feat(user-creator-chat): WebSocket 세션 레지스트리를 추가한다

src/main/kotlin/kr/co/vividnext/sodalive/v2/usercreatorchat/websocket/UserCreatorChatWebSocketSessionRegistry.kt

@@ -0,0 +1,55 @@
+package kr.co.vividnext.sodalive.v2.usercreatorchat.websocket
+
+import org.springframework.stereotype.Component
+import org.springframework.web.socket.WebSocketSession
+import java.util.concurrent.ConcurrentHashMap
+
+@Component
+class UserCreatorChatWebSocketSessionRegistry {
+    private val sessionsByRoomMember = ConcurrentHashMap<RoomMemberKey, ConcurrentHashMap<String, WebSocketSession>>()
+    private val sessionIndexes = ConcurrentHashMap<String, RoomMemberKey>()
+    private val lockStripes = Array(LOCK_STRIPE_COUNT) { Any() }
+
+    fun register(roomId: Long, memberId: Long, session: WebSocketSession) {
+        val sessionId = session.id
+        synchronized(lockFor(sessionId)) {
+            removeLocked(sessionId)
+
+            val key = RoomMemberKey(roomId, memberId)
+            sessionsByRoomMember.computeIfAbsent(key) { ConcurrentHashMap() }[sessionId] = session
+            sessionIndexes[sessionId] = key
+        }
+    }
+
+    fun findSessions(roomId: Long, memberId: Long): List<WebSocketSession> {
+        return sessionsByRoomMember[RoomMemberKey(roomId, memberId)]?.values?.toList() ?: emptyList()
+    }
+
+    fun remove(sessionId: String) {
+        synchronized(lockFor(sessionId)) {
+            removeLocked(sessionId)
+        }
+    }
+
+    private fun removeLocked(sessionId: String) {
+        val key = sessionIndexes.remove(sessionId) ?: return
+        val sessions = sessionsByRoomMember[key] ?: return
+        sessions.remove(sessionId)
+        if (sessions.isEmpty()) {
+            sessionsByRoomMember.remove(key, sessions)
+        }
+    }
+
+    private fun lockFor(sessionId: String): Any {
+        return lockStripes[Math.floorMod(sessionId.hashCode(), lockStripes.size)]
+    }
+
+    private data class RoomMemberKey(
+        val roomId: Long,
+        val memberId: Long
+    )
+
+    companion object {
+        private const val LOCK_STRIPE_COUNT = 64
+    }
+}