/*
* Copyright (c) 2010-2012 Grid Dynamics Consulting Services, Inc, All Rights Reserved
* http://www.griddynamics.com
*
* This library is free software; you can redistribute it and/or modify it under the terms of
* the Apache License; either
* version 2.0 of the License, or any later version.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.griddynamics.jagger.invoker;
import com.griddynamics.jagger.util.Pair;
import java.util.Iterator;
/** Schedules queries across endpoints one by one
* @author Mairbek Khadikov
* @n
* @par Details:
* @details . "One by one" algorithm - for input endpoints [e1, e2] and queries [q1, q2, q3]
* executes actions in following order: @n
* (e1, q1), (e2, q1), (e1, q2), (e2, q2), (e1, q3), (e2, q3). @n
* @n
*
* @param <Q> Query type
* @param <E> Endpoint type
*
* @ingroup Main_Distributors_group */
public class OneByOneLoadBalancer<Q, E> extends QueryPoolLoadBalancer<Q, E> {
public OneByOneLoadBalancer(){
super();
}
public OneByOneLoadBalancer(Iterable<Q> queryProvider, Iterable<E> endpointProvider){
super(queryProvider, endpointProvider);
}
/** Returns an iterator over pairs
* @author Grid Dynamics
* @n
* @par Details:
* @details Returns an iterator over pairs, which were created by "One by one" algorithm
*
* @return iterator over pairs */
@Override
public Iterator<Pair<Q, E>> provide() {
final CircularSupplier<Q> querySupplier = CircularSupplier.create(queryProvider);
final CircularSupplier<E> endpointSupplier = CircularSupplier.create(endpointProvider);
return new Iterator<Pair<Q, E>>() {
@Override
public boolean hasNext() {
return true;
}
@Override
public Pair<Q, E> next() {
boolean exceeded = endpointSupplier.exceeded();
E endpoint = endpointSupplier.pop();
Q query = exceeded ? querySupplier.pop() : querySupplier.peek();
return Pair.of(query, endpoint);
}
@Override
public void remove() {
throw new UnsupportedOperationException("Read only iterator");
}
@Override
public String toString() {
return "OneByOneLoadBalancer iterator";
}
};
}
@Override
public String toString() {
return "OneByOneLoadBalancer";
}
}