cloud.opencode.base.cache.RefreshAheadCache<K,V>

Type Parameters:

K - key type | 键类型

V - value type | 值类型

Security | 安全性:

Thread-safe: Yes - 线程安全: 是
Null-safe: Partial (null values not allowed) - 空值安全: 部分（不允许 null 值）

All Implemented Interfaces:: Cache<K,V>, AutoCloseable

public final class RefreshAheadCache<K,V> extends Object implements Cache<K,V>, AutoCloseable

Refresh Ahead Cache - Proactive cache refresh decorator 提前刷新缓存 - 主动缓存刷新装饰器

Wraps an existing cache to automatically refresh entries before they expire, ensuring cache hits even during refresh. This prevents cache stampede and improves latency by refreshing entries in the background.

包装现有缓存以在条目过期前自动刷新，确保在刷新期间仍能命中缓存。这可以防止缓存击穿并通过后台刷新提高延迟性能。

Features | 主要功能:

Proactive refresh before expiration - 过期前主动刷新
Background async refresh - 后台异步刷新
Stale-while-revalidate pattern - 验证时提供过期数据模式
Configurable refresh policy - 可配置的刷新策略
Single-flight refresh prevention - 单次刷新防止重复

Usage Examples | 使用示例:

// Create cache with refresh-ahead
Cache<String, User> cache = OpenCache.getOrCreate("users");
RefreshAheadCache<String, User> refreshCache = RefreshAheadCache.wrap(cache)
    .refreshPolicy(RefreshAheadPolicy.percentageOfTtl(0.8))
    .loader(key -> userService.findById(key))
    .ttl(Duration.ofMinutes(30))
    .build();

// Value will be refreshed in background when 80% of TTL has elapsed
User user = refreshCache.get("user:1");

// With custom executor
RefreshAheadCache<String, User> refreshCache = RefreshAheadCache.wrap(cache)
    .refreshPolicy(RefreshAheadPolicy.beforeExpiration(Duration.ofSeconds(30)))
    .loader(key -> userService.findById(key))
    .executor(Executors.newVirtualThreadPerTaskExecutor())
    .build();

Since:

JDK 25, opencode-base-cache V2.0.0

Author:

Leon Soo www.LeonSoo.com

See Also:

Nested Class Summary

Nested Classes

Modifier and Type

Class

Description

static class

RefreshAheadCache.Builder<K,V>

Builder for RefreshAheadCache

static final record

RefreshAheadCache.RefreshStats

Refresh statistics record 刷新统计记录
Field Summary

Fields inherited from interface Cache
MAX_GLOB_LENGTH
Method Summary

Modifier and Type

Method

Description

ConcurrentMap<K,V>

asMap()

Get a concurrent map view of this cache 获取 ConcurrentMap 视图

AsyncCache<K,V>

async()

Get async view of this cache 获取异步视图

int

cancelAllPendingRefreshes()

Cancel all pending refreshes 取消所有待处理的刷新

boolean

cancelPendingRefresh(K key)

Cancel a pending refresh for a specific key 取消特定键的待处理刷新

void

cleanUp()

Perform cleanup (expired entries, etc.)

void

close()

Close this cache, releasing all resources by delegating to shutdown().

V

compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction)

Compute a new value for the key 计算键的新值

V

computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction)

Compute a new value if key is present 如果键存在则计算新值

boolean

containsKey(K key)

Check if key exists 检查键是否存在

Set<Map.Entry<K,V>>

entries()

Get snapshot of all entries 获取所有条目的快照

long

estimatedSize()

Get estimated entry count (fast) 获取估算条目数（快速）

CompletableFuture<V>

forceRefresh(K key)

Force refresh a specific key 强制刷新特定键

V

get(K key)

Get value by key, returns null if not present 根据键获取值，不存在返回 null

V

get(K key, Function<? super K, ? extends V> loader)

Get value by key, load using loader if not present 根据键获取值，不存在时通过 loader 加载

Map<K,V>

getAll(Iterable<? extends K> keys)

Get all values for given keys, returns only existing entries 批量获取，仅返回存在的条目

Map<K,V>

getAll(Iterable<? extends K> keys, Function<? super Set<? extends K>, ? extends Map<K,V>> loader)

