github.com/m3db/m3@v1.5.0/src/aggregator/bitset/bitset.go (about)

     1  // Copyright (c) 2018 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package bitset
    22  
    23  import (
    24  	"github.com/willf/bitset"
    25  )
    26  
    27  // BitSet is a specialized bitset that does not perform heap allocations if the
    28  // range of values in the bitset is small (e.g., [0, 64)). It falls back to
    29  // github.com/willf/bitset for large value ranges.
    30  type BitSet struct {
    31  	bs         *bitset.BitSet
    32  	val        uint64
    33  	smallRange bool
    34  }
    35  
    36  // New can be used to keep track of values between [0, maxExclusive).
    37  // Calling APIs with values outside that range may lead to incorrect results.
    38  func New(maxExclusive uint) BitSet {
    39  	if maxExclusive <= 64 {
    40  		return BitSet{smallRange: true}
    41  	}
    42  	return BitSet{bs: bitset.New(maxExclusive)}
    43  }
    44  
    45  // Set sets the bit associated with the given value.
    46  func (bs *BitSet) Set(i uint) {
    47  	if bs.smallRange {
    48  		bs.val = bs.val | (1 << i)
    49  		return
    50  	}
    51  	bs.bs.Set(i)
    52  }
    53  
    54  // All returns true if all the bits for values between [0, maxExclusive)
    55  // are set.
    56  func (bs *BitSet) All(maxExclusive uint) bool {
    57  	if bs.smallRange {
    58  		mask := uint64((1 << maxExclusive) - 1)
    59  		return (bs.val & mask) == mask
    60  	}
    61  	for i := uint(0); i < maxExclusive; i++ {
    62  		if !bs.bs.Test(i) {
    63  			return false
    64  		}
    65  	}
    66  	return true
    67  }