Metrics: Implement ExportComponent, make ProducerManager abstract. (#1347)

* Metrics: Implement ExportComponent, make ProducerManager abstract.

* Metrics: Add impl and impllite.

* Resolve two TODOs.

* Fix import path, leave a TODO for getMetricRegistry.

* Make NoopMetricProducerManager private. Add missing since tag.

6 files changed, 323 insertions, 0 deletions

diff --git a/impl_core/src/main/java/io/opencensus/implcore/metrics/MetricsComponentImplBase.java b/impl_core/src/main/java/io/opencensus/implcore/metrics/MetricsComponentImplBase.java
new file mode 100644
index 00000000..312b702e
--- /dev/null
+++ b/impl_core/src/main/java/io/opencensus/implcore/metrics/MetricsComponentImplBase.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2018, OpenCensus Authors
+ *
+ * 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 io.opencensus.implcore.metrics;
+
+import io.opencensus.implcore.metrics.export.ExportComponentImpl;
+import io.opencensus.metrics.MetricRegistry;
+import io.opencensus.metrics.MetricsComponent;
+
+/** Implementation of {@link MetricsComponent}. */
+public class MetricsComponentImplBase extends MetricsComponent {
+
+  private final ExportComponentImpl exportComponent;
+
+  @Override
+  public ExportComponentImpl getExportComponent() {
+    return exportComponent;
+  }
+
+  @Override
+  public MetricRegistry getMetricRegistry() {
+    // TODO: implement this method
+    throw new UnsupportedOperationException("not implemented");
+  }
+
+  public MetricsComponentImplBase() {
+    exportComponent = new ExportComponentImpl();
+  }
+}
diff --git a/impl_core/src/main/java/io/opencensus/implcore/metrics/export/ExportComponentImpl.java b/impl_core/src/main/java/io/opencensus/implcore/metrics/export/ExportComponentImpl.java
new file mode 100644
index 00000000..173c3aec
--- /dev/null
+++ b/impl_core/src/main/java/io/opencensus/implcore/metrics/export/ExportComponentImpl.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright 2018, OpenCensus Authors
+ *
+ * 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 io.opencensus.implcore.metrics.export;
+
+import io.opencensus.metrics.export.ExportComponent;
+import io.opencensus.metrics.export.MetricProducerManager;
+
+/** Implementation of {@link ExportComponent}. */
+public final class ExportComponentImpl extends ExportComponent {
+
+  private final MetricProducerManager metricProducerManager = new MetricProducerManagerImpl();
+
+  @Override
+  public MetricProducerManager getMetricProducerManager() {
+    return metricProducerManager;
+  }
+}
diff --git a/impl_core/src/main/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImpl.java b/impl_core/src/main/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImpl.java
new file mode 100644
index 00000000..fc9db5c1
--- /dev/null
+++ b/impl_core/src/main/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImpl.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2018, OpenCensus Authors
+ *
+ * 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 io.opencensus.implcore.metrics.export;
+
+import com.google.common.base.Preconditions;
+import io.opencensus.metrics.MetricProducer;
+import io.opencensus.metrics.export.MetricProducerManager;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.Set;
+import javax.annotation.concurrent.ThreadSafe;
+
+/** Implementation of {@link MetricProducerManager}. */
+@ThreadSafe
+public final class MetricProducerManagerImpl extends MetricProducerManager {
+
+  private volatile Set<MetricProducer> metricProducers =
+      Collections.unmodifiableSet(new LinkedHashSet<MetricProducer>());
+
+  @Override
+  public synchronized void add(MetricProducer metricProducer) {
+    Preconditions.checkNotNull(metricProducer, "metricProducer");
+    // Updating the set of MetricProducers happens under a lock to avoid multiple add or remove
+    // operations to happen in the same time.
+    Set<MetricProducer> newMetricProducers = new LinkedHashSet<MetricProducer>(metricProducers);
+    if (!newMetricProducers.add(metricProducer)) {
+      // The element already present, no need to update the current set of MetricProducers.
+      return;
+    }
+    metricProducers = Collections.unmodifiableSet(newMetricProducers);
+  }
+
+  @Override
+  public synchronized void remove(MetricProducer metricProducer) {
+    Preconditions.checkNotNull(metricProducer, "metricProducer");
+    // Updating the set of MetricProducers happens under a lock to avoid multiple add or remove
+    // operations to happen in the same time.
+    Set<MetricProducer> newMetricProducers = new LinkedHashSet<MetricProducer>(metricProducers);
+    if (!newMetricProducers.remove(metricProducer)) {
+      // The element not present, no need to update the current set of MetricProducers.
+      return;
+    }
+    metricProducers = Collections.unmodifiableSet(newMetricProducers);
+  }
+
+  @Override
+  public Set<MetricProducer> getAllMetricProducer() {
+    return metricProducers;
+  }
+}
diff --git a/impl_core/src/test/java/io/opencensus/implcore/metrics/MetricsComponentImplBaseTest.java b/impl_core/src/test/java/io/opencensus/implcore/metrics/MetricsComponentImplBaseTest.java
new file mode 100644
index 00000000..a86a53d9
--- /dev/null
+++ b/impl_core/src/test/java/io/opencensus/implcore/metrics/MetricsComponentImplBaseTest.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2018, OpenCensus Authors
+ *
+ * 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 io.opencensus.implcore.metrics;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import io.opencensus.implcore.metrics.export.ExportComponentImpl;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link MetricsComponentