28738321635

Committed 05 Jul 2026 10:51AM UTC coverage: 90.457% (+0.04%) from 90.421%

Build # 28738321635

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push

github

Committed by

Hyshmily

Commit Message

refactor: extract interfaces for 12 core classes (Batch 1+2)

Extract interfaces from concrete classes, impls moved to impl/ subpackages:

Batch 1 (HotPath):
- CircuitBreaker, ExpireManager, SingleFlight
- KeyReporter, RuleMatcher, HealthView

Batch 2 (Supporting):
- VersionController, RingManager, HotKeyStateMachine
- SystemLoadMonitor, BbrRateLimiter, SreRateLimiter

Pattern: interface at original package, impl named XxxImpl under impl/

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59.7

/common/src/main/java/io/github/hyshmily/hotkey/autoconfigure/HotKeyAutoConfiguration.java

/*
 * Copyright 2026 Hyshmily. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.github.hyshmily.hotkey.autoconfigure;

import static io.github.hyshmily.hotkey.util.TimeSource.currentTimeMillis;

import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.Caffeine;
import com.github.benmanes.caffeine.cache.Expiry;
import io.github.hyshmily.hotkey.Internal;
import io.github.hyshmily.hotkey.cache.HotKeyCache;
import io.github.hyshmily.hotkey.cache.cachesupport.ExpireManager;
import io.github.hyshmily.hotkey.cache.cachesupport.impl.ExpireManagerImpl;
import io.github.hyshmily.hotkey.cache.cachesupport.impl.CircuitBreakerImpl;
import io.github.hyshmily.hotkey.cache.cachesupport.SingleFlight;
import io.github.hyshmily.hotkey.cache.cachesupport.impl.SingleFlightImpl;
import io.github.hyshmily.hotkey.constants.HotKeyConstants;
import io.github.hyshmily.hotkey.hotkeydetector.HotKeyDetector;
import io.github.hyshmily.hotkey.hotkeydetector.heavykeeper.HeavyKeeper;
import io.github.hyshmily.hotkey.hotkeydetector.heavykeeper.TopK;
import io.github.hyshmily.hotkey.model.CacheEntry;
import io.github.hyshmily.hotkey.reporting.KeyReporter;
import io.github.hyshmily.hotkey.rule.RuleMatcher;
import io.github.hyshmily.hotkey.rule.impl.RuleMatcherImpl;
import io.github.hyshmily.hotkey.sharding.HealthView;
import io.github.hyshmily.hotkey.sharding.impl.HealthViewImpl;
import io.github.hyshmily.hotkey.sync.local.CacheSyncPublisher;
import io.github.hyshmily.hotkey.util.version.VersionController;
import io.github.hyshmily.hotkey.util.version.impl.VersionControllerImpl;
import java.util.Optional;
import java.util.concurrent.Executor;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import lombok.extern.slf4j.Slf4j;
import org.jspecify.annotations.NonNull;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.AutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

/**
 * App-side autoconfiguration for the HotKey library.
 *
 * <p>Creates the app-side {@link TopK} detector (HeavyKeeper), L1 Caffeine
 * cache, {@link SingleFlight} deduplication layer, executor, and the
 * primary {@link HotKeyCache} (without Redis version tracking when Redis
 * is absent).
 *
 * <p><b>Condition:</b> this configuration is <em>skipped</em> when the
 * Worker is active ({@code hotkey.worker.enabled=true}). It runs when
 * Worker is disabled or the property is absent.
 */
@Internal
@AutoConfiguration(after = RedisAutoConfiguration.class)
@ConditionalOnProperty(prefix = "hotkey.worker", name = "enabled", havingValue = "false", matchIfMissing = true)
@EnableConfigurationProperties(HotKeyProperties.class)
@Slf4j
public class HotKeyAutoConfiguration {

  /**
   * Create the app-side TopK instance (HeavyKeeper) as a standalone bean.
   *
   * <p>The HeavyKeeper uses a Count-Min Sketch augmented with a minimum-count
   * threshold and exponential decay to track the top-K hottest keys with high
   * accuracy and low memory footprint. Configuration parameters (width, depth,
   * decay, minCount, topK capacity, expelled queue capacity) are read from
   * {@link HotKeyProperties}.
   *
   * @param properties the HotKey configuration properties (never {@code null})
   * @return a new HeavyKeeper TopK instance
   */
  @Bean
  @ConditionalOnMissingBean
  public HeavyKeeper heavyKeeper(HotKeyProperties properties) {
    return new HeavyKeeper(
      properties.getTopK(),
      properties.getWidth(),
      properties.getDepth(),
      properties.getDecay(),
      properties.getMinCount(),
      properties.getExpelledQueueCapacity(),
      properties.getSketchWindowCount()
    );
  }

