github.com/m3db/m3@v1.5.0/src/m3ninx/postings/pilosa/iterator.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 pilosa
    22  
    23  import (
    24  	"github.com/m3db/m3/src/m3ninx/postings"
    25  	"github.com/m3dbx/pilosa/roaring"
    26  )
    27  
    28  // NB: need to do this to find a path into our postings list which doesn't require every
    29  // insert to grab a lock. Need to make a non thread-safe version of our api.
    30  // FOLLOWUP(prateek): tracking this issue in https://github.com/m3db/m3ninx/issues/65
    31  
    32  type iterator struct {
    33  	iter    *roaring.Iterator
    34  	current uint64
    35  	hasNext bool
    36  }
    37  
    38  var _ postings.Iterator = &iterator{}
    39  
    40  // NewIterator returns a postings.Iterator wrapping a pilosa roaring.Iterator.
    41  func NewIterator(iter *roaring.Iterator) postings.Iterator {
    42  	return &iterator{
    43  		iter:    iter,
    44  		hasNext: true,
    45  	}
    46  }
    47  
    48  func (p *iterator) Next() bool {
    49  	if !p.hasNext {
    50  		return false
    51  	}
    52  	v, eof := p.iter.Next()
    53  	p.current = v
    54  	p.hasNext = !eof
    55  	return p.hasNext
    56  }
    57  
    58  func (p *iterator) Current() postings.ID {
    59  	return postings.ID(p.current)
    60  }
    61  
    62  func (p *iterator) Err() error {
    63  	return nil
    64  }
    65  
    66  func (p *iterator) Close() error {
    67  	p.iter = nil
    68  	p.hasNext = false
    69  	return nil
    70  }