Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Fuzzy generics
Search
Alexey Palazhchenko
February 05, 2022
Programming
0
110
Fuzzy generics
Alexey Palazhchenko
February 05, 2022
Tweet
Share
More Decks by Alexey Palazhchenko
See All by Alexey Palazhchenko
Песнь Хорьков и Гоферов
aleksi
0
280
On Ferrets and Gophers
aleksi
0
210
How to Go Wrong with Concurrency
aleksi
2
710
Adding context to existing code
aleksi
1
99
Зачем и как написать свой database/sql драйвер
aleksi
1
120
Cooking gRPC
aleksi
1
750
Profiling and Optimizing Go Programs
aleksi
1
1.7k
Go: начало
aleksi
0
90
What the fuzz?
aleksi
0
460
Other Decks in Programming
See All in Programming
今インフラ技術をイチから学び直すなら
yuhta28
1
140
RAGの回答精度評価用のQAデータセットを生成AIに作らせた話
kurahara
0
260
API Platform for Laravel
dunglas
1
610
いまから追い上げる、Jetpack Compose トレーニング
nyafunta9858
0
620
全部見せます! クラシルリワードのSwiftTesting移行プロジェクト
uetyo
0
210
Regular Expressions, REXML, Automata Learning
makenowjust
0
220
Kotlin 2.0が与えるAndroid開発の進化
masayukisuda
1
420
React + TextAliveでカッコいいLyric Applicatioinを作ろう!!
tosuri13
0
400
意外とフォントが大事だった話 / Font Issues on Internationalization
fumi23
0
110
Developer Joy == Developer Productivity (really!)
hollycummins
1
220
Jakarta EE meets AI
ivargrimstad
0
390
Perl 5 OOP機構30年史 - Perl 5's OOP Mechanism over the past 30 years
moznion
0
390
Featured
See All Featured
Fashionably flexible responsive web design (full day workshop)
malarkey
401
65k
What’s in a name? Adding method to the madness
productmarketing
PRO
21
3k
Rails Girls Zürich Keynote
gr2m
93
13k
Making Projects Easy
brettharned
113
5.8k
The Pragmatic Product Professional
lauravandoore
31
6.2k
Designing Dashboards & Data Visualisations in Web Apps
destraynor
227
52k
Creatively Recalculating Your Daily Design Routine
revolveconf
215
12k
Become a Pro
speakerdeck
PRO
22
4.9k
Save Time (by Creating Custom Rails Generators)
garrettdimon
PRO
24
610
How GitHub (no longer) Works
holman
310
140k
10 Git Anti Patterns You Should be Aware of
lemiorhan
653
58k
A Tale of Four Properties
chriscoyier
155
22k
Transcript
Fuzzy generics Several months of using 1.18 features Alexey Palazhchenko
FOSDEM 2022-02-05
None
Why Go 1.18?
Why Go 1.18? Generics
Why Go 1.18? Generics Fuzzing
Why Go 1.18? Generics Fuzzing
Generics
Generics • Generics do not work there; let's go back
to interfaces
Generics • Generics do not work there; let's go back
to interfaces • Let me extract a small example for a talk
Generics • Generics do not work there; let's go back
to interfaces • Let me extract a small example for a talk • Hm, that's not that bad
BSON Document
BSON Document • Ordered map
BSON Document • Ordered map • Keys – string, values
– any BSON value, including other documents
BSON Document • Ordered map • Keys – string, values
– any BSON value, including other documents • The central data structure in FerretDB
Interfaces type BSONType interface { bsontype() // sealed } type
Int int func (Int) bsontype() {} type String string func (String) bsontype() {}
Interfaces type BSONType interface { bsontype() // sealed } type
Int int func (Int) bsontype() {} type String string func (String) bsontype() {} type Document struct { m map[string]BSONType keys []string } func (*Document) bsontype() {}
Interfaces func (d *Document) Set(key String, value BSONType) { if
_, ok := d.m[key]; !ok { d.keys = append(d.keys, key) } d.m[key] = value }
Interfaces d.Set("foo", Int(42))
Interfaces d.Set("foo", Int(42)) d.Set("qux", nil)
Generics type BSONType interface { int | string | *Document
}
Generics type BSONType interface { int | string | *Document
} type Document struct { m map[string]any keys []string }
Generics func (d *Document) Set[T BSONType](key string, value T) {
if _, ok := d.m[key]; !ok { d.keys = append(d.keys, key) } d.m[key] = value }
Generics func (d *Document) Set[T BSONType](key string, value T) {
if _, ok := d.m[key]; !ok { d.keys = append(d.keys, key) } d.m[key] = value } syntax error: method must have no type parameters
Generics func DocumentSet[T BSONType](d *Document, key string, value T) {
