{"id":1351,"date":"2023-06-27T13:54:26","date_gmt":"2023-06-27T05:54:26","guid":{"rendered":"https:\/\/xinchewhd.com.cn\/?p=1351"},"modified":"2023-06-27T13:54:26","modified_gmt":"2023-06-27T05:54:26","slug":"%e9%9d%a2%e8%af%95%e5%ae%98-exchanger%e5%9c%a8%e9%a1%b9%e7%9b%ae%e4%b8%ad%e6%9c%89%e4%bd%bf%e7%94%a8%e8%bf%87%e5%90%97%ef%bc%9f%e8%af%b4%e8%af%b4%e7%9c%8b%e6%ba%90%e7%a0%81%e5%89%96%e6%9e%90","status":"publish","type":"post","link":"https:\/\/xinchewhd.com.cn\/index.php\/java\/%e9%9d%a2%e8%af%95%e5%ae%98-exchanger%e5%9c%a8%e9%a1%b9%e7%9b%ae%e4%b8%ad%e6%9c%89%e4%bd%bf%e7%94%a8%e8%bf%87%e5%90%97%ef%bc%9f%e8%af%b4%e8%af%b4%e7%9c%8b%e6%ba%90%e7%a0%81%e5%89%96%e6%9e%90\/","title":{"rendered":"\u9762\u8bd5\u5b98: Exchanger\u5728\u9879\u76ee\u4e2d\u6709\u4f7f\u7528\u8fc7\u5417\uff1f\u8bf4\u8bf4\u770b(\u6e90\u7801\u5256\u6790)"},"content":{"rendered":"
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<\/span>\u9762\u8bd5\u5b98: Exchanger\u5728\u9879\u76ee\u4e2d\u6709\u4f7f\u7528\u8fc7\u5417\uff1f\u8bf4\u8bf4\u770b(\u6e90\u7801\u5256\u6790)<\/span><\/span><\/h1>\n

<\/span>\u524d\u8a00<\/span><\/span><\/h2>\n

\u76ee\u524d\u6b63\u5728\u51fa\u4e00\u4e2aJava\u591a\u7ebf\u7a0b\u4e13\u9898<\/code>\u957f\u671f\u7cfb\u5217\u6559\u7a0b\uff0c\u4ece\u5165\u95e8\u5230\u8fdb\u9636\u542b\u6e90\u7801\u89e3\u8bfb<\/code>, \u7bc7\u5e45\u4f1a\u8f83\u591a, \u559c\u6b22\u7684\u8bdd\uff0c\u7ed9\u4e2a\u5173\u6ce8\u2764\ufe0f ~<\/p>\n

<\/mpprofile><\/section>\n

Java\u63d0\u4f9b\u4e86\u4e00\u4e9b\u975e\u5e38\u597d\u7528\u7684\u5e76\u53d1\u5de5\u5177\u7c7b\uff0c\u4e0d\u9700\u8981\u6211\u4eec\u91cd\u590d\u9020\u8f6e\u5b50\uff0c\u672c\u8282\u6211\u4eec\u8bb2\u89e3Exchanger<\/code>,\u4e00\u8d77\u6765\u770b\u4e0b\u5427~<\/p>\n

<\/span>Exchanger<\/span><\/span><\/h2>\n

Exchanger<\/code>\u7c7b\u7528\u4e8e\u4e24\u4e2a\u7ebf\u7a0b\u4ea4\u6362\u6570\u636e,\u652f\u6301\u6cdb\u578b,\u4e0b\u9762\u6211\u4eec\u901a\u8fc7\u4f8b\u5b50\u611f\u53d7\u4e00\u4e0b:<\/p>\n

<\/span>    private<\/span> final<\/span> Object slotExchange<\/span>(Object item, boolean<\/span> timed, long<\/span> ns)<\/span> <\/span>{
        \/\/ \u83b7\u53d6\u5f53\u524d\u7ebf\u7a0b\u7684\u4ea4\u6362\u8282\u70b9<\/span>
        Node p = participant.get();
        Thread t = Thread.currentThread();
        if<\/span> (t.isInterrupted()) \/\/ preserve interrupt status so caller can recheck<\/span>
            return<\/span> null<\/span>;

        \/\/ \u5e38\u89c4\u81ea\u65cb\u64cd\u4f5c<\/span>
        for<\/span> (Node q;;) {
            \/\/ \u5982\u679c q\u4e0d\u4e3a\u7a7a \u8bf4\u660eq\u5df2\u7ecf\u88ab\u5360\u4e86<\/span>
            if<\/span> ((q = slot) != null<\/span>) {
                if<\/span> (U.compareAndSwapObject(this<\/span>, SLOT, q, null<\/span>)) {
                    \/\/ \u83b7\u53d6\u4ea4\u6362\u503c<\/span>
                    Object v = q.item;
                    \/\/ \u8bbe\u7f6e\u4ea4\u6362\u503c<\/span>
                    q.match = item;
                    Thread w = q.parked;
                    \/\/ \u5524\u9192\u7b49\u5f85\u7ebf\u7a0b<\/span>
                    if<\/span> (w != null<\/span>)
                        U.unpark(w);
                    \/\/ \u4ea4\u6362\u6210\u529f\u8fd4\u56de\u7ed3\u679c    <\/span>
                    return<\/span> v;
                }

