vitess.io/vitess@v0.16.2/go/vt/vtgate/vindexes/binarymd5.go (about)

     1  /*
     2  Copyright 2019 The Vitess Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package vindexes
    18  
    19  import (
    20  	"bytes"
    21  	"context"
    22  	"crypto/md5"
    23  
    24  	"vitess.io/vitess/go/sqltypes"
    25  	"vitess.io/vitess/go/vt/key"
    26  )
    27  
    28  var (
    29  	_ SingleColumn = (*BinaryMD5)(nil)
    30  	_ Hashing      = (*BinaryMD5)(nil)
    31  )
    32  
    33  // BinaryMD5 is a vindex that hashes binary bits to a keyspace id.
    34  type BinaryMD5 struct {
    35  	name string
    36  }
    37  
    38  // NewBinaryMD5 creates a new BinaryMD5.
    39  func NewBinaryMD5(name string, _ map[string]string) (Vindex, error) {
    40  	return &BinaryMD5{name: name}, nil
    41  }
    42  
    43  // String returns the name of the vindex.
    44  func (vind *BinaryMD5) String() string {
    45  	return vind.name
    46  }
    47  
    48  // Cost returns the cost as 1.
    49  func (vind *BinaryMD5) Cost() int {
    50  	return 1
    51  }
    52  
    53  // IsUnique returns true since the Vindex is unique.
    54  func (vind *BinaryMD5) IsUnique() bool {
    55  	return true
    56  }
    57  
    58  // NeedsVCursor satisfies the Vindex interface.
    59  func (vind *BinaryMD5) NeedsVCursor() bool {
    60  	return false
    61  }
    62  
    63  // Verify returns true if ids maps to ksids.
    64  func (vind *BinaryMD5) Verify(ctx context.Context, vcursor VCursor, ids []sqltypes.Value, ksids [][]byte) ([]bool, error) {
    65  	out := make([]bool, 0, len(ids))
    66  	for i, id := range ids {
    67  		ksid, err := vind.Hash(id)
    68  		if err != nil {
    69  			return nil, err
    70  		}
    71  		out = append(out, bytes.Equal(ksid, ksids[i]))
    72  	}
    73  	return out, nil
    74  }
    75  
    76  // Map can map ids to key.Destination objects.
    77  func (vind *BinaryMD5) Map(ctx context.Context, vcursor VCursor, ids []sqltypes.Value) ([]key.Destination, error) {
    78  	out := make([]key.Destination, 0, len(ids))
    79  	for _, id := range ids {
    80  		ksid, err := vind.Hash(id)
    81  		if err != nil {
    82  			return out, err
    83  		}
    84  		out = append(out, key.DestinationKeyspaceID(ksid))
    85  	}
    86  	return out, nil
    87  }
    88  
    89  func (vind *BinaryMD5) Hash(id sqltypes.Value) ([]byte, error) {
    90  	idBytes, err := id.ToBytes()
    91  	if err != nil {
    92  		return nil, err
    93  	}
    94  	return vMD5Hash(idBytes), nil
    95  }
    96  
    97  func vMD5Hash(source []byte) []byte {
    98  	sum := md5.Sum(source)
    99  	return sum[:]
   100  }
   101  
   102  func init() {
   103  	Register("binary_md5", NewBinaryMD5)
   104  }