[ONOS-7818] Implement a device behaviour to get table statistics. Make FlowRuleDriverProvider periodically call FlowRuleProviderService.pushTableStatistics().

Change-Id: Ife2b67b8c6c3582281704afe6f9a90538afbc798
(cherry picked from commit 1e8a1bd5cef7dda8aaaa453bcd96033f79be0e98)
diff --git a/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/P4RuntimeTableStatisticsDiscovery.java b/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/P4RuntimeTableStatisticsDiscovery.java
new file mode 100644
index 0000000..f130732
--- /dev/null
+++ b/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/P4RuntimeTableStatisticsDiscovery.java
@@ -0,0 +1,156 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.drivers.p4runtime;
+
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.behaviour.TableStatisticsDiscovery;
+import org.onosproject.net.flow.FlowRuleService;
+import org.onosproject.net.flow.FlowEntry;
+import org.onosproject.net.flow.TableId;
+import org.onosproject.net.flow.IndexTableId;
+import org.onosproject.net.flow.TableStatisticsEntry;
+import org.onosproject.net.flow.DefaultTableStatisticsEntry;
+import org.onosproject.net.pi.model.PiPipelineModel;
+import org.onosproject.net.pi.model.PiPipelineInterpreter;
+import org.onosproject.net.pi.model.PiTableId;
+import org.onosproject.net.pi.model.PiTableModel;
+
+import java.util.List;
+import java.util.Collections;
+import java.util.Map;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.ArrayList;
+
+import static com.google.common.collect.Lists.newArrayList;
+
+/**
+ * Implementation of behaviour TableStatisticsDiscovery for P4Runtime.
+ */
+public class P4RuntimeTableStatisticsDiscovery extends AbstractP4RuntimeHandlerBehaviour
+        implements TableStatisticsDiscovery {
+
+    @Override
+    public List<TableStatisticsEntry> getTableStatistics() {
+        if (!setupBehaviour()) {
+            return Collections.emptyList();
+        }
+        FlowRuleService flowService = handler().get(FlowRuleService.class);
+        PiPipelineInterpreter interpreter = getInterpreter();
+        PiPipelineModel model = pipeconf.pipelineModel();
+        List<TableStatisticsEntry> tableStatsList;
+
+        List<FlowEntry> rules = newArrayList(flowService.getFlowEntries(deviceId));
+        Map<PiTableId, Integer> piTableFlowCount = piFlowRuleCounting(model, interpreter, rules);
+        Map<PiTableId, Long> piTableMatchCount = piMatchedCounting(model, interpreter, rules);
+        tableStatsList = generatePiFlowTableStatistics(piTableFlowCount, piTableMatchCount, model, deviceId);
+
+        return tableStatsList;
+    }
+
+    /**
+     * Returns the number of added flows in each table.
+     *
+     * @param model pipeline model
+     * @param interpreter pipeline interpreter
+     * @param rules flow rules in this device
+     * @return hashmap containing matched packet counting for each table
+     */
+    private Map<PiTableId, Integer> piFlowRuleCounting(PiPipelineModel model, PiPipelineInterpreter interpreter,
+                                                       List<FlowEntry> rules) {
+        Map<PiTableId, Integer> piTableFlowCount = new HashMap<>();
+        for (PiTableModel tableModel : model.tables()) {
+            piTableFlowCount.put(tableModel.id(), 0);
+        }
+        for (FlowEntry f : rules) {
+            if (f.state() == FlowEntry.FlowEntryState.ADDED) {
+                PiTableId piTableId = getPiTableId(f, interpreter);
+                if (piTableId != null) {
+                    piTableFlowCount.put(piTableId, piTableFlowCount.get(piTableId) + 1);
+                }
+            }
+        }
+        return piTableFlowCount;
+    }
+
+    /**
+     * Returns the number of matched packets for each table.
