前言
- 一个哈希表，它支持检索的完全并发性和更新的高期望并发性。
- 此类遵循与{@link java.util.Hashtable}相同的功能规范，
- 并且包括与{@code Hashtable}的每个方法相对应的方法版本。
- 但是，即使所有操作都是线程安全的，检索操作也不需要进行锁定，并且不支持以阻止所有访问的方式锁定整个表。
- 在依赖于其线程安全性而不依赖于其同步详细信息的程序中，此类可以与{@code Hashtable}完全互操作。
- 检索操作（包括{@code get}）通常不会阻塞，因此可能与更新操作（包括{@code put}和{@code remove}）重叠。
- 检索反映了自启动以来最新完成的更新操作的结果。
- （更正式地说，给定键的更新操作与该键的任何（非空）检索报告更新后的值之间具有事前关联。）
- 对于汇总操作，例如{@code putAll}和{@code clear} ，并发检索可能仅反映某些条目的插入或删除。
- 同样，迭代器，拆分器和枚举返回的元素反映了在创建迭代器/枚举时或此后某个时刻哈希表的状态。
- 他们不会抛出{@link java.util.ConcurrentModificationException ConcurrentModificationException}。
- 但是，迭代器被设计为一次只能由一个线程使用。
- 请记住，包括{@code size}，{@code isEmpty}
- 和{@code containsValue}在内的聚合状态方法的结果通常仅在映射未在其他线程中进行并发更新时才有用。
- 否则，这些方法的结果将反映可能足以用于监视或估计目的但不适用于程序控制的瞬态。
- 当发生太多冲突（即键具有不同的哈希码但以表大小为模的同一时隙）时，将动态扩展表，
- 并且预期平均效果是每个映射大约维护两个bin（对应于0.75负载）调整大小的系数阈值）。
- 添加和删除映射时，此平均值附近可能会有很大的差异，但是总的来说，这保持了哈希表的公认的时间/空间权衡。
- 但是，调整此哈希表或任何其他类型的哈希表的大小可能是一个相对较慢的操作。
- 如果可能，最好将大小估计值作为可选的{@code initialCapacity}构造函数参数提供。
- 附加的可选{@code loadFactor}构造函数参数提供了一种进一步的方法，可通过指定表密度来自定义初始表容量，
- 该表密度将用于计算为给定数量的元素分配的空间量。
- 另外，为了与此类的早期版本兼容，构造函数可以选择指定期望的{@code concurrencyLevel}作为内部调整的附加提示。
- 请注意，使用许多键具有完全相同的{@code hashCode（）}是降低任何哈希表性能的。
- 为了改善影响，当键为{@link Comparable}时，此类可以使用键之间的比较顺序来帮助打破平局。
- 当仅在意key，并且映射的value 没有（或暂时没有）被使用或者全部使用相同的值时，ConcurrentHashMap 的 Set的映射可以被创建或者查看。
- 创建使用 newKeySet() 或者 newKeySet(int)，查看使用 keySet(Object)
- 通过使用{@link java.util.concurrent.atomic.LongAdder}值并通过{@link #computeIfAbsent computeIfAbsent}进行初始化，
- 可以将ConcurrentHashMap用作可伸缩的频率图（直方图或多集形式）。
- 例如，要将计数添加到{@code ConcurrentHashMap <String，LongAdder> freqs}，
- 可以使用{@code freqs.computeIfAbsent（k-> new LongAdder（））。increment（）;}
- 此类及其视图和迭代器实现{@link Map}和{@link Iterator}接口的所有可选方法。
- 类似于{@link Hashtable}，但与{@link HashMap}不同，此类不允许{@code null}用作键或值。
- ConcurrentHashMaps支持一组顺序和并行的批量操作，
- 与大多数{@link Stream}方法不同，该操作被设计为即使在其他线程同时更新的地图上也可以安全且通常明智地应用。
- 例如，在计算共享注册表中值的快照摘要时。
- 共有三种操作，每种都有四种形式，它们接受带有键，值，条目和（键，值）参数和/或返回值的函数。
- 因为ConcurrentHashMap的元素没有以任何特定的方式排序，并且可以在不同的并行执行中以不同的顺序进行处理，
- 所以提供的函数的正确性不应该依赖于任何顺序，也不应该依赖于任何其他对象或值，这些对象或值在运行时可能会瞬时改变计算正在进行中；
- 除了forEach动作外，理想情况下应无副作用。 {@link java.util.Map.Entry}对象上的批量操作不支持方法{@code setValue}。
- forEach：对每个元素执行给定的操作。变体形式在执行操作之前对每个元素应用给定的转换。
- search：返回在每个元素上应用给定函数的第一个可用的非空结果；找到结果时跳过进一步的搜索。
- reduce：累积每个元素。提供的归约函数不能依赖于排序（更正式地说，它应该是关联的和可交换的）。
- 有五种变体：
- Plain reductions。 （由于没有对应的返回类型，因此（键，值）函数参数没有此方法的形式。）
- Mapped reductions。积累了应用于每个元素的给定函数的结果。
- double long int 的 Reduction ，使用给定的基础值。
- 这些批量操作接受{@code parallelismThreshold}参数。
- 如果当前地图的大小估计小于给定的阈值，则方法将按顺序进行。
- 使用{@code Long.MAX_VALUE}的值将抑制所有并行性。
- 使用{@code 1}值可通过划分为足够的子任务来充分利用用于所有并行计算的{@link ForkJoinPool＃commonPool（）}，从而实现最大的并行度。
- 通常，您最初会选择这些极值之一，然后使用权衡开销与吞吐量的中间值来衡量性能。
- 批量操作的并发属性遵循ConcurrentHashMap的并发属性：从{@code get（key）}和相关访问方法返回的任何非空结果都与关联的插入或更新具有事前关系。
- 任何批量操作的结果都反映了这些每个元素关系的组成（但对于整个地图而言，不一定是原子的，除非以某种方式已知它是静态的）。
- 相反，由于映射中的键和值永远不会为null，因此null可作为当前缺少任何结果的可靠原子指示。
- 为了保持此属性，null用作所有非标量 reduction 操作的隐式基础。
- 对于double，long和int版本，其基础应该是当与任何其他值组合时返回该其他值的基础（更正式地说，它应该是简化的标识元素）。
- 最常见的还原具有这些特性。例如，计算基数为0的总和或基数为MAX_VALUE的最小值。
- 作为参数提供的搜索和转换功能应类似地返回null，以指示缺少任何结果（在这种情况下将不使用它）。
- 在mapped reductions的情况下，这还使 transformation 能够用作 filter，
- 如果不应组合元素，则返回null（或者在原始专业化的情况下，返回基于身份的基础）。
- 您可以在搜索或归约运算中使用它们之前，根据“null意味着现在什么也没有”规则将它们自己组合起来，从而创建复合转换和过滤。
- 接受和/或返回Entry参数的方法维护键-值关联。
- 例如，当找到最大值的key时，它们可能会很有用。
- 请注意，可以使用{@code new AbstractMap.SimpleEntry（k，v）}提供“普通”条目自变量。
- 批量操作可能会突然完成，从而引发所提供功能的应用程序中遇到的异常。
- 处理此类异常时请记住，其他并发执行的函数也可能抛出异常，或者如果没有发生第一个异常，则可能会抛出异常。
- 与顺序形式相比，并行加速是常见的，但不能保证。
- 如果并行化计算的基础工作比计算本身更昂贵，则涉及small map 上简短功能的并行操作的执行速度可能会比顺序形式慢。
- 同样，如果所有处理器都在忙于执行无关的任务，那么并行化可能不会导致很多实际的并行性。
源码
package java.util.concurrent;
public class ConcurrentHashMap<K,V> extends AbstractMap<K,V>
implements ConcurrentMap<K,V>, Serializable {
private static final long serialVersionUID = 7249069246763182397L;
/* 此哈希表的主要设计目标是保持并发可读性（通常是get（）方法，还包括迭代器和相关方法），同时最大程度地减少更新争用。
* 次要目标是使空间消耗保持与java.util.HashMap相同或更好，并通过许多线程支持在空表上的高初始插入率。
* 该映射通常充当装箱（存储桶）的哈希表。
* 每个键值映射都保存在一个节点中。
* 大多数节点是基本Node类的实例，具有哈希，键，值和下一个字段。
* 但是，存在各种子类：TreeNode被安排在平衡树中，而不是列表中。
* TreeBins拥有TreeNodes集的根。
* 在调整大小期间，ForwardingNodes放置在垃圾箱的顶部。
* 在computeIfAbsent和相关方法中建立值时，ReservationNode用作占位符。
* TreeBin，ForwardingNode和ReservationNode类型不包含常规用户键，值或哈希，并且在搜索等过程中易于区分，
* 因为它们具有负的哈希字段以及空键和值字段。
* （这些特殊节点是不常见的或瞬态的，因此携带一些未使用的字段的影响微不足道。）
* 该表在第一次插入时被延迟初始化为2的幂。
* 表中的每个bin通常包含一个Node列表（大多数情况下，该列表只有零个或一个Node）。
* 表访问需要 volatile/atomic 的 读，写和CAS。
* 由于无法在不增加其他间接调用的情况下进行安排，因此我们使用内部函数（sun.misc.Unsafe）。
*
* 我们将Node哈希字段的最高（符号）位用于控制目的-由于寻址限制，它始终可用。
* 带有负哈希字段的节点在map方法中经过特殊处理或忽略。
*
* 将第一个节点插入（通过put或其变体）到空容器中，只需将其CAS到容器中即可。
* 到目前为止，这是大多数键/哈希分布下的put操作的最常见情况。
* 其他更新操作（插入，删除和替换）需要锁。
* 我们不想浪费将不同的锁对象与每个bin关联所需的空间，因此可以将bin列表本身的第一个节点用作锁。
* （问题记录： 如果要修改第一个节点呢？ java允许修改锁。）
* 对这些锁的锁定支持依赖于内置的“同步”监视器。
* 但是，将列表的第一个节点用作锁定本身并不能满足要求：锁定节点时，任何更新都必须首先确认它仍然是锁定后的第一个节点，否则重试。
* 由于新节点总是添加到列表中，因此一旦节点首次位于bin中，它将一直保持到删除或bin无效（调整大小后）。
*
* 每个bin都加锁的主要缺点是，受相同锁保护的bin列表中其他节点上的其他更新操作可能会停止，
* 例如，当用户equals（）或映射函数花费很长时间时。
* 但是，从统计学上讲，在随机哈希码下，这不是一个普遍的问题。
* 理想情况下，箱中节点的频率遵循泊松分布（http://en.wikipedia.org/wiki/Poisson_distribution），
* 平均参数约为0.5（给定调整大小阈值0.75），尽管由于调整粒度。
* 忽略方差，列表大小k的预期出现次数是（exp（-0.5）*pow（0.5，k）/factorial（k））。第一个值是：
*
* 0: 0.60653066
* 1: 0.30326533
* 2: 0.07581633
* 3: 0.01263606
* 4: 0.00157952
* 5: 0.00015795
* 6: 0.00001316
* 7: 0.00000094
* 8: 0.00000006
* more: less than 1 in ten million
*
* 在随机哈希下，两个线程访问不同元素的锁争用概率大约为1 /（8 * 元素数量）。
* 在实践中遇到的实际哈希码分布有时会明显偏离统一的随机性。
* 这包括N>（1 << 30）的情况，因此某些键必须发生冲突。
* 类似地，对于愚蠢或恶意的用法，其中多个密钥被设计为具有相同的哈希码或仅在被掩盖的高位上有所不同的哈希码。
* 因此，我们使用了二级策略，该策略在bin中的节点数超过阈值时适用。
* 这些TreeBins使用平衡树来保存节点（红黑树的一种特殊形式），将搜索时间限制为O（log N）。
* TreeBin中的每个搜索步骤的速度至少是常规列表中速度的两倍，但是考虑到N不能超过（1 << 64）（在地址用尽之前），因此可以合理地限制搜索步骤，
* 锁定保持时间等只要键是可比较的（很常见-字符串，长整数等），就可以使用常量（每次操作最多检查100个节点）。
* TreeBin节点（TreeNodes）还维护与常规节点相同的“下一个”遍历指针，因此可以在迭代器中以相同的方式遍历。
*
* 当占用率超过百分比阈值（标称值为0.75，但请参见下文）时，将调整表的大小。
* 在启动线程分配并设置替换阵列之后，任何注意到bin满的线程都可以帮助调整大小。
* 但是，这些其他线程可能会进行插入操作，而不是停滞不前。
* 使用TreeBins可以避免我们在调整大小时发生最坏情况下的过度填充影响。
* 调整大小是通过将垃圾箱从一个表一个接一个地转移到下一个表来进行的。
* 但是，线程在这样做之前要求小的索引块进行传输（通过字段transferIndex），从而减少了争用。
* 字段sizeCtl中的世代标记可确保调整大小不会重叠。
* 因为我们使用的是2的幂，所以每个bin中的元素必须保持相同的索引，或者以2的幂偏移。
* 我们通过捕获旧节点可以重复使用的情况（因为它们的下一个字段不会更改）来消除不必要的节点创建。
* 平均而言，当表加倍时，只有大约六分之一需要克隆。
* 一旦它们被并发遍历表中的任何读取器线程不再引用，它们替换的节点将立即被垃圾回收。
* 传输后，旧表容器仅包含一个特殊的转发节点（哈希字段为“ MOVED”），该节点包含下一个表作为其关键字。
* 遇到转发节点时，将使用新表重新启动访问和更新操作。
*
* 每次bin传输都需要其bin锁，该bin锁可以在调整大小时停止等待锁。
* 但是，由于其他线程可以加入并帮助调整大小而不是争夺锁，因此随着调整大小的进展，平均聚合等待时间会缩短。
* 转移操作还必须确保任何遍历都可以使用旧表和新表中的所有可访问bin。
* 这是通过从最后一个bin（table.length-1）到第一个bin进行部分安排的。
* 看到转发节点后，遍历（请参见Traverser类）安排在不重新访问节点的情况下移至新表。
* 为了确保即使在无序移动时也不会跳过中间节点，在遍历过程中第一次遇到转发节点时会创建一个堆栈（请参见TableTable类），
* 以在以后处理当前表时保持其位置。
* 这些保存/恢复机制的需求相对很少，但是当遇到一个转发节点时，通常会更多。
* 因此，遍历器使用一种简单的缓存方案来避免创建许多新的TableStack节点。
* （感谢Peter Levart建议在此处使用堆栈。）
*
* 遍历方案也适用于部分范围的bin（通过备用Traverser构造函数），以支持分区聚合操作。
* 同样，只读操作如果转发到空表也将放弃，该操作提供了对关机样式清除的支持，该功能目前还没有实现。
*
* 惰性表初始化可最大程度地减少首次使用之前的占用空间，并且当第一个操作来自putAll，带有map参数的构造函数或反序列化时，还避免了调整大小。
* 这些情况试图超越初始容量设置，但在比赛中无害地无法生效。
*
* 元素计数使用LongAdder的特殊化来维护。
* 我们需要合并一个专业化对象，而不仅仅是使用LongAdder来访问隐式竞争感应，从而导致创建多个CounterCell。
* 计数器机制避免了更新争用，但如果在并发访问期间读取得太频繁，则可能会遇到缓存崩溃的情况。
* 为避免经常阅读，仅在添加到已容纳两个或更多节点的容器中后，才尝试在竞争下调整大小。
* 在统一的哈希分布下，在阈值处发生这种情况的可能性约为13％，这意味着只有八分之一的位置放置了检查阈值（并且在调整大小之后，这样做的人要少得多）。
*
* TreeBins使用一种特殊的比较形式来进行搜索和相关操作（这是我们不能使用TreeMap等现有集合的主要原因）。
* TreeBins包含Comparable元素，但可能包含其他元素，以及对于同一T可比较但不一定可比较的元素，因此我们无法在其中调用compareTo。
* 为了解决这个问题，树主要是按哈希值排序，然后按Comparable.compareTo排序（如果适用）。
* 在节点上查找时，如果元素不可比较或比较为0，则在绑定哈希值的情况下，可能需要同时搜索左右子节点。
* （这对应于如果所有元素都是不可比较的并且具有散列哈希的完整列表搜索。）
* 在插入时，为了保持重新平衡的总顺序（或此处要求的最接近），我们比较类和identityHashCodes作为决胜局。
* 红黑平衡代码从jdk之前的收藏集（http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java）更新而来，
* 依次基于Cormen，Leiserson和Rivest算法”（CLR）。
*
* TreeBins还需要其他锁定机制。
* 尽管即使在更新过程中，读者始终可以遍历列表，但无法遍历树，主要是因为树的旋转可能会更改根节点和/或其链接。
* TreeBins包括一个寄生在主要bin同步策略上的简单读写锁定机制：
* 与插入或删除相关的结构调整已被bin锁定（因此不能与其他编写器发生冲突），但必须等待正在进行的读取器完成。
* 由于只能有一个这样的服务员，因此我们使用一个简单的方案，即使用单个“服务员”字段来阻止作者。
* 但是，读者永远不需要阻塞。
* 如果持有根锁，则它们将沿着慢速遍历路径（通过下一个指针）前进，直到锁可用或列表用完为止，以先到者为准。
* 这些情况不是很快，但是会最大化合计预期吞吐量。
*
* 与此类的早期版本保持API和序列化兼容性会带来一些奇怪的问题。
* 主要是：我们保持不变，但未使用的构造函数参数引用了concurrencyLevel。
* 我们接受loadFactor构造函数参数，但仅将其应用于初始表容量（这是我们唯一可以保证兑现它的时间。）
* 我们还声明了一个未使用的“段”类，该类仅在序列化时以最小形式实例化。
*
* 同样，仅出于与此类以前版本的兼容性的考虑，它扩展了AbstractMap，即使其所有方法都被覆盖，因此也只是无济于事。
*
* 该文件的组织结构使它们在阅读时比在其他情况下更易于理解：
* 首先是主要的静态声明和实用程序，然后是字段，然后是主要的公共方法（将多个公共方法分解成多个内部方法），然后调整大小。
* 方法，树，遍历器和批量操作。
*/
private static final int MAXIMUM_CAPACITY = 1 << 30;
private static final int DEFAULT_CAPACITY = 16;
static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
private static final int DEFAULT_CONCURRENCY_LEVEL = 16;
private static final float LOAD_FACTOR = 0.75f;
/**
* 使用树而不是列表列出容器的容器计数阈值。
* 将元素添加到至少具有这么多节点的容器中时，容器将转换为树。
* 该值必须大于2，并且至少应为8才能与树删除的假设相吻合，该假设是在收缩时将树转换回普通箱。
*/
static final int TREEIFY_THRESHOLD = 8;
/**
* 在调整大小操作期间用于取消树状化（拆分的）箱的箱计数阈值。应小于TREEIFY_THRESHOLD，并且最大为6以与移除下的收缩检测相啮合。
*/
static final int UNTREEIFY_THRESHOLD = 6;
/**
* 可将其分类为树木的最小table容量。 （否则，如果bin中的节点过多，则将调整表的大小。）
* 该值应至少为4 *TREEIFY_THRESHOLD，以避免调整大小和树化阈值之间发生冲突。
*/
static final int MIN_TREEIFY_CAPACITY = 64;
/**
* 每个传输步骤的最小重新绑定数量。范围被细分为允许多个调整程序线程。
* 此值用作下限，以避免调整器遇到过多的内存争用。该值应至少为DEFAULT_CAPACITY。
*/
private static final int MIN_TRANSFER_STRIDE = 16;
private static int RESIZE_STAMP_BITS = 16;
private static final int MAX_RESIZERS = (1 << (32 - RESIZE_STAMP_BITS)) - 1;
private static final int RESIZE_STAMP_SHIFT = 32 - RESIZE_STAMP_BITS;
static final int MOVED = -1;
static final int TREEBIN = -2;
static final int RESERVED = -3;
static final int HASH_BITS = 0x7fffffff;
/** Number of CPUS, to place bounds on some sizings */
static final int NCPU = Runtime.getRuntime().availableProcessors();
/** For serialization compatibility. */
private static final ObjectStreamField[] serialPersistentFields = {
new ObjectStreamField("segments", Segment[].class),
new ObjectStreamField("segmentMask", Integer.TYPE),
new ObjectStreamField("segmentShift", Integer.TYPE)
};
/* ---------------- Nodes -------------- */
static class Node<K,V> implements Map.Entry<K,V> {
final int hash;
final K key;
volatile V val;
volatile Node<K,V> next;
Node(int hash, K key, V val, Node<K,V> next) {
this.hash = hash;
this.key = key;
this.val = val;
this.next = next;
}
public final K getKey() { return key; }
public final V getValue() { return val; }
public final int hashCode() { return key.hashCode() ^ val.hashCode(); }
public final String toString(){ return key + "=" + val; }
public final V setValue(V value) {
throw new UnsupportedOperationException();
}
public final boolean equals(Object o) {
Object k, v, u; Map.Entry<?,?> e;
return ((o instanceof Map.Entry) &&
(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
(v = e.getValue()) != null &&
(k == key || k.equals(key)) &&
(v == (u = val) || v.equals(u)));
}
Node<K,V> find(int h, Object k) {
Node<K,V> e = this;
if (k != null) {
do {
K ek;
if (e.hash == h &&
((ek = e.key) == k || (ek != null && k.equals(ek))))
return e;
} while ((e = e.next) != null);
}
return null;
}
}
/* ---------------- Static utilities -------------- */
/**
* 由于该表使用二乘幂掩码，因此仅在当前掩码上方的位中变化的哈希集将始终发生冲突。
* （众所周知的示例是在小表中包含连续整数的Float键集。）
* 因此，我们应用了一种变换，将向下传播较高位的影响。
* 在速度，实用性和位扩展质量之间需要权衡。
* 由于许多常见的哈希集已经合理分布（因此无法从扩展中受益），并且由于我们使用树来处理容器中的大量冲突，
* 因此我们仅以最便宜的方式对某些移位后的位进行XOR，以减少系统损失，以及合并最高位的影响，
* 否则由于表范围的限制，这些位将永远不会在索引计算中使用。
*
*/
static final int spread(int h) {
return (h ^ (h >>> 16)) & HASH_BITS;
}
private static final int tableSizeFor(int c) {
int n = c - 1;
n |= n >>> 1;
n |= n >>> 2;
n |= n >>> 4;
n |= n >>> 8;
n |= n >>> 16;
return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
}
static Class<?> comparableClassFor(Object x) {
if (x instanceof Comparable) {
Class<?> c; Type[] ts, as; Type t; ParameterizedType p;
if ((c = x.getClass()) == String.class) // bypass checks
return c;
if ((ts = c.getGenericInterfaces()) != null) {
for (int i = 0; i < ts.length; ++i) {
if (((t = ts[i]) instanceof ParameterizedType) &&
((p = (ParameterizedType)t).getRawType() ==
Comparable.class) &&
(as = p.getActualTypeArguments()) != null &&
as.length == 1 && as[0] == c) // type arg is c
return c;
}
}
}
return null;
}
@SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
static int compareComparables(Class<?> kc, Object k, Object x) {
return (x == null || x.getClass() != kc ? 0 :
((Comparable)k).compareTo(x));
}
/* ---------------- Table element access -------------- */
/*
* 在调整大小时，易失性访问方法用于表元素以及进行中的下一个表的元素。
* 选项卡参数的所有使用都必须由调用方检查为null。
* 所有调用者还偏执地预先检查tab的长度是否不为零（或等效检查），从而确保任何采用哈希值形式且以（length-1）开头的索引参数都是有效索引。
* 请注意，要纠正用户的任意并发错误，这些检查必须对局部变量进行操作，这将在下面说明某些奇怪的内联分配。
* 请注意，对setTabAt的调用始终在锁定区域内进行，因此原则上仅需要发布顺序，而不需要完全易失的语义，但是为了保守起见，当前将其编码为易失性写入。
*/
@SuppressWarnings("unchecked")
static final <K,V> Node<K,V> tabAt(Node<K,V>[] tab, int i) {
return (Node<K,V>)U.getObjectVolatile(tab, ((long)i << ASHIFT) + ABASE);
}
static final <K,V> boolean casTabAt(Node<K,V>[] tab, int i,
Node<K,V> c, Node<K,V> v) {
return U.compareAndSwapObject(tab, ((long)i << ASHIFT) + ABASE, c, v);
}
static final <K,V> void setTabAt(Node<K,V>[] tab, int i, Node<K,V> v) {
U.putObjectVolatile(tab, ((long)i << ASHIFT) + ABASE, v);
}
/* ---------------- Fields -------------- */
transient volatile Node<K,V>[] table;
private transient volatile Node<K,V>[] nextTable;
private transient volatile long baseCount;
private transient volatile int sizeCtl;
private transient volatile int transferIndex;
private transient volatile int cellsBusy;
private transient volatile CounterCell[] counterCells;
private transient KeySetView<K,V> keySet;
private transient ValuesView<K,V> values;
private transient EntrySetView<K,V> entrySet;
/* ---------------- Public operations -------------- */
public ConcurrentHashMap() {
}
public ConcurrentHashMap(int initialCapacity) {}
public ConcurrentHashMap(Map<? extends K, ? extends V> m) {}
public ConcurrentHashMap(int initialCapacity, float loadFactor) {}
public ConcurrentHashMap(int initialCapacity, float loadFactor, int concurrencyLevel) {}
public int size() {
long n = sumCount();
return ((n < 0L) ? 0 :
(n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE :
(int)n);
}
public boolean isEmpty() {
return sumCount() <= 0L; // ignore transient negative values
}
public V get(Object key) {
Node<K,V>[] tab; Node<K,V> e, p; int n, eh; K ek;
int h = spread(key.hashCode());
if ((tab = table) != null && (n = tab.length) > 0 &&
(e = tabAt(tab, (n - 1) & h)) != null) {
if ((eh = e.hash) == h) {
if ((ek = e.key) == key || (ek != null && key.equals(ek)))
return e.val;
}
else if (eh < 0)
return (p = e.find(h, key)) != null ? p.val : null;
while ((e = e.next) != null) {
if (e.hash == h &&
((ek = e.key) == key || (ek != null && key.equals(ek))))
return e.val;
}
}
return null;
}
public boolean containsKey(Object key) {
return get(key) != null;
}
public boolean containsValue(Object value) {
if (value == null)
throw new NullPointerException();
Node<K,V>[] t;
if ((t = table) != null) {
Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
for (Node<K,V> p; (p = it.advance()) != null; ) {
V v;
if ((v = p.val) == value || (v != null && value.equals(v)))
return true;
}
}
return false;
}
public V put(K key, V value) {
return putVal(key, value, false);
}
/** Implementation for put and putIfAbsent */
final V putVal(K key, V value, boolean onlyIfAbsent) {
if (key == null || value == null) throw new NullPointerException();
int hash = spread(key.hashCode());
int binCount = 0;
for (Node<K,V>[] tab = table;;) {
Node<K,V> f; int n, i, fh;
if (tab == null || (n = tab.length) == 0)
tab = initTable();
else if ((f = tabAt(tab, i = (n - 1) & hash)) == null) {
if (casTabAt(tab, i, null,
new Node<K,V>(hash, key, value, null)))
break; // no lock when adding to empty bin
}
else if ((fh = f.hash) == MOVED)
tab = helpTransfer(tab, f);
else {
V oldVal = null;
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
binCount = 1;
for (Node<K,V> e = f;; ++binCount) {
K ek;
if (e.hash == hash &&
((ek = e.key) == key ||
(ek != null && key.equals(ek)))) {
oldVal = e.val;
if (!onlyIfAbsent)
e.val = value;
break;
}
Node<K,V> pred = e;
if ((e = e.next) == null) {
pred.next = new Node<K,V>(hash, key,
value, null);
break;
}
}
}
else if (f instanceof TreeBin) {
Node<K,V> p;
binCount = 2;
if ((p = ((TreeBin<K,V>)f).putTreeVal(hash, key,
value)) != null) {
oldVal = p.val;
if (!onlyIfAbsent)
p.val = value;
}
}
}
}
if (binCount != 0) {
if (binCount >= TREEIFY_THRESHOLD)
treeifyBin(tab, i);
if (oldVal != null)
return oldVal;
break;
}
}
}
addCount(1L, binCount);
return null;
}
public void putAll(Map<? extends K, ? extends V> m) {
tryPresize(m.size());
for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
putVal(e.getKey(), e.getValue(), false);
}
public V remove(Object key) {
return replaceNode(key, null, null);
}
final V replaceNode(Object key, V value, Object cv) {
int hash = spread(key.hashCode());
for (Node<K,V>[] tab = table;;) {
Node<K,V> f; int n, i, fh;
if (tab == null || (n = tab.length) == 0 ||
(f = tabAt(tab, i = (n - 1) & hash)) == null)
break;
else if ((fh = f.hash) == MOVED)
tab = helpTransfer(tab, f);
else {
V oldVal = null;
boolean validated = false;
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
validated = true;
for (Node<K,V> e = f, pred = null;;) {
K ek;
if (e.hash == hash &&
((ek = e.key) == key ||
(ek != null && key.equals(ek)))) {
V ev = e.val;
if (cv == null || cv == ev ||
(ev != null && cv.equals(ev))) {
oldVal = ev;
if (value != null)
e.val = value;
else if (pred != null)
pred.next = e.next;
else
setTabAt(tab, i, e.next);
}
break;
}
pred = e;
if ((e = e.next) == null)
break;
}
}
else if (f instanceof TreeBin) {
validated = true;
TreeBin<K,V> t = (TreeBin<K,V>)f;
TreeNode<K,V> r, p;
if ((r = t.root) != null &&
(p = r.findTreeNode(hash, key, null)) != null) {
V pv = p.val;
if (cv == null || cv == pv ||
(pv != null && cv.equals(pv))) {
oldVal = pv;
if (value != null)
p.val = value;
else if (t.removeTreeNode(p))
setTabAt(tab, i, untreeify(t.first));
}
}
}
}
}
if (validated) {
if (oldVal != null) {
if (value == null)
addCount(-1L, -1);
return oldVal;
}
break;
}
}
}
return null;
}
public void clear() {
long delta = 0L;
int i = 0;
Node<K,V>[] tab = table;
while (tab != null && i < tab.length) {