  /**
   * Create the app-side {@link HotKeyDetector} facade that wraps the HeavyKeeper TopK
   * and schedules periodic decay.
   *
   * <p>The detector provides the primary hot-key detection API ({@code add()}, {@code list()},
   * {@code total()}) and schedules the periodic HeavyKeeper decay using the shared scheduler.
   * This bean is the {@code @Qualifier("hotKeyDetector")} target for injection into
   * {@link HotKeyCache} and other components.
   *
   * @param heavyKeeper      the HeavyKeeper TopK instance (never {@code null})
   * @param hotKeyScheduler  the shared scheduler for periodic tasks (never {@code null})
   * @return a new HotKeyDetector instance
   */
  @Bean
  @ConditionalOnMissingBean
  @SuppressWarnings("SpringJavaInjectionPointsAutowiringInspection")
  public HotKeyDetector hotKeyDetector(
    HeavyKeeper heavyKeeper,
    @Qualifier("hotKeyScheduler") ScheduledExecutorService hotKeyScheduler
  ) {
    return new HotKeyDetector(heavyKeeper, hotKeyScheduler);
  }

  /**
   * Create the SingleFlight deduplication layer for concurrent cache-load requests.
   *
   * <p>When multiple threads request the same key simultaneously (a cache miss), the
   * first caller triggers the load and subsequent callers wait for the same result
   * rather than duplicating the load. Configuration parameters (max in-flight entries,
   * TTL, timeout) are read from {@link HotKeyProperties}.
   *
   * @param properties     the HotKey configuration properties (never {@code null})
   * @param hotKeyExecutor the dedicated HotKey executor for async load execution (never {@code null})
   * @return a new SingleFlight instance
   */
  @Bean
  @ConditionalOnMissingBean
  public SingleFlight singleFlight(HotKeyProperties properties, @Qualifier("hotKeyExecutor") Executor hotKeyExecutor) {
    return new SingleFlightImpl(
      properties.getInflightMaxSize(),
      properties.getInflightTtlSeconds(),
      properties.getInflightTimeoutSeconds(),
      hotKeyExecutor,
      new CircuitBreakerImpl(properties.getCircuitBreaker())
    );
  }

  /**
   * Create the soft/hard expiration manager that manages time-based eviction.
   *
   * <p>The soft-expire mechanism triggers an asynchronous refresh when a configurable
   * portion of the TTL has elapsed, serving stale data while fetching a fresh value
   * in the background. The hard-expire is the absolute maximum TTL enforced at the
   * Caffeine level. The refresh pool size limits concurrent background refresh tasks
   * to prevent resource exhaustion under high cache-miss rates.
   *
   * @param hotLocalCache  the L1 Caffeine cache (never {@code null})
   * @param hotKeyExecutor the dedicated HotKey executor for async refresh tasks (never {@code null})
   * @param properties     the HotKey configuration properties (never {@code null})
   * @return a new ExpireManagerImpl instance
   */
  @Bean
  @ConditionalOnMissingBean
  public ExpireManager expireManager(
    Cache<String, Object> hotLocalCache,
    @Qualifier("hotKeyExecutor") Executor hotKeyExecutor,
    HotKeyProperties properties
  ) {
    return new ExpireManagerImpl(hotLocalCache, hotKeyExecutor, properties, properties.getRefreshMaxPools());
  }

  /**
   * Create the dedicated thread-pool executor for asynchronous cache operations.
   *
   * <p>This executor handles all async operations in the HotKey data path: cache loading
   * via SingleFlight, soft-expiry refresh tasks, and cross-instance broadcast callbacks.
   * Uses a bounded thread pool to limit concurrent AMQP channel usage (RabbitMQ's
   * {@code CachingConnectionFactory} associates channels with platform threads, so
   * unbounded virtual-thread concurrency causes channel-open timeouts). The pool is
   * configured with core/max pool size, bounded queue capacity, and a rejection policy
   * that throws {@link RejectedExecutionException} when the queue is full. On shutdown,
   * in-progress tasks are allowed to complete with a 60-second grace period.
   *
   * @param properties the HotKey configuration properties (never {@code null})
   * @return a configured {@link ThreadPoolTaskExecutor}
   */
  @Bean("hotKeyExecutor")
  @ConditionalOnMissingBean(name = "hotKeyExecutor")
  public Executor hotKeyExecutor(HotKeyProperties properties) {
    ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
    executor.setCorePoolSize(0);
    executor.setMaxPoolSize(properties.getExecutorMaxPoolSize());
    executor.setQueueCapacity(properties.getExecutorQueueCapacity());
    executor.setAllowCoreThreadTimeOut(true);
    executor.setThreadNamePrefix(HotKeyConstants.THREAD_PREFIX_HOTKEY);
    executor.setWaitForTasksToCompleteOnShutdown(true);
    executor.setAwaitTerminationSeconds(60);
    executor.setRejectedExecutionHandler((r, exe) -> {
      log.warn(
        "HotKey executor task rejected: corePool={}, maxPool={}, queueCapacity={}",
        properties.getExecutorCorePoolSize(),
        properties.getExecutorMaxPoolSize(),
        properties.getExecutorQueueCapacity()
      );
      throw new RejectedExecutionException("HotKey executor queue full");
    });
    executor.initialize();
    return executor;
  }

