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| 1 | +package fybug.nulll.pdcache; |
| 2 | +import org.jetbrains.annotations.NotNull; |
| 3 | +import org.jetbrains.annotations.Nullable; |
| 4 | + |
| 5 | +import java.lang.ref.Cleaner; |
| 6 | +import java.lang.ref.Reference; |
| 7 | +import java.lang.ref.SoftReference; |
| 8 | +import java.lang.ref.WeakReference; |
| 9 | + |
| 10 | +import fybug.nulll.pdconcurrent.SyLock; |
| 11 | + |
| 12 | +/** |
| 13 | + * <h2>数据缓存通用类.</h2> |
| 14 | + * <p> |
| 15 | + * 用于缓存单个数据的缓存工具,数据对象可实现 {@link CanClean} 接口返回数据回收时的处理方法<br/> |
| 16 | + * 包含缓存的引用,缓存获取方法 {@link #getdata()},缓存回收接口以及并发管理 |
| 17 | + * |
| 18 | + * @author fybug |
| 19 | + * @version 0.0.1 |
| 20 | + * @since PDCache 0.0.1 |
| 21 | + */ |
| 22 | +public abstract |
| 23 | +class CacheOb<V> { |
| 24 | + /** 缓存引用类型 */ |
| 25 | + protected final Class<? extends Reference<V>> refClass; |
| 26 | + /** 缓存引用 */ |
| 27 | + protected volatile Reference<V> cache = new WeakReference<>(null); |
| 28 | + |
| 29 | + /** 数据回收接口 */ |
| 30 | + protected volatile Cleaner.Cleanable cleanable = null; |
| 31 | + |
| 32 | + /** 并发管理 */ |
| 33 | + protected final SyLock LOCK; |
| 34 | + |
| 35 | + //---------------------------------------------------------------------------------------------- |
| 36 | + |
| 37 | + /** 构造缓存,指定缓存方式 */ |
| 38 | + protected |
| 39 | + CacheOb(@NotNull Class<? extends Reference> refc) {this(refc, SyLock.newRWLock()); } |
| 40 | + |
| 41 | + /** 构造缓存,指定缓存方式和并发管理 */ |
| 42 | + protected |
| 43 | + CacheOb(@NotNull Class<? extends Reference> refc, @NotNull SyLock syLock) { |
| 44 | + this.refClass = (Class<Reference<V>>) refc; |
| 45 | + LOCK = syLock; |
| 46 | + } |
| 47 | + |
| 48 | + //---------------------------------------------------------------------------------------------- |
| 49 | + |
| 50 | + /** |
| 51 | + * 获取缓存 |
| 52 | + * |
| 53 | + * @return 当前缓存的数据 |
| 54 | + */ |
| 55 | + @Nullable |
| 56 | + protected |
| 57 | + V getdata() throws Exception { |
| 58 | + var ref = new Object() { |
| 59 | + V item; |
| 60 | + }; |
| 61 | + |
| 62 | + // 赋予强引用,防止进入回收队列 |
| 63 | + LOCK.tryread(Exception.class, () -> ref.item = cache.get()); |
| 64 | + |
| 65 | + // 校验数据 |
| 66 | + if (ref.item == null) |
| 67 | + // 锁定数据 |
| 68 | + return LOCK.trywrite(Exception.class, () -> { |
| 69 | + /* 梅开二度 */ |
| 70 | + if ((ref.item = cache.get()) == null) { |
| 71 | + // 等待清理 |
| 72 | + while( cleanable != null ) |
| 73 | + ; |
| 74 | + // 无缓存处理 |
| 75 | + return emptyData(); |
| 76 | + } |
| 77 | + |
| 78 | + return ref.item; |
| 79 | + }); |
| 80 | + |
| 81 | + return ref.item; |
| 82 | + } |
| 83 | + |
| 84 | + /** |
| 85 | + * 无数据时的数据 |
| 86 | + * |
| 87 | + * @return 在没有缓存时返回的数据 |
| 88 | + */ |
| 89 | + @Nullable |