Get all values, load missing keys using loader 批量获取，缺失的键通过 loader 加载

V

getAndRemove(K key)

Get value and remove the entry atomically 原子地获取值并删除条目

int

getInFlightRefreshCount()

Get count of in-flight refreshes 获取正在进行的刷新数量

V

getOrDefault(K key, V defaultValue)

Get value or return default if not present 获取值，不存在则返回默认值

RefreshAheadCache.RefreshStats

getRefreshStats()

Get refresh statistics 获取刷新统计

void

invalidate(K key)

Invalidate a single key 使单个键失效

void

invalidateAll()

Invalidate all entries 清空所有缓存

void

invalidateAll(Iterable<? extends K> keys)

Invalidate multiple keys 批量失效

boolean

isRefreshInProgress(K key)

Check if a refresh is in progress for a specific key 检查特定键是否正在刷新

Set<K>

keys()

Get snapshot of all keys 获取所有键的快照

CacheMetrics

metrics()

Get detailed cache metrics with latency percentiles 获取带延迟百分位数的详细缓存指标

String

name()

Get cache name 获取缓存名称

void

put(K key, V value)

Put a key-value pair into cache 放入键值对

void

putAll(Map<? extends K, ? extends V> map)

Put all key-value pairs into cache 批量放入

void

putAllWithTtl(Map<? extends K, ? extends V> map, Duration ttl)

Put all entries with custom TTL 批量放入并指定自定义 TTL

boolean

putIfAbsent(K key, V value)

Put if the key is absent, returns true if successful 不存在时放入，成功返回 true

boolean

putIfAbsentWithTtl(K key, V value, Duration ttl)

Put if absent with custom TTL 不存在时放入并指定自定义 TTL

void

putWithTtl(K key, V value, Duration ttl)

Put a key-value pair with custom TTL (overrides default expiration) 放入键值对并指定自定义 TTL（覆盖默认过期时间）

V

replace(K key, V value)

Replace value only if key is present 仅在键存在时替换值

boolean

replace(K key, V oldValue, V newValue)

Replace value only if current value equals expected value 仅在当前值等于期望值时替换

void

shutdown()

Shutdown the refresh-ahead cache, cancelling pending refreshes and releasing resources 关闭提前刷新缓存，取消待处理的刷新并释放资源

long

size()

Get exact entry count (may be slow) 获取精确条目数（可能较慢）

CacheStats

stats()

Get cache statistics 获取缓存统计信息

Collection<V>

values()

Get snapshot of all values 获取所有值的快照

static <K,V> RefreshAheadCache.Builder<K,V>

wrap(Cache<K,V> cache)

Wrap a cache with refresh-ahead behavior 使用提前刷新行为包装缓存

Methods inherited from class Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface Cache
clear, computeIfAbsent, computeIfMatch, containsValue, entryIterator, entryParallelStream, entryStream, forEach, forEachKey, forEachValue, getByPattern, getIfPresent, getOptional, getOrNull, invalidateByPattern, invalidateByValue, invalidateIf, isEmpty, keyIterator, keyParallelStream, keyStream, merge, putAllIfAbsent, putIfPresent, removeIfEquals, removeIfPresent, replaceAll, replaceIf, resetStats, updateAll, updateTtl, updateTtl, updateTtlAll, valueParallelStream, valueStream

Method Details
- wrap
  
  public static <K,V> RefreshAheadCache.Builder<K,V> wrap(Cache<K,V> cache)
  
  Wrap a cache with refresh-ahead behavior 使用提前刷新行为包装缓存
  
  Type Parameters:
  
  K - key type | 键类型
  
  V - value type | 值类型
  
  Parameters:
  
  cache - cache to wrap | 要包装的缓存
  
  Returns:
  
  builder | 构建器
- get
  
  public V get(K key)
  
  Description copied from interface: Cache
  
  Get value by key, returns null if not present 根据键获取值，不存在返回 null
  
  Specified by:
  
  get in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  Returns:
  
  the value or null | 值或 null
- get
  
  public V get(K key, Function<? super K, ? extends V> loader)
  
  Description copied from interface: Cache
  
  Get value by key, load using loader if not present 根据键获取值，不存在时通过 loader 加载
  
  Specified by:
  
  get in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  loader - the loader function | 加载函数
  
