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POHow to read unique elements from array per thread?
 

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  1. POHow to read unique elements from array per thread?
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    <p>I have an object based on array, which implements the following interface:</p> <pre><code>public interface PairSupplier&lt;Q, E&gt; { public int size(); public Pair&lt;Q, E&gt; get(int index); } </code></pre> <p>I would like to create a specific iterator over it: </p> <pre><code>public boolean hasNext(){ return true; } public Pair&lt;Q, E&gt; next(){ //some magic } </code></pre> <p>In method <strong>next</strong> I would like to return some element from <strong>PairSupplier</strong>. </p> <p>This element should be unique for thread, other threads should not have this element. </p> <p>Since PairSupplier has a final size, this situation is not always possible, but I would like to approach it. </p> <p>The <strong>order</strong> of elements doesn't matter, thread can take same element at a <strong>different</strong> time. </p> <p><strong>Example</strong>: <code>2 Threads</code>, <code>5 elements</code> - <strong><code>{1,2,3,4,5}</code></strong></p> <pre><code>Thread 1 | Thread 2 1 2 3 4 5 1 3 2 4 5 </code></pre> <p><strong>My solution</strong>:</p> <p>I create AtomicInteger index, which I increment on every <strong>next</strong> call.</p> <pre><code>PairSupplier pairs; AtomicInteger index; public boolean hasNext(){ return true; } public Pair&lt;Q, E&gt; next(){ int position = index.incrementAndGet() % pairs.size; if (position &lt; 0) { position *= -1; position = pairs.size - position; } return pairs.get(position); } </code></pre> <p><strong>pairs</strong> and <strong>index</strong> are shared among all threads.</p> <p>I found this solution not scalable (because all threads go for increment), maybe someone have better ideas?</p> <p>This iterator will be used by <strong>50-1000 threads</strong>.</p>
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    1. USSergey Weiss
    1. USMary Ryllo
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    1. COIs that complete code ?
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      1. USSachin Thapa
    2. COthis [example(s)](http://arashmd.blogspot.com/2013/07/java-thread-example.html#ai) may help.
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    3. CO@SachinThapa no, I only would like to show the problem and a part of possible solution
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      1. USMary Ryllo
 

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