github.com/m3db/m3@v1.5.0/src/m3ninx/persist/reader.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 persist
    22  
    23  import (
    24  	"fmt"
    25  	"io"
    26  
    27  	"github.com/m3db/m3/src/m3ninx/index/segment/fst"
    28  	"github.com/m3db/m3/src/m3ninx/x"
    29  )
    30  
    31  // NewSegment returns a new fst.Segment backed by the provided fileset.
    32  // NB: this method takes ownership of the provided fileset files, in case of both errors,
    33  // and success. i.e. users are not expected to call Close on any of the provided fileset.Files()
    34  // after invoking this function.
    35  func NewSegment(fileset IndexSegmentFileSet, opts fst.Options) (fst.Segment, error) {
    36  	success := false
    37  	safeCloser := newSafeIndexSegmentFileSetCloser(fileset)
    38  	defer func() {
    39  		if !success {
    40  			safeCloser.Close()
    41  		}
    42  	}()
    43  
    44  	if t := fileset.SegmentType(); t != FSTIndexSegmentType {
    45  		return nil, fmt.Errorf("unknown segment type: %s", t)
    46  	}
    47  
    48  	sd, err := filesetToSegmentData(fileset)
    49  	if err != nil {
    50  		return nil, err
    51  	}
    52  	sd.Closer = safeCloser
    53  
    54  	segment, err := fst.NewSegment(sd, opts)
    55  	if err != nil {
    56  		return nil, err
    57  	}
    58  
    59  	// indicate we don't need to close files in the defer above.
    60  	success = true
    61  
    62  	// segment assumes ownership of the safeCloser at this point.
    63  	return segment, nil
    64  }
    65  
    66  func filesetToSegmentData(fileset IndexSegmentFileSet) (fst.SegmentData, error) {
    67  	var (
    68  		sd = fst.SegmentData{
    69  			Version: fst.Version{
    70  				Major: fileset.MajorVersion(),
    71  				Minor: fileset.MinorVersion(),
    72  			},
    73  			Metadata: fileset.SegmentMetadata(),
    74  		}
    75  		err error
    76  	)
    77  
    78  	for _, f := range fileset.Files() {
    79  		fileType := f.SegmentFileType()
    80  		switch fileType {
    81  		case DocumentDataIndexSegmentFileType:
    82  			sd.DocsData, err = f.Mmap()
    83  			if err != nil {
    84  				return sd, err
    85  			}
    86  		case DocumentIndexIndexSegmentFileType:
    87  			sd.DocsIdxData, err = f.Mmap()
    88  			if err != nil {
    89  				return sd, err
    90  			}
    91  		case PostingsIndexSegmentFileType:
    92  			sd.PostingsData, err = f.Mmap()
    93  			if err != nil {
    94  				return sd, err
    95  			}
    96  		case FSTFieldsIndexSegmentFileType:
    97  			sd.FSTFieldsData, err = f.Mmap()
    98  			if err != nil {
    99  				return sd, err
   100  			}
   101  		case FSTTermsIndexSegmentFileType:
   102  			sd.FSTTermsData, err = f.Mmap()
   103  			if err != nil {
   104  				return sd, err
   105  			}
   106  		default:
   107  			return sd, fmt.Errorf("unknown fileType: %s provided", fileType)
   108  		}
   109  	}
   110  
   111  	return sd, nil
   112  }
   113  
   114  func newSafeIndexSegmentFileSetCloser(fileset IndexSegmentFileSet) io.Closer {
   115  	closers := make([]io.Closer, 0, len(fileset.Files()))
   116  	for _, f := range fileset.Files() {
   117  		closers = append(closers, f)
   118  	}
   119  	return x.NewSafeMultiCloser(closers...)
   120  }