Let met just keep this short and let the code speak for itself:
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// The next fields counts the number of time the decide method is called
// IMPORTANT: This field can be updated by multiple threads. It follows that
// its values may *not* be incremented sequentially. However, we don't care
// about the actual value of the field except that from time to time the
// expression (invocationCounter++ & 0xF) == 0xF) should be true.
private long invocationCounter = 0;
Three letters apply here.