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withContextͬͯ
εϨουΓସ͑Ҏ֎ʹ
͑Δͬͯͬͯͨʁ
2024/06/22 (Sat)
Kotlin Fest 2024
T45K
@getupmax
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ࢿྉͪ͜Β
https://x.com/getupmax
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Kotlin Coroutine
ͬͯ·͔͢ʁ
🙋
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Coroutine͓͞Β͍
~ AndroidΛࡐͱͯ͠ ~
https://developer.android.com/kotlin/coroutines
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UIεϨου্Ͱ
͕͔͔࣌ؒΔॲཧΛͦͷ··ॻ͘
Coroutine͓͞Β͍
https://developer.android.com/kotlin/coroutines#executing-in-a-background-thread
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UIεϨου্Ͱ
͕͔͔࣌ؒΔॲཧΛͦͷ··ॻ͘
↓
ϑϦʔζ͢Δ
Coroutine͓͞Β͍
https://developer.android.com/kotlin/coroutines#executing-in-a-background-thread
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class LoginRepository(private val responseParser: LoginResponseParser) {
private const val loginUrl = "https://example.com/login"
// ݱࡏͷεϨουΛϒϩοΫ͢ΔɺωοτϫʔΫϦΫΤετΛߦ͏ؔ
// ͭ·ΓɺϩάΠϯ͕ྃ͢Δ·ͰΞϓϦ͕ϑϦʔζ͢Δ
fun makeLoginRequest(jsonBody: String): Result {
val url = URL(loginUrl)
(url.openConnection() as? HttpURLConnection)?.run {
...
}
return ...
}
}
https://developer.android.com/kotlin/coroutines#executing-in-a-background-thread
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APIݺͼग़͠ΛIOεϨουͰΓ͍ͨ
Coroutine͓͞Β͍
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APIݺͼग़͠ΛIOεϨουͰΓ͍ͨ
↓
withContext(Dispatchers.IO)ͰғΉ
Coroutine͓͞Β͍
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class LoginRepository(...) {
...
suspend fun makeLoginRequest(jsonBody: String): Result {
// APIݺͼग़͠ΛIO DispatcherͰ࣮ߦ͢Δ
return withContext(Dispatchers.IO) {
val url = URL(loginUrl)
(url.openConnection() as? HttpURLConnection)?.run {
...
}
return ...
}
}
}
https://developer.android.com/kotlin/coroutines#use-coroutines-for-main-safety
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class LoginViewModel(private val loginRepository: LoginRepository) :
ViewModel() {
fun login(username: String, token: String) {
viewModelScope.launch {
val jsonBody = "{ username: \"$username\", token: \"$token\"}"
// makeLoginRequestͷ࣮ߦIOεϨουͰߦΘΕΔ
// ͦͷؒɺUIεϨουϒϩοΫ͞Εͳ͍ͷͰɺϢʔβૢ࡞Λड͚͚ΒΕΔ
val result = loginRepository.makeLoginRequest(jsonBody)
// ݁ՌΛUIεϨουͰॲཧ͢Δ
when (result) {
is Result.Success -> ...
else -> ...
}
}
}
}
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ϩάΠϯதʹΞϓϦ͕
ϑϦʔζ͠ͳ͘ͳͬͨ 🎉
Coroutine͓͞Β͍
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withContext(Dispatchers.XXX) ?