int fh;
Node<K,V> f = tabAt(tab, i);
if (f == null)
++i;
else if ((fh = f.hash) == MOVED) {
tab = helpTransfer(tab, f);
i = 0;
}
else {
synchronized (f) {
if (tabAt(tab, i) == f) {
Node<K,V> p = (fh >= 0 ? f :
(f instanceof TreeBin) ?
((TreeBin<K,V>)f).first : null);
while (p != null) {
--delta;
p = p.next;
}
setTabAt(tab, i++, null);
}
}
}
}
if (delta != 0L)
addCount(delta, -1);
}
public KeySetView<K,V> keySet() {
KeySetView<K,V> ks;
return (ks = keySet) != null ? ks : (keySet = new KeySetView<K,V>(this, null));
}
public Collection<V> values() {
ValuesView<K,V> vs;
return (vs = values) != null ? vs : (values = new ValuesView<K,V>(this));
}
public Set<Map.Entry<K,V>> entrySet() {
EntrySetView<K,V> es;
return (es = entrySet) != null ? es : (entrySet = new EntrySetView<K,V>(this));
}
public int hashCode() {
int h = 0;
Node<K,V>[] t;
if ((t = table) != null) {
Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
for (Node<K,V> p; (p = it.advance()) != null; )
h += p.key.hashCode() ^ p.val.hashCode();
}
return h;
}
public String toString() {
Node<K,V>[] t;
int f = (t = table) == null ? 0 : t.length;
Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
StringBuilder sb = new StringBuilder();
sb.append('{');
Node<K,V> p;
if ((p = it.advance()) != null) {
for (;;) {
K k = p.key;
V v = p.val;
sb.append(k == this ? "(this Map)" : k);
sb.append('=');
sb.append(v == this ? "(this Map)" : v);
if ((p = it.advance()) == null)
break;
sb.append(',').append(' ');
}
}
return sb.append('}').toString();
}
public boolean equals(Object o) {
if (o != this) {
if (!(o instanceof Map))
return false;
Map<?,?> m = (Map<?,?>) o;
Node<K,V>[] t;
int f = (t = table) == null ? 0 : t.length;
Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
for (Node<K,V> p; (p = it.advance()) != null; ) {
V val = p.val;
Object v = m.get(p.key);
if (v == null || (v != val && !v.equals(val)))
return false;
}
for (Map.Entry<?,?> e : m.entrySet()) {
Object mk, mv, v;
if ((mk = e.getKey()) == null ||
(mv = e.getValue()) == null ||
(v = get(mk)) == null ||
(mv != v && !mv.equals(v)))
return false;
}
}
return true;
}
static class Segment<K,V> extends ReentrantLock implements Serializable {
private static final long serialVersionUID = 2249069246763182397L;
final float loadFactor;
Segment(float lf) { this.loadFactor = lf; }
}
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
int sshift = 0;
int ssize = 1;
while (ssize < DEFAULT_CONCURRENCY_LEVEL) {
++sshift;
ssize <<= 1;
}
int segmentShift = 32 - sshift;
int segmentMask = ssize - 1;
@SuppressWarnings("unchecked")
Segment<K,V>[] segments = (Segment<K,V>[])
new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL];
for (int i = 0; i < segments.length; ++i)
segments[i] = new Segment<K,V>(LOAD_FACTOR);
s.putFields().put("segments", segments);
s.putFields().put("segmentShift", segmentShift);
s.putFields().put("segmentMask", segmentMask);
s.writeFields();
Node<K,V>[] t;
if ((t = table) != null) {
Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
for (Node<K,V> p; (p = it.advance()) != null; ) {
s.writeObject(p.key);
s.writeObject(p.val);
}
}
s.writeObject(null);
s.writeObject(null);
segments = null;
}
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
sizeCtl = -1;
s.defaultReadObject();
long size = 0L;
Node<K,V> p = null;
for (;;) {
@SuppressWarnings("unchecked")
K k = (K) s.readObject();
@SuppressWarnings("unchecked")
V v = (V) s.readObject();
if (k != null && v != null) {
p = new Node<K,V>(spread(k.hashCode()), k, v, p);
++size;
}
else
break;
}
if (size == 0L)
sizeCtl = 0;
else {
int n;
if (size >= (long)(MAXIMUM_CAPACITY >>> 1))
n = MAXIMUM_CAPACITY;
else {
int sz = (int)size;
n = tableSizeFor(sz + (sz >>> 1) + 1);
}
@SuppressWarnings("unchecked")
Node<K,V>[] tab = (Node<K,V>[])new Node<?,?>[n];
int mask = n - 1;
long added = 0L;
while (p != null) {
boolean insertAtFront;
Node<K,V> next = p.next, first;
int h = p.hash, j = h & mask;
if ((first = tabAt(tab, j)) == null)
insertAtFront = true;
else {
K k = p.key;
if (first.hash < 0) {
TreeBin<K,V> t = (TreeBin<K,V>)first;
if (t.putTreeVal(h, k, p.val) == null)
++added;
insertAtFront = false;
}
else {
int binCount = 0;
insertAtFront = true;
Node<K,V> q; K qk;
for (q = first; q != null; q = q.next) {
if (q.hash == h &&
((qk = q.key) == k ||
(qk != null && k.equals(qk)))) {
insertAtFront = false;
break;
}
++binCount;
}
if (insertAtFront && binCount >= TREEIFY_THRESHOLD) {
insertAtFront = false;
++added;
p.next = first;
TreeNode<K,V> hd = null, tl = null;
for (q = p; q != null; q = q.next) {
TreeNode<K,V> t = new TreeNode<K,V>
(q.hash, q.key, q.val, null, null);
if ((t.prev = tl) == null)
hd = t;
else
tl.next = t;
tl = t;
}
setTabAt(tab, j, new TreeBin<K,V>(hd));
}
}
}
if (insertAtFront) {
++added;
p.next = first;
setTabAt(tab, j, p);
}
p = next;
}
table = tab;
sizeCtl = n - (n >>> 2);
baseCount = added;
}
}
// ConcurrentMap methods
public V putIfAbsent(K key, V value) {
return putVal(key, value, true);
}
public boolean remove(Object key, Object value) {
if (key == null)
throw new NullPointerException();
return value != null && replaceNode(key, null, value) != null;
}
public boolean replace(K key, V oldValue, V newValue) {
if (key == null || oldValue == null || newValue == null)
throw new NullPointerException();
return replaceNode(key, newValue, oldValue) != null;
}
public V replace(K key, V value) {
if (key == null || value == null)
throw new NullPointerException();
return replaceNode(key, value, null);
}
/*
* 返回指定键映射到的值，如果此映射不包含键的映射关系，则返回给定的默认值。
*/
public V getOrDefault(Object key, V defaultValue) {
V v;
return (v = get(key)) == null ? defaultValue : v;
}
public void forEach(BiConsumer<? super K, ? super V> action) {
if (action == null) throw new NullPointerException();
Node<K,V>[] t;
if ((t = table) != null) {
Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
for (Node<K,V> p; (p = it.advance()) != null; ) {
action.accept(p.key, p.val);
}
}
}
public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
if (function == null) throw new NullPointerException();
Node<K,V>[] t;
if ((t = table) != null) {
Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
for (Node<K,V> p; (p = it.advance()) != null; ) {
V oldValue = p.val;
for (K key = p.key;;) {
V newValue = function.apply(key, oldValue);
if (newValue == null)
throw new NullPointerException();
if (replaceNode(key, newValue, oldValue) != null ||
(oldValue = get(key)) == null)
break;
}
}
}
}
/**
* 如果指定的键尚未与值相关联，请尝试使用给定的映射函数计算其值，并将其输入此映射中，除非{@code null}。
* 整个方法调用是原子执行的，因此每个key最多可应用一次该功能。
* 在进行计算时，可能会阻止其他线程在此映射上进行的某些尝试的更新操作，因此计算应简短而简单，并且不得尝试更新此映射的任何其他映射。
*/
public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
if (key == null || mappingFunction == null)
throw new NullPointerException();
int h = spread(key.hashCode());
V val = null;
int binCount = 0;
for (Node<K,V>[] tab = table;;) {
Node<K,V> f; int n, i, fh;
if (tab == null || (n = tab.length) == 0)
tab = initTable();
else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
Node<K,V> r = new ReservationNode<K,V>();
synchronized (r) {
if (casTabAt(tab, i, null, r)) {
binCount = 1;
Node<K,V> node = null;
try {
if ((val = mappingFunction.apply(key)) != null)
node = new Node<K,V>(h, key, val, null);
} finally {
setTabAt(tab, i, node);
}
}
}
if (binCount != 0)
break;
}
else if ((fh = f.hash) == MOVED)
tab = helpTransfer(tab, f);
else {
boolean added = false;
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
binCount = 1;
for (Node<K,V> e = f;; ++binCount) {
K ek; V ev;
if (e.hash == h &&
((ek = e.key) == key ||
(ek != null && key.equals(ek)))) {
val = e.val;
break;
}
Node<K,V> pred = e;
if ((e = e.next) == null) {
if ((val = mappingFunction.apply(key)) != null) {
added = true;
pred.next = new Node<K,V>(h, key, val, null);
}
break;
}
}
}
else if (f instanceof TreeBin) {
binCount = 2;
TreeBin<K,V> t = (TreeBin<K,V>)f;
TreeNode<K,V> r, p;
if ((r = t.root) != null &&
(p = r.findTreeNode(h, key, null)) != null)
val = p.val;
else if ((val = mappingFunction.apply(key)) != null) {
added = true;
t.putTreeVal(h, key, val);
}
}
}
}
if (binCount != 0) {
if (binCount >= TREEIFY_THRESHOLD)
treeifyBin(tab, i);
if (!added)
return val;
break;
}
}
}
if (val != null)
addCount(1L, binCount);
return val;
}
public V compute(K key,
BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
if (key == null || remappingFunction == null)
throw new NullPointerException();
int h = spread(key.hashCode());
V val = null;
int delta = 0;
int binCount = 0;
for (Node<K,V>[] tab = table;;) {
Node<K,V> f; int n, i, fh;
if (tab == null || (n = tab.length) == 0)
tab = initTable();
else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
Node<K,V> r = new ReservationNode<K,V>();
synchronized (r) {
if (casTabAt(tab, i, null, r)) {
binCount = 1;
Node<K,V> node = null;
try {
if ((val = remappingFunction.apply(key, null)) != null) {
delta = 1;
node = new Node<K,V>(h, key, val, null);
}
} finally {
setTabAt(tab, i, node);
}
}
}
if (binCount != 0)
break;
}
else if ((fh = f.hash) == MOVED)
tab = helpTransfer(tab, f);
else {
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
