[Add] 增加自动清理机制;

[Add] AutoCleanTimer, Cleanable 增加定时清理器和所需实现的接口;
[Update] HashCacheStore 实现了 Cleanable 接口, 并使用了一种简单但效率较低的遍历清除方法, 有待改进;

ContentGrabbingJi-CacheStore-local/src/main/java/net/lamgc/cgj/bot/cache/local/AutoCleanTimer.java

@@ -0,0 +1,85 @@
+package net.lamgc.cgj.bot.cache.local;
+
+import com.google.common.base.Throwables;
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * 定时清理机制.
+ * <p>定时通知已实现 {@link Cleanable} 接口的对象进行清理.
+ * @see Cleanable
+ * @author LamGC
+ */
+public class AutoCleanTimer implements Runnable {
+
+    private final static Set<Cleanable> CLEANABLE_STORE_SET = new CopyOnWriteArraySet<>();
+
+    private final static ScheduledExecutorService SCHEDULED_EXECUTOR =
+            new ScheduledThreadPoolExecutor(1,
+                    new ThreadFactoryBuilder()
+                            .setDaemon(true)
+                            .setNameFormat("Thread-AutoClean-%d")
+                            .build()
+            );
+
+    private final static Logger log = LoggerFactory.getLogger(AutoCleanTimer.class);
+
+    private final static AtomicBoolean DEBUG_ENABLE = new AtomicBoolean(false);
+
+    static {
+        SCHEDULED_EXECUTOR.scheduleAtFixedRate(new AutoCleanTimer(), 100L, 100L, TimeUnit.MILLISECONDS);
+        Thread shutdownHook = new Thread(SCHEDULED_EXECUTOR::shutdown);
+        shutdownHook.setName("ShutdownThread-AutoClean");
+        Runtime.getRuntime().addShutdownHook(shutdownHook);
+    }
+
+    /**
+     * 是否启用调试模式.
+     * <p>启用后将会打印相关日志.
+     * @param enable 是否启用调试模式.
+     */
+    public static void setDebugEnable(boolean enable) {
+        DEBUG_ENABLE.set(enable);
+    }
+
+    /**
+     * 增加需要定时执行清理的缓存库
+     * @param store 已实现Cleanable的对象
+     */
+    public static void add(Cleanable store) {
+        CLEANABLE_STORE_SET.add(store);
+    }
+
+    /**
+     * 移除已添加的缓存库
+     * @param store 需要从AutoCleanTimer移除的对象
+     */
+    public static void remove(Cleanable store) {
+        CLEANABLE_STORE_SET.remove(store);
+    }
+
+    private AutoCleanTimer() {}
+
+    @Override
+    public void run() {
+        if (CLEANABLE_STORE_SET.size() == 0) {
+            return;
+        }
+
+        CLEANABLE_STORE_SET.forEach(cleanable -> {
+            try {
+                cleanable.clean();
+            } catch (Exception e) {
+                log.error("{} 执行清理动作时发生异常:\n{}", cleanable.toString(), Throwables.getStackTraceAsString(e));
+            }
+        });
+    }
+}

ContentGrabbingJi-CacheStore-local/src/main/java/net/lamgc/cgj/bot/cache/local/Cleanable.java

@@ -0,0 +1,16 @@
+package net.lamgc.cgj.bot.cache.local;
+
+/**
+ * 可清理接口, 实现该接口代表该类具有清理动作.
+ * @author LamGC
+ */
+public interface Cleanable {
+
+    /**
+     * 该方法需要CacheStore完成对过期Entry的清除.
+     * @return 返回已清理数量.
+     * @throws Exception 即使该方法抛出异常, 也不会影响后续情况.
+     */
+    long clean() throws Exception;
+
+}

ContentGrabbingJi-CacheStore-local/src/main/java/net/lamgc/cgj/bot/cache/local/HashCacheStore.java

@@ -20,6 +20,7 @@ package net.lamgc.cgj.bot.cache.local;
 import net.lamgc.cgj.bot.cache.CacheStore;
 
 import java.util.*;
+import java.util.concurrent.atomic.AtomicLong;
 
 /**
  * 基于 {@link Hashtable} 的缓存存储容器.
@@ -28,7 +29,7 @@ import java.util.*;
  * @see net.lamgc.cgj.bot.cache.CacheStore
  * @see Hashtable
  */
-public abstract class HashCacheStore<V> implements CacheStore<V> {
+public abstract class HashCacheStore<V> implements CacheStore<V>, Cleanable {
 
     private final Map<String, CacheItem<V>> cacheMap = new Hashtable<>();
 
@@ -100,6 +101,22 @@ public abstract class HashCacheStore<V> implements CacheStore<V> {
         return Collections.unmodifiableSet(cacheMap.keySet());
     }
 
+    @Override
+    public long clean() {
+        Map<String, CacheItem<V>> cacheMap = getCacheMap();
+        Date currentDate = new Date();
+        AtomicLong cleanCount = new AtomicLong(0);
+        cacheMap.keySet().removeIf(key -> {
+            CacheItem<V> item = cacheMap.get(key);
+            if (item != null && item.isExpire(currentDate)) {
+                cleanCount.incrementAndGet();
+                return true;
+            }
+            return false;
+        });
+        return cleanCount.get();
+    }
+
     /**
      * 缓存项.
      * @author LamGC