Coroutine͓͞Β͍
ωοτϫʔΫॲཧ
ܭࢉྔଟ͍ॲཧ
UIपΓͷॲཧ
Dispatchers.IO
Dispatchers.Default
Dispatchers.Main
→
→
→
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withContext
εϨουΓସ͑༻ʁ🤔
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🙅
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withContext
CoroutineContextΛ
Γସ͑Δ
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https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.coroutines/-coroutine-context/
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CoroutineContext.KeyΛΩʔ
CoroutineContext.ElementΛόϦϡʔ
ͱͨࣙ͠ॻ
CoroutineContext
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https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.coroutines/-coroutine-context/
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// StringܕΛอ࣋͢ΔίϯςΩετ
class CoroutineContextA(val value: String) :
CoroutineContext.Element {
companion object Key : CoroutineContext.Key
override val key: CoroutineContext.Key<*> = Key
}
// IntܕΛอ࣋͢ΔίϯςΩετ
class CoroutineContextB(val value: Int) :
CoroutineContext.Element {
companion object Key : CoroutineContext.Key
override val key: CoroutineContext.Key<*> = Key
}
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val contextA = CoroutineContextA("test")
val contextB = CoroutineContextB(1)
contextA[CoroutineContextA.Key]?.value == "test"
contextB[CoroutineContextA.Key] == null
val contextAB = contextA + contextB
contextAB[CoroutineContextA.Key]?.value == "test"
contextAB[CoroutineContextB.Key]?.value == 1
val contextABMinusA = contextAB.minusKey(CoroutineContextA.Key)
contextABMinusA[CoroutineContextA.Key] == null
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val contextA = CoroutineContextA("test")
val contextB = CoroutineContextB(1)
contextA[CoroutineContextA.Key]?.value == "test"
contextB[CoroutineContextA.Key] == null
val contextAB = contextA + contextB
contextAB[CoroutineContextA.Key]?.value == "test"
contextAB[CoroutineContextB.Key]?.value == 1
val contextABMinusA = contextAB.minusKey(CoroutineContextA.Key)
contextABMinusA[CoroutineContextA.Key] == null
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val contextA = CoroutineContextA("test")
val contextB = CoroutineContextB(1)
contextA[CoroutineContextA.Key]?.value == "test"
contextB[CoroutineContextA.Key] == null
val contextAB = contextA + contextB
contextAB[CoroutineContextA.Key]?.value == "test"
contextAB[CoroutineContextB.Key]?.value == 1
val contextABMinusA = contextAB.minusKey(CoroutineContextA.Key)
contextABMinusA[CoroutineContextA.Key] == null
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val contextA = CoroutineContextA("test")
val contextB = CoroutineContextB(1)
contextA[CoroutineContextA.Key]?.value == "test"
contextB[CoroutineContextA.Key] == null
val contextAB = contextA + contextB
contextAB[CoroutineContextA.Key]?.value == "test"
contextAB[CoroutineContextB.Key]?.value == 1
val contextABMinusA = contextAB.minusKey(CoroutineContextA.Key)
contextABMinusA[CoroutineContextA.Key] == null
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1. ҾͰ༩͑ΒΕͨCoroutineContextΛ
2. ݱࡏͷCoroutineContextʹՃ͑ͯ
3. ϒϩοΫΛ࣮ߦ͢Δ
withContext
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val contextA = CoroutineContextA("test")
val contextB = CoroutineContextB(1)
withContext(a) {
withContext(b) {
currentCoroutineContext()[CoroutineContextA.Key]?.value == "test"
currentCoroutineContext()[CoroutineContextB.Key]?.value == 1
}
currentCoroutineContext()[CoroutineContextA.Key]?.value == "test"
currentCoroutineContext()[CoroutineContextB.Key] == null
}
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Կʹ͑Δʁ
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CoroutineContextʹΛೖΕͯ
withContextʹ͢͜ͱͰ
ίϯςΩετมͱͯ͠ѻ͑Δ
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ࠓ·ͰThreadLocalͱ͔Ͱ
ཧ͍ͯͨ͠ΞϨίϨΛ
CoroutineͰ͑ͦ͏
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ར༻ྫ1
τϥϯβΫγϣϯཧ
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౷తͳWeb FrameworkͰ
ThreadLocalͰτϥϯβΫγϣϯΛཧ
τϥϯβΫγϣϯཧ
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ྫ) Spring Framework
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Coroutine࣮ߦεϨουΛΓସ͑Δ
→ThreadLocal͑ͳ͍
τϥϯβΫγϣϯཧ
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Coroutine࣮ߦεϨουΛΓସ͑Δ
→ThreadLocal͑ͳ͍
ͷͰɺࣗલཧ
τϥϯβΫγϣϯཧ
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εϨουΛཧ͢ΔΦϒδΣΫτΛ
CoroutineContextʹೖΕͯཧ͢Δ
τϥϯβΫγϣϯཧ
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jOOQͰͷτϥϯβΫγϣϯཧ
val dsl: DSLContext = xxx
dsl.transactionCoroutine { config ->
config.dsl().execute("insert into table1 ...")
config.dsl().execute("insert into table2 ...")
}
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class UseCase(private val dsl: DSLContext, private val service: Service) {
suspend fun execute() {
dsl.transactionCoroutine { config ->
service.execute(config.dsl())
}
}
}
class Service(private val repo: Repository) {
suspend fun execute(ctx: DSLContext) {
repo.save(ctx)
}
}
class Repository {
suspend fun save(ctx: DSLContext) {
ctx.execute("insert into table1 ...")
}
}
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DSLContextΦϒδΣΫτΛ
CoroutineContextʹೖΕͯཧ͢Δ
jOOQͷτϥϯβΫγϣϯཧ
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// DSLContextΛอ࣋͢ΔElement
class TransactionElement(val ctx: DSLContext) :
AbstractCoroutineContextElement(TransactionElement) {
companion object Key : CoroutineContext.Key
}
class TransactionManager(private val ctx: DSLContext) {
suspend fun execute(block: suspend () -> T): T =
ctx.transactionCoroutine { config ->
withContext(TransactionElement(config.dsl())) {
block()
}
}
}
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class Repository(private val dsl: DSLContext) {
suspend fun save() {
(coroutineContext[TransactionElement]?.ctx ?: this.ctx)
.execute("insert into table1 ...")
