-
Notifications
You must be signed in to change notification settings - Fork 6
/
db.go
143 lines (114 loc) · 3.99 KB
/
db.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
// @license
// Copyright (C) 2022 Dinko Korunic
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
package db
import (
"errors"
"fmt"
"strconv"
"time"
"github.com/dgraph-io/badger/v4"
"github.com/dkorunic/e-dnevnik-bot/logger"
)
const (
DefaultDBPath = ".e-dnevnik.db" // default BadgerDB folder
DefaultTTL = time.Hour * 9000 // a bit more than 1 year TTL
DefaultDiscardRatio = 0.5 // recommended discard ratio from Badger docs
)
// Edb holds e-dnevnik structure including Bardger struct.
type Edb struct {
db *badger.DB
isExisting bool // already created/initialized db
}
// New opens a new database, flagging if the database already preexisting.
func New(filePath string) (*Edb, error) {
if filePath == "" {
filePath = DefaultDBPath
}
isExisting := dbExists(filePath)
logger.Debug().Msgf("Opening database: %v", filePath)
opts := badger.DefaultOptions(filePath)
// adapt for low memory environment
//nolint:gomnd
if strconv.IntSize == 32 {
logger.Info().Msg("Detected 32-bit environment, tuning DB for lower memory usage")
opts.ValueLogFileSize = 1 << 20 //nolint:gomnd
}
db, err := badger.Open(opts.WithLogger(nil)) // disable Badger verbose logging
if err != nil {
if isExisting {
return nil, fmt.Errorf("could not open database: %w", err)
}
return nil, fmt.Errorf("could not create database: %w", err)
}
edb := &Edb{db: db, isExisting: isExisting}
return edb, nil
}
// Close closes database, optionally running GC (removing state data from value log file).
func (db *Edb) Close() error {
logger.Debug().Msg("Running database GC")
again:
err := db.db.RunValueLogGC(DefaultDiscardRatio)
if err == nil {
goto again
}
logger.Debug().Msg("Closing database")
return db.db.Close()
}
// CheckAndFlag checks presence of a SHA256(bucket, subBucket, []target) in a KV database, returning if it has been
// found or not, flagging it for the next time and returning error if encountered.
func (db *Edb) CheckAndFlag(bucket, subBucket string, target []string) (bool, error) {
// SHA256 hash of (bucket, subBucket, []target)
key := hashContent(bucket, subBucket, target)
var found bool
// check if key exists
err := db.db.View(func(txn *badger.Txn) error {
_, err := txn.Get(key)
switch {
// key not found (found=false)
case errors.Is(err, badger.ErrKeyNotFound):
return nil
// key found (found=true)
case err == nil:
found = true
return nil
}
// all other errors (found=false)
return err
})
if err != nil {
// return quickly: (fatal) error + found=false
return false, err
} else if found {
// return quickly: no error + found=true
return true, nil
}
// key hasn't been found yet, so mark the key and set 1+year TTL
err = db.db.Update(func(txn *badger.Txn) error {
e := badger.NewEntry(key, []byte("")).WithTTL(DefaultTTL)
return txn.SetEntry(e)
})
// found=false
return false, err
}
// Existing returns if the database was freshly initialized.
func (db *Edb) Existing() bool {
return db.isExisting
}