feat: 同じ内容のリクエストが同時多発的に発生しない仕組みを追加

src/main/kotlin/dev/usbharu/hideout/service/ap/resource/APResourceResolveService.kt

@@ -0,0 +1,9 @@
+package dev.usbharu.hideout.service.ap.resource
+
+import dev.usbharu.hideout.domain.model.ap.Object
+import dev.usbharu.hideout.domain.model.hideout.entity.User
+
+interface APResourceResolveService {
+    suspend fun resolve(url: String, singerId: Long?): Object
+    suspend fun resolve(url: String, singer: User?): Object
+}

src/main/kotlin/dev/usbharu/hideout/service/ap/resource/APResourceResolveServiceImpl.kt

@@ -0,0 +1,70 @@
+package dev.usbharu.hideout.service.ap.resource
+
+import dev.usbharu.hideout.domain.model.ap.Object
+import dev.usbharu.hideout.domain.model.hideout.entity.User
+import dev.usbharu.hideout.repository.UserRepository
+import io.ktor.client.*
+import io.ktor.client.call.*
+import io.ktor.client.request.*
+import kotlinx.coroutines.delay
+import java.time.Instant
+import java.util.*
+import java.util.concurrent.ConcurrentHashMap
+
+class APResourceResolveServiceImpl(private val httpClient: HttpClient, private val userRepository: UserRepository) :
+    APResourceResolveService {
+
+    override suspend fun resolve(url: String, singerId: Long?): Object {
+        return internalResolve(url, singerId)
+    }
+
+    override suspend fun resolve(url: String, singer: User?): Object {
+        return internalResolve(url, singer)
+    }
+
+    private suspend fun internalResolve(url: String, singerId: Long?): Object {
+
+        val key = genCacheKey(url, singerId)
+        val ifAbsent = cacheKey.putIfAbsent(key, Instant.now().toEpochMilli())
+        if (ifAbsent == null) {
+            val resolve = runResolve(url, singerId?.let { userRepository.findById(it) })
+            valueStore.putIfAbsent(key, resolve)
+            return resolve
+        }
+        return wait(key)
+    }
+
+    private suspend fun internalResolve(url: String, singer: User?): Object {
+        val key = genCacheKey(url, singer?.id)
+        val ifAbsent = cacheKey.putIfAbsent(key, Instant.now().toEpochMilli())
+        if (ifAbsent == null) {
+            val resolve = runResolve(url, singer)
+            valueStore.putIfAbsent(key, resolve)
+            return resolve
+        }
+        return wait(key)
+    }
+
+    private suspend fun wait(key: String): Object {
+        while (valueStore.containsKey(key).not()) {
+            delay(1)
+        }
+        return valueStore.getValue(key) as Object
+    }
+
+    private suspend fun runResolve(url: String, singer: User?): Object {
+        return httpClient.get(url).body<Object>()
+    }
+
+    private fun genCacheKey(url: String, singerId: Long?): String {
+        if (singerId != null) {
+            return "$url-$singerId"
+        }
+        return url
+    }
+
+    companion object {
+        private val cacheKey = ConcurrentHashMap<String, Long>()
+        private val valueStore = Collections.synchronizedMap(mutableMapOf<String, Object>())
+    }
+}