binCount = 1;
for (Node<K,V> e = f, pred = null;; ++binCount) {
K ek;
if (e.hash == h &&
((ek = e.key) == key ||
(ek != null && key.equals(ek)))) {
val = remappingFunction.apply(key, e.val);
if (val != null)
e.val = val;
else {
delta = -1;
Node<K,V> en = e.next;
if (pred != null)
pred.next = en;
else
setTabAt(tab, i, en);
}
break;
}
pred = e;
if ((e = e.next) == null) {
val = remappingFunction.apply(key, null);
if (val != null) {
delta = 1;
pred.next =
new Node<K,V>(h, key, val, null);
}
break;
}
}
}
else if (f instanceof TreeBin) {
binCount = 1;
TreeBin<K,V> t = (TreeBin<K,V>)f;
TreeNode<K,V> r, p;
if ((r = t.root) != null)
p = r.findTreeNode(h, key, null);
else
p = null;
V pv = (p == null) ? null : p.val;
val = remappingFunction.apply(key, pv);
if (val != null) {
if (p != null)
p.val = val;
else {
delta = 1;
t.putTreeVal(h, key, val);
}
}
else if (p != null) {
delta = -1;
if (t.removeTreeNode(p))
setTabAt(tab, i, untreeify(t.first));
}
}
}
}
if (binCount != 0) {
if (binCount >= TREEIFY_THRESHOLD)
treeifyBin(tab, i);
break;
}
}
}
if (delta != 0)
addCount((long)delta, binCount);
return val;
}
/**
* 如果指定的键尚未与（非空）值关联，请将其与给定值关联。
* 否则，用给定的重映射函数的结果替换该值，或者如果{@code null}则将其删除。
* 整个方法调用是原子执行的。在计算进行过程中，可能会阻止其他线程对该映射进行的某些尝试的更新操作，
* 因此计算应简短而简单，并且不得尝试更新此Map的任何其他映射。
*/
public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
if (key == null || value == null || remappingFunction == null)
throw new NullPointerException();
int h = spread(key.hashCode());
V val = null;
int delta = 0;
int binCount = 0;
for (Node<K,V>[] tab = table;;) {
Node<K,V> f; int n, i, fh;
if (tab == null || (n = tab.length) == 0)
tab = initTable();
else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
if (casTabAt(tab, i, null, new Node<K,V>(h, key, value, null))) {
delta = 1;
val = value;
break;
}
}
else if ((fh = f.hash) == MOVED)
tab = helpTransfer(tab, f);
else {
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
binCount = 1;
for (Node<K,V> e = f, pred = null;; ++binCount) {
K ek;
if (e.hash == h &&
((ek = e.key) == key ||
(ek != null && key.equals(ek)))) {
val = remappingFunction.apply(e.val, value);
if (val != null)
e.val = val;
else {
delta = -1;
Node<K,V> en = e.next;
if (pred != null)
pred.next = en;
else
setTabAt(tab, i, en);
}
break;
}
pred = e;
if ((e = e.next) == null) {
delta = 1;
val = value;
pred.next =
new Node<K,V>(h, key, val, null);
break;
}
}
}
else if (f instanceof TreeBin) {
binCount = 2;
TreeBin<K,V> t = (TreeBin<K,V>)f;
TreeNode<K,V> r = t.root;
TreeNode<K,V> p = (r == null) ? null :
r.findTreeNode(h, key, null);
val = (p == null) ? value :
remappingFunction.apply(p.val, value);
if (val != null) {
if (p != null)
p.val = val;
else {
delta = 1;
t.putTreeVal(h, key, val);
}
}
else if (p != null) {
delta = -1;
if (t.removeTreeNode(p))
setTabAt(tab, i, untreeify(t.first));
}
}
}
}
if (binCount != 0) {
if (binCount >= TREEIFY_THRESHOLD)
treeifyBin(tab, i);
break;
}
}
}
if (delta != 0)
addCount((long)delta, binCount);
return val;
}
// Hashtable legacy methods
public boolean contains(Object value) {
return containsValue(value);
}
public Enumeration<K> keys() {
Node<K,V>[] t;
int f = (t = table) == null ? 0 : t.length;
return new KeyIterator<K,V>(t, f, 0, f, this);
}
public Enumeration<V> elements() {
Node<K,V>[] t;
int f = (t = table) == null ? 0 : t.length;
return new ValueIterator<K,V>(t, f, 0, f, this);
}
// ConcurrentHashMap-only methods
public long mappingCount() {
long n = sumCount();
return (n < 0L) ? 0L : n; // ignore transient negative values
}
public static <K> KeySetView<K,Boolean> newKeySet() {
return new KeySetView<K,Boolean>
(new ConcurrentHashMap<K,Boolean>(), Boolean.TRUE);
}
public static <K> KeySetView<K,Boolean> newKeySet(int initialCapacity) {
return new KeySetView<K,Boolean>
(new ConcurrentHashMap<K,Boolean>(initialCapacity), Boolean.TRUE);
}
public KeySetView<K,V> keySet(V mappedValue) {
if (mappedValue == null)
throw new NullPointerException();
return new KeySetView<K,V>(this, mappedValue);
}
/* ---------------- Special Nodes -------------- */
static final class ForwardingNode<K,V> extends Node<K,V> {
final Node<K,V>[] nextTable;
ForwardingNode(Node<K,V>[] tab) {
super(MOVED, null, null, null);
this.nextTable = tab;
}
Node<K,V> find(int h, Object k) {
outer: for (Node<K,V>[] tab = nextTable;;) {
Node<K,V> e; int n;
if (k == null || tab == null || (n = tab.length) == 0 ||
(e = tabAt(tab, (n - 1) & h)) == null)
return null;
for (;;) {
int eh; K ek;
if ((eh = e.hash) == h &&
((ek = e.key) == k || (ek != null && k.equals(ek))))
return e;
if (eh < 0) {
if (e instanceof ForwardingNode) {
tab = ((ForwardingNode<K,V>)e).nextTable;
continue outer;
}
else
return e.find(h, k);
}
if ((e = e.next) == null)
return null;
}
}
}
}
static final class ReservationNode<K,V> extends Node<K,V> {
ReservationNode() {
super(RESERVED, null, null, null);
}
Node<K,V> find(int h, Object k) {
return null;
}
}
/* ---------------- Table Initialization and Resizing -------------- */
static final int resizeStamp(int n) {
return Integer.numberOfLeadingZeros(n) | (1 << (RESIZE_STAMP_BITS - 1));
}
private final Node<K,V>[] initTable() {
Node<K,V>[] tab; int sc;
while ((tab = table) == null || tab.length == 0) {
if ((sc = sizeCtl) < 0)
Thread.yield();
else if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
try {
if ((tab = table) == null || tab.length == 0) {
int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
@SuppressWarnings("unchecked")
Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n];
table = tab = nt;
sc = n - (n >>> 2);
}
} finally {
sizeCtl = sc;
}
break;
}
}
return tab;
}
private final void addCount(long x, int check) {
CounterCell[] as; long b, s;
if ((as = counterCells) != null ||
!U.compareAndSwapLong(this, BASECOUNT, b = baseCount, s = b + x)) {
CounterCell a; long v; int m;
boolean uncontended = true;
if (as == null || (m = as.length - 1) < 0 ||
(a = as[ThreadLocalRandom.getProbe() & m]) == null ||
!(uncontended =
U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))) {
fullAddCount(x, uncontended);
return;
}
if (check <= 1)
return;
s = sumCount();
}
if (check >= 0) {
Node<K,V>[] tab, nt; int n, sc;
while (s >= (long)(sc = sizeCtl) && (tab = table) != null &&
(n = tab.length) < MAXIMUM_CAPACITY) {
int rs = resizeStamp(n);
if (sc < 0) {
if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 ||
sc == rs + MAX_RESIZERS || (nt = nextTable) == null ||
transferIndex <= 0)
break;
if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1))
transfer(tab, nt);
}
else if (U.compareAndSwapInt(this, SIZECTL, sc,
(rs << RESIZE_STAMP_SHIFT) + 2))
transfer(tab, null);
s = sumCount();
}
}
}
final Node<K,V>[] helpTransfer(Node<K,V>[] tab, Node<K,V> f) {
Node<K,V>[] nextTab; int sc;
if (tab != null && (f instanceof ForwardingNode) &&
(nextTab = ((ForwardingNode<K,V>)f).nextTable) != null) {
int rs = resizeStamp(tab.length);
while (nextTab == nextTable && table == tab &&
(sc = sizeCtl) < 0) {
if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 ||
sc == rs + MAX_RESIZERS || transferIndex <= 0)
break;
if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1)) {
transfer(tab, nextTab);
break;
}
}
return nextTab;
}
return table;
}
private final void tryPresize(int size) {
int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
tableSizeFor(size + (size >>> 1) + 1);
int sc;
while ((sc = sizeCtl) >= 0) {
Node<K,V>[] tab = table; int n;
if (tab == null || (n = tab.length) == 0) {
n = (sc > c) ? sc : c;
if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
try {
if (table == tab) {
@SuppressWarnings("unchecked")
Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n];
table = nt;
sc = n - (n >>> 2);
}
} finally {
sizeCtl = sc;
}
}
}
else if (c <= sc || n >= MAXIMUM_CAPACITY)
break;
else if (tab == table) {
int rs = resizeStamp(n);
if (sc < 0) {
Node<K,V>[] nt;
if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 ||
sc == rs + MAX_RESIZERS || (nt = nextTable) == null ||
transferIndex <= 0)
break;
if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1))
transfer(tab, nt);
}
else if (U.compareAndSwapInt(this, SIZECTL, sc,
(rs << RESIZE_STAMP_SHIFT) + 2))
transfer(tab, null);
}
}
}
private final void transfer(Node<K,V>[] tab, Node<K,V>[] nextTab) {
int n = tab.length, stride;
if ((stride = (NCPU > 1) ? (n >>> 3) / NCPU : n) < MIN_TRANSFER_STRIDE)
stride = MIN_TRANSFER_STRIDE;
if (nextTab == null) {
try {
@SuppressWarnings("unchecked")
Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n << 1];
nextTab = nt;
} catch (Throwable ex) {
sizeCtl = Integer.MAX_VALUE;
return;
}
nextTable = nextTab;
transferIndex = n;
}
int nextn = nextTab.length;
ForwardingNode<K,V> fwd = new ForwardingNode<K,V>(nextTab);
boolean advance = true;
boolean finishing = false;
for (int i = 0, bound = 0;;) {
Node<K,V> f; int fh;
while (advance) {
int nextIndex, nextBound;
if (--i >= bound || finishing)
advance = false;
else if ((nextIndex = transferIndex) <= 0) {
i = -1;
advance = false;
}
else if (U.compareAndSwapInt
(this, TRANSFERINDEX, nextIndex,
nextBound = (nextIndex > stride ?
