github.com/m3db/m3@v1.5.0/src/m3ninx/index/metadata_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 index
    22  
    23  import (
    24  	"errors"
    25  
    26  	"github.com/m3db/m3/src/m3ninx/doc"
    27  	"github.com/m3db/m3/src/m3ninx/postings"
    28  )
    29  
    30  var errIteratorClosed = errors.New("iterator has been closed")
    31  
    32  type idDocIterator struct {
    33  	retriever    MetadataRetriever
    34  	postingsIter postings.Iterator
    35  
    36  	currDoc doc.Metadata
    37  	currID  postings.ID
    38  	closed  bool
    39  	err     error
    40  }
    41  
    42  // NewIDDocIterator returns a new NewIDDocIterator.
    43  func NewIDDocIterator(r MetadataRetriever, pi postings.Iterator) IDDocIterator {
    44  	return &idDocIterator{
    45  		retriever:    r,
    46  		postingsIter: pi,
    47  	}
    48  }
    49  
    50  func (it *idDocIterator) Next() bool {
    51  	if it.closed || it.err != nil || !it.postingsIter.Next() {
    52  		return false
    53  	}
    54  	id := it.postingsIter.Current()
    55  	it.currID = id
    56  
    57  	d, err := it.retriever.Metadata(id)
    58  	if err != nil {
    59  		it.err = err
    60  		return false
    61  	}
    62  	it.currDoc = d
    63  	return true
    64  }
    65  
    66  func (it *idDocIterator) Current() doc.Metadata {
    67  	return it.currDoc
    68  }
    69  
    70  func (it *idDocIterator) PostingsID() postings.ID {
    71  	return it.currID
    72  }
    73  
    74  func (it *idDocIterator) Err() error {
    75  	return it.err
    76  }
    77  
    78  func (it *idDocIterator) Close() error {
    79  	if it.closed {
    80  		return errIteratorClosed
    81  	}
    82  	it.closed = true
    83  	it.currDoc = doc.Metadata{}
    84  	it.currID = postings.ID(0)
    85  	err := it.postingsIter.Close()
    86  	return err
    87  }