org.opennms.netmgt.bsm.service.model.functions.reduce.ExponentialPropagation.java Source code

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Here is the source code for org.opennms.netmgt.bsm.service.model.functions.reduce.ExponentialPropagation.java

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package org.opennms.netmgt.bsm.service.model.functions.reduce;

import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;

import org.opennms.netmgt.bsm.service.model.Status;
import org.opennms.netmgt.bsm.service.model.StatusWithIndex;
import org.opennms.netmgt.bsm.service.model.StatusWithIndices;
import org.opennms.netmgt.bsm.service.model.functions.annotations.Function;
import org.opennms.netmgt.bsm.service.model.functions.annotations.Parameter;

import com.google.common.base.Preconditions;
import com.google.common.collect.Iterables;

@Function(name = "ExponentialPropagation", description = "Propagate severities using a given base number")
public class ExponentialPropagation implements ReductionFunction {

    @Parameter(key = "base", defaultValue = "2.0", description = "The base used to calculate the required elements for propagation")
    private double base;

    @Override
    public Optional<StatusWithIndices> reduce(List<StatusWithIndex> statuses) {
        // Exit early for no incoming statuses
        if (statuses.isEmpty()) {
            return Optional.empty();
        }

        // Unfortunately, our computation will result in a normal severity when all input statuses are
        // indeterminate. So, we have to handle this case explicitly here...
        if (Iterables.all(statuses, si -> si.getStatus() == Status.INDETERMINATE)) {
            return Optional.empty();
        }

        // Get the exponential sum of all child states
        final double sum = statuses.stream().filter(si -> si.getStatus().ordinal() >= Status.WARNING.ordinal()) // Ignore normal and indeterminate
                .mapToDouble(si -> Math.pow(this.base, si.getStatus().ordinal() - Status.WARNING.ordinal())) // Offset to warning = n^0
                .sum();

        // Grab the indices from all the statuses that contributed to the sum
        // since these contribute to the cause
        final List<Integer> contributingIndices = statuses.stream()
                .filter(si -> si.getStatus().ordinal() >= Status.WARNING.ordinal()).map(si -> si.getIndex())
                .distinct().sorted().collect(Collectors.toList());

        // Get the log n of the sum
        final int res = (int) Math.floor(Math.log(sum) / Math.log(this.base)) + Status.WARNING.ordinal(); // Revert offset from above

        // Find the resulting status and treat values lower than NORMAL.ordinal() as NORMAL.ordinal() and
        // all values higher than CRITICAL.ordinal() as CRITICAL.ordinal()
        final Status effectiveStatus = Status
                .get(Math.max(Math.min(res, Status.CRITICAL.ordinal()), Status.NORMAL.ordinal()));
        return Optional.of(new StatusWithIndices(effectiveStatus, contributingIndices));
    }

    public void setBase(final double base) {
        Preconditions.checkArgument(base > 1.0);

        this.base = base;
    }

    public double getBase() {
        return this.base;
    }

    @Override
    public <T> T accept(ReduceFunctionVisitor<T> visitor) {
        return visitor.visit(this);
    }
}