java代码规范制定

  

    // 方法throw折行空4个空格    
    private void writeObject(java.io.ObjectOutputStream s)
        throws java.io.IOException {
        s.defaultWriteObject();
        s.writeObject(getException());
    }

    // (ForkJoinTask.class.getDeclaredField("status"))参数折行     
    static {
        exceptionTableLock = new ReentrantLock();
        exceptionTableRefQueue = new ReferenceQueue<Object>();
        exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY];
        try {
            UNSAFE = sun.misc.Unsafe.getUnsafe();
            statusOffset = UNSAFE.objectFieldOffset
                (ForkJoinTask.class.getDeclaredField("status"));
        } catch (Exception e) {
            throw new Error(e);
        }
    }

  /**
     * Wakes up or creates a worker.
     */
    final void signalWork() {
        /*
         * The while condition is true if: (there is are too few total
         * workers OR there is at least one waiter) AND (there are too
         * few active workers OR the pool is terminating).  The value
         * of e distinguishes the remaining cases: zero (no waiters)
         * for create, negative if terminating (in which case do
         * nothing), else release a waiter. The secondary checks for
         * release (non-null array etc) can fail if the pool begins
         * terminating after the test, and don't impose any added cost
         * because JVMs must perform null and bounds checks anyway.
         */
        long c; int e, u;
        while ((((e = (int)(c = ctl)) | (u = (int)(c >>> 32))) &
                (INT_SIGN|SHORT_SIGN)) == (INT_SIGN|SHORT_SIGN) && e >= 0) {
            if (e > 0) {                         // release a waiting worker
                int i; ForkJoinWorkerThread w; ForkJoinWorkerThread[] ws;
                if ((ws = workers) == null ||
                    (i = ~e & SMASK) >= ws.length ||
                    (w = ws[i]) == null)
                    break;
                long nc = (((long)(w.nextWait & E_MASK)) |
                           ((long)(u + UAC_UNIT) << 32));
                if (w.eventCount == e &&
                    UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) {
                    w.eventCount = (e + EC_UNIT) & E_MASK;
                    if (w.parked)
                        UNSAFE.unpark(w);
                    break;
                }
            }
            else if (UNSAFE.compareAndSwapLong
                     (this, ctlOffset, c,
                      (long)(((u + UTC_UNIT) & UTC_MASK) |
                             ((u + UAC_UNIT) & UAC_MASK)) << 32)) {
                addWorker();
                break;
            }
        }
    }

   
    private boolean tryReleaseWaiter() {
        long c; int e, i; ForkJoinWorkerThread w; ForkJoinWorkerThread[] ws;
        if ((e = (int)(c = ctl)) > 0 &&
            (int)(c >> AC_SHIFT) < 0 &&
            (ws = workers) != null &&
            (i = ~e & SMASK) < ws.length &&
            (w = ws[i]) != null) {
            long nc = ((long)(w.nextWait & E_MASK) |
                       ((c + AC_UNIT) & (AC_MASK|TC_MASK)));
            if (w.eventCount != e ||
                !UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc))
                return false;
            w.eventCount = (e + EC_UNIT) & E_MASK;
            if (w.parked)
                UNSAFE.unpark(w);
        }
        return true;
    }
  

 

 
    final int idlePerActive() {
        // Approximate at powers of two for small values, saturate past 4
        int p = parallelism;
        int a = p + (int)(ctl >> AC_SHIFT);
        return (a > (p >>>= 1) ? 0 :
                a > (p >>>= 1) ? 1 :
                a > (p >>>= 1) ? 2 :
                a > (p >>>= 1) ? 4 :
                8);
    }

    /**
     * Final callback from terminating worker.  Removes record of
     * worker from array, and adjusts counts. If pool is shutting
     * down, tries to complete termination.
     *
     * @param w the worker
     */
    final void deregisterWorker(ForkJoinWorkerThread w, Throwable ex) {
        int idx = w.poolIndex;
        int sc = w.stealCount;
        int steps = 0;
        // Remove from array, adjust worker counts and collect steal count.
        // We can intermix failed removes or adjusts with steal updates
        do {
            long s, c;
            int g;
            if (steps == 0 && ((g = scanGuard) & SG_UNIT) == 0 &&
                UNSAFE.compareAndSwapInt(this, scanGuardOffset,
                                         g, g |= SG_UNIT)) {
                ForkJoinWorkerThread[] ws = workers;
                if (ws != null && idx >= 0 &&
                    idx < ws.length && ws[idx] == w)
                    ws[idx] = null;    // verify
                nextWorkerIndex = idx;
                scanGuard = g + SG_UNIT;
                steps = 1;
            }
            if (steps == 1 &&
                UNSAFE.compareAndSwapLong(this, ctlOffset, c = ctl,
                                          (((c - AC_UNIT) & AC_MASK) |
                                           ((c - TC_UNIT) & TC_MASK) |
                                           (c & ~(AC_MASK|TC_MASK)))))
                steps = 2;
            if (sc != 0 &&
                UNSAFE.compareAndSwapLong(this, stealCountOffset,
                                          s = stealCount, s + sc))
                sc = 0;
        } while (steps != 2 || sc != 0);
        if (!tryTerminate(false)) {
            if (ex != null)   // possibly replace if died abnormally
                signalWork();
            else
                tryReleaseWaiter();
        }
    }

  

 
    public final Throwable getException() {
        int s = status;
        return ((s >= NORMAL)    ? null :
                (s == CANCELLED) ? new CancellationException() :
                getThrowableException());
    }
  

    public static ForkJoinPool getPool() {
        Thread t = Thread.currentThread();
        return (t instanceof ForkJoinWorkerThread) ?
            ((ForkJoinWorkerThread) t).pool : null;
    }

    public boolean tryUnfork() {
        return ((ForkJoinWorkerThread) Thread.currentThread())
            .unpushTask(this);
    }

    public static ExecutorService newSingleThreadExecutor() {
        return new FinalizableDelegatedExecutorService
            (new ThreadPoolExecutor(1, 1,
                                    0L, TimeUnit.MILLISECONDS,
                                    new LinkedBlockingQueue<Runnable>()));
    }

    private static final long SHRINK_RATE =
        4L * 1000L * 1000L * 1000L; // 4 seconds

            boolean casNext(SNode cmp, SNode val) {
                return cmp == next &&
                    UNSAFE.compareAndSwapObject(this, nextOffset, cmp, val);
            }