nextIndex - stride : 0))) {
bound = nextBound;
i = nextIndex - 1;
advance = false;
}
}
if (i < 0 || i >= n || i + n >= nextn) {
int sc;
if (finishing) {
nextTable = null;
table = nextTab;
sizeCtl = (n << 1) - (n >>> 1);
return;
}
if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, sc - 1)) {
if ((sc - 2) != resizeStamp(n) << RESIZE_STAMP_SHIFT)
return;
finishing = advance = true;
i = n;
}
}
else if ((f = tabAt(tab, i)) == null)
advance = casTabAt(tab, i, null, fwd);
else if ((fh = f.hash) == MOVED)
advance = true;
else {
synchronized (f) {
if (tabAt(tab, i) == f) {
Node<K,V> ln, hn;
if (fh >= 0) {
int runBit = fh & n;
Node<K,V> lastRun = f;
for (Node<K,V> p = f.next; p != null; p = p.next) {
int b = p.hash & n;
if (b != runBit) {
runBit = b;
lastRun = p;
}
}
if (runBit == 0) {
ln = lastRun;
hn = null;
}
else {
hn = lastRun;
ln = null;
}
for (Node<K,V> p = f; p != lastRun; p = p.next) {
int ph = p.hash; K pk = p.key; V pv = p.val;
if ((ph & n) == 0)
ln = new Node<K,V>(ph, pk, pv, ln);
else
hn = new Node<K,V>(ph, pk, pv, hn);
}
setTabAt(nextTab, i, ln);
setTabAt(nextTab, i + n, hn);
setTabAt(tab, i, fwd);
advance = true;
}
else if (f instanceof TreeBin) {
TreeBin<K,V> t = (TreeBin<K,V>)f;
TreeNode<K,V> lo = null, loTail = null;
TreeNode<K,V> hi = null, hiTail = null;
int lc = 0, hc = 0;
for (Node<K,V> e = t.first; e != null; e = e.next) {
int h = e.hash;
TreeNode<K,V> p = new TreeNode<K,V>
(h, e.key, e.val, null, null);
if ((h & n) == 0) {
if ((p.prev = loTail) == null)
lo = p;
else
loTail.next = p;
loTail = p;
++lc;
}
else {
if ((p.prev = hiTail) == null)
hi = p;
else
hiTail.next = p;
hiTail = p;
++hc;
}
}
ln = (lc <= UNTREEIFY_THRESHOLD) ? untreeify(lo) :
(hc != 0) ? new TreeBin<K,V>(lo) : t;
hn = (hc <= UNTREEIFY_THRESHOLD) ? untreeify(hi) :
(lc != 0) ? new TreeBin<K,V>(hi) : t;
setTabAt(nextTab, i, ln);
setTabAt(nextTab, i + n, hn);
setTabAt(tab, i, fwd);
advance = true;
}
}
}
}
}
}
/* ---------------- Counter support -------------- */
@sun.misc.Contended static final class CounterCell {
volatile long value;
CounterCell(long x) { value = x; }
}
final long sumCount() {
CounterCell[] as = counterCells; CounterCell a;
long sum = baseCount;
if (as != null) {
for (int i = 0; i < as.length; ++i) {
if ((a = as[i]) != null)
sum += a.value;
}
}
return sum;
}
// See LongAdder version for explanation
private final void fullAddCount(long x, boolean wasUncontended) {
int h;
if ((h = ThreadLocalRandom.getProbe()) == 0) {
ThreadLocalRandom.localInit(); // force initialization
h = ThreadLocalRandom.getProbe();
wasUncontended = true;
}
boolean collide = false; // True if last slot nonempty
for (;;) {
CounterCell[] as; CounterCell a; int n; long v;
if ((as = counterCells) != null && (n = as.length) > 0) {
if ((a = as[(n - 1) & h]) == null) {
if (cellsBusy == 0) { // Try to attach new Cell
CounterCell r = new CounterCell(x); // Optimistic create
if (cellsBusy == 0 &&
U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
boolean created = false;
try { // Recheck under lock
CounterCell[] rs; int m, j;
if ((rs = counterCells) != null &&
(m = rs.length) > 0 &&
rs[j = (m - 1) & h] == null) {
rs[j] = r;
created = true;
}
} finally {
cellsBusy = 0;
}
if (created)
break;
continue; // Slot is now non-empty
}
}
collide = false;
}
else if (!wasUncontended) // CAS already known to fail
wasUncontended = true; // Continue after rehash
else if (U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))
break;
else if (counterCells != as || n >= NCPU)
collide = false; // At max size or stale
else if (!collide)
collide = true;
else if (cellsBusy == 0 &&
U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
try {
if (counterCells == as) {// Expand table unless stale
CounterCell[] rs = new CounterCell[n << 1];
for (int i = 0; i < n; ++i)
rs[i] = as[i];
counterCells = rs;
}
} finally {
cellsBusy = 0;
}
collide = false;
continue; // Retry with expanded table
}
h = ThreadLocalRandom.advanceProbe(h);
}
else if (cellsBusy == 0 && counterCells == as &&
U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
boolean init = false;
try { // Initialize table
if (counterCells == as) {
CounterCell[] rs = new CounterCell[2];
rs[h & 1] = new CounterCell(x);
counterCells = rs;
init = true;
}
} finally {
cellsBusy = 0;
}
if (init)
break;
}
else if (U.compareAndSwapLong(this, BASECOUNT, v = baseCount, v + x))
break;
}
}
/* ---------------- Conversion from/to TreeBins -------------- */
private final void treeifyBin(Node<K,V>[] tab, int index) {
Node<K,V> b; int n, sc;
if (tab != null) {
if ((n = tab.length) < MIN_TREEIFY_CAPACITY)
tryPresize(n << 1);
else if ((b = tabAt(tab, index)) != null && b.hash >= 0) {
synchronized (b) {
if (tabAt(tab, index) == b) {
TreeNode<K,V> hd = null, tl = null;
for (Node<K,V> e = b; e != null; e = e.next) {
TreeNode<K,V> p =
new TreeNode<K,V>(e.hash, e.key, e.val,
null, null);
if ((p.prev = tl) == null)
hd = p;
else
tl.next = p;
tl = p;
}
setTabAt(tab, index, new TreeBin<K,V>(hd));
}
}
}
}
}
static <K,V> Node<K,V> untreeify(Node<K,V> b) {
Node<K,V> hd = null, tl = null;
for (Node<K,V> q = b; q != null; q = q.next) {
Node<K,V> p = new Node<K,V>(q.hash, q.key, q.val, null);
if (tl == null)
hd = p;
else
tl.next = p;
tl = p;
}
return hd;
}
/* ---------------- TreeNodes -------------- */
static final class TreeNode<K,V> extends Node<K,V> {
TreeNode<K,V> parent; // red-black tree links
TreeNode<K,V> left;
TreeNode<K,V> right;
TreeNode<K,V> prev; // needed to unlink next upon deletion
boolean red;
TreeNode(int hash, K key, V val, Node<K,V> next,
TreeNode<K,V> parent) {
super(hash, key, val, next);
this.parent = parent;
}
Node<K,V> find(int h, Object k) {
return findTreeNode(h, k, null);
}
/**
* Returns the TreeNode (or null if not found) for the given key
* starting at given root.
*/
final TreeNode<K,V> findTreeNode(int h, Object k, Class<?> kc) {
if (k != null) {
TreeNode<K,V> p = this;
do {
int ph, dir; K pk; TreeNode<K,V> q;
TreeNode<K,V> pl = p.left, pr = p.right;
if ((ph = p.hash) > h)
p = pl;
else if (ph < h)
p = pr;
else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
return p;
else if (pl == null)
p = pr;
else if (pr == null)
p = pl;
else if ((kc != null ||
(kc = comparableClassFor(k)) != null) &&
(dir = compareComparables(kc, k, pk)) != 0)
p = (dir < 0) ? pl : pr;
else if ((q = pr.findTreeNode(h, k, kc)) != null)
return q;
else
p = pl;
} while (p != null);
}
return null;
}
}
/* ---------------- TreeBins -------------- */
static final class TreeBin<K,V> extends Node<K,V> {
TreeNode<K,V> root;
volatile TreeNode<K,V> first;
volatile Thread waiter;
volatile int lockState;
// values for lockState
static final int WRITER = 1; // set while holding write lock
static final int WAITER = 2; // set when waiting for write lock
static final int READER = 4; // increment value for setting read lock
/**
* Tie-breaking utility for ordering insertions when equal
* hashCodes and non-comparable. We don't require a total
* order, just a consistent insertion rule to maintain
* equivalence across rebalancings. Tie-breaking further than
* necessary simplifies testing a bit.
*/
static int tieBreakOrder(Object a, Object b) {
int d;
if (a == null || b == null ||
(d = a.getClass().getName().
