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Java線程池隊(duì)列LinkedBlockingDeque

更新時(shí)間：2022年12月11日 14:07:52 作者：刨紅薯的小羊竿爾

這篇文章主要為大家介紹了Java線程池隊(duì)列LinkedBlockingDeque示例詳解，有需要的朋友可以借鑒參考下，希望能夠有所幫助，祝大家多多進(jìn)步，早日升職加薪

正文

public enum QueueTypeEnum {
    ARRAY_BLOCKING_QUEUE(1, "ArrayBlockingQueue"),
    LINKED_BLOCKING_QUEUE(2, "LinkedBlockingQueue"),
    DELAY_QUEUE(3, "DelayQueue"),
    PRIORITY_BLOCKING_QUEUE(4, "PriorityBlockingQueue"),
    SYNCHRONOUS_QUEUE(5, "SynchronousQueue"),
    LINKED_TRANSFER_QUEUE(6, "LinkedTransferQueue"),
    LINKED_BLOCKING_DEQUE(7, "LinkedBlockingDeque"),
    VARIABLE_LINKED_BLOCKING_QUEUE(8, "VariableLinkedBlockingQueue"),
    MEMORY_SAFE_LINKED_BLOCKING_QUEUE(9, "MemorySafeLinkedBlockingQueue");
}

LinkedBlockingDeque

LinkedBlockingDeque：使用雙向隊(duì)列實(shí)現(xiàn)的有界雙端阻塞隊(duì)列。雙端意味著可以像普通隊(duì)列一樣 FIFO（先進(jìn)先出），也可以像棧一樣 FILO（先進(jìn)后出）。

LinkedBlockingDeque是一個(gè)基于鏈表的雙端阻塞隊(duì)列，和LinkedBlockingQueue類似，區(qū)別在于該類實(shí)現(xiàn)了Deque接口，而LinkedBlockingQueue實(shí)現(xiàn)了Queue接口。

LinkedBlockingDeque是一個(gè)可選容量的阻塞隊(duì)列，如果沒有設(shè)置容量，那么容量將是Int的最大值。

LinkedBlockingDeque的重要字段有如下幾個(gè)：

//隊(duì)列的頭節(jié)點(diǎn)
transient Node<E> first;
//隊(duì)列的尾節(jié)點(diǎn)
transient Node<E> last;
//隊(duì)列中元素的個(gè)數(shù)
private transient int count;
//隊(duì)列中元素的最大個(gè)數(shù)
private final int capacity;
//鎖
final ReentrantLock lock = new ReentrantLock();
//隊(duì)列為空時(shí)，阻塞take線程的條件隊(duì)列
private final Condition notEmpty = lock.newCondition();
//隊(duì)列滿時(shí)，阻塞put線程的條件隊(duì)列
private final Condition notFull = lock.newCondition();

從上面的字段，可以看到LinkedBlockingDeque內(nèi)部只有一把鎖以及該鎖上關(guān)聯(lián)的兩個(gè)條件，所以可以推斷同一時(shí)刻只有一個(gè)線程可以在隊(duì)頭或者隊(duì)尾執(zhí)行入隊(duì)或出隊(duì)操作?？梢园l(fā)現(xiàn)這點(diǎn)和LinkedBlockingQueue不同，LinkedBlockingQueue可以同時(shí)有兩個(gè)線程在兩端執(zhí)行操作。

由于LinkedBlockingDeque是一個(gè)雙端隊(duì)列，所以就可以在隊(duì)頭執(zhí)行入隊(duì)和出隊(duì)操作，也可以在隊(duì)尾執(zhí)行入隊(duì)和出隊(duì)操作。

public LinkedBlockingDeque() {
    this(Integer.MAX_VALUE);
}
public LinkedBlockingDeque(int capacity) {
    if (capacity <= 0) throw new IllegalArgumentException();
    this.capacity = capacity;
}
public LinkedBlockingDeque(Collection<? extends E> c) {
    this(Integer.MAX_VALUE);
    final ReentrantLock lock = this.lock;
    lock.lock(); // Never contended, but necessary for visibility
    try {
        for (E e : c) {
            if (e == null)
                throw new NullPointerException();
            if (!linkLast(new Node<E>(e)))
                throw new IllegalStateException("Deque full");
        }
    } finally {
        lock.unlock();
    }
}