Implement host probing retry with major refactoring

- Implement probe retry
- Switch to typical core/provider design pattern for HostProbingService
  and as a result decoupling the dependency between SR and HostLocationProvider

Change-Id: I33a15af580677ea376b421ac3e26f9821dcca844
diff --git a/apps/segmentrouting/app/src/test/java/org/onosproject/segmentrouting/MockHostProbingService.java b/apps/segmentrouting/app/src/test/java/org/onosproject/segmentrouting/MockHostProbingService.java
new file mode 100644
index 0000000..807db0c
--- /dev/null
+++ b/apps/segmentrouting/app/src/test/java/org/onosproject/segmentrouting/MockHostProbingService.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright 2017-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.segmentrouting;
+
+import com.google.common.collect.Lists;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.Host;
+import org.onosproject.net.host.HostProbingService;
+import org.onosproject.net.host.ProbeMode;
+
+import java.util.List;
+import java.util.Objects;
+
+public class MockHostProbingService implements HostProbingService {
+    List<Probe> probes;
+
+    private class Probe {
+        private Host host;
+        private ConnectPoint connectPoint;
+        private ProbeMode probeMode;
+
+        Probe(Host host, ConnectPoint connectPoint, ProbeMode probeMode) {
+            this.host = host;
+            this.connectPoint = connectPoint;
+            this.probeMode = probeMode;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) {
+                return true;
+            }
+            if (!(o instanceof Probe)) {
+                return false;
+            }
+            Probe that = (Probe) o;
+            return (Objects.equals(this.host, that.host) &&
+                    Objects.equals(this.connectPoint, that.connectPoint) &&
+                    Objects.equals(this.probeMode, that.probeMode));
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(host, connectPoint, probeMode);
+        }
+    }
+
+    MockHostProbingService() {
+        probes = Lists.newArrayList();
+    }
+
+    boolean verifyProbe(Host host, ConnectPoint connectPoint, ProbeMode probeMode) {
+        Probe probe = new Probe(host, connectPoint, probeMode);
+        return probes.contains(probe);
+    }
+
+    @Override
+    public void probeHost(Host host, ConnectPoint connectPoint, ProbeMode probeMode) {
+        probes.add(new Probe(host, connectPoint, probeMode));
+    }
+}