Implementation of Hybrid Logical Clock Service.
Change-Id: I52e231433d044f9e6156db7e28bde9fd199118e8
diff --git a/core/net/src/main/java/org/onosproject/core/impl/HybridLogicalClockManager.java b/core/net/src/main/java/org/onosproject/core/impl/HybridLogicalClockManager.java
new file mode 100644
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--- /dev/null
+++ b/core/net/src/main/java/org/onosproject/core/impl/HybridLogicalClockManager.java
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+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * 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.core.impl;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+import java.util.function.Supplier;
+
+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.Service;
+import org.onosproject.core.HybridLogicalClockService;
+import org.onosproject.core.HybridLogicalTime;
+import org.slf4j.Logger;
+
+/**
+ * Implementation of {@link HybridLogicalClockService}.
+ * <p>
+ * Implementation is based on HLT <a href="http://www.cse.buffalo.edu/tech-reports/2014-04.pdf">paper</a>.
+ */
+@Component(immediate = true)
+@Service
+public class HybridLogicalClockManager implements HybridLogicalClockService {
+
+ private final Logger log = getLogger(getClass());
+
+ protected Supplier<Long> physicalTimeSource = System::currentTimeMillis;
+
+ private long logicalTime = 0;
+ private long logicalCounter = 0;
+
+ @Activate
+ public void activate() {
+ log.info("Started");
+ }
+
+ @Deactivate
+ public void deactivate() {
+ log.info("Stopped");
+ }
+
+ @Override
+ public synchronized HybridLogicalTime timeNow() {
+ final long oldLogicalTime = logicalTime;
+ logicalTime = Math.max(oldLogicalTime, physicalTimeSource.get());
+ if (logicalTime == oldLogicalTime) {
+ logicalCounter++;
+ } else {
+ logicalCounter = 0;
+ }
+ return new HybridLogicalTime(logicalTime, logicalCounter);
+ }
+
+ @Override
+ public synchronized void recordEventTime(HybridLogicalTime eTime) {
+ final long oldLogicalTime = logicalTime;
+ logicalTime = Math.max(oldLogicalTime, Math.max(eTime.logicalTime(), physicalTimeSource.get()));
+ if (logicalTime == oldLogicalTime && oldLogicalTime == eTime.logicalTime()) {
+ logicalCounter = Math.max(logicalCounter, eTime.logicalCounter()) + 1;
+ } else if (logicalTime == oldLogicalTime) {
+ logicalCounter++;
+ } else if (logicalTime == eTime.logicalTime()) {
+ logicalCounter = eTime.logicalCounter() + 1;
+ } else {
+ logicalCounter = 0;
+ }
+ }
+
+ protected long logicalTime() {
+ return logicalTime;
+ }
+
+ protected long logicalCounter() {
+ return logicalCounter;
+ }
+}
diff --git a/core/net/src/test/java/org/onosproject/core/impl/HybridLogicalClockManagerTest.java b/core/net/src/test/java/org/onosproject/core/impl/HybridLogicalClockManagerTest.java
new file mode 100644
index 0000000..806b417
--- /dev/null
+++ b/core/net/src/test/java/org/onosproject/core/impl/HybridLogicalClockManagerTest.java
@@ -0,0 +1,99 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * 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.core.impl;
+
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.Supplier;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.onosproject.core.HybridLogicalTime;
+
+/**
+ * Unit tests for {@link HybridLogicalClockManager}.
+ */
+public class HybridLogicalClockManagerTest {
+
+ @Test
+ public void testLocalEvents() {
+ AtomicLong ticker = new AtomicLong();
+ Supplier<Long> ptSource = ticker::get;
+ HybridLogicalClockManager clockManager = new HybridLogicalClockManager();
+ clockManager.physicalTimeSource = ptSource;
+
+ HybridLogicalTime time1 = clockManager.timeNow();
+ Assert.assertEquals(0, time1.logicalTime());
+ Assert.assertEquals(1, time1.logicalCounter());
+
+ HybridLogicalTime time2 = clockManager.timeNow();
+ Assert.assertEquals(0, time2.logicalTime());
+ Assert.assertEquals(2, time2.logicalCounter());
+
+ ticker.incrementAndGet();
+
+ HybridLogicalTime time3 = clockManager.timeNow();
+ Assert.assertEquals(1, time3.logicalTime());
+ Assert.assertEquals(0, time3.logicalCounter());
+
+ HybridLogicalTime time4 = clockManager.timeNow();
+ Assert.assertEquals(1, time4.logicalTime());
+ Assert.assertEquals(1, time4.logicalCounter());
+ }
+
+ @Test
+ public void testReceiveEvents() {
+ AtomicLong ticker = new AtomicLong(1);
+ Supplier<Long> ptSource = ticker::get;
+ HybridLogicalClockManager clockManager = new HybridLogicalClockManager();
+ clockManager.physicalTimeSource = ptSource;
+
+ HybridLogicalTime time1 = clockManager.timeNow();
+ Assert.assertEquals(1, time1.logicalTime());
+ Assert.assertEquals(0, time1.logicalCounter());
+
+ HybridLogicalTime eventTime1 = new HybridLogicalTime(1, 0);
+ clockManager.recordEventTime(eventTime1);
+
+ Assert.assertEquals(1, clockManager.logicalTime());
+ Assert.assertEquals(1, clockManager.logicalCounter());
+
+ HybridLogicalTime eventTime2 = new HybridLogicalTime(2, 0);
+ clockManager.recordEventTime(eventTime2);
+
+ Assert.assertEquals(2, clockManager.logicalTime());
+ Assert.assertEquals(1, clockManager.logicalCounter());
+
+ HybridLogicalTime eventTime3 = new HybridLogicalTime(2, 2);
+ clockManager.recordEventTime(eventTime3);
+
+ Assert.assertEquals(2, clockManager.logicalTime());
+ Assert.assertEquals(3, clockManager.logicalCounter());
+
+ HybridLogicalTime eventTime4 = new HybridLogicalTime(2, 1);
+ clockManager.recordEventTime(eventTime4);
+
+ Assert.assertEquals(2, clockManager.logicalTime());
+ Assert.assertEquals(4, clockManager.logicalCounter());
+
+ ticker.set(4);
+
+ HybridLogicalTime eventTime5 = new HybridLogicalTime(3, 0);
+ clockManager.recordEventTime(eventTime5);
+
+ Assert.assertEquals(4, clockManager.logicalTime());
+ Assert.assertEquals(0, clockManager.logicalCounter());
+ }
+}