}
}
class UseCase(
private val manager: TransactionManager,
private val service: Service
) {
suspend fun execute() {
manager.execute {
service.execute(config.dsl())
}
}
}
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ར༻ྫ2
Ϣʔβใͷཧ
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ϦΫΤετॲཧͷ࠷ॳ͔Β࠷ޙ·Ͱ
ใΛอ͍࣋ͨ͠
e.g., Tenant IDͳͲ
Ϣʔβใͷཧ
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class Controller(private val service: Service) {
suspend fun get(session: Session) {
val tenantId = session.getTenantId()
service.execute(tenantId)
}
}
class Service(private val repo: Repository) {
suspend fun execute(tenantId: Long) {
repo.select(tenantId)
}
}
class Repository(private val ctx: DSLContext) {
suspend fun select(tenantId: Long) {
ctx.execute("select * table where tenant_id = ?", tenantId)
}
}
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ϦΫΤετॲཧͷ࠷ॳ͔Β࠷ޙ·Ͱ
ใΛอ͍࣋ͨ͠
e.g., Tenant IDͳͲ
Ϣʔβใͷཧ
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ϦΫΤετॲཧͷ࠷ॳ͔Β࠷ޙ·Ͱ
ใΛอ͍࣋ͨ͠
e.g., Tenant IDͳͲ
→ CoroutineContextʹೖΕΔ
Ϣʔβใͷཧ
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class UserInfoElement(val tenantId: Long) :
AbstractCoroutineContextElement(UserInfoElement) {
companion object Key : CoroutineContext.Key
}
suspend fun getTenantId(): Long = coroutineContext[UserInfoElement]!!.tenantId
class Controller(private val service: Service) {
suspend fun get(session: Session) =
withContext(UserInfoElement(session.getTenantId())){
service.execute()
}
}
class Service(private val repo: Repository) {
suspend fun execute() {
repo.select()
}
}
class Repository(private val ctx: DSLContext) {
suspend fun select() {
ctx.execute("select * table where tenant_id = ?", getTenantId())
}
}
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ͱ͜ΖͰ
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͜Εͬͯ
Context Parameterͷํ͕ྑ͍ʁ
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withͷมΛݺͼग़͠ઌͰࢀরͰ͖Δػೳ
ʢͱͱContext Receiverʣ
Kotlin 2.1ΑΓಋೖ༧ఆ
ʢexperimentalͱͯ͠ར༻Մೳʣ
Context Parameter
https://github.com/Kotlin/KEEP/blob/context-parameters/proposals/context-receivers.md
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data class UserInfo(val tenantId: String)
class ItemDao {
context(UserInfo)
fun selectById(itemId: Int): Item? =
execute("""
select * from item
where id = $itemId
and tenant_id = $tenantId
""")
}
get("/") {
with(UserInfo("123456")) {
call.respond(...)
}
}
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CoroutineContextͱൺֱͯ͠...
👍 ίϯύΠϧ࣌ʹίϯςΩετͷݕ͕ࠪ͞ΕΔ
👍 Coroutine͡Όͳͯ͑͘Δ
👎 Experimental
👎 ϥΠϒϥϦ/ϑϨʔϜϫʔΫͷαϙʔτ͕ෆे
Context Parameter
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● ϢʔβใContext Receiver͕ྑͦ͞͏
○ શͯͷϝιουʹ͓͍ͯඞਢ
○ ଘࡏ͢Δ͜ͱΛίϯύΠϧ࣌ʹอূ͍ͨ͠
● τϥϯβΫγϣϯCoroutineContext͕ྑͦ͞͏
○ ଘࡏ͢Δ͜ͱΛίϯύΠϧ࣌ʹอূ͢Δඞཁ͕ͳ͍
○ ʢSpring AOP͕Context ReceiverʹରԠ͍ͯ͠ͳ͍ʣ
͍͚
https://github.com/Kotlin/KEEP/blob/context-parameters/proposals/context-parameters.md
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·ͱΊ
● withContextCoroutineContextΛΓସ͑Δ
● ಠࣗͷCoroutineContextΛఆٛ͢Δ͜ͱͰ
ίϯςΩετมΛѻ͑Δ
● Context ParameterͱΈ͚Ͱ͖ͦ͏
● Kotlin 2.1ָ͠Έ✌
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No content
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ͨ·͝εϙϯαʔͬͯ·͢
ϊϕϧςΟதͰ͢
KotlinΤϯδχΞืूͯ͠·͢
Android/αʔόʔαΠυΘͣ
એ