  /**
   * Create the {@link RuleMatcher} for key matching against user-defined rules.
   *
   * <p>This variant is wired with an empty Redis provider and an optional sync
   * publisher, since no {@link StringRedisTemplate} is available in the non-Redis
   * deployment mode. Rules are kept in-memory only and do not survive restarts.
   * When Redis is available, {@link HotKeyRedisAutoConfiguration#ruleMatcher}
   * takes over with Redis persistence.
   *
   * @param publisherProvider optional provider for the cache sync publisher (may be absent)
   * @return a new RuleMatcher instance (in-memory only)
   */
  @Bean
  @ConditionalOnMissingBean({ RuleMatcher.class, StringRedisTemplate.class })
  public RuleMatcher ruleMatcher(ObjectProvider<CacheSyncPublisher> publisherProvider) {
    return new RuleMatcherImpl(Optional.empty(), Optional.ofNullable(publisherProvider.getIfAvailable()));
  }

  /**
   * Create the {@link HotKeyCache} (non-Redis variant).
   *
   * <p>Only active when {@code RedisTemplate} is absent; otherwise
   * {@link HotKeyRedisAutoConfiguration#hotKeyCache} takes over. Creates a
   * {@link VersionController} with an empty Redis provider (falling back to
   * node-local counters) and default ring manager / health view when none are
   * available from the application context.
   *
   * @param hotKeyDetector            the app-side TopK detector (never {@code null})
   * @param hotLocalCache             the L1 Caffeine cache (never {@code null})
   * @param singleFlight              the deduplication layer (never {@code null})
   * @param expireManager             the soft/hard expiration manager (never {@code null})
   * @param syncPublisher             optional cache sync publisher (may be absent)
   * @param hotKeyReporter            optional hot key reporter (may be absent; e.g. in Worker-only mode)
   * @param hotKeyExecutor            the dedicated HotKey executor (never {@code null})
   * @param properties                the HotKey configuration properties (never {@code null})
   * @param ruleMatcher               the rule matcher instance (never {@code null})
   * @param healthViewProvider        provider for the cluster health view (creates default if absent)
   * @return a new HotKeyCache instance with node-local version tracking
   */
  @Bean
  @ConditionalOnMissingBean(type = "org.springframework.data.redis.core.RedisTemplate")
  public HotKeyCache hotKeyCache(
    @Qualifier("hotKeyDetector") HotKeyDetector hotKeyDetector,
    Cache<String, Object> hotLocalCache,
    SingleFlight singleFlight,
    ExpireManager expireManager,
    Optional<CacheSyncPublisher> syncPublisher,
    Optional<KeyReporter> hotKeyReporter,
    @Qualifier("hotKeyExecutor") Executor hotKeyExecutor,
    HotKeyProperties properties,
    RuleMatcher ruleMatcher,
    ObjectProvider<HealthView> healthViewProvider
  ) {
    return new HotKeyCache(
      hotKeyDetector,
      hotLocalCache,
      singleFlight,
      expireManager,
      hotKeyExecutor,
      syncPublisher,
      hotKeyReporter,
      ruleMatcher,
      new VersionControllerImpl(Optional.empty(), properties.getVersionKeyTtlMinutes()),
      properties,
      healthViewProvider.getIfAvailable(() ->
        new HealthViewImpl(
          properties.getExpectedWorkerCount(),
          properties.getHeartbeat().getTimeoutMs(),
          properties.getHeartbeat().getDegradeAfterFailures()
        )
      )
    );
  }

  /**
   * Create the L1 Caffeine cache instance.
   *
   * <p>Time-based expiry operates at the <em>Caffeine</em> level via a custom
   * {@link Expiry} implementation, computing remaining nanoseconds from
   * . Entries with
   * {@code hardExpireAtMs == Long.MAX_VALUE} are purely logical-expiry
   * — Caffeine never evicts them by time; they live until size eviction or
   * manual invalidation. Reads never extend the expiry duration (no read-based
   * refresh), ensuring predictable TTL behavior.
   *
   * <p>The maximum cache size is configured via {@code hotkey.local.local-cache-max-size}
   * (default 1000 entries). Time-based TTL for entries without an explicit hard-expire
   * timestamp defaults to {@code hotkey.local.local-cache-ttl-minutes} (default 5 minutes).
   *
   * @param properties the HotKey configuration properties (never {@code null})
   * @return a configured Caffeine {@link Cache} instance
   */
  @Bean
  @ConditionalOnMissingBean
  public Cache<String, Object> hotLocalCache(HotKeyProperties properties) {
    Caffeine<Object, Object> builder = Caffeine.newBuilder()
      .maximumSize(properties.getLocalCacheMaxSize())
      .expireAfter(
        new Expiry<>() {
          /**
           * Compute the time-to-live for a newly created cache entry.
           * Returns {@link Long#MAX_VALUE} for pure logical-expiry entries
           * (where {@code hardExpireAtMs == Long.MAX_VALUE}); otherwise
           * computes the remaining wall-clock time.
           *
           * @param key              the cache key
           * @param value            the cache value (expected to be a {@link CacheEntry})
           * @param currentTimeNanos the current time in nanoseconds (provided by Caffeine)
           * @return the expiry duration in nanoseconds, or {@link Long#MAX_VALUE} for no expiry
           */
          @Override
          public long expireAfterCreate(@NonNull Object key, @NonNull Object value, long currentTimeNanos) {
            if (value instanceof CacheEntry entry) {
              if (entry.getHardExpireAtMs() == Long.MAX_VALUE) {
                // Pure logical expiry: Caffeine never time-evicts this entry.
                // See Expiry Javadoc: Long.MAX_VALUE signals "no expiration".
                return Long.MAX_VALUE;
              }
              long remainingMs = entry.getHardExpireAtMs() - currentTimeMillis();
              return TimeUnit.MILLISECONDS.toNanos(Math.max(1, remainingMs));
            }
            return TimeUnit.MINUTES.toNanos(properties.getLocalCacheTtlMinutes());
          }

          /**
           * Re-compute the expiry duration after an entry is updated.
           * Preserves pure logical expiry across updates; otherwise
           * recalculates from the entry's {@code hardExpireAtMs}.
           *
           * @param key              the cache key
           * @param value            the cache value (expected to be a {@link CacheEntry})
           * @param currentTimeNanos the current time in nanoseconds (provided by Caffeine)
           * @param currentDuration  the current expiry duration in nanoseconds
           * @return the updated expiry duration in nanoseconds, or {@link Long#MAX_VALUE} for no expiry
           */
          @Override
          public long expireAfterUpdate(
            @NonNull Object key,
            @NonNull Object value,
            long currentTimeNanos,
            long currentDuration
          ) {
            if (value instanceof CacheEntry entry) {
              if (entry.getHardExpireAtMs() == Long.MAX_VALUE) {
                // Preserve pure logical expiry across updates (e.g. broadcast refresh).
                return Long.MAX_VALUE;
              }
              long remainingMs = entry.getHardExpireAtMs() - currentTimeMillis();
              return TimeUnit.MILLISECONDS.toNanos(Math.max(1, remainingMs));
            }
            return currentDuration;
          }

          /**
           * Preserve the current expiry duration on read — reads never
           * extend or shorten the entry's time-to-live.
           *
           * @param key              the cache key
           * @param value            the cache value
           * @param currentTimeNanos the current time in nanoseconds (provided by Caffeine)
           * @param currentDuration  the current expiry duration in nanoseconds
           * @return the unchanged expiry duration in nanoseconds
           */
          @Override
          public long expireAfterRead(
            @NonNull Object key,
            @NonNull Object value,
            long currentTimeNanos,
            long currentDuration
          ) {
            return currentDuration;
          }
        }
      );
    return builder.build();
  }
}

