feat: 이동 윈도 로깅 알고리즘 생성, 조회 API 구현

Author: jay-so

src/main/java/com/systemdesign/slidingwindowlog/controller/SlidingWindowLogController.java

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+package com.systemdesign.slidingwindowlog.controller;
+
+import com.systemdesign.slidingwindowlog.dto.response.SlidingWindowLogProfileResponse;
+import com.systemdesign.slidingwindowlog.dto.response.SlidingWindowLogResponse;
+import com.systemdesign.slidingwindowlog.exception.RateLimitExceededException;
+import com.systemdesign.slidingwindowlog.service.SlidingWindowLogService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import static org.springframework.http.HttpStatus.*;
+
+@RestController
+@RequiredArgsConstructor
+@RequestMapping("sliding-window-log")
+public class SlidingWindowLogController {
+
+    private final SlidingWindowLogService slidingWindowLogService;
+
+    @GetMapping
+    public Mono<ResponseEntity<Flux<SlidingWindowLogResponse>>> findAllSlidingWindowLog() {
+        return Mono.just(
+                ResponseEntity.ok()
+                        .body(slidingWindowLogService.findAllSlidingWindowLog())
+        );
+    }
+
+    @PostMapping
+    public Mono<ResponseEntity<SlidingWindowLogProfileResponse>> createSlidingWindowLog() {
+        return slidingWindowLogService.createSlidingWindowLog()
+                .map(response -> ResponseEntity.status(CREATED).body(response))
+                .onErrorResume(RateLimitExceededException.class, e ->
+                        Mono.just(ResponseEntity.status(TOO_MANY_REQUESTS).build())
+                );
+    }
+}

src/main/java/com/systemdesign/slidingwindowlog/dto/response/SlidingWindowLogProfileResponse.java

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+package com.systemdesign.slidingwindowlog.dto.response;
+
+import lombok.Builder;
+import lombok.Getter;
+
+import java.util.List;
+
+@Getter
+@Builder
+public class SlidingWindowLogProfileResponse {
+
+    private List<SlidingWindowLogResponse> counters;
+
+    public static SlidingWindowLogProfileResponse from(List<SlidingWindowLogResponse> counters) {
+        return SlidingWindowLogProfileResponse.builder()
+                .counters(counters)
+                .build();
+    }
+}

src/main/java/com/systemdesign/slidingwindowlog/dto/response/SlidingWindowLogResponse.java

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+package com.systemdesign.slidingwindowlog.dto.response;
+
+import lombok.Builder;
+import lombok.Getter;
+
+@Getter
+@Builder
+public class SlidingWindowLogResponse {
+
+    private String key;
+    private Long requestCount;
+
+    public static SlidingWindowLogResponse from(String key, Long requestCount) {
+        return SlidingWindowLogResponse.builder()
+                .key(key)
+                .requestCount(requestCount)
+                .build();
+    }
+}

src/main/java/com/systemdesign/slidingwindowlog/exception/RateExceptionCode.java

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+package com.systemdesign.slidingwindowlog.exception;
+
+import com.systemdesign.slidingwindowlog.common.exception.ExceptionCode;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+
+import static org.springframework.http.HttpStatus.TOO_MANY_REQUESTS;
+
+@Getter
+@RequiredArgsConstructor
+public enum RateExceptionCode implements ExceptionCode {
+
+    COMMON_TOO_MANY_REQUESTS(TOO_MANY_REQUESTS, "RAT-001", "사용자 요청 횟수 초과"),
+    ;
+
+    private final HttpStatus status;
+    private final String code;
+    private final String message;
+}

src/main/java/com/systemdesign/slidingwindowlog/exception/RateLimitExceededException.java

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+package com.systemdesign.slidingwindowlog.exception;
+
+import com.systemdesign.slidingwindowlog.common.exception.BusinessException;
+import com.systemdesign.slidingwindowlog.common.exception.ExceptionCode;
+
+public class RateLimitExceededException extends BusinessException {
+
+    public RateLimitExceededException(ExceptionCode exceptionCode, Object... rejectedValues) {
+        super(exceptionCode, rejectedValues);
+    }
+}

src/main/java/com/systemdesign/slidingwindowlog/service/SlidingWindowLogService.java

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+package com.systemdesign.slidingwindowlog.service;
+
+import com.systemdesign.slidingwindowlog.dto.response.SlidingWindowLogProfileResponse;
+import com.systemdesign.slidingwindowlog.dto.response.SlidingWindowLogResponse;
+import com.systemdesign.slidingwindowlog.exception.RateExceptionCode;
+import com.systemdesign.slidingwindowlog.exception.RateLimitExceededException;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.domain.Range;
+import org.springframework.data.redis.core.ReactiveRedisTemplate;
+import org.springframework.stereotype.Service;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.util.List;
+
+@Slf4j
+@Service
+@RequiredArgsConstructor
+public class SlidingWindowLogService {
+
+    private final ReactiveRedisTemplate<String, Object> redisTemplate;
+    private final static String SLIDING_WINDOW_KEY = "SlidingWindow:"; // 키
+    private final static long SLIDING_WINDOW_MAX_REQUEST = 1000; // 최대 요청 허용 수
+    private final static long SLIDING_WINDOW_DURATION = 60; // 60초
+
+    public Mono<SlidingWindowLogProfileResponse> createSlidingWindowLog() {
+        long currentTimestamp = System.currentTimeMillis();
+        String redisKey = generateRedisKey("requests");
+        log.info("Sliding Window Counter created. key: {}", redisKey);
+
+        return redisTemplate.opsForZSet()
+                .add(redisKey, String.valueOf(currentTimestamp), currentTimestamp)
+                .flatMap(added -> redisTemplate.opsForZSet().removeRangeByScore(redisKey, Range.closed(0D,
+                        calculateTimeRange())))
+                .flatMap(removed -> redisTemplate.opsForZSet().count(redisKey,
+                        Range.closed(calculateTimeRange(), (double) currentTimestamp)))
+                .flatMap(count -> {
+                    log.info("Sliding Window Counter count: {}", count);
+
+                    if (count >= SLIDING_WINDOW_MAX_REQUEST) {
+                        log.error("Rate limit exceeded. key: {}", redisKey);
+                        return Mono.error(new RateLimitExceededException(RateExceptionCode.COMMON_TOO_MANY_REQUESTS, count));
+                    }
+                    return Mono.just(SlidingWindowLogProfileResponse.from(List.of(SlidingWindowLogResponse.from(redisKey, count + 1))));
+                });
+    }
+
+    public Flux<SlidingWindowLogResponse> findAllSlidingWindowLog() {
+        String redisKey = generateRedisKey("requests");
+        long currentTimestamp = System.currentTimeMillis();
+        log.info("Sliding Window Counter find all. key: {}", redisKey);
+
+        return redisTemplate.opsForZSet().rangeByScore(redisKey,
+                        Range.closed(calculateTimeRange(), (double) currentTimestamp))
+                .map(value -> {
+                    log.info("Sliding Window Counter value: {}", value);
+                    return SlidingWindowLogResponse.from(redisKey, Long.parseLong((String) value));
+                });
+    }
+
+    private double calculateTimeRange() {
+        long currentTimestamp = System.currentTimeMillis();
+        return currentTimestamp - SLIDING_WINDOW_DURATION * 1000;
+    }
+
+    private String generateRedisKey(String requestType) {
+        return SLIDING_WINDOW_KEY + requestType;
+    }
+}