feat(Entry): Implement auto-stock restoration on reservation token expiration

Author: kimdem

entry-service/src/main/java/com/axon/entry_service/config/RedisConfig.java

@@ -4,6 +4,7 @@
 import org.springframework.context.annotation.Configuration;
 import org.springframework.data.redis.connection.RedisConnectionFactory;
 import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.data.redis.listener.RedisMessageListenerContainer;
 import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
 import org.springframework.data.redis.serializer.StringRedisSerializer;
 
@@ -30,4 +31,11 @@ public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisC
         redisTemplate.setHashValueSerializer(new GenericJackson2JsonRedisSerializer());
         return redisTemplate;
     }
+
+    @Bean
+    public RedisMessageListenerContainer redisMessageListenerContainer(RedisConnectionFactory connectionFactory) {
+        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
+        container.setConnectionFactory(connectionFactory);
+        return container;
+    }
 }

entry-service/src/main/java/com/axon/entry_service/service/redisListener/ReservationExpirationListener.java

@@ -0,0 +1,64 @@
+package com.axon.entry_service.service.redisListener;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.redis.connection.Message;
+import org.springframework.data.redis.core.StringRedisTemplate;
+import org.springframework.data.redis.listener.KeyExpirationEventMessageListener;
+import org.springframework.data.redis.listener.RedisMessageListenerContainer;
+import org.springframework.stereotype.Component;
+
+import java.nio.charset.StandardCharsets;
+import java.time.Duration;
+import java.util.Base64;
+
+@Slf4j
+@Component
+public class ReservationExpirationListener extends KeyExpirationEventMessageListener {
+    private final StringRedisTemplate redisTemplate;
+
+    public ReservationExpirationListener(RedisMessageListenerContainer listener, StringRedisTemplate redisTemplate) {
+        super(listener);
+        this.redisTemplate = redisTemplate;
+    }
+
+    @Override
+    public void onMessage(Message message, byte[] pattern) {
+        String expiredKey =  message.toString(); // 1차 토큰 전체 문장
+
+        // 1차 토큰 만료인지 확인
+        if(!expiredKey.startsWith("RESERVATION_TOKEN:")) {return;}
+
+        try {
+            String tokenValue = expiredKey.replace("RESERVATION_TOKEN:", "");
+            String decoded = new String(Base64.getDecoder().decode(tokenValue), StandardCharsets.UTF_8);
+
+            String[] parts = decoded.split(":");
+            if(parts.length < 2) {
+                log.warn("Invalid token format ignored: {}", decoded);
+                return;
+            }
+
+            String userId = parts[0];
+            String campaignActivityId = parts[1];
+
+            // 각 파드간 중복 실행 방지용
+            String lockKey = "processed:restore:" + tokenValue;
+            Boolean isWinner = redisTemplate.opsForValue()
+                    .setIfAbsent(lockKey, "1", Duration.ofMinutes(1));
+
+            if(Boolean.TRUE.equals(isWinner)) {
+                String counterKey = "campaign:" + campaignActivityId + ":counter";
+                Long remaining = redisTemplate.opsForValue().decrement(counterKey);
+
+                String usersKey = "campaign:" + campaignActivityId + ":users";
+                redisTemplate.opsForSet().remove(usersKey, userId);
+
+                log.info("♻️ Stock Restored! Activity: {}, User: {}, Remaining: {}", campaignActivityId, userId, remaining);
+            } else {
+                log.debug("Another pod Accessed and Skipped decrease request");
+            }
+        } catch (Exception e) {
+            log.error("1차 토큰 만료로 인한 재고 복구 실패 token={}", expiredKey, e);
+        }
+    }
+}