Elasticsearch 게시글 검색에 Redis 도입

README.md

@@ -27,6 +27,7 @@
 - **카테고리 분류**: TECH, LIFE, TRAVEL, FOOD, HOBBY 카테고리
 - **실시간 통계**: 조회수, 좋아요 수, 댓글 수 추적
 - **도메인 이벤트**: 비즈니스 이벤트 기반 사이드 이펙트 처리
+- **검색 캐시**: Elasticsearch 키워드 검색 결과를 Redis에 3분 TTL로 캐싱하여 응답 지연 최소화
 
 ### 댓글 시스템
 - **계층형 댓글**: 대댓글 지원으로 깊이 있는 토론

build.gradle.kts

@@ -83,6 +83,10 @@ jmh {
     resultsFile.set(layout.buildDirectory.file("reports/jmh/post-search.json"))
 }
 
+tasks.named<Zip>("jmhJar") {
+    isZip64 = true
+}
+
 
 
 tasks.named<Test>("test") {

src/gatling/scala/dooya/see/search/PostSearchSimulation.scala

@@ -17,21 +17,40 @@ class PostSearchSimulation extends Simulation {
     .acceptHeader("application/json")
     .contentTypeHeader("application/json")
 
-  private val feeder = Iterator.continually(Map(
-    "keyword" -> keywords(Random.nextInt(keywords.size))
-  ))
+  private val feeder = Iterator.continually {
+    val baseKeyword = keywords(Random.nextInt(keywords.size))
+    Map(
+      "hotKeyword" -> baseKeyword,
+      "coldKeyword" -> s"$baseKeyword-${System.nanoTime()}"
+    )
+  }
 
   private val dbSearch = exec(
     http("db-search")
       .get("/api/posts/search")
-      .queryParam("keyword", "${keyword}")
+      .queryParam("keyword", "${hotKeyword}")
       .check(status.is(200))
   )
 
   private val esSearch = exec(
-    http("es-search")
+    http("es-cold-search")
+      .get("/api/v1/posts/elasticsearch")
+      .queryParam("keyword", "${coldKeyword}")
+      .check(status.is(200))
+  )
+
+  private val esCacheWarm = exec(
+    http("es-cache-warm")
+      .get("/api/v1/posts/elasticsearch")
+      .queryParam("keyword", "${hotKeyword}")
+      .check(status.is(200))
+      .silent
+  )
+
+  private val esCacheHit = exec(
+    http("es-cache-hit")
       .get("/api/v1/posts/elasticsearch")
-      .queryParam("keyword", "${keyword}")
+      .queryParam("keyword", "${hotKeyword}")
       .check(status.is(200))
   )
 
@@ -44,6 +63,10 @@ class PostSearchSimulation extends Simulation {
     .exec(dbSearch)
     .pause(500.milliseconds, 2.seconds)
     .exec(esSearch)
+    .pause(200.milliseconds, 500.milliseconds)
+    .exec(esCacheWarm)
+    .pause(100.milliseconds)
+    .exec(esCacheHit)
 
   setUp(
     scenarioBuilder.inject(

src/jmh/java/dooya/see/benchmark/PostSearchBenchmark.java

@@ -1,12 +1,25 @@
 package dooya.see.benchmark;
 
 import dooya.see.SeeApplication;
-import dooya.see.application.post.provided.PostFinder;
 import dooya.see.application.post.dto.PostSearchResult;
+import dooya.see.application.post.provided.PostFinder;
+import dooya.see.application.post.required.PostSearchCacheRepository;
 import dooya.see.domain.post.dto.PostSearchRequest;
-import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.TearDown;
+import org.openjdk.jmh.annotations.Warmup;
 import org.openjdk.jmh.infra.Blackhole;
 import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.WebApplicationType;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.data.domain.Page;
 
@@ -19,27 +32,28 @@
 @Fork(1)
 public class PostSearchBenchmark {
 
-    @State(Scope.Benchmark)
-    public static class BenchmarkState {
-        private ConfigurableApplicationContext context;
-        private PostFinder postFinder;
-        private SearchBenchmarkScenario scenario;
+    private abstract static class AbstractBenchmarkState {
+        protected ConfigurableApplicationContext context;
+        protected PostFinder postFinder;
+        protected PostSearchCacheRepository cacheRepository;
+        protected SearchBenchmarkScenario scenario;
+        protected SearchBenchmarkScenario.SearchQuery cacheHitQuery;
 
