api and manager for statistic service

Change-Id: If00b8b43a2bd780ae3c05321697896290fb0f415

+package org.onlab.onos.net.statistic;
+
+/**
+ * Simple data repository for link load information.
+ */
+public interface Load {
+
+    /**
+     * Obtain the current observed rate on a link.
+     * @return long value
+     */
+    long rate();
+
+    /**
+     * Obtain the latest counter viewed on that link.
+     * @return long value
+     */
+    long latest();
+
+}

+package org.onlab.onos.net.statistic;
+
+import org.onlab.onos.net.ConnectPoint;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.Path;
+import org.onlab.onos.net.flow.FlowRule;
+
+/**
+ * Service for obtaining statistic information about link in the system.
+ * Statistics are obtained from the FlowRuleService in order to minimize the
+ * amount of hammering occuring at the dataplane.
+ */
+public interface StatisticService {
+
+    /**
+     * Obtain the load for a the ingress to the given link.
+     * @param link the link to query.
+     * @return a {@link org.onlab.onos.net.statistic.Load Load}
+     */
+    Load load(Link link);
+
+    /**
+     * Obtain the load for the given port.
+     * @param connectPoint the port to query
+     * @return a {@link org.onlab.onos.net.statistic.Load}
+     */
+    Load load(ConnectPoint connectPoint);
+
+    /**
+     * Find the most loaded link along a path.
+     * @param path the path to search in
+     * @return the most loaded {@link org.onlab.onos.net.Link}.
+     */
+    Link max(Path path);
+
+    /**
+     * Find the least loaded link along a path.
+     * @param path the path to search in
+     * @return the least loaded {@link org.onlab.onos.net.Link}.
+     */
+    Link min(Path path);
+
+    /**
+     * Returns the highest hitter (a flow rule) of for a given port, ie. the
+     * flow rule which is generating the most load.
+     * @param connectPoint the port
+     * @return the flow rule
+     */
+    FlowRule highestHitter(ConnectPoint connectPoint);
+
+}

+package org.onlab.onos.net.statistic;
+
+import org.onlab.onos.net.ConnectPoint;
+import org.onlab.onos.net.flow.FlowEntry;
+import org.onlab.onos.net.flow.FlowRule;
+
+import java.util.Set;
+
+/**
+ * Store to house the computed statistics.
+ */
+public interface StatisticStore {
+
+    /**
+     * Lay the foundation for receiving flow stats for this rule.
+     * @param rule a {@link org.onlab.onos.net.flow.FlowRule}
+     */
+    void prepareForStatistics(FlowRule rule);
+
+    /**
+     * Remove entries associated with this rule.
+     a @param rule {@link org.onlab.onos.net.flow.FlowRule}
+     */
+    void removeFromStatistics(FlowRule rule);
+
+    /**
+     * Adds a stats observation for a flow rule.
+     * @param rule a {@link org.onlab.onos.net.flow.FlowEntry}
+     */
+    void addOrUpdateStatistic(FlowEntry rule);
+
+    /**
+     * Fetches the current observed stats values.
+     * @param connectPoint the port to fetch information for
+     * @return set of current flow rules
+     */
+    Set<FlowEntry> getCurrentStatistic(ConnectPoint connectPoint);
+
+    /**
+     * Fetches the current observed stats values.
+     * @param connectPoint the port to fetch information for
+     * @return set of current values
+     */
+    Set<FlowEntry> getPreviousStatistic(ConnectPoint connectPoint);
+}

+/**
+ * Service for looking up statistics on links.
+ */
+package org.onlab.onos.net.statistic;
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+package org.onlab.onos.net.statistic.impl;
+
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.apache.felix.scr.annotations.Service;
+import org.onlab.onos.net.ConnectPoint;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.Path;
+import org.onlab.onos.net.flow.FlowRule;
+import org.onlab.onos.net.flow.FlowRuleEvent;
+import org.onlab.onos.net.flow.FlowRuleListener;
+import org.onlab.onos.net.flow.FlowRuleService;
+import org.onlab.onos.net.statistic.Load;
+import org.onlab.onos.net.statistic.StatisticService;
+import org.onlab.onos.net.statistic.StatisticStore;
+import org.slf4j.Logger;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Provides an implementation of the Statistic Service.
+ */
+@Component(immediate = true)
+@Service
+public class StatisticManager implements StatisticService {
+
+    private final Logger log = getLogger(getClass());
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected FlowRuleService flowRuleService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected StatisticStore statisticStore;
+
+    private final InternalFlowRuleListener listener = new InternalFlowRuleListener();
+
+    @Activate
+    public void activate() {
+        flowRuleService.addListener(listener);
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        flowRuleService.removeListener(listener);
+        log.info("Stopped");
+    }
+
+    @Override
+    public Load load(Link link) {
+        return null;
+    }
+
+    @Override
+    public Load load(ConnectPoint connectPoint) {
+        return null;
+    }
+
+    @Override
+    public Link max(Path path) {
+        return null;
+    }
+
+    @Override
+    public Link min(Path path) {
+        return null;
+    }
+
+    @Override
+    public FlowRule highestHitter(ConnectPoint connectPoint) {
+        return null;
+    }
+
+    /**
+     * Internal flow rule event listener.
+     */
+    private class InternalFlowRuleListener implements FlowRuleListener {
+
+        @Override
+        public void event(FlowRuleEvent event) {
+
+        }
+    }
+
+
+}

+/**
+ * Core subsystem for responding to statistical inquiries.
+ */
+package org.onlab.onos.net.statistic.impl;
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