1	/*
2	* Copyright 2026 Hyshmily. All Rights Reserved.
3	*
4	* Licensed under the Apache License, Version 2.0 (the "License");
5	* you may not use this file except in compliance with the License.
6	* You may obtain a copy of the License at
7	*
8	* http://www.apache.org/licenses/LICENSE-2.0
9	*
10	* Unless required by applicable law or agreed to in writing, software
11	* distributed under the License is distributed on an "AS IS" BASIS,
12	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13	* See the License for the specific language governing permissions and
14	* limitations under the License.
15	*/
16	package io.github.hyshmily.hotkey.autoconfigure;
17
18	import static io.github.hyshmily.hotkey.util.TimeSource.currentTimeMillis;
19
20	import com.github.benmanes.caffeine.cache.Cache;
21	import com.github.benmanes.caffeine.cache.Caffeine;
22	import com.github.benmanes.caffeine.cache.Expiry;
23	import io.github.hyshmily.hotkey.Internal;
24	import io.github.hyshmily.hotkey.cache.HotKeyCache;
25	import io.github.hyshmily.hotkey.cache.cachesupport.ExpireManager;
26	import io.github.hyshmily.hotkey.cache.cachesupport.impl.ExpireManagerImpl;
27	import io.github.hyshmily.hotkey.cache.cachesupport.impl.CircuitBreakerImpl;
28	import io.github.hyshmily.hotkey.cache.cachesupport.SingleFlight;
29	import io.github.hyshmily.hotkey.cache.cachesupport.impl.SingleFlightImpl;
30	import io.github.hyshmily.hotkey.constants.HotKeyConstants;
31	import io.github.hyshmily.hotkey.hotkeydetector.HotKeyDetector;
32	import io.github.hyshmily.hotkey.hotkeydetector.heavykeeper.HeavyKeeper;
33	import io.github.hyshmily.hotkey.hotkeydetector.heavykeeper.TopK;
34	import io.github.hyshmily.hotkey.model.CacheEntry;
35	import io.github.hyshmily.hotkey.reporting.KeyReporter;
36	import io.github.hyshmily.hotkey.rule.RuleMatcher;
37	import io.github.hyshmily.hotkey.rule.impl.RuleMatcherImpl;
38	import io.github.hyshmily.hotkey.sharding.HealthView;
39	import io.github.hyshmily.hotkey.sharding.impl.HealthViewImpl;
40	import io.github.hyshmily.hotkey.sync.local.CacheSyncPublisher;
41	import io.github.hyshmily.hotkey.util.version.VersionController;
42	import io.github.hyshmily.hotkey.util.version.impl.VersionControllerImpl;
43	import java.util.Optional;
44	import java.util.concurrent.Executor;
45	import java.util.concurrent.RejectedExecutionException;
46	import java.util.concurrent.ScheduledExecutorService;
47	import java.util.concurrent.TimeUnit;
48	import lombok.extern.slf4j.Slf4j;
49	import org.jspecify.annotations.NonNull;
50	import org.springframework.beans.factory.ObjectProvider;
51	import org.springframework.beans.factory.annotation.Qualifier;
52	import org.springframework.boot.autoconfigure.AutoConfiguration;
53	import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
54	import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
55	import org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration;
56	import org.springframework.boot.context.properties.EnableConfigurationProperties;
57	import org.springframework.context.annotation.Bean;
58	import org.springframework.data.redis.core.StringRedisTemplate;
59	import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
60
61	/**
62	* App-side autoconfiguration for the HotKey library.
63	*
64	* <p>Creates the app-side {@link TopK} detector (HeavyKeeper), L1 Caffeine
65	* cache, {@link SingleFlight} deduplication layer, executor, and the
66	* primary {@link HotKeyCache} (without Redis version tracking when Redis
67	* is absent).
68	*
69	* <p><b>Condition:</b> this configuration is <em>skipped</em> when the
70	* Worker is active ({@code hotkey.worker.enabled=true}). It runs when
71	* Worker is disabled or the property is absent.
72	*/
73	@Internal
74	@AutoConfiguration(after = RedisAutoConfiguration.class)
75	@ConditionalOnProperty(prefix = "hotkey.worker", name = "enabled", havingValue = "false", matchIfMissing = true)
76	@EnableConfigurationProperties(HotKeyProperties.class)
77	@Slf4j	4✔
78	public class HotKeyAutoConfiguration {	3✔
79
80	/**
81	* Create the app-side TopK instance (HeavyKeeper) as a standalone bean.
82	*
83	* <p>The HeavyKeeper uses a Count-Min Sketch augmented with a minimum-count
84	* threshold and exponential decay to track the top-K hottest keys with high
85	* accuracy and low memory footprint. Configuration parameters (width, depth,
86	* decay, minCount, topK capacity, expelled queue capacity) are read from
87	* {@link HotKeyProperties}.
88	*