if _, ok := d.m[key]; !ok { d.keys = append(d.keys, key) } d.m[key] = value }
Generics DocumentSet(d, "foo", 42)
Generics DocumentSet(d, "foo", 42) // DocumentSet(d, "qux", nil)
Interfaces func MakeDocument(pairs ...BSONType) (*Document, error) { l := len(pairs)
if l%2 != 0 { return nil, fmt.Errorf("%d arguments", l)
Interfaces
Interfaces MakeDocument( String("foo"), Int(42), String("bar"), String("baz"), )
Interfaces MakeDocument( String("foo"), Int(42), String("bar"), String("baz"), ) MakeDocument(String("invalid number of
arguments"))
Interfaces MakeDocument( String("foo"), Int(42), String("bar"), String("baz"), ) MakeDocument(String("invalid number of
arguments")) MakeDocument(Int(42), String("invalid key type"))
Generics
Generics func MakeDocument[T BSONType](key string, value T) *Document
Generics func MakeDocument[T BSONType](key string, value T) *Document func MakeDocument2[T1,
T2 BSONType](key1 string, value1 T1, key2 string, value2 T2) *Document
Generics func MakeDocument[T BSONType](key string, value T) *Document func MakeDocument2[T1,
T2 BSONType](key1 string, value1 T1, key2 string, value2 T2) *Document func MakeDocument3[T1, T2, T3 BSONType](key1 string, value1 T1, key2 string, value2 T2, key3 string, value3 T3) *Document
Interfaces
Interfaces func (d *Document) Get(key String) BSONType { return d.m[key]
}
Interfaces func (d *Document) Get(key String) BSONType { return d.m[key]
} assert.Equal(t, Int(42), d.Get("foo")) assert.Equal(t, nil, d.Get("baz"))
Generics
Generics func DocumentGet[T BSONType](d *Document, key string) T { v,
_ := d.m[key].(T) return v }
Generics func DocumentGet[T BSONType](d *Document, key string) T { v,
_ := d.m[key].(T) return v } assert.Equal(t, 42, DocumentGet[int](d, "foo")) assert.Equal(t, "", DocumentGet[string](d, "foo"))
Generics vs Interfaces
Generics vs Interfaces • Better in some aspects
Generics vs Interfaces • Better in some aspects • Worse
in others
Generics vs Interfaces • Better in some aspects • Worse
in others
Fuzzing
Fuzzing • testing/quick on steroids
Fuzzing • testing/quick on steroids • MongoDB binary protocol parsing
packages
Fuzzing • testing/quick on steroids • MongoDB binary protocol parsing
packages • FerretDB had fuzzing tests even before unit tests
Table-driven tests type testCase struct { name string b []byte
v bsontype err error }
Table-driven tests type testCase struct { name string b []byte
v bsontype err error } • Unmarshal b to (v2, err2) • compare with v or err • Marshal v2 to b2 • compare with b
Table-driven tests func TestDocument(t *testing.T) { for _, tc :=
range testCases { tc := tc t.Run(tc.name, func(t *testing.T) {
Fuzzing func FuzzDocument(f *testing.F) { for _, tc := range
testCases { f.Add(tc.b) } f.Fuzz(func(t *testing.T, b []byte) {
When b2 != b
When b2 != b • b might be larger than
needed
When b2 != b • b might be larger than
needed • The unread portion of b should be removed
When b2 != b • b might be larger than
needed • The unread portion of b should be removed • Some bytes might be insigni fi cant
When b2 != b • b might be larger than
needed • The unread portion of b should be removed • Some bytes might be insigni fi cant • Use canonization (json.Compact, etc)
Fuzzing issues
Fuzzing issues • No subtests (testing.F.Run)
Fuzzing issues • No subtests (testing.F.Run) • Unnamed seed values
Fuzzing issues • No subtests (testing.F.Run) • Unnamed seed values
• Hanging detection is unreliable with unset GOMAXPROCS
Fuzzing
Fuzzing • Found a few bugs in `go test -fuzz`
Fuzzing • Found a few bugs in `go test -fuzz`
• Found many many bugs in FerretDB
Fuzzing • Found a few bugs in `go test -fuzz`
• Found many many bugs in FerretDB • De fi nitely use it for parsing
Links • https://github.com/AlekSi/ generics-vs-interfaces • https://github.com/akutz/ go-generics-the-hard-way • https://go.dev/doc/tutorial/ •
https://go.dev/doc/fuzz/ • https://www.ferretdb.io • https://github.com/FerretDB ⭐ • https://github.com/AlekSi • @paaleksey