                \/\/ CPU\u6838\u6570\u6570\u591a\u4e8e1\u4e2a, \u4e14bound\u4e3a0\u65f6\u521b\u5efaarena\u6570\u7ec4\uff0c\u5e76\u5c06bound\u8bbe\u7f6e\u4e3aSEQ\u5927\u5c0f<\/span>
                if<\/span> (NCPU > 1<\/span> && bound == 0<\/span> &&
                    U.compareAndSwapInt(this<\/span>, BOUND, 0<\/span>, SEQ))
                    arena = new<\/span> Node[(FULL + 2<\/span>) << ASHIFT];
            }
            \/\/ \u91cd\u5b9a\u5411\u5230\u591a\u69fd\u4ea4\u6362 arenaExchange<\/span>
            else<\/span> if<\/span> (arena != null<\/span>)
                return<\/span> null<\/span>; \/\/ caller must reroute to arenaExchange<\/span>
            else<\/span> {
                \/\/ \u5360\u7528slot<\/span>
                p.item = item;
                if<\/span> (U.compareAndSwapObject(this<\/span>, SLOT, null<\/span>, p))
                    break<\/span>;
                \/\/ \u5931\u8d25\u8bbe\u7f6e\u4e3anull \u8fdb\u5165\u4e0b\u4e00\u6b21\u81ea\u65cb   <\/span>
                p.item = null<\/span>;
            }
        }

        \/\/ \u4e0b\u9762\u7684\u64cd\u4f5c\u4e3b\u8981\u662f\u5339\u914d\u7b49\u5f85\u63a5\u6536\u7684\u7ebf\u7a0b<\/span>
        int<\/span> h = p.hash;
        long<\/span> end = timed ? System.nanoTime() + ns : 0L<\/span>;
        \/\/ \u81ea\u65cb\u7684\u6b21\u6570<\/span>
        int<\/span> spins = (NCPU > 1<\/span>) ? SPINS : 1<\/span>;
        Object v;

        \/\/ \u5339\u914d\u7ebf\u7a0b\u672a\u5230 \u5c31\u8fdb\u5165\u81ea\u65cb<\/span>
        while<\/span> ((v = p.match) == null<\/span>) {
            if<\/span> (spins > 0<\/span>) {
                \/\/ \u4f18\u5316\u64cd\u4f5c<\/span>
                h ^= h << 1<\/span>; h ^= h >>> 3<\/span>; h ^= h << 10<\/span>;
                if<\/span> (h == 0<\/span>)
                    h = SPINS | (int<\/span>)t.getId();
                else<\/span> if<\/span> (h < 0<\/span> && (--spins & ((SPINS >>> 1<\/span>) - 1<\/span>)) == 0<\/span>)
                    Thread.yield();
            }
            \/\/ \u8bf4\u660e\u5339\u914d\u7ebf\u7a0b\u5df2\u627e\u5230 \u4f46\u662f\u8fd8\u672a\u5b8c\u5168\u51c6\u5907\u597d<\/span>
            else<\/span> if<\/span> (slot != p)
                spins = SPINS;
            \/\/ \u81ea\u9009\u65f6\u95f4\u8fc7\u957f \u8fd8\u672a\u5339\u914d\u5230\u8fdb\u5165\u963b\u585e\uff0c\u5e38\u89c4\u64cd\u4f5c<\/span>
            else<\/span> if<\/span> (!t.isInterrupted() && arena == null<\/span> &&
                     (!timed || (ns = end - System.nanoTime()) > 0L<\/span>)) {
                U.putObject(t, BLOCKER, this<\/span>);
                p.parked = t;
                if<\/span> (slot == p)
                    U.park(false<\/span>, ns);
                p.parked = null<\/span>;
                U.putObject(t, BLOCKER, null<\/span>);
            }
            \/\/ \u8d85\u65f6 \u8ba9\u51fa\u7ed9\u5176\u5b83\u7ebf\u7a0b<\/span>
            else<\/span> if<\/span> (U.compareAndSwapObject(this<\/span>, SLOT, p, null<\/span>)) {
                v = timed && ns <= 0L<\/span> && !t.isInterrupted() ? TIMED_OUT : null<\/span>;
                break<\/span>;
            }
        }
        U.putOrderedObject(p, MATCH, null<\/span>);
        p.item = null<\/span>;
        p.hash = h;
        return<\/span> v;
    }
<\/code><\/pre>\n
<\/span>arenaExchange<\/span><\/span><\/h3>\n
\u64cd\u4f5c\u4e0eslotExchange<\/code>\u7c7b\u4f3c\uff0c\u4f46\u662f\u5b83\u66f4\u590d\u6742\u4e00\u70b9\uff0c\u9700\u8981\u901a\u8fc7index<\/code>\u6765\u547d\u4e2d\uff0c\u8fd9\u91cc\u5c31\u4e0d\u5e26\u5927\u5bb6\u770b\u4e86\uff0c\u6709\u5174\u8da3\u7684\u540c\u5b66\u53ef\u4ee5\u81ea\u5df1\u53bb\u770b\u4e0b<\/p>\n
<\/span>\u7ed3\u675f\u8bed<\/span><\/span><\/h2>\n
\u4e0b\u8282\u7ed9\u5927\u5bb6\u8bb2\u4e0bCountDownLatch<\/code> ~<\/p>\n
<\/mp-miniprogram><\/p>\n
<\/span>\u5f80\u671f\u5185\u5bb9\u63a8\u8350<\/span><\/span><\/h2>\n