github.com/songzhibin97/gkit@v1.2.13/structure/skipmap/flag.go (about)

     1  // Copyright 2021 ByteDance Inc.
     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 skipmap
    16  
    17  import "sync/atomic"
    18  
    19  const (
    20  	fullyLinked = 1 << iota
    21  	marked
    22  )
    23  
    24  // concurrent-safe bitflag.
    25  type bitflag struct {
    26  	data uint32
    27  }
    28  
    29  func (f *bitflag) SetTrue(flags uint32) {
    30  	for {
    31  		old := atomic.LoadUint32(&f.data)
    32  		if old&flags == flags {
    33  			return
    34  		}
    35  		// Flag is 0, need set it to 1.
    36  		n := old | flags
    37  		if atomic.CompareAndSwapUint32(&f.data, old, n) {
    38  			return
    39  		}
    40  		continue
    41  	}
    42  }
    43  
    44  func (f *bitflag) SetFalse(flags uint32) {
    45  	for {
    46  		old := atomic.LoadUint32(&f.data)
    47  		check := old & flags
    48  		if check == 0 {
    49  			return
    50  		}
    51  		// Flag is 1, need set it to 0.
    52  		n := old ^ check
    53  		if atomic.CompareAndSwapUint32(&f.data, old, n) {
    54  			return
    55  		}
    56  		continue
    57  	}
    58  }
    59  
    60  func (f *bitflag) Get(flag uint32) bool {
    61  	return (atomic.LoadUint32(&f.data) & flag) != 0
    62  }
    63  
    64  func (f *bitflag) MGet(check, expect uint32) bool {
    65  	return (atomic.LoadUint32(&f.data) & check) == expect
    66  }