github.com/m3db/m3@v1.5.0/src/dbnode/persist/schema/index_entry_hasher.go (about)

     1  // Copyright (c) 2020 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 schema
    22  
    23  import (
    24  	"github.com/cespare/xxhash/v2"
    25  
    26  	"github.com/m3db/m3/src/dbnode/ts"
    27  	"github.com/m3db/m3/src/x/ident"
    28  )
    29  
    30  type xxHasher struct{}
    31  
    32  // NewXXHasher returns an IndexEntryHasher utilizing xxHash hashing.
    33  func NewXXHasher() IndexEntryHasher {
    34  	return xxHasher{}
    35  }
    36  
    37  func (x xxHasher) HashIndexEntry(
    38  	id ident.BytesID,
    39  	encodedTags ts.EncodedTags,
    40  	dataChecksum int64,
    41  ) int64 {
    42  	hash := uint64(7)
    43  	hash = 31*hash + xxhash.Sum64(id)
    44  	hash = 31*hash + xxhash.Sum64(encodedTags)
    45  	hash = 31*hash + uint64(dataChecksum)
    46  
    47  	return int64(hash)
    48  }