+     *
+     * @param model pipeline model
+     * @param interpreter pipeline interpreter
+     * @param rules flow rules in this device
+     * @return hashmap containing flow rule counting for each table
+     */
+    private Map<PiTableId, Long> piMatchedCounting(PiPipelineModel model, PiPipelineInterpreter interpreter,
+                                                   List<FlowEntry> rules) {
+        Map<PiTableId, Long> piTableMatchCount = new HashMap<>();
+        for (PiTableModel tableModel : model.tables()) {
+            piTableMatchCount.put(tableModel.id(), (long) 0);
+        }
+        for (FlowEntry f : rules) {
+            if (f.state() == FlowEntry.FlowEntryState.ADDED) {
+                PiTableId piTableId = getPiTableId(f, interpreter);
+                if (piTableId != null) {
+                    piTableMatchCount.put(piTableId, piTableMatchCount.get(piTableId) + f.packets());
+                }
+            }
+        }
+        return piTableMatchCount;
+    }
+
+    /**
+     * Returns the PiTableId of the pipeline independent table that contains the flow rule. If null is returned, it
+     * means that the given flow rule's table ID is index table ID without a mapping with a pipeline independent table
+     * ID.
+     *
+     * @param flowEntry flow rule
+     * @param interpreter pipeline interpreter
+     * @return PiTableId of the table containing input FlowEntry or null
+     */
+    private PiTableId getPiTableId(FlowEntry flowEntry, PiPipelineInterpreter interpreter) {
+        return flowEntry.table().type() == TableId.Type.PIPELINE_INDEPENDENT ?  (PiTableId) flowEntry.table() :
+                interpreter.mapFlowRuleTableId(((IndexTableId) flowEntry.table()).id()).orElse(null);
+    }
+
+    /**
+     * Returns the list of table statistics for P4 switch.
+     *
+     * @param piTableFlowCount hashmap containing the number of flow rules for each table
+     * @param piTableMatchCount hashmap containing the number of matched packets for each table
+     * @param model pipeline model
+     * @param deviceId device ID
+     * @return list of table statistics for P4 switch
+     */
+    private List<TableStatisticsEntry> generatePiFlowTableStatistics(Map<PiTableId, Integer> piTableFlowCount,
+                                                                       Map<PiTableId, Long> piTableMatchCount,
+                                                                       PiPipelineModel model, DeviceId deviceId) {
+        List<TableStatisticsEntry> tableStatsList;
+        Iterator it = piTableFlowCount.entrySet().iterator();
+        tableStatsList = new ArrayList<>();
+        while (it.hasNext()) {
+            Map.Entry pair = (Map.Entry) it.next();
+            TableStatisticsEntry tableStat = DefaultTableStatisticsEntry.builder()
+                    .withDeviceId(deviceId)
+                    .withTableId((PiTableId) pair.getKey())
+                    .withActiveFlowEntries(piTableFlowCount.get(pair.getKey()))
+                    .withPacketsMatchedCount(piTableMatchCount.get(pair.getKey()))
+                    .withMaxSize(model.table((PiTableId) pair.getKey()).get().maxSize()).build();
+            tableStatsList.add(tableStat);
+            it.remove();
+        }
+        return tableStatsList;
+    }
+}
diff --git a/drivers/p4runtime/src/main/resources/p4runtime-drivers.xml b/drivers/p4runtime/src/main/resources/p4runtime-drivers.xml
index 7464e14..78188a7 100644
--- a/drivers/p4runtime/src/main/resources/p4runtime-drivers.xml
+++ b/drivers/p4runtime/src/main/resources/p4runtime-drivers.xml
@@ -16,6 +16,8 @@
   -->
 <drivers>
     <driver name="p4runtime" manufacturer="p4.org" hwVersion="master" swVersion="master">
+        <behaviour api="org.onosproject.net.behaviour.TableStatisticsDiscovery"
+                   impl="org.onosproject.drivers.p4runtime.P4RuntimeTableStatisticsDiscovery"/>
         <behaviour api="org.onosproject.net.device.DeviceHandshaker"
                    impl="org.onosproject.drivers.p4runtime.P4RuntimeHandshaker"/>
         <behaviour api="org.onosproject.net.packet.PacketProgrammable"