         @Setup(Level.Trial)
         public void setUp() {
             context = new SpringApplicationBuilder(SeeApplication.class)
-                    .profiles("benchmark")
+                    .profiles("benchmark", "benchmark-data")
+                    .web(WebApplicationType.NONE)
                     .logStartupInfo(false)
                     .run();
             postFinder = context.getBean(PostFinder.class);
+            cacheRepository = context.getBean(PostSearchCacheRepository.class);
             scenario = context.getBean(SearchBenchmarkScenarioProvider.class).createScenario();
 
-            // warm-up search to prime caches
-            for (int i = 0; i < 20; i++) {
-                SearchBenchmarkScenario.SearchQuery query = scenario.next();
-                postFinder.search(buildRequest(query.keyword()), query.pageable());
-                postFinder.searchPosts(query.keyword(), query.pageable());
-            }
+            cacheHitQuery = scenario.next();
+            // warm up DB and cache flows with the hot keyword
+            postFinder.search(buildRequest(cacheHitQuery.keyword()), cacheHitQuery.pageable());
+            postFinder.searchPosts(cacheHitQuery.keyword(), cacheHitQuery.pageable());
         }
 
         @TearDown(Level.Trial)
@@ -48,26 +62,62 @@ public void tearDown() {
                 context.close();
             }
         }
+
+        protected SearchBenchmarkScenario.SearchQuery nextQuery() {
+            return scenario.next();
+        }
+
+        protected SearchBenchmarkScenario.SearchQuery cacheHitQuery() {
+            return cacheHitQuery;
+        }
+
+        protected static PostSearchRequest buildRequest(String keyword) {
+            return PostSearchRequest.builder()
+                    .keyword(keyword)
+                    .status(null)
+                    .build();
+        }
+    }
+
+    @State(Scope.Benchmark)
+    public static class DatabaseSearchState extends AbstractBenchmarkState {
+        // inherits base set-up
+    }
+
+    @State(Scope.Benchmark)
+    public static class ColdSearchState extends AbstractBenchmarkState {
+        @Setup(Level.Invocation)
+        public void clearCache() {
+            cacheRepository.evictAll();
+        }
+    }
+
+    @State(Scope.Benchmark)
+    public static class CachedSearchState extends AbstractBenchmarkState {
+        // inherits warm-up behaviour
     }
 
     @Benchmark
-    public void databaseSearch(BenchmarkState state, Blackhole blackhole) {
-        SearchBenchmarkScenario.SearchQuery query = state.scenario.next();
-        Page<?> result = state.postFinder.search(buildRequest(query.keyword()), query.pageable());
+    public void elasticsearchCold(ColdSearchState state, Blackhole blackhole) {
+        SearchBenchmarkScenario.SearchQuery query = state.nextQuery();
+        Page<PostSearchResult> result = state.postFinder.searchPosts(query.keyword(), query.pageable());
         blackhole.consume(result.getTotalElements());
     }
 
     @Benchmark
-    public void elasticsearchSearch(BenchmarkState state, Blackhole blackhole) {
-        SearchBenchmarkScenario.SearchQuery query = state.scenario.next();
+    public void elasticsearchCached(CachedSearchState state, Blackhole blackhole) {
+        SearchBenchmarkScenario.SearchQuery query = state.cacheHitQuery();
         Page<PostSearchResult> result = state.postFinder.searchPosts(query.keyword(), query.pageable());
         blackhole.consume(result.getTotalElements());
     }
 
-    private static PostSearchRequest buildRequest(String keyword) {
-        return PostSearchRequest.builder()
-                .keyword(keyword)
-                .status(null)
-                .build();
+    @Benchmark
+    public void databaseSearch(DatabaseSearchState state, Blackhole blackhole) {
+        SearchBenchmarkScenario.SearchQuery query = state.nextQuery();
+        Page<?> result = state.postFinder.search(
+                AbstractBenchmarkState.buildRequest(query.keyword()),
+                query.pageable()
+        );
+        blackhole.consume(result.getTotalElements());
     }
 }

src/main/java/dooya/see/adapter/integration/cache/RedisPostSearchCacheRepository.java