  Returns:
  
  the value | 值
- getOrDefault
  
  public V getOrDefault(K key, V defaultValue)
  
  Description copied from interface: Cache
  
  Get value or return default if not present 获取值，不存在则返回默认值
  
  Specified by:
  
  getOrDefault in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  defaultValue - the default value | 默认值
  
  Returns:
  
  the value or default | 值或默认值
- put
  
  public void put(K key, V value)
  
  Description copied from interface: Cache
  
  Put a key-value pair into cache 放入键值对
  
  Specified by:
  
  put in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  value - the value | 值
- putAll
  
  public void putAll(Map<? extends K, ? extends V> map)
  
  Description copied from interface: Cache
  
  Put all key-value pairs into cache 批量放入
  
  Specified by:
  
  putAll in interface Cache<K,V>
  
  Parameters:
  
  map - the key-value pairs | 键值对 Map
- putIfAbsent
  
  public boolean putIfAbsent(K key, V value)
  
  Description copied from interface: Cache
  
  Put if the key is absent, returns true if successful 不存在时放入，成功返回 true
  
  Specified by:
  
  putIfAbsent in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  value - the value | 值
  
  Returns:
  
  true if put successfully | 成功放入返回 true
- putWithTtl
  
  public void putWithTtl(K key, V value, Duration ttl)
  
  Description copied from interface: Cache
  
  Put a key-value pair with custom TTL (overrides default expiration) 放入键值对并指定自定义 TTL（覆盖默认过期时间）
  
  Specified by:
  
  putWithTtl in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  value - the value | 值
  
  ttl - the time-to-live for this entry | 此条目的存活时间
- putAllWithTtl
  
  public void putAllWithTtl(Map<? extends K, ? extends V> map, Duration ttl)
  
  Description copied from interface: Cache
  
  Put all entries with custom TTL 批量放入并指定自定义 TTL
  
  Specified by:
  
  putAllWithTtl in interface Cache<K,V>
  
  Parameters:
  
  map - the key-value pairs | 键值对 Map
  
  ttl - the time-to-live for all entries | 所有条目的存活时间
- putIfAbsentWithTtl
  
  public boolean putIfAbsentWithTtl(K key, V value, Duration ttl)
  
  Description copied from interface: Cache
  
  Put if absent with custom TTL 不存在时放入并指定自定义 TTL
  
  Specified by:
  
  putIfAbsentWithTtl in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  value - the value | 值
  
  ttl - the time-to-live | 存活时间
  
  Returns:
  
  true if put successfully | 成功放入返回 true
- getAll
  
  public Map<K,V> getAll(Iterable<? extends K> keys)
  
  Description copied from interface: Cache
  
  Get all values for given keys, returns only existing entries 批量获取，仅返回存在的条目
  
  Specified by:
  
  getAll in interface Cache<K,V>
  
  Parameters:
  
  keys - the keys | 键集合
  
  Returns:
  
  map of existing entries | 存在的条目 Map
- getAll
  
  public Map<K,V> getAll(Iterable<? extends K> keys, Function<? super Set<? extends K>, ? extends Map<K,V>> loader)
  
  Description copied from interface: Cache
  
  Get all values, load missing keys using loader 批量获取，缺失的键通过 loader 加载
  
  Specified by:
  
  getAll in interface Cache<K,V>
  
  Parameters:
  
  keys - the keys | 键集合
  
  loader - the batch loader function | 批量加载函数
  
  Returns:
  
  map of all entries | 所有条目 Map
- computeIfPresent
  
  public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction)
  
  Description copied from interface: Cache
  
  Compute a new value if key is present 如果键存在则计算新值
  If the key is present and the remapping function returns non-null, the value is replaced. If the function returns null, the entry is removed.
  
  如果键存在且映射函数返回非 null，则替换值。如果函数返回 null，则删除条目。
  
  Specified by:
  
  computeIfPresent in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  remappingFunction - the function to compute new value | 计算新值的函数
  
  Returns:
  
  the new value or null if removed/absent | 新值，如果被删除或不存在则返回 null
- compute
  
  public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction)
  
  Description copied from interface: Cache
  
  Compute a new value for the key 计算键的新值
  Atomically computes a new value. If the key is absent and the function returns non-null, a new entry is created. If the key is present and the function returns null, the entry is removed.
  