compareTo(b.getClass().getName())) == 0)
d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
-1 : 1);
return d;
}
TreeBin(TreeNode<K,V> b) {
super(TREEBIN, null, null, null);
this.first = b;
TreeNode<K,V> r = null;
for (TreeNode<K,V> x = b, next; x != null; x = next) {
next = (TreeNode<K,V>)x.next;
x.left = x.right = null;
if (r == null) {
x.parent = null;
x.red = false;
r = x;
}
else {
K k = x.key;
int h = x.hash;
Class<?> kc = null;
for (TreeNode<K,V> p = r;;) {
int dir, ph;
K pk = p.key;
if ((ph = p.hash) > h)
dir = -1;
else if (ph < h)
dir = 1;
else if ((kc == null &&
(kc = comparableClassFor(k)) == null) ||
(dir = compareComparables(kc, k, pk)) == 0)
dir = tieBreakOrder(k, pk);
TreeNode<K,V> xp = p;
if ((p = (dir <= 0) ? p.left : p.right) == null) {
x.parent = xp;
if (dir <= 0)
xp.left = x;
else
xp.right = x;
r = balanceInsertion(r, x);
break;
}
}
}
}
this.root = r;
assert checkInvariants(root);
}
private final void lockRoot() {
if (!U.compareAndSwapInt(this, LOCKSTATE, 0, WRITER))
contendedLock(); // offload to separate method
}
private final void unlockRoot() {
lockState = 0;
}
private final void contendedLock() {
boolean waiting = false;
for (int s;;) {
if (((s = lockState) & ~WAITER) == 0) {
if (U.compareAndSwapInt(this, LOCKSTATE, s, WRITER)) {
if (waiting)
waiter = null;
return;
}
}
else if ((s & WAITER) == 0) {
if (U.compareAndSwapInt(this, LOCKSTATE, s, s | WAITER)) {
waiting = true;
waiter = Thread.currentThread();
}
}
else if (waiting)
LockSupport.park(this);
}
}
final Node<K,V> find(int h, Object k) {
if (k != null) {
for (Node<K,V> e = first; e != null; ) {
int s; K ek;
if (((s = lockState) & (WAITER|WRITER)) != 0) {
if (e.hash == h &&
((ek = e.key) == k || (ek != null && k.equals(ek))))
return e;
e = e.next;
}
else if (U.compareAndSwapInt(this, LOCKSTATE, s,
s + READER)) {
TreeNode<K,V> r, p;
try {
p = ((r = root) == null ? null :
r.findTreeNode(h, k, null));
} finally {
Thread w;
if (U.getAndAddInt(this, LOCKSTATE, -READER) ==
(READER|WAITER) && (w = waiter) != null)
LockSupport.unpark(w);
}
return p;
}
}
}
return null;
}
final TreeNode<K,V> putTreeVal(int h, K k, V v) {
Class<?> kc = null;
boolean searched = false;
for (TreeNode<K,V> p = root;;) {
int dir, ph; K pk;
if (p == null) {
first = root = new TreeNode<K,V>(h, k, v, null, null);
break;
}
else if ((ph = p.hash) > h)
dir = -1;
else if (ph < h)
dir = 1;
else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
return p;
else if ((kc == null &&
(kc = comparableClassFor(k)) == null) ||
(dir = compareComparables(kc, k, pk)) == 0) {
if (!searched) {
TreeNode<K,V> q, ch;
searched = true;
if (((ch = p.left) != null &&
(q = ch.findTreeNode(h, k, kc)) != null) ||
((ch = p.right) != null &&
(q = ch.findTreeNode(h, k, kc)) != null))
return q;
}
dir = tieBreakOrder(k, pk);
}
TreeNode<K,V> xp = p;
if ((p = (dir <= 0) ? p.left : p.right) == null) {
TreeNode<K,V> x, f = first;
first = x = new TreeNode<K,V>(h, k, v, f, xp);
if (f != null)
f.prev = x;
if (dir <= 0)
xp.left = x;
else
xp.right = x;
if (!xp.red)
x.red = true;
else {
lockRoot();
try {
root = balanceInsertion(root, x);
} finally {
unlockRoot();
}
}
break;
}
}
assert checkInvariants(root);
return null;
}
final boolean removeTreeNode(TreeNode<K,V> p) {
TreeNode<K,V> next = (TreeNode<K,V>)p.next;
TreeNode<K,V> pred = p.prev; // unlink traversal pointers
TreeNode<K,V> r, rl;
if (pred == null)
first = next;
else
pred.next = next;
if (next != null)
next.prev = pred;
if (first == null) {
root = null;
return true;
}
if ((r = root) == null || r.right == null || // too small
(rl = r.left) == null || rl.left == null)
return true;
lockRoot();
try {
TreeNode<K,V> replacement;
TreeNode<K,V> pl = p.left;
TreeNode<K,V> pr = p.right;
if (pl != null && pr != null) {
TreeNode<K,V> s = pr, sl;
while ((sl = s.left) != null) // find successor
s = sl;
boolean c = s.red; s.red = p.red; p.red = c; // swap colors
TreeNode<K,V> sr = s.right;
TreeNode<K,V> pp = p.parent;
if (s == pr) { // p was s's direct parent
p.parent = s;
s.right = p;
}
else {
TreeNode<K,V> sp = s.parent;
if ((p.parent = sp) != null) {
if (s == sp.left)
sp.left = p;
else
sp.right = p;
}
if ((s.right = pr) != null)
pr.parent = s;
}
p.left = null;
if ((p.right = sr) != null)
sr.parent = p;
if ((s.left = pl) != null)
pl.parent = s;
if ((s.parent = pp) == null)
r = s;
else if (p == pp.left)
pp.left = s;
else
pp.right = s;
if (sr != null)
replacement = sr;
else
replacement = p;
}
else if (pl != null)
replacement = pl;
else if (pr != null)
replacement = pr;
else
replacement = p;
if (replacement != p) {
TreeNode<K,V> pp = replacement.parent = p.parent;
if (pp == null)
r = replacement;
else if (p == pp.left)
pp.left = replacement;
else
pp.right = replacement;
p.left = p.right = p.parent = null;
}
root = (p.red) ? r : balanceDeletion(r, replacement);
if (p == replacement) { // detach pointers
TreeNode<K,V> pp;
if ((pp = p.parent) != null) {
if (p == pp.left)
pp.left = null;
else if (p == pp.right)
pp.right = null;
p.parent = null;
}
}
} finally {
unlockRoot();
}
assert checkInvariants(root);
return false;
}
/* ------------------------------------------------------------ */
// 红黑树方法
static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
TreeNode<K,V> p) {
TreeNode<K,V> r, pp, rl;
if (p != null && (r = p.right) != null) {
if ((rl = p.right = r.left) != null)
rl.parent = p;
if ((pp = r.parent = p.parent) == null)
(root = r).red = false;
else if (pp.left == p)
pp.left = r;
else
pp.right = r;
r.left = p;
p.parent = r;
}
return root;
}
static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
TreeNode<K,V> p) {
TreeNode<K,V> l, pp, lr;
if (p != null && (l = p.left) != null) {
if ((lr = p.left = l.right) != null)
lr.parent = p;
if ((pp = l.parent = p.parent) == null)
(root = l).red = false;
else if (pp.right == p)
pp.right = l;
else
pp.left = l;
l.right = p;
p.parent = l;
}
return root;
}
static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
TreeNode<K,V> x) {
x.red = true;
for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
if ((xp = x.parent) == null) {
x.red = false;
return x;
}
else if (!xp.red || (xpp = xp.parent) == null)
return root;
if (xp == (xppl = xpp.left)) {
if ((xppr = xpp.right) != null && xppr.red) {
xppr.red = false;
xp.red = false;
xpp.red = true;
x = xpp;
}
else {
if (x == xp.right) {
root = rotateLeft(root, x = xp);
xpp = (xp = x.parent) == null ? null : xp.parent;
}
if (xp != null) {
xp.red = false;
if (xpp != null) {
xpp.red = true;
root = rotateRight(root, xpp);
}
}
}
}
else {
if (xppl != null && xppl.red) {
xppl.red = false;
xp.red = false;
xpp.red = true;
x = xpp;
}
else {
if (x == xp.left) {
root = rotateRight(root, x = xp);
xpp = (xp = x.parent) == null ? null : xp.parent;
}
if (xp != null) {
xp.red = false;
if (xpp != null) {
xpp.red = true;
root = rotateLeft(root, xpp);
}
}
}
}
}
}
static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
TreeNode<K,V> x) {
for (TreeNode<K,V> xp, xpl, xpr;;) {
if (x == null || x == root)
return root;
else if ((xp = x.parent) == null) {
x.red = false;
return x;
}
else if (x.red) {
x.red = false;
return root;
}
else if ((xpl = xp.left) == x) {
if ((xpr = xp.right) != null && xpr.red) {
xpr.red = false;
xp.red = true;
root = rotateLeft(root, xp);
xpr = (xp = x.parent) == null ? null : xp.right;
}
if (xpr == null)
x = xp;
else {
TreeNode<K,V> sl = xpr.left, sr = xpr.right;
if ((sr == null || !sr.red) &&
(sl == null || !sl.red)) {
xpr.red = true;
x = xp;
}
else {
if (sr == null || !sr.red) {
if (sl != null)
sl.red = false;
xpr.red = true;
root = rotateRight(root, xpr);
xpr = (xp = x.parent) == null ?
null : xp.right;
}
if (xpr != null) {
xpr.red = (xp == null) ? false : xp.red;
if ((sr = xpr.right) != null)
sr.red = false;
}
if (xp != null) {
xp.red = false;
root = rotateLeft(root, xp);
}
x = root;
}
}
}
else { // symmetric
if (xpl != null && xpl.red) {
xpl.red = false;
xp.red = true;
root = rotateRight(root, xp);
xpl = (xp = x.parent) == null ? null : xp.left;
}
if (xpl == null)
x = xp;
else {
TreeNode<K,V> sl = xpl.left, sr = xpl.right;
if ((sl == null || !sl.red) &&
(sr == null || !sr.red)) {
xpl.red = true;
x = xp;
}
else {
if (sl == null || !sl.red) {
if (sr != null)
sr.red = false;
xpl.red = true;
root = rotateLeft(root, xpl);
xpl = (xp = x.parent) == null ?
null : xp.left;
}
if (xpl != null) {
xpl.red = (xp == null) ? false : xp.red;
if ((sl = xpl.left) != null)
sl.red = false;
}
if (xp != null) {
xp.red = false;
root = rotateRight(root, xp);
}
x = root;
}
}
}
}
}
static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
tb = t.prev, tn = (TreeNode<K,V>)t.next;
if (tb != null && tb.next != t)
return false;
if (tn != null && tn.prev != t)
return false;
if (tp != null && t != tp.left && t != tp.right)
return false;
if (tl != null && (tl.parent != t || tl.hash > t.hash))
return false;
if (tr != null && (tr.parent != t || tr.hash < t.hash))
return false;
if (t.red && tl != null && tl.red && tr != null && tr.red)
return false;
if (tl != null && !checkInvariants(tl))
return false;
if (tr != null && !checkInvariants(tr))
return false;
return true;
}
private static final sun.misc.Unsafe U;
private static final long LOCKSTATE;
static {
try {
U = sun.misc.Unsafe.getUnsafe();
Class<?> k = TreeBin.class;
LOCKSTATE = U.objectFieldOffset
(k.getDeclaredField("lockState"));
} catch (Exception e) {
throw new Error(e);
}
}
}
/* ----------------Table Traversal -------------- */
static final class TableStack<K,V> {
int length;
int index;
Node<K,V>[] tab;
TableStack<K,V> next;
}
static class Traverser<K,V> {
Node<K,V>[] tab;
Node<K,V> next;
TableStack<K,V> stack, spare;
int index;
int baseIndex;
int baseLimit;
final int baseSize;
Traverser(Node<K,V>[] tab, int size, int index, int limit) {
this.tab = tab;
this.baseSize = size;
this.baseIndex = this.index = index;
this.baseLimit = limit;
this.next = null;
}
final Node<K,V> advance() {
Node<K,V> e;
if ((e = next) != null)
e = e.next;
for (;;) {
Node<K,V>[] t; int i, n;
if (e != null)
return next = e;
if (baseIndex >= baseLimit || (t = tab) == null ||
(n = t.length) <= (i = index) || i < 0)
return next = null;
if ((e = tabAt(t, i)) != null && e.hash < 0) {
if (e instanceof ForwardingNode) {
tab = ((ForwardingNode<K,V>)e).nextTable;
e = null;
pushState(t, i, n);
continue;
}
else if (e instanceof TreeBin)
e = ((TreeBin<K,V>)e).first;
else
e = null;
}
if (stack != null)
recoverState(n);
else if ((index = i + baseSize) >= n)
index = ++baseIndex;
}
}
private void pushState(Node<K,V>[] t, int i, int n) {
TableStack<K,V> s = spare;
if (s != null)
spare = s.next;
else
s = new TableStack<K,V>();
s.tab = t;
s.length = n;
s.index = i;
s.next = stack;
stack = s;
}
private void recoverState(int n) {
TableStack<K,V> s; int len;
while ((s = stack) != null && (index += (len = s.length)) >= n) {
n = len;
index = s.index;
tab = s.tab;
s.tab = null;
TableStack<K,V> next = s.next;
s.next = spare;
stack = next;
spare = s;
}
if (s == null && (index += baseSize) >= n)
index = ++baseIndex;
}
}
static class BaseIterator<K,V> extends Traverser<K,V> {
final ConcurrentHashMap<K,V> map;
Node<K,V> lastReturned;
BaseIterator(Node<K,V>[] tab, int size, int index, int limit,
ConcurrentHashMap<K,V> map) {
super(tab, size, index, limit);
this.map = map;
advance();
}
public final boolean hasNext() { return next != null; }
public final boolean hasMoreElements() { return next != null; }
public final void remove() {
Node<K,V> p;
if ((p = lastReturned) == null)
throw new IllegalStateException();
lastReturned = null;
map.replaceNode(p.key, null, null);
}
}
static final class KeyIterator<K,V> extends BaseIterator<K,V>
implements Iterator<K>, Enumeration<K> {
KeyIterator(Node<K,V>[] tab, int index, int size, int limit,
ConcurrentHashMap<K,V> map) {
super(tab, index, size, limit, map);
}
public final K next() {
Node<K,V> p;
if ((p = next) == null)
throw new NoSuchElementException();
K k = p.key;
lastReturned = p;
advance();
return k;
}
public final K nextElement() { return next(); }
}
static final class ValueIterator<K,V> extends BaseIterator<K,V>
implements Iterator<V>, Enumeration<V> {
ValueIterator(Node<K,V>[] tab, int index, int size, int limit,
ConcurrentHashMap<K,V> map) {
super(tab, index, size, limit, map);