@@ -0,0 +1,103 @@
+package dooya.see.adapter.integration.cache;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import dooya.see.adapter.integration.cache.config.PostSearchCacheProperties;
+import dooya.see.adapter.integration.cache.key.PostCacheKey;
+import dooya.see.application.post.dto.PostSearchResult;
+import dooya.see.application.post.required.PostSearchCacheRepository;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageImpl;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.stereotype.Component;
+
+import java.time.Duration;
+import java.util.List;
+import java.util.Locale;
+import java.util.Optional;
+import java.util.Set;
+
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class RedisPostSearchCacheRepository implements PostSearchCacheRepository {
+    private static final String SEARCH_KEY_PATTERN = "post:search:*";
+
+    private final RedisTemplate<String, String> redisTemplate;
+    private final ObjectMapper objectMapper;
+    private final PostSearchCacheProperties properties;
+
+    @Override
+    public Optional<Page<PostSearchResult>> find(String keyword, Pageable pageable) {
+        String key = buildKey(keyword, pageable);
+        String cached = redisTemplate.opsForValue().get(key);
+
+        if (cached == null) {
+            return Optional.empty();
+        }
+
+        try {
+            CachedPage cachedPage = objectMapper.readValue(cached, CachedPage.class);
+            return Optional.of(cachedPage.toPage(pageable));
+        } catch (JsonProcessingException e) {
+            log.warn("검색 캐시 역직렬화 실패: key={}", key, e);
+            redisTemplate.delete(key);
+            return Optional.empty();
+        }
+    }
+
+    @Override
+    public void save(String keyword, Pageable pageable, Page<PostSearchResult> page) {
+        String key = buildKey(keyword, pageable);
+        CachedPage cachedPage = CachedPage.from(page);
+
+        try {
+            String serialized = objectMapper.writeValueAsString(cachedPage);
+            Duration ttl = properties.getTtl();
+            if (ttl == null || ttl.isZero() || ttl.isNegative()) {
+                redisTemplate.opsForValue().set(key, serialized);
+            } else {
+                redisTemplate.opsForValue().set(key, serialized, ttl);
+            }
+        } catch (JsonProcessingException e) {
+            log.warn("검색 캐시 직렬화 실패: key={}", key, e);
+        }
+    }
+
+    @Override
+    public void evictAll() {
+        Set<String> keys = redisTemplate.keys(SEARCH_KEY_PATTERN);
+        if (keys == null || keys.isEmpty()) {
+            return;
+        }
+        redisTemplate.delete(keys);
+    }
+
+    private String buildKey(String keyword, Pageable pageable) {
+        String normalized = normalize(keyword);
+        return PostCacheKey.search(normalized, pageable.getPageNumber(), pageable.getPageSize());
+    }
+
+    private String normalize(String keyword) {
+        if (keyword == null) {
+            return "";
+        }
+        return keyword.trim().toLowerCase(Locale.ROOT);
+    }
+
+    private record CachedPage(
+            List<PostSearchResult> content,
+            long totalElements
+    ) {
+        private Page<PostSearchResult> toPage(Pageable pageable) {
+            return new PageImpl<>(content, pageable, totalElements);
+        }
+
+        private static CachedPage from(Page<PostSearchResult> page) {
+            return new CachedPage(page.getContent(), page.getTotalElements());
+        }
+    }
+}

src/main/java/dooya/see/adapter/integration/cache/config/PostSearchCacheProperties.java

@@ -0,0 +1,21 @@
+package dooya.see.adapter.integration.cache.config;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+import java.time.Duration;
+
+@ConfigurationProperties(prefix = "see.cache.post-search")
+public class PostSearchCacheProperties {
+    /**
+     * 검색 결과 캐시 TTL.
+     */
+    private Duration ttl = Duration.ofMinutes(3);
+
+    public Duration getTtl() {
+        return ttl;
+    }
+
+    public void setTtl(Duration ttl) {
+        this.ttl = ttl;
+    }
+}

src/main/java/dooya/see/adapter/integration/cache/config/RedisConfig.java

@@ -1,12 +1,14 @@
 package dooya.see.adapter.integration.cache.config;
 
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 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.serializer.StringRedisSerializer;
 
 @Configuration
+@EnableConfigurationProperties(PostSearchCacheProperties.class)
 public class RedisConfig {
     @Bean
     RedisTemplate<String, String> redisTemplate(RedisConnectionFactory connectionFactory) {