  原子地计算新值。如果键不存在且函数返回非 null，则创建新条目。如果键存在且函数返回 null，则删除条目。
  
  Specified by:
  
  compute in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  remappingFunction - the function to compute value | 计算值的函数
  
  Returns:
  
  the new value or null if removed | 新值，如果被删除则返回 null
- getAndRemove
  
  public V getAndRemove(K key)
  
  Description copied from interface: Cache
  
  Get value and remove the entry atomically 原子地获取值并删除条目
  
  Specified by:
  
  getAndRemove in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  Returns:
  
  the value or null if not present | 值，不存在则返回 null
- replace
  
  public V replace(K key, V value)
  
  Description copied from interface: Cache
  
  Replace value only if key is present 仅在键存在时替换值
  
  Specified by:
  
  replace in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  value - the new value | 新值
  
  Returns:
  
  the old value or null if not present | 旧值，不存在则返回 null
- replace
  
  public boolean replace(K key, V oldValue, V newValue)
  
  Description copied from interface: Cache
  
  Replace value only if current value equals expected value 仅在当前值等于期望值时替换
  
  Specified by:
  
  replace in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  oldValue - the expected current value | 期望的当前值
  
  newValue - the new value | 新值
  
  Returns:
  
  true if replaced | 替换成功返回 true
- invalidate
  
  public void invalidate(K key)
  
  Description copied from interface: Cache
  
  Invalidate a single key 使单个键失效
  
  Specified by:
  
  invalidate in interface Cache<K,V>
  
  Parameters:
  
  key - the key to invalidate | 要失效的键
- invalidateAll
  
  public void invalidateAll(Iterable<? extends K> keys)
  
  Description copied from interface: Cache
  
  Invalidate multiple keys 批量失效
  
  Specified by:
  
  invalidateAll in interface Cache<K,V>
  
  Parameters:
  
  keys - the keys to invalidate | 要失效的键集合
- invalidateAll
  
  public void invalidateAll()
  
  Description copied from interface: Cache
  
  Invalidate all entries 清空所有缓存
  
  Specified by:
  
  invalidateAll in interface Cache<K,V>
- containsKey
  
  public boolean containsKey(K key)
  
  Description copied from interface: Cache
  
  Check if key exists 检查键是否存在
  
  Specified by:
  
  containsKey in interface Cache<K,V>
  
  Parameters:
  
  key - the key | 键
  
  Returns:
  
  true if exists | 存在返回 true
- size
  
  public long size()
  
  Description copied from interface: Cache
  
  Get exact entry count (may be slow) 获取精确条目数（可能较慢）
  
  Specified by:
  
  size in interface Cache<K,V>
  
  Returns:
  
  entry count | 条目数
- estimatedSize
  
  public long estimatedSize()
  
  Description copied from interface: Cache
  
  Get estimated entry count (fast) 获取估算条目数（快速）
  
  Specified by:
  
  estimatedSize in interface Cache<K,V>
  
  Returns:
  
  estimated count | 估算数量
- keys
  
  public Set<K> keys()
  
  Description copied from interface: Cache
  
  Get snapshot of all keys 获取所有键的快照
  
  Specified by:
  
  keys in interface Cache<K,V>
  
  Returns:
  
  set of keys | 键集合
- values
  
  public Collection<V> values()
  
  Description copied from interface: Cache
  
  Get snapshot of all values 获取所有值的快照
  
  Specified by:
  
  values in interface Cache<K,V>
  
  Returns:
  
  collection of values | 值集合
- entries
  
  public Set<Map.Entry<K,V>> entries()
  
  Description copied from interface: Cache
  
  Get snapshot of all entries 获取所有条目的快照
  
  Specified by:
  
  entries in interface Cache<K,V>
  
  Returns:
  
  set of entries | 条目集合
- asMap
  
  public ConcurrentMap<K,V> asMap()
  
  Description copied from interface: Cache
  
  Get a concurrent map view of this cache 获取 ConcurrentMap 视图
  
  Specified by:
  
  asMap in interface Cache<K,V>
  
  Returns:
  
  concurrent map view | ConcurrentMap 视图
- stats
  
  public CacheStats stats()
  