| 90 | + protected abstract |
| 91 | + V emptyData() throws Exception; |
| 92 | + |
| 93 | + //----------------------------------- |
| 94 | + |
| 95 | + /** |
| 96 | + * 放入数据 |
| 97 | + * |
| 98 | + * @param v 数据 |
| 99 | + */ |
| 100 | + protected |
| 101 | + void putdata(@Nullable V v) throws Exception { |
| 102 | + LOCK.trywrite(Exception.class, () -> { |
| 103 | + // 获取对象的回收方法 |
| 104 | + if (v instanceof CanClean) { |
| 105 | + var c = ((CanClean) v).getclean(); |
| 106 | + // 注册回收方法 |
| 107 | + cleanable = CacheGcThrea.binClean(v, () -> { |
| 108 | + c.run(); |
| 109 | + cleanable = null; |
| 110 | + }); |
| 111 | + } |
| 112 | + |
| 113 | + // 绑定缓存 |
| 114 | + cache = refClass.getConstructor(Object.class).newInstance(v); |
| 115 | + }); |
| 116 | + } |
| 117 | + |
| 118 | + /** |
| 119 | + * 移除缓存 |
| 120 | + * <p> |
| 121 | + * 强制释放缓存内容<br/> |
| 122 | + * 将缓存内容主动加入回收队列 |
| 123 | + */ |
| 124 | + public |
| 125 | + void clear() { |
| 126 | + LOCK.write(() -> { |
| 127 | + // 正在被回收 |
| 128 | + if (cache.isEnqueued()) |
| 129 | + return; |
| 130 | + /* 释放 */ |
| 131 | + if (cleanable != null) |
| 132 | + cleanable.clean(); |
| 133 | + // GC mark |
| 134 | + cleanable = null; |
| 135 | + cache.clear(); |
| 136 | + }); |
| 137 | + } |
| 138 | + |
| 139 | + /*--------------------------------------------------------------------------------------------*/ |
| 140 | + |
| 141 | + /** |
| 142 | + * {@link CacheOb} 子类通用构造工具 |
| 143 | + * <p> |
| 144 | + * 使用 {@link #refernce(Class)} 绑定缓存方式<br/> |
| 145 | + * 使用 {@link #lockBy(SyLock)} 绑定并发管理<br/> |
| 146 | + * 使用 {@link #build()} 进行构造 |
| 147 | + * |
| 148 | + * @version 0.0.1 |
| 149 | + * @since CacheOb 0.0.1 |
| 150 | + */ |
| 151 | + @SuppressWarnings( "unchecked" ) |
| 152 | + protected static abstract |
| 153 | + class Build<V, B extends Build<V, B>> { |
| 154 | + /** 缓存引用类型 */ |
| 155 | + protected Class<? extends Reference> refernce = SoftReference.class; |
| 156 | + /** 并发管理 */ |
| 157 | + protected SyLock lockBy = SyLock.newRWLock(); |
| 158 | + |
| 159 | + //------------------------------------------------------------------------------------------ |
| 160 | + |
| 161 | + /** 设置缓存引用类型 */ |
| 162 | + @NotNull |
| 163 | + public final |
| 164 | + B refernce(Class<? extends Reference> refernce) { |
| 165 | + this.refernce = refernce; |
| 166 | + return (B) this; |
| 167 | + } |
| 168 | + |
| 169 | + /** 设置并发管理 */ |
| 170 | + @NotNull |
| 171 | + public final |
| 172 | + B lockBy(@NotNull SyLock lockBy) { |
| 173 | + this.lockBy = lockBy; |
| 174 | + return (B) this; |
| 175 | + } |
| 176 | + |
| 177 | + @NotNull |
| 178 | + public abstract |
| 179 | + CacheOb<V> build(); |
| 180 | + } |
| 181 | +} |
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