github.com/m3db/m3@v1.5.0/src/query/block/empty.go (about)

     1  // Copyright (c) 2019 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 block
    22  
    23  type emptyBlock struct {
    24  	meta Metadata
    25  }
    26  
    27  // NewEmptyBlock creates an empty block with the given metadata.
    28  func NewEmptyBlock(meta Metadata) Block {
    29  	return &emptyBlock{meta: meta}
    30  }
    31  
    32  func (b *emptyBlock) Close() error { return nil }
    33  
    34  func (b *emptyBlock) Info() BlockInfo {
    35  	return NewBlockInfo(BlockEmpty)
    36  }
    37  
    38  func (b *emptyBlock) Meta() Metadata {
    39  	return b.meta
    40  }
    41  
    42  func (b *emptyBlock) StepIter() (StepIter, error) {
    43  	return &emptyStepIter{steps: b.meta.Bounds.Steps()}, nil
    44  }
    45  
    46  type emptyStepIter struct {
    47  	steps int
    48  }
    49  
    50  func (it *emptyStepIter) Close()                   {}
    51  func (it *emptyStepIter) Err() error               { return nil }
    52  func (it *emptyStepIter) StepCount() int           { return it.steps }
    53  func (it *emptyStepIter) SeriesMeta() []SeriesMeta { return []SeriesMeta{} }
    54  func (it *emptyStepIter) Next() bool               { return false }
    55  func (it *emptyStepIter) Current() Step            { return nil }
    56  
    57  func (b *emptyBlock) SeriesIter() (SeriesIter, error) {
    58  	return &emptySeriesIter{}, nil
    59  }
    60  
    61  type emptySeriesIter struct{}
    62  
    63  func (it *emptySeriesIter) Close()                        {}
    64  func (it *emptySeriesIter) Err() error                    { return nil }
    65  func (it *emptySeriesIter) SeriesCount() int              { return 0 }
    66  func (it *emptySeriesIter) SeriesMeta() []SeriesMeta      { return []SeriesMeta{} }
    67  func (it *emptySeriesIter) Next() bool                    { return false }
    68  func (it *emptySeriesIter) Current() UnconsolidatedSeries { return UnconsolidatedSeries{} }
    69  
    70  func (b *emptyBlock) MultiSeriesIter(
    71  	concurrency int,
    72  ) ([]SeriesIterBatch, error) {
    73  	batch := make([]SeriesIterBatch, concurrency)
    74  	for i := range batch {
    75  		batch[i] = SeriesIterBatch{
    76  			Size: 1,
    77  			Iter: &emptySeriesIter{},
    78  		}
    79  	}
    80  
    81  	return batch, nil
    82  }