brooklyn.policy.loadbalancing.PolicyUtilForPool Maven / Gradle / Ivy

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package brooklyn.policy.loadbalancing;

import java.util.Set;

/**
 * Provides conveniences for searching for hot/cold containers in a provided pool model.
 * Ported from Monterey v3, with irrelevant bits removed.
 */
public class PolicyUtilForPool {
    
    private final BalanceablePoolModel model;
    
    
    public PolicyUtilForPool (BalanceablePoolModel model) {
        this.model = model;
    }
    
    public ContainerType findColdestContainer(Set excludedContainers) {
        return findColdestContainer(excludedContainers, null);
    }
    
    /**
     * Identifies the container with the maximum spare capacity (highThreshold - currentWorkrate),
     * returns null if none of the model's nodes has spare capacity.
     */
    public ContainerType findColdestContainer(Set excludedContainers, LocationConstraint locationConstraint) {
        double maxSpareCapacity = 0;
        ContainerType coldest = null;
        
        for (ContainerType c : model.getPoolContents()) {
            if (excludedContainers.contains(c))
                continue;
            if (locationConstraint != null && !locationConstraint.isPermitted(model.getLocation(c)))
                continue;
            
            double highThreshold = model.getHighThreshold(c);
            double totalWorkrate = model.getTotalWorkrate(c);
            double spareCapacity = highThreshold - totalWorkrate;
            
            if (highThreshold == -1 || totalWorkrate == -1) {
                continue; // container presumably has been removed
            }
            if (spareCapacity > maxSpareCapacity) {
                maxSpareCapacity = spareCapacity;
                coldest = c;
            }
        }
        return coldest;
    }
    
    /**
     * Identifies the container with the maximum overshoot (currentWorkrate - highThreshold),
     * returns null if none of the model's  nodes has an overshoot.
     */
    public ContainerType findHottestContainer(Set excludedContainers) {
        double maxOvershoot = 0;
        ContainerType hottest = null;
        
        for (ContainerType c : model.getPoolContents()) {
            if (excludedContainers.contains(c))
                continue;
            
            double totalWorkrate = model.getTotalWorkrate(c);
            double highThreshold = model.getHighThreshold(c);
            double overshoot = totalWorkrate - highThreshold;
            
            if (highThreshold == -1 || totalWorkrate == -1) {
                continue; // container presumably has been removed
            }
            if (overshoot > maxOvershoot) {
                maxOvershoot = overshoot;
                hottest = c;
            }
        }
        return hottest;
    }
    
}