  Description copied from interface: Cache
  
  Get cache statistics 获取缓存统计信息
  
  Specified by:
  
  stats in interface Cache<K,V>
  
  Returns:
  
  cache statistics | 缓存统计
- metrics
  
  public CacheMetrics metrics()
  
  Description copied from interface: Cache
  
  Get detailed cache metrics with latency percentiles 获取带延迟百分位数的详细缓存指标
  
  Specified by:
  
  metrics in interface Cache<K,V>
  
  Returns:
  
  cache metrics or null if not enabled | 缓存指标，未启用则返回 null
- cleanUp
  
  public void cleanUp()
  
  Description copied from interface: Cache
  
  Perform cleanup (expired entries, etc.) 执行清理（过期条目等）
  
  Specified by:
  
  cleanUp in interface Cache<K,V>
- async
  
  public AsyncCache<K,V> async()
  
  Description copied from interface: Cache
  
  Get async view of this cache 获取异步视图
  
  Specified by:
  
  async in interface Cache<K,V>
  
  Returns:
  
  async cache view | 异步缓存视图
- name
  
  public String name()
  
  Description copied from interface: Cache
  
  Get cache name 获取缓存名称
  
  Specified by:
  
  name in interface Cache<K,V>
  
  Returns:
  
  cache name | 缓存名称
- getRefreshStats
  
  public RefreshAheadCache.RefreshStats getRefreshStats()
  
  Get refresh statistics 获取刷新统计
  
  Returns:
  
  refresh stats | 刷新统计
- forceRefresh
  
  public CompletableFuture<V> forceRefresh(K key)
  
  Force refresh a specific key 强制刷新特定键
  
  Parameters:
  
  key - the key to refresh | 要刷新的键
  
  Returns:
  
  future with new value | 包含新值的 Future
- cancelPendingRefresh
  
  public boolean cancelPendingRefresh(K key)
  
  Cancel a pending refresh for a specific key 取消特定键的待处理刷新
  
  Parameters:
  
  key - the key to cancel refresh for | 要取消刷新的键
  
  Returns:
  
  true if a refresh was cancelled | 如果取消了刷新返回 true
  
  Since:
  
  V2.0.1
- cancelAllPendingRefreshes
  
  public int cancelAllPendingRefreshes()
  
  Cancel all pending refreshes 取消所有待处理的刷新
  
  Returns:
  
  count of cancelled refreshes | 取消的刷新数量
  
  Since:
  
  V2.0.1
- shutdown
  
  public void shutdown()
  
  Shutdown the refresh-ahead cache, cancelling pending refreshes and releasing resources 关闭提前刷新缓存，取消待处理的刷新并释放资源
  
  Since:
  
  V2.0.6
- close
  
  public void close()
  
  Close this cache, releasing all resources by delegating to shutdown(). 关闭此缓存，通过委托给 shutdown() 释放所有资源。
  
  Specified by:
  
  close in interface AutoCloseable
  
  Since:
  
  V1.0.3
- isRefreshInProgress
  
  public boolean isRefreshInProgress(K key)
  
  Check if a refresh is in progress for a specific key 检查特定键是否正在刷新
  
  Parameters:
  
  key - the key to check | 要检查的键
  
  Returns:
  
  true if refresh is in progress | 正在刷新返回 true
  
  Since:
  
  V2.0.1
- getInFlightRefreshCount
  
  public int getInFlightRefreshCount()
  
  Get count of in-flight refreshes 获取正在进行的刷新数量
  
  Returns:
  
  count of in-flight refreshes | 进行中的刷新数量
  
  Since:
  
  V2.0.1

Class RefreshAheadCache<K,V>

Nested Class Summary

Field Summary

Fields inherited from interface Cache

Method Summary

Methods inherited from class Object

Methods inherited from interface Cache

Method Details

wrap

get

get

getOrDefault

put

putAll

putIfAbsent

putWithTtl

putAllWithTtl

putIfAbsentWithTtl

getAll

getAll

computeIfPresent

compute

getAndRemove

replace

replace

invalidate

invalidateAll

invalidateAll

containsKey

size

estimatedSize

keys

values

entries

asMap

stats

metrics

cleanUp

async

name

getRefreshStats

forceRefresh

cancelPendingRefresh

cancelAllPendingRefreshes

shutdown

close

isRefreshInProgress

getInFlightRefreshCount