
    17  import (
    18  	"sync"
    19  )
    20  
    21  type waiterQueue interface {
    22  	len() int
    23  	reset()
    24  	pop() (*waiter, []*waiter)
    25  	put(...*waiter)
    26  	iter(func([]byte) bool)
    27  }
    28  
    29  func newWaiterQueue() *sliceBasedWaiterQueue {
    30  	return &sliceBasedWaiterQueue{}
    31  }
    32  
    33  type sliceBasedWaiterQueue struct {
    34  	sync.RWMutex
    35  	offset  int
    36  	waiters []*waiter
    37  }
    38  
    39  func (q *sliceBasedWaiterQueue) len() int {
    40  	q.RLock()
    41  	defer q.RUnlock()
    42  	return len(q.waiters) - q.offset
    43  }
    44  
    45  func (q *sliceBasedWaiterQueue) pop() (*waiter, []*waiter) {
    46  	if q.len() == 0 {
    47  		panic("BUG: no waiter in queue")
    48  	}
    49  
    50  	q.Lock()
    51  	defer q.Unlock()
    52  	v := q.waiters[q.offset]
    53  	q.waiters[q.offset] = nil
    54  	q.offset++
    55  	return v, q.waiters[q.offset:]
    56  }
    57  
    58  func (q *sliceBasedWaiterQueue) put(w ...*waiter) {
    59  	q.Lock()
    60  	defer q.Unlock()
    61  	if len(q.waiters) == 0 {
    62  		q.waiters = w
    63  	} else {
    64  		q.waiters = append(q.waiters, w...)
    65  	}
    66  }
    67  
    68  func (q *sliceBasedWaiterQueue) iter(fn func([]byte) bool) {
    69  	q.RLock()
    70  	defer q.RUnlock()
    71  	n := len(q.waiters)
    72  	for i := q.offset; i < n; i++ {
    73  		if !fn(q.waiters[i].txnID) {
    74  			return
    75  		}
    76  	}
    77  }
    78  
    79  func (q *sliceBasedWaiterQueue) reset() {
    80  	q.Lock()
    81  	defer q.Unlock()
    82  	q.waiters = q.waiters[:0]
    83  	q.offset = 0
    84  }