Examples of javolution.context.ConcurrentContext

javolution.context.ConcurrentContext
ct multiplication. } else { // Karatsuba multiplication in O(n^log2(3)) int bitLength=this.bitLength(); int n=(bitLength >> 1) + (bitLength & 1); // this = a + 2^n b, that = c + 2^n d LargeInteger b = this.shiftRight(n); LargeInteger a = this.minus(b.shiftLeft(n)); LargeInteger d = that.shiftRight(n); LargeInteger c = that.minus(d.shiftLeft(n)); Multiply ac = Multiply.valueOf(a, c); Multiply bd = Multiply.valueOf(b, d); Multiply abcd = Multiply.valueOf(a.plus(b), c.plus(d)); ConcurrentContext.execute(ac, bd, abcd); // a*c + ((a+b)*(c+d)-a*c-b*d) 2^n + b*d 2^2n return ac.value().plus( abcd.value().minus(ac.value().plus(bd.value())).shiftWordLeft(n)).plus( bd.value().shiftWordLeft(n << 1)); } } private static class Multiply implements Runnable { LargeInteger _left, _right, _value; static Multiply valueOf(LargeInteger left, LargeInteger right) { Multiply multiply = new Multiply(); // Or use an ObjectFactory (to allow stack allocation). multiply._left = left; multiply._right = right; return multiply; } public void run() { _value = _left.times(_right); // Recursive. } public LargeInteger value() { return _result; } };[/code] Here is a concurrent/recursive quick/merge sort using anonymous inner classes (the same method is used for benchmark):[code] private void quickSort(final FastTable table) { final int size = table.size(); if (size < 100) { table.sort(); // Direct quick sort. } else { // Splits table in two and sort both part concurrently. final FastTable t1 = FastTable.newInstance(); final FastTable t2 = FastTable.newInstance(); ConcurrentContext.enter(); try { ConcurrentContext.execute(new Runnable() { public void run() { t1.addAll(table.subList(0, size / 2)); quickSort(t1); // Recursive. } }); ConcurrentContext.execute(new Runnable() { public void run() { t2.addAll(table.subList(size / 2, size)); quickSort(t2); // Recursive. } }); } finally { ConcurrentContext.exit(); } // Merges results. for (int i=0, i1=0, i2=0; i < size; i++) { if (i1>= t1.size()) { table.set(i, t2.get(i2++)); } else if (i2 >= t2.size()) { table.set(i, t1.get(i1++)); } else { Comparable o1 = t1.get(i1); Comparable o2 = t2.get(i2); if (o1.compareTo(o2) < 0) { table.set(i, o1); i1++; } else { table.set(i, o2); i2++; } } } FastTable.recycle(t1); FastTable.recycle(t2); } }[/code]
{@link #getConcurrency() Concurrency} can be {@link LocalContext locally}adjusted. For example:[code] LocalContext.enter(); try { // Do not use more than half of the processors during analysis. ConcurrentContext.setConcurrency((Runtime.getRuntime().availableProcessors() / 2) - 1); runAnalysis(); // Use concurrent contexts internally. } finally { LocalContext.exit(); }[/code]
It should be noted that the concurrency cannot be increased above the configurable {@link #MAXIMUM_CONCURRENCY maximum concurrency}. In other words, if the maximum concurrency is 0, concurrency is disabled regardless of local concurrency settings.
@author Jean-Marie Dautelle @version 5.1, July 2, 2007

    }


    @Override
    public void perform(final Consumer<CollectionService<E>> action,
            CollectionService<E> view) {
        ConcurrentContext ctx = ConcurrentContext.enter();
        try {
            int concurrency = ctx.getConcurrency();
            CollectionService<E>[] subViews = view.split(concurrency + 1, false);
            for (int i = 1; i < subViews.length; i++) {
                final CollectionService<E> subView = subViews[i];
                ctx.execute(new Runnable() {
                    @Override
                    public void run() {
                        target().perform(action, subView);
                    }
                });
            }
            target().perform(action, subViews[0]); // This thread works too !
        } finally {
            // Any exception raised during parallel iterations will be re-raised here.                       
            ctx.exit();
        }
    }

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    }


    @Override
    public void update(final Consumer<CollectionService<E>> action,
            CollectionService<E> view) {
        ConcurrentContext ctx = ConcurrentContext.enter();
        try {
            int concurrency = ctx.getConcurrency();
            CollectionService<E>[] subViews = view.split(concurrency + 1, true);
            for (int i = 1; i < subViews.length; i++) {
                final CollectionService<E> subView = subViews[i];
                ctx.execute(new Runnable() {
                    @Override
                    public void run() {
                        target().update(action, subView);
                    }
                });
            }
            target().perform(action, subViews[0]); // This thread works too !
        } finally {
            // Any exception raised during parallel iterations will be re-raised here.                       
            ctx.exit();
        }
    }

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    }


    @Override
    public void perform(final Consumer<MapService<K, V>> action,
            MapService<K, V> view) {
        ConcurrentContext ctx = ConcurrentContext.enter();
        try {
            int concurrency = ctx.getConcurrency();
            MapService<K, V>[] subViews = view.split(concurrency + 1, false);
            for (int i = 1; i < subViews.length; i++) {
                final MapService<K, V> subView = subViews[i];
                ctx.execute(new Runnable() {
                    @Override
                    public void run() {
                        target().perform(action, subView);
                    }
                });
            }
            target().perform(action, subViews[0]); // This thread works too !
        } finally {
            // Any exception raised during parallel iterations will be re-raised here.                       
            ctx.exit();
        }
    }

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    }


    @Override
    public void update(final Consumer<MapService<K, V>> action,
            MapService<K, V> view) {
        ConcurrentContext ctx = ConcurrentContext.enter();
        try {
            int concurrency = ctx.getConcurrency();
            MapService<K, V>[] subViews = view.split(concurrency + 1, true);
            for (int i = 1; i < subViews.length; i++) {
                final MapService<K, V> subView = subViews[i];
                ctx.execute(new Runnable() {
                    @Override
                    public void run() {
                        target().update(action, subView);
                    }
                });
            }
            target().perform(action, subViews[0]); // This thread works too !
        } finally {
            // Any exception raised during parallel iterations will be re-raised here.                       
            ctx.exit();
        }
    }

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Related Classes of javolution.context.ConcurrentContext

javolution.util.internal.collection.ParallelCollectionImpl

javolution.util.internal.map.ParallelMapImpl

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