Add latency constraint

Change-Id: If9936e995e5a40370965b9693ff7dda941d8c5b8

+/*
+ * Copyright 2014 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.onlab.onos.net.intent.constraint;
+
+import com.google.common.base.MoreObjects;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.Path;
+import org.onlab.onos.net.intent.Constraint;
+import org.onlab.onos.net.resource.LinkResourceService;
+
+import java.time.Duration;
+import java.time.temporal.ChronoUnit;
+import java.util.Objects;
+
+/**
+ * Constraint that evaluates the latency through a path.
+ */
+public class LatencyConstraint implements Constraint {
+
+    // TODO: formalize the key for latency all over the codes.
+    private static final String LATENCY_KEY = "latency";
+
+    private final Duration latency;
+
+    /**
+     * Creates a new constraint to keep under specified latency through a path.
+     * @param latency latency to be kept
+     */
+    public LatencyConstraint(Duration latency) {
+        this.latency = latency;
+    }
+
+    public Duration getLatency() {
+        return latency;
+    }
+
+    @Override
+    public double cost(Link link, LinkResourceService resourceService) {
+        String value = link.annotations().value(LATENCY_KEY);
+
+        double latencyInMicroSec;
+        try {
+            latencyInMicroSec = Double.parseDouble(value);
+        } catch (NumberFormatException e) {
+            latencyInMicroSec = 1.0;
+        }
+
+        return latencyInMicroSec;
+    }
+
+    @Override
+    public boolean validate(Path path, LinkResourceService resourceService) {
+        double pathLatency = path.links().stream().mapToDouble(link -> cost(link, resourceService)).sum();
+        return Duration.of((long) pathLatency, ChronoUnit.MICROS).compareTo(latency) <= 0;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(latency);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (!(obj instanceof LatencyConstraint)) {
+            return false;
+        }
+
+        final LatencyConstraint that = (LatencyConstraint) obj;
+        return Objects.equals(this.latency, that.latency);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(this)
+                .add("latency", latency)
+                .toString();
+    }
+}

+/*
+ * Copyright 2014 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.onlab.onos.net.intent.constraint;
+
+import com.google.common.testing.EqualsTester;
+import org.junit.Before;
+import org.junit.Test;
+import org.onlab.onos.net.Annotations;
+import org.onlab.onos.net.DefaultAnnotations;
+import org.onlab.onos.net.DefaultLink;
+import org.onlab.onos.net.DefaultPath;
+import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.Path;
+import org.onlab.onos.net.PortNumber;
+import org.onlab.onos.net.provider.ProviderId;
+import org.onlab.onos.net.resource.LinkResourceService;
+
+import java.time.Duration;
+import java.time.temporal.ChronoUnit;
+import java.util.Arrays;
+
+import static org.easymock.EasyMock.createMock;
+import static org.hamcrest.Matchers.closeTo;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
+import static org.onlab.onos.net.DefaultLinkTest.cp;
+import static org.onlab.onos.net.DeviceId.deviceId;
+import static org.onlab.onos.net.Link.Type.DIRECT;
+
+public class LatencyConstraintTest {
+
+    private static final DeviceId DID1 = deviceId("of:1");
+    private static final DeviceId DID2 = deviceId("of:2");
+    private static final DeviceId DID3 = deviceId("of:3");
+    private static final PortNumber PN1 = PortNumber.portNumber(1);
+    private static final PortNumber PN2 = PortNumber.portNumber(2);
+    private static final PortNumber PN3 = PortNumber.portNumber(3);
+    private static final PortNumber PN4 = PortNumber.portNumber(4);
+    private static final ProviderId PROVIDER_ID = new ProviderId("of", "foo");
+    private static final String LATENCY_KEY = "latency";
+    private static final String LATENCY1 = "3.0";
+    private static final String LATENCY2 = "4.0";
+
+    private LatencyConstraint sut;
+    private LinkResourceService linkResourceService;
+
+    private Path path;
+    private Link link1;
+    private Link link2;
+
+    @Before
+    public void setUp() {
+        linkResourceService = createMock(LinkResourceService.class);
+
+        Annotations annotations1 = DefaultAnnotations.builder().set(LATENCY_KEY, LATENCY1).build();
+        Annotations annotations2 = DefaultAnnotations.builder().set(LATENCY_KEY, LATENCY2).build();
+
+        link1 = new DefaultLink(PROVIDER_ID, cp(DID1, PN1), cp(DID2, PN2), DIRECT, annotations1);
+        link2 = new DefaultLink(PROVIDER_ID, cp(DID2, PN3), cp(DID3, PN4), DIRECT, annotations2);
+        path = new DefaultPath(PROVIDER_ID, Arrays.asList(link1, link2), 10);
+    }
+
+    /**
+     * Tests the path latency is less than the supplied constraint.
+     */
+    @Test
+    public void testLessThanLatency() {
+        sut = new LatencyConstraint(Duration.of(10, ChronoUnit.MICROS));
+
+        assertThat(sut.validate(path, linkResourceService), is(true));
+    }
+
+    /**
+     * Tests the path latency is more than the supplied constraint.
+     */
+    @Test
+    public void testMoreThanLatency() {
+        sut = new LatencyConstraint(Duration.of(3, ChronoUnit.MICROS));
+
+        assertThat(sut.validate(path, linkResourceService), is(false));
+    }
+
+    /**
+     * Tests the link latency is equal to "latency" annotated value.
+     */
+    @Test
+    public void testCost() {
+        sut = new LatencyConstraint(Duration.of(10, ChronoUnit.MICROS));
+
+        assertThat(sut.cost(link1, linkResourceService), is(closeTo(Double.parseDouble(LATENCY1), 1.0e-6)));
+        assertThat(sut.cost(link2, linkResourceService), is(closeTo(Double.parseDouble(LATENCY2), 1.0e-6)));
+    }
+
+    /**
+     * Tests equality of the instances.
+     */
+    @Test
+    public void testEquality() {
+        LatencyConstraint c1 = new LatencyConstraint(Duration.of(1, ChronoUnit.SECONDS));
+        LatencyConstraint c2 = new LatencyConstraint(Duration.of(1000, ChronoUnit.MILLIS));
+
+        LatencyConstraint c3 = new LatencyConstraint(Duration.of(2, ChronoUnit.SECONDS));
+        LatencyConstraint c4 = new LatencyConstraint(Duration.of(2000, ChronoUnit.MILLIS));
+
+        new EqualsTester()
+                .addEqualityGroup(c1, c2)
+                .addEqualityGroup(c3, c4)
+                .testEquals();
+    }
+}