89	* @param properties the HotKey configuration properties (never {@code null})
90	* @return a new HeavyKeeper TopK instance
91	*/
92	@Bean
93	@ConditionalOnMissingBean
94	public HeavyKeeper heavyKeeper(HotKeyProperties properties) {
95	return new HeavyKeeper(	4✔
96	properties.getTopK(),	2✔
97	properties.getWidth(),	2✔
98	properties.getDepth(),	2✔
99	properties.getDecay(),	2✔
100	properties.getMinCount(),	2✔
101	properties.getExpelledQueueCapacity(),	2✔
102	properties.getSketchWindowCount()	2✔
103	);
104	}
105
106	/**
107	* Create the app-side {@link HotKeyDetector} facade that wraps the HeavyKeeper TopK
108	* and schedules periodic decay.
109	*
110	* <p>The detector provides the primary hot-key detection API ({@code add()}, {@code list()},
111	* {@code total()}) and schedules the periodic HeavyKeeper decay using the shared scheduler.
112	* This bean is the {@code @Qualifier("hotKeyDetector")} target for injection into
113	* {@link HotKeyCache} and other components.
114	*
115	* @param heavyKeeper the HeavyKeeper TopK instance (never {@code null})
116	* @param hotKeyScheduler the shared scheduler for periodic tasks (never {@code null})
117	* @return a new HotKeyDetector instance
118	*/
119	@Bean
120	@ConditionalOnMissingBean
121	@SuppressWarnings("SpringJavaInjectionPointsAutowiringInspection")
122	public HotKeyDetector hotKeyDetector(
123	HeavyKeeper heavyKeeper,
124	@Qualifier("hotKeyScheduler") ScheduledExecutorService hotKeyScheduler
125	) {
126	return new HotKeyDetector(heavyKeeper, hotKeyScheduler);	6✔
127	}
128
129	/**
130	* Create the SingleFlight deduplication layer for concurrent cache-load requests.
131	*
132	* <p>When multiple threads request the same key simultaneously (a cache miss), the
133	* first caller triggers the load and subsequent callers wait for the same result
134	* rather than duplicating the load. Configuration parameters (max in-flight entries,
135	* TTL, timeout) are read from {@link HotKeyProperties}.
136	*
137	* @param properties the HotKey configuration properties (never {@code null})
138	* @param hotKeyExecutor the dedicated HotKey executor for async load execution (never {@code null})
139	* @return a new SingleFlight instance
140	*/
141	@Bean
142	@ConditionalOnMissingBean
143	public SingleFlight singleFlight(HotKeyProperties properties, @Qualifier("hotKeyExecutor") Executor hotKeyExecutor) {
144	return new SingleFlightImpl(	4✔
145	properties.getInflightMaxSize(),	2✔
146	properties.getInflightTtlSeconds(),	2✔
147	properties.getInflightTimeoutSeconds(),	5✔
148	hotKeyExecutor,
149	new CircuitBreakerImpl(properties.getCircuitBreaker())	3✔
150	);
151	}
152
153	/**
154	* Create the soft/hard expiration manager that manages time-based eviction.
155	*
156	* <p>The soft-expire mechanism triggers an asynchronous refresh when a configurable
157	* portion of the TTL has elapsed, serving stale data while fetching a fresh value
158	* in the background. The hard-expire is the absolute maximum TTL enforced at the
159	* Caffeine level. The refresh pool size limits concurrent background refresh tasks
160	* to prevent resource exhaustion under high cache-miss rates.
161	*
162	* @param hotLocalCache the L1 Caffeine cache (never {@code null})
163	* @param hotKeyExecutor the dedicated HotKey executor for async refresh tasks (never {@code null})
164	* @param properties the HotKey configuration properties (never {@code null})
165	* @return a new ExpireManagerImpl instance
166	*/
167	@Bean
168	@ConditionalOnMissingBean
169	public ExpireManager expireManager(
170	Cache<String, Object> hotLocalCache,
171	@Qualifier("hotKeyExecutor") Executor hotKeyExecutor,
172	HotKeyProperties properties
173	) {
174	return new ExpireManagerImpl(hotLocalCache, hotKeyExecutor, properties, properties.getRefreshMaxPools());	9✔
175	}
176
177	/**
178	* Create the dedicated thread-pool executor for asynchronous cache operations.
179	*
180	* <p>This executor handles all async operations in the HotKey data path: cache loading
181	* via SingleFlight, soft-expiry refresh tasks, and cross-instance broadcast callbacks.
182	* Uses a bounded thread pool to limit concurrent AMQP channel usage (RabbitMQ's
183	* {@code CachingConnectionFactory} associates channels with platform threads, so
184	* unbounded virtual-thread concurrency causes channel-open timeouts). The pool is
185	* configured with core/max pool size, bounded queue capacity, and a rejection policy
186	* that throws {@link RejectedExecutionException} when the queue is full. On shutdown,
