github.com/m3db/m3@v1.5.0/src/m3ninx/index/segment/mem/merge.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 mem
    22  
    23  import (
    24  	"io"
    25  
    26  	"github.com/m3db/m3/src/m3ninx/index"
    27  	sgmt "github.com/m3db/m3/src/m3ninx/index/segment"
    28  	"github.com/m3db/m3/src/m3ninx/x"
    29  )
    30  
    31  // Merge merges the segments `srcs` into `target`.
    32  func Merge(target sgmt.MutableSegment, srcs ...sgmt.MutableSegment) error {
    33  	safeClosers := []io.Closer{}
    34  	defer func() {
    35  		for _, c := range safeClosers {
    36  			c.Close()
    37  		}
    38  	}()
    39  
    40  	// for each src
    41  	for _, src := range srcs {
    42  		// get reader for `src`
    43  		reader, err := src.Reader()
    44  		if err != nil {
    45  			return err
    46  		}
    47  
    48  		// ensure readers are all closed.
    49  		readerCloser := x.NewSafeCloser(reader)
    50  		safeClosers = append(safeClosers, readerCloser)
    51  
    52  		// retrieve all docs known to the reader
    53  		dIter, err := reader.AllDocs()
    54  		if err != nil {
    55  			return err
    56  		}
    57  
    58  		// iterate over all known docs
    59  		for dIter.Next() {
    60  			d := dIter.Current()
    61  			_, err := target.Insert(d)
    62  			if err == nil || err == index.ErrDuplicateID {
    63  				continue
    64  			}
    65  			return err
    66  		}
    67  
    68  		// ensure no errors while iterating
    69  		if err := dIter.Err(); err != nil {
    70  			return err
    71  		}
    72  
    73  		// ensure no errors while closing reader
    74  		if err := readerCloser.Close(); err != nil {
    75  			return err
    76  		}
    77  	}
    78  
    79  	// all good
    80  	return nil
    81  }