}
public final V next() {
Node<K,V> p;
if ((p = next) == null)
throw new NoSuchElementException();
V v = p.val;
lastReturned = p;
advance();
return v;
}
public final V nextElement() { return next(); }
}
static final class EntryIterator<K,V> extends BaseIterator<K,V>
implements Iterator<Map.Entry<K,V>> {
EntryIterator(Node<K,V>[] tab, int index, int size, int limit,
ConcurrentHashMap<K,V> map) {
super(tab, index, size, limit, map);
}
public final Map.Entry<K,V> next() {
Node<K,V> p;
if ((p = next) == null)
throw new NoSuchElementException();
K k = p.key;
V v = p.val;
lastReturned = p;
advance();
return new MapEntry<K,V>(k, v, map);
}
}
/**
* Exported Entry for EntryIterator
*/
static final class MapEntry<K,V> implements Map.Entry<K,V> {
final K key;
V val;
final ConcurrentHashMap<K,V> map;
MapEntry(K key, V val, ConcurrentHashMap<K,V> map) {
this.key = key;
this.val = val;
this.map = map;
}
public K getKey() { return key; }
public V getValue() { return val; }
public int hashCode() { return key.hashCode() ^ val.hashCode(); }
public String toString() { return key + "=" + val; }
public boolean equals(Object o) {
Object k, v; Map.Entry<?,?> e;
return ((o instanceof Map.Entry) &&
(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
(v = e.getValue()) != null &&
(k == key || k.equals(key)) &&
(v == val || v.equals(val)));
}
public V setValue(V value) {
if (value == null) throw new NullPointerException();
V v = val;
val = value;
map.put(key, value);
return v;
}
}
static final class KeySpliterator<K,V> extends Traverser<K,V>
implements Spliterator<K> {
long est;
KeySpliterator(Node<K,V>[] tab, int size, int index, int limit,
long est) {
super(tab, size, index, limit);
this.est = est;
}
public Spliterator<K> trySplit() {
int i, f, h;
return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
new KeySpliterator<K,V>(tab, baseSize, baseLimit = h,
f, est >>>= 1);
}
public void forEachRemaining(Consumer<? super K> action) {
if (action == null) throw new NullPointerException();
for (Node<K,V> p; (p = advance()) != null;)
action.accept(p.key);
}
public boolean tryAdvance(Consumer<? super K> action) {
if (action == null) throw new NullPointerException();
Node<K,V> p;
if ((p = advance()) == null)
return false;
action.accept(p.key);
return true;
}
public long estimateSize() { return est; }
public int characteristics() {
return Spliterator.DISTINCT | Spliterator.CONCURRENT |
Spliterator.NONNULL;
}
}
static final class ValueSpliterator<K,V> extends Traverser<K,V>
implements Spliterator<V> {
long est;
ValueSpliterator(Node<K,V>[] tab, int size, int index, int limit,
long est) {
super(tab, size, index, limit);
this.est = est;
}
public Spliterator<V> trySplit() {
int i, f, h;
return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
new ValueSpliterator<K,V>(tab, baseSize, baseLimit = h,
f, est >>>= 1);
}
public void forEachRemaining(Consumer<? super V> action) {
if (action == null) throw new NullPointerException();
for (Node<K,V> p; (p = advance()) != null;)
action.accept(p.val);
}
public boolean tryAdvance(Consumer<? super V> action) {
if (action == null) throw new NullPointerException();
Node<K,V> p;
if ((p = advance()) == null)
return false;
action.accept(p.val);
return true;
}
public long estimateSize() { return est; }
public int characteristics() {
return Spliterator.CONCURRENT | Spliterator.NONNULL;
}
}
static final class EntrySpliterator<K,V> extends Traverser<K,V>
implements Spliterator<Map.Entry<K,V>> {
final ConcurrentHashMap<K,V> map;
long est;
EntrySpliterator(Node<K,V>[] tab, int size, int index, int limit,
long est, ConcurrentHashMap<K,V> map) {
super(tab, size, index, limit);
this.map = map;
this.est = est;
}
public Spliterator<Map.Entry<K,V>> trySplit() {
int i, f, h;
return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
new EntrySpliterator<K,V>(tab, baseSize, baseLimit = h,
f, est >>>= 1, map);
}
public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
if (action == null) throw new NullPointerException();
for (Node<K,V> p; (p = advance()) != null; )
action.accept(new MapEntry<K,V>(p.key, p.val, map));
}
public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
if (action == null) throw new NullPointerException();
Node<K,V> p;
if ((p = advance()) == null)
return false;
action.accept(new MapEntry<K,V>(p.key, p.val, map));
return true;
}
public long estimateSize() { return est; }
public int characteristics() {
return Spliterator.DISTINCT | Spliterator.CONCURRENT |
Spliterator.NONNULL;
}
}
// Parallel bulk operations
final int batchFor(long b) {
long n;
if (b == Long.MAX_VALUE || (n = sumCount()) <= 1L || n < b)
return 0;
int sp = ForkJoinPool.getCommonPoolParallelism() << 2; // slack of 4
return (b <= 0L || (n /= b) >= sp) ? sp : (int)n;
}
public void forEach(long parallelismThreshold,
BiConsumer<? super K,? super V> action) {
if (action == null) throw new NullPointerException();
new ForEachMappingTask<K,V>
(null, batchFor(parallelismThreshold), 0, 0, table,
action).invoke();
}
public <U> void forEach(long parallelismThreshold,
BiFunction<? super K, ? super V, ? extends U> transformer,
Consumer<? super U> action) {
if (transformer == null || action == null)
throw new NullPointerException();
new ForEachTransformedMappingTask<K,V,U>
(null, batchFor(parallelismThreshold), 0, 0, table,
transformer, action).invoke();
}
public <U> U search(long parallelismThreshold,
BiFunction<? super K, ? super V, ? extends U> searchFunction) {
if (searchFunction == null) throw new NullPointerException();
return new SearchMappingsTask<K,V,U>
(null, batchFor(parallelismThreshold), 0, 0, table,
searchFunction, new AtomicReference<U>()).invoke();
}
public <U> U reduce(long parallelismThreshold,
BiFunction<? super K, ? super V, ? extends U> transformer,
BiFunction<? super U, ? super U, ? extends U> reducer) {
if (transformer == null || reducer == null)
throw new NullPointerException();
return new MapReduceMappingsTask<K,V,U>
(null, batchFor(parallelismThreshold), 0, 0, table,
null, transformer, reducer).invoke();
}
public double reduceToDouble(long parallelismThreshold,
ToDoubleBiFunction<? super K, ? super V> transformer,
double basis,
DoubleBinaryOperator reducer) {
if (transformer == null || reducer == null)
throw new NullPointerException();
return new MapReduceMappingsToDoubleTask<K,V>
(null, batchFor(parallelismThreshold), 0, 0, table,
null, transformer, basis, reducer).invoke();
}
public long reduceToLong(long parallelismThreshold,
ToLongBiFunction<? super K, ? super V> transformer,
long basis,
LongBinaryOperator reducer) {
if (transformer == null || reducer == null)
throw new NullPointerException();
return new MapReduceMappingsToLongTask<K,V>
(null, batchFor(parallelismThreshold), 0, 0, table,
null, transformer, basis, reducer).invoke();
}
public int reduceToInt(long parallelismThreshold,
ToIntBiFunction<? super K, ? super V> transformer,
int basis,
IntBinaryOperator reducer) {
if (transformer == null || reducer == null)
throw new NullPointerException();
return new MapReduceMappingsToIntTask<K,V>
(null, batchFor(parallelismThreshold), 0, 0, table,
null, transformer, basis, reducer).invoke();
}
public void forEachKey(long parallelismThreshold,
Consumer<? super K> action) {
if (action == null) throw new NullPointerException();
new ForEachKeyTask<K,V>
(null, batchFor(parallelismThreshold), 0, 0, table,
action).invoke();
}
public <U> U searchKeys(long parallelismThreshold,
Function<? super K, ? extends U> searchFunction) {
if (searchFunction == null) throw new NullPointerException();
return new SearchKeysTask<K,V,U>
(null, batchFor(parallelismThreshold), 0, 0, table,
searchFunction, new AtomicReference<U>()).invoke();
}
/**
* 返回使用给定的reducer组合值来累积所有键的结果；如果没有，则返回null。
*/
public K reduceKeys(long parallelismThreshold,
BiFunction<? super K, ? super K, ? extends K> reducer) {
if (reducer == null) throw new NullPointerException();
return new ReduceKeysTask<K,V>
(null, batchFor(parallelismThreshold), 0, 0, table,
null, reducer).invoke();
}
/**
* 通过将给定搜索功能应用于每个值，返回非null的结果；
* 如果没有，则返回null。
* 成功后，将禁止进一步的元素处理，并且将忽略搜索功能的任何其他并行调用的结果。
*/
public <U> U searchValues(long parallelismThreshold,
Function<? super V, ? extends U> searchFunction) {
if (searchFunction == null) throw new NullPointerException();
return new SearchValuesTask<K,V,U>
(null, batchFor(parallelismThreshold), 0, 0, table,
searchFunction, new AtomicReference<U>()).invoke();
}
/**
* 返回使用给定的reducer合并值来累加所有值的结果；如果没有，则返回null。
*/
public V reduceValues(long parallelismThreshold,
BiFunction<? super V, ? super V, ? extends V> reducer) {
if (reducer == null) throw new NullPointerException();
return new ReduceValuesTask<K,V>
(null, batchFor(parallelismThreshold), 0, 0, table,
null, reducer).invoke();
}
// 各种reduceValues 略
public void forEachEntry(long parallelismThreshold,
Consumer<? super Map.Entry<K,V>> action) {
if (action == null) throw new NullPointerException();
new ForEachEntryTask<K,V>(null, batchFor(parallelismThreshold), 0, 0, table,
action).invoke();
}
public <U> void forEachEntry(long parallelismThreshold,
Function<Map.Entry<K,V>, ? extends U> transformer,
Consumer<? super U> action) {
if (transformer == null || action == null)
throw new NullPointerException();
new ForEachTransformedEntryTask<K,V,U>
(null, batchFor(parallelismThreshold), 0, 0, table,
transformer, action).invoke();
}
/**
* 通过对每个条目应用给定的搜索功能，返回非空结果；如果不存在，则返回空值。
* 成功后，将禁止进一步的元素处理，并且将忽略搜索功能的任何其他并行调用的结果。
*/
public <U> U searchEntries(long parallelismThreshold,
Function<Map.Entry<K,V>, ? extends U> searchFunction) {
if (searchFunction == null) throw new NullPointerException();
return new SearchEntriesTask<K,V,U>
(null, batchFor(parallelismThreshold), 0, 0, table,
searchFunction, new AtomicReference<U>()).invoke();
}
public Map.Entry<K,V> reduceEntries(long parallelismThreshold,
BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
if (reducer == null) throw new NullPointerException();
return new ReduceEntriesTask<K,V>
(null, batchFor(parallelismThreshold), 0, 0, table,
null, reducer).invoke();
}
// 略 各种reduceEntries方法。
/* ----------------Views -------------- */
abstract static class CollectionView<K,V,E>
implements Collection<E>, java.io.Serializable {
private static final long serialVersionUID = 7249069246763182397L;
final ConcurrentHashMap<K,V> map;
CollectionView(ConcurrentHashMap<K,V> map) { this.map = map; }
public ConcurrentHashMap<K,V> getMap() { return map; }
public final void clear() { map.clear(); }
public final int size() { return map.size(); }
public final boolean isEmpty() { return map.isEmpty(); }
public abstract Iterator<E> iterator();
public abstract boolean contains(Object o);
public abstract boolean remove(Object o);
private static final String oomeMsg = "Required array size too large";
public final Object[] toArray() {
long sz = map.mappingCount();
if (sz > MAX_ARRAY_SIZE)
throw new OutOfMemoryError(oomeMsg);
int n = (int)sz;
Object[] r = new Object[n];
int i = 0;
for (E e : this) {
if (i == n) {
if (n >= MAX_ARRAY_SIZE)
throw new OutOfMemoryError(oomeMsg);
if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
n = MAX_ARRAY_SIZE;
else
n += (n >>> 1) + 1;
r = Arrays.copyOf(r, n);
}
r[i++] = e;
}
return (i == n) ? r : Arrays.copyOf(r, i);
}
@SuppressWarnings("unchecked")
public final <T> T[] toArray(T[] a) {
long sz = map.mappingCount();
if (sz > MAX_ARRAY_SIZE)
throw new OutOfMemoryError(oomeMsg);
int m = (int)sz;
T[] r = (a.length >= m) ? a :
(T[])java.lang.reflect.Array
.newInstance(a.getClass().getComponentType(), m);
int n = r.length;
int i = 0;
for (E e : this) {
if (i == n) {
if (n >= MAX_ARRAY_SIZE)
throw new OutOfMemoryError(oomeMsg);
if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
n = MAX_ARRAY_SIZE;
else
n += (n >>> 1) + 1;
r = Arrays.copyOf(r, n);
}
r[i++] = (T)e;
}
if (a == r && i < n) {
r[i] = null; // null-terminate
return r;
}
return (i == n) ? r : Arrays.copyOf(r, i);
}
public final String toString() {
StringBuilder sb = new StringBuilder();
sb.append('[');
Iterator<E> it = iterator();
if (it.hasNext()) {
for (;;) {
Object e = it.next();
sb.append(e == this ? "(this Collection)" : e);
if (!it.hasNext())
break;
sb.append(',').append(' ');
}
}
return sb.append(']').toString();
}
public final boolean containsAll(Collection<?> c) {
if (c != this) {
for (Object e : c) {
if (e == null || !contains(e))
return false;
}
}
return true;
}
public final boolean removeAll(Collection<?> c) {
if (c == null) throw new NullPointerException();
boolean modified = false;
for (Iterator<E> it = iterator(); it.hasNext();) {
if (c.contains(it.next())) {
it.remove();
modified = true;
}
}
return modified;
}
public final boolean retainAll(Collection<?> c) {
if (c == null) throw new NullPointerException();
boolean modified = false;
for (Iterator<E> it = iterator(); it.hasNext();) {
if (!c.contains(it.next())) {
it.remove();
modified = true;
}
}
return modified;
}
}
public static class KeySetView<K,V> extends CollectionView<K,V,K>
implements Set<K>, java.io.Serializable {
private static final long serialVersionUID = 7249069246763182397L;
private final V value;
KeySetView(ConcurrentHashMap<K,V> map, V value) {
super(map);
this.value = value;
}
public V getMappedValue() { return value; }
public boolean contains(Object o) { return map.containsKey(o); }
public boolean remove(Object o) { return map.remove(o) != null; }
public Iterator<K> iterator() {
Node<K,V>[] t;
ConcurrentHashMap<K,V> m = map;
int f = (t = m.table) == null ? 0 : t.length;
return new KeyIterator<K,V>(t, f, 0, f, m);
}
public boolean add(K e) {
V v;
if ((v = value) == null)
throw new UnsupportedOperationException();
return map.putVal(e, v, true) == null;
}
public boolean addAll(Collection<? extends K> c) {
boolean added = false;
V v;
if ((v = value) == null)
throw new UnsupportedOperationException();
for (K e : c) {
if (map.putVal(e, v, true) == null)
added = true;
}
return added;
}
public int hashCode() {
int h = 0;
for (K e : this)
h += e.hashCode();
return h;
}
public boolean equals(Object o) {
Set<?> c;
return ((o instanceof Set) &&
((c = (Set<?>)o) == this ||
(containsAll(c) && c.containsAll(this))));
}
public Spliterator<K> spliterator() {
Node<K,V>[] t;
ConcurrentHashMap<K,V> m = map;
long n = m.sumCount();
int f = (t = m.table) == null ? 0 : t.length;
return new KeySpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n);
}
public void forEach(Consumer<? super K> action) {
if (action == null) throw new NullPointerException();
Node<K,V>[] t;
if ((t = map.table) != null) {
Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
for (Node<K,V> p; (p = it.advance()) != null; )
action.accept(p.key);
}
}
}
static final class ValuesView<K,V> extends CollectionView<K,V,V>
implements Collection<V>, java.io.Serializable {
private static final long serialVersionUID = 2249069246763182397L;
ValuesView(ConcurrentHashMap<K,V> map) { super(map); }
public final boolean contains(Object o) {
return map.containsValue(o);
}
public final boolean remove(Object o) {
if (o != null) {
for (Iterator<V> it = iterator(); it.hasNext();) {
if (o.equals(it.next())) {
it.remove();
return true;
}
}
}
return false;
}
public final Iterator<V> iterator() {
ConcurrentHashMap<K,V> m = map;
Node<K,V>[] t;
int f = (t = m.table) == null ? 0 : t.length;
return new ValueIterator<K,V>(t, f, 0, f, m);
}
public final boolean add(V e) {
throw new UnsupportedOperationException();
}
public final boolean addAll(Collection<? extends V> c) {
throw new UnsupportedOperationException();
}
public Spliterator<V> spliterator() {
Node<K,V>[] t;
ConcurrentHashMap<K,V> m = map;
long n = m.sumCount();
int f = (t = m.table) == null ? 0 : t.length;
return new ValueSpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n);
}
public void forEach(Consumer<? super V> action) {
if (action == null) throw new NullPointerException();
Node<K,V>[] t;
if ((t = map.table) != null) {
Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
for (Node<K,V> p; (p = it.advance()) != null; )
action.accept(p.val);
}
}
}
static final class EntrySetView<K,V> extends CollectionView<K,V,Map.Entry<K,V>>
implements Set<Map.Entry<K,V>>, java.io.Serializable {
private static final long serialVersionUID = 2249069246763182397L;
EntrySetView(ConcurrentHashMap<K,V> map) { super(map); }
public boolean contains(Object o) {
Object k, v, r; Map.Entry<?,?> e;
return ((o instanceof Map.Entry) &&
(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
(r = map.get(k)) != null &&
(v = e.getValue()) != null &&
(v == r || v.equals(r)));
}
public boolean remove(Object o) {
Object k, v; Map.Entry<?,?> e;
return ((o instanceof Map.Entry) &&
(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
(v = e.getValue()) != null &&
map.remove(k, v));
}
/**
* @return an iterator over the entries of the backing map
*/
public Iterator<Map.Entry<K,V>> iterator() {
ConcurrentHashMap<K,V> m = map;
Node<K,V>[] t;
int f = (t = m.table) == null ? 0 : t.length;
return new EntryIterator<K,V>(t, f, 0, f, m);
}
public boolean add(Entry<K,V> e) {
return map.putVal(e.getKey(), e.getValue(), false) == null;
}
public boolean addAll(Collection<? extends Entry<K,V>> c) {
boolean added = false;
for (Entry<K,V> e : c) {
if (add(e))
added = true;
}
return added;
}
public final int hashCode() {
int h = 0;
Node<K,V>[] t;
if ((t = map.table) != null) {
Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
for (Node<K,V> p; (p = it.advance()) != null; ) {
h += p.hashCode();
}
}
return h;
}
public final boolean equals(Object o) {
Set<?> c;
return ((o instanceof Set) &&
((c = (Set<?>)o) == this ||
(containsAll(c) && c.containsAll(this))));
}
public Spliterator<Map.Entry<K,V>> spliterator() {
Node<K,V>[] t;
ConcurrentHashMap<K,V> m = map;
long n = m.sumCount();
int f = (t = m.table) == null ? 0 : t.length;
return new EntrySpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n, m);
}
public void forEach(Consumer<? super Map.Entry<K,V>> action) {
if (action == null) throw new NullPointerException();
Node<K,V>[] t;
if ((t = map.table) != null) {
Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
for (Node<K,V> p; (p = it.advance()) != null; )
action.accept(new MapEntry<K,V>(p.key, p.val, map));
}
}
}
@SuppressWarnings("serial")
abstract static class BulkTask<K,V,R> extends CountedCompleter<R> {
Node<K,V>[] tab; // same as Traverser
Node<K,V> next;
TableStack<K,V> stack, spare;
int index;
int baseIndex;
int baseLimit;
final int baseSize;
int batch; // split control
BulkTask(BulkTask<K,V,?> par, int b, int i, int f, Node<K,V>[] t) {
super(par);
this.batch = b;
this.index = this.baseIndex = i;
if ((this.tab = t) == null)
this.baseSize = this.baseLimit = 0;
else if (par == null)
this.baseSize = this.baseLimit = t.length;
else {
this.baseLimit = f;
this.baseSize = par.baseSize;
}
}
final Node<K,V> advance() {
Node<K,V> e;
if ((e = next) != null)
e = e.next;
for (;;) {
Node<K,V>[] t; int i, n;
if (e != null)
return next = e;
if (baseIndex >= baseLimit || (t = tab) == null ||
(n = t.length) <= (i = index) || i < 0)
return next = null;
if ((e = tabAt(t, i)) != null && e.hash < 0) {
if (e instanceof ForwardingNode) {
tab = ((ForwardingNode<K,V>)e).nextTable;
e = null;
pushState(t, i, n);
continue;
}
else if (e instanceof TreeBin)
e = ((TreeBin<K,V>)e).first;
else
e = null;
}
if (stack != null)
recoverState(n);
else if ((index = i + baseSize) >= n)
index = ++baseIndex;
}
}
private void pushState(Node<K,V>[] t, int i, int n) {
TableStack<K,V> s = spare;
if (s != null)
spare = s.next;
else
s = new TableStack<K,V>();
s.tab = t;
s.length = n;
s.index = i;
s.next = stack;
stack = s;
}
private void recoverState(int n) {
TableStack<K,V> s; int len;
while ((s = stack) != null && (index += (len = s.length)) >= n) {
n = len;
index = s.index;
tab = s.tab;
s.tab = null;
TableStack<K,V> next = s.next;
s.next = spare; // save for reuse
stack = next;
spare = s;
}
if (s == null && (index += baseSize) >= n)
index = ++baseIndex;
}
}
@SuppressWarnings("serial")
static final class ForEachKeyTask<K,V>
extends BulkTask<K,V,Void> {
...
}
@SuppressWarnings("serial")
static final class ForEachValueTask<K,V>
extends BulkTask<K,V,Void> {
...
}
@SuppressWarnings("serial")
static final class ForEachEntryTask<K,V>
extends BulkTask<K,V,Void> {
...
}
@SuppressWarnings("serial")
static final class ForEachMappingTask<K,V>
extends BulkTask<K,V,Void> {
...
}
@SuppressWarnings("serial")
static final class ForEachTransformedKeyTask<K,V,U>
extends BulkTask<K,V,Void> {
...
}
@SuppressWarnings("serial")
static final class ForEachTransformedValueTask<K,V,U>
extends BulkTask<K,V,Void> {
...
}
@SuppressWarnings("serial")
static final class ForEachTransformedEntryTask<K,V,U>
extends BulkTask<K,V,Void> {
...
}
@SuppressWarnings("serial")
static final class ForEachTransformedMappingTask<K,V,U>
extends BulkTask<K,V,Void> {
...
}
@SuppressWarnings("serial")
static final class SearchKeysTask<K,V,U>
extends BulkTask<K,V,U> {
...
}
@SuppressWarnings("serial")
static final class SearchValuesTask<K,V,U>
extends BulkTask<K,V,U> {
...
}
@SuppressWarnings("serial")
static final class SearchEntriesTask<K,V,U>
extends BulkTask<K,V,U> {
...
}
@SuppressWarnings("serial")
static final class SearchMappingsTask<K,V,U>
extends BulkTask<K,V,U> {
...
}
@SuppressWarnings("serial")
static final class ReduceKeysTask<K,V>
extends BulkTask<K,V,K> {
...
}
@SuppressWarnings("serial")
static final class ReduceValuesTask<K,V>
extends BulkTask<K,V,V> {
...
}
@SuppressWarnings("serial")
static final class ReduceEntriesTask<K,V>
extends BulkTask<K,V,Map.Entry<K,V>> {
...
}
@SuppressWarnings("serial")
static final class MapReduceKeysTask<K,V,U>
extends BulkTask<K,V,U> {
...
}
@SuppressWarnings("serial")
static final class MapReduceValuesTask<K,V,U>
extends BulkTask<K,V,U> {
...
}
@SuppressWarnings("serial")
static final class MapReduceEntriesTask<K,V,U>
extends BulkTask<K,V,U> {
...
}
@SuppressWarnings("serial")
static final class MapReduceMappingsTask<K,V,U>
extends BulkTask<K,V,U> {
...
}
@SuppressWarnings("serial")
static final class MapReduceKeysToDoubleTask<K,V>
extends BulkTask<K,V,Double> {
...
}
@SuppressWarnings("serial")
static final class MapReduceValuesToDoubleTask<K,V>
extends BulkTask<K,V,Double> {
...
}
@SuppressWarnings("serial")
static final class MapReduceEntriesToDoubleTask<K,V>
extends BulkTask<K,V,Double> {
...
}
@SuppressWarnings("serial")
static final class MapReduceMappingsToDoubleTask<K,V>
extends BulkTask<K,V,Double> {
...
}
@SuppressWarnings("serial")
static final class MapReduceKeysToLongTask<K,V>
extends BulkTask<K,V,Long> {
...
}
@SuppressWarnings("serial")
static final class MapReduceValuesToLongTask<K,V>
extends BulkTask<K,V,Long> {
...
}
@SuppressWarnings("serial")
static final class MapReduceEntriesToLongTask<K,V>
extends BulkTask<K,V,Long> {
...
}
@SuppressWarnings("serial")
static final class MapReduceMappingsToLongTask<K,V>
...
}
@SuppressWarnings("serial")
static final class MapReduceKeysToIntTask<K,V>
extends BulkTask<K,V,Integer> {
...
}
@SuppressWarnings("serial")
static final class MapReduceValuesToIntTask<K,V>
extends BulkTask<K,V,Integer> {
...
}
@SuppressWarnings("serial")
static final class MapReduceEntriesToIntTask<K,V>
extends BulkTask<K,V,Integer> {
...
}
@SuppressWarnings("serial")
static final class MapReduceMappingsToIntTask<K,V>
extends BulkTask<K,V,Integer> {
...
}
// Unsafe mechanics
private static final sun.misc.Unsafe U;
private static final long SIZECTL;
private static final long TRANSFERINDEX;
private static final long BASECOUNT;
private static final long CELLSBUSY;
private static final long CELLVALUE;
private static final long ABASE;
private static final int ASHIFT;
static {
try {
U = sun.misc.Unsafe.getUnsafe();
Class<?> k = ConcurrentHashMap.class;
SIZECTL = U.objectFieldOffset
(k.getDeclaredField("sizeCtl"));
TRANSFERINDEX = U.objectFieldOffset
(k.getDeclaredField("transferIndex"));
BASECOUNT = U.objectFieldOffset
(k.getDeclaredField("baseCount"));
CELLSBUSY = U.objectFieldOffset
(k.getDeclaredField("cellsBusy"));
Class<?> ck = CounterCell.class;
CELLVALUE = U.objectFieldOffset
(ck.getDeclaredField("value"));
Class<?> ak = Node[].class;
ABASE = U.arrayBaseOffset(ak);
int scale = U.arrayIndexScale(ak);
if ((scale & (scale - 1)) != 0)
throw new Error("data type scale not a power of two");
ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
} catch (Exception e) {
throw new Error(e);
}
}
}
问题记录
- BiFunction && Function 接口的区别。
- 源码中这么多Task类是干嘛用的？