187	* in-progress tasks are allowed to complete with a 60-second grace period.
188	*
189	* @param properties the HotKey configuration properties (never {@code null})
190	* @return a configured {@link ThreadPoolTaskExecutor}
191	*/
192	@Bean("hotKeyExecutor")
193	@ConditionalOnMissingBean(name = "hotKeyExecutor")
194	public Executor hotKeyExecutor(HotKeyProperties properties) {
195	ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();	4✔
196	executor.setCorePoolSize(0);	3✔
197	executor.setMaxPoolSize(properties.getExecutorMaxPoolSize());	4✔
198	executor.setQueueCapacity(properties.getExecutorQueueCapacity());	4✔
199	executor.setAllowCoreThreadTimeOut(true);	3✔
200	executor.setThreadNamePrefix(HotKeyConstants.THREAD_PREFIX_HOTKEY);	3✔
201	executor.setWaitForTasksToCompleteOnShutdown(true);	3✔
202	executor.setAwaitTerminationSeconds(60);	3✔
203	executor.setRejectedExecutionHandler((r, exe) -> {	4✔
204	log.warn(	×
205	"HotKey executor task rejected: corePool={}, maxPool={}, queueCapacity={}",
206	properties.getExecutorCorePoolSize(),	×
207	properties.getExecutorMaxPoolSize(),	×
208	properties.getExecutorQueueCapacity()	×
209	);
210	throw new RejectedExecutionException("HotKey executor queue full");	×
211	});
212	executor.initialize();	2✔
213	return executor;	2✔
214	}
215
216	/**
217	* Create the {@link RuleMatcher} for key matching against user-defined rules.
218	*
219	* <p>This variant is wired with an empty Redis provider and an optional sync
220	* publisher, since no {@link StringRedisTemplate} is available in the non-Redis
221	* deployment mode. Rules are kept in-memory only and do not survive restarts.
222	* When Redis is available, {@link HotKeyRedisAutoConfiguration#ruleMatcher}
223	* takes over with Redis persistence.
224	*
225	* @param publisherProvider optional provider for the cache sync publisher (may be absent)
226	* @return a new RuleMatcher instance (in-memory only)
227	*/
228	@Bean
229	@ConditionalOnMissingBean({ RuleMatcher.class, StringRedisTemplate.class })
230	public RuleMatcher ruleMatcher(ObjectProvider<CacheSyncPublisher> publisherProvider) {
231	return new RuleMatcherImpl(Optional.empty(), Optional.ofNullable(publisherProvider.getIfAvailable()));	9✔
232	}
233
234	/**
235	* Create the {@link HotKeyCache} (non-Redis variant).
236	*
237	* <p>Only active when {@code RedisTemplate} is absent; otherwise
238	* {@link HotKeyRedisAutoConfiguration#hotKeyCache} takes over. Creates a
239	* {@link VersionController} with an empty Redis provider (falling back to
240	* node-local counters) and default ring manager / health view when none are
241	* available from the application context.
242	*
243	* @param hotKeyDetector the app-side TopK detector (never {@code null})
244	* @param hotLocalCache the L1 Caffeine cache (never {@code null})
245	* @param singleFlight the deduplication layer (never {@code null})
246	* @param expireManager the soft/hard expiration manager (never {@code null})
247	* @param syncPublisher optional cache sync publisher (may be absent)
248	* @param hotKeyReporter optional hot key reporter (may be absent; e.g. in Worker-only mode)
249	* @param hotKeyExecutor the dedicated HotKey executor (never {@code null})
250	* @param properties the HotKey configuration properties (never {@code null})
251	* @param ruleMatcher the rule matcher instance (never {@code null})
252	* @param healthViewProvider provider for the cluster health view (creates default if absent)
253	* @return a new HotKeyCache instance with node-local version tracking
254	*/
255	@Bean
256	@ConditionalOnMissingBean(type = "org.springframework.data.redis.core.RedisTemplate")
257	public HotKeyCache hotKeyCache(
258	@Qualifier("hotKeyDetector") HotKeyDetector hotKeyDetector,
259	Cache<String, Object> hotLocalCache,
260	SingleFlight singleFlight,
261	ExpireManager expireManager,
262	Optional<CacheSyncPublisher> syncPublisher,
263	Optional<KeyReporter> hotKeyReporter,
264	@Qualifier("hotKeyExecutor") Executor hotKeyExecutor,
265	HotKeyProperties properties,
266	RuleMatcher ruleMatcher,
267	ObjectProvider<HealthView> healthViewProvider
268	) {
269	return new HotKeyCache(	13✔
270	hotKeyDetector,
271	hotLocalCache,
272	singleFlight,
273	expireManager,
274	hotKeyExecutor,
275	syncPublisher,
276	hotKeyReporter,
277	ruleMatcher,
278	new VersionControllerImpl(Optional.empty(), properties.getVersionKeyTtlMinutes()),	8✔
279	properties,
280	healthViewProvider.getIfAvailable(() ->	3✔
NEW 281	new HealthViewImpl(	×
282	properties.getExpectedWorkerCount(),	×
283	properties.getHeartbeat().getTimeoutMs(),	×
284	properties.getHeartbeat().getDegradeAfterFailures()	×
285	)
286	)
287	);
288	}
289
290	/**
291	* Create the L1 Caffeine cache instance.
292	*
293	* <p>Time-based expiry operates at the <em>Caffeine</em> level via a custom
294	* {@link Expiry} implementation, computing remaining nanoseconds from
295	* . Entries with
296	* {@code hardExpireAtMs == Long.MAX_VALUE} are purely logical-expiry
297	* — Caffeine never evicts them by time; they live until size eviction or
298	* manual invalidation. Reads never extend the expiry duration (no read-based
299	* refresh), ensuring predictable TTL behavior.
300	*
301	* <p>The maximum cache size is configured via {@code hotkey.local.local-cache-max-size}
302	* (default 1000 entries). Time-based TTL for entries without an explicit hard-expire
303	* timestamp defaults to {@code hotkey.local.local-cache-ttl-minutes} (default 5 minutes).
304	*
305	* @param properties the HotKey configuration properties (never {@code null})
306	* @return a configured Caffeine {@link Cache} instance
307	*/
308	@Bean
309	@ConditionalOnMissingBean
310	public Cache<String, Object> hotLocalCache(HotKeyProperties properties) {
311	Caffeine<Object, Object> builder = Caffeine.newBuilder()	2✔
312	.maximumSize(properties.getLocalCacheMaxSize())	8✔
313	.expireAfter(	2✔
314	new Expiry<>() {	9✔
315	/**
316	* Compute the time-to-live for a newly created cache entry.
317	* Returns {@link Long#MAX_VALUE} for pure logical-expiry entries
318	* (where {@code hardExpireAtMs == Long.MAX_VALUE}); otherwise
319	* computes the remaining wall-clock time.
320	*
321	* @param key the cache key
322	* @param value the cache value (expected to be a {@link CacheEntry})
323	* @param currentTimeNanos the current time in nanoseconds (provided by Caffeine)
324	* @return the expiry duration in nanoseconds, or {@link Long#MAX_VALUE} for no expiry
325	*/
326	@Override
327	public long expireAfterCreate(@NonNull Object key, @NonNull Object value, long currentTimeNanos) {
328	if (value instanceof CacheEntry entry) {	3!
329	if (entry.getHardExpireAtMs() == Long.MAX_VALUE) {	×
330	// Pure logical expiry: Caffeine never time-evicts this entry.
331	// See Expiry Javadoc: Long.MAX_VALUE signals "no expiration".
332	return Long.MAX_VALUE;	×
333	}
334	long remainingMs = entry.getHardExpireAtMs() - currentTimeMillis();	×
335	return TimeUnit.MILLISECONDS.toNanos(Math.max(1, remainingMs));	×
336	}
337	return TimeUnit.MINUTES.toNanos(properties.getLocalCacheTtlMinutes());	7✔
338	}
339
340	/**
341	* Re-compute the expiry duration after an entry is updated.
342	* Preserves pure logical expiry across updates; otherwise
343	* recalculates from the entry's {@code hardExpireAtMs}.
344	*
345	* @param key the cache key
346	* @param value the cache value (expected to be a {@link CacheEntry})
347	* @param currentTimeNanos the current time in nanoseconds (provided by Caffeine)
348	* @param currentDuration the current expiry duration in nanoseconds
349	* @return the updated expiry duration in nanoseconds, or {@link Long#MAX_VALUE} for no expiry
350	*/
351	@Override
352	public long expireAfterUpdate(
353	@NonNull Object key,
354	@NonNull Object value,
355	long currentTimeNanos,
356	long currentDuration
357	) {
358	if (value instanceof CacheEntry entry) {	×
359	if (entry.getHardExpireAtMs() == Long.MAX_VALUE) {	×
360	// Preserve pure logical expiry across updates (e.g. broadcast refresh).
361	return Long.MAX_VALUE;	×
362	}
363	long remainingMs = entry.getHardExpireAtMs() - currentTimeMillis();	×
364	return TimeUnit.MILLISECONDS.toNanos(Math.max(1, remainingMs));	×
365	}
366	return currentDuration;	×
367	}
368
369	/**
370	* Preserve the current expiry duration on read — reads never
371	* extend or shorten the entry's time-to-live.
372	*
373	* @param key the cache key
374	* @param value the cache value
375	* @param currentTimeNanos the current time in nanoseconds (provided by Caffeine)
376	* @param currentDuration the current expiry duration in nanoseconds
377	* @return the unchanged expiry duration in nanoseconds
378	*/
379	@Override
380	public long expireAfterRead(
381	@NonNull Object key,
382	@NonNull Object value,
383	long currentTimeNanos,
384	long currentDuration
385	) {
386	return currentDuration;	×
387	}
388	}
389	);
390	return builder.build();	3✔
391	}
392	}

Hyshmily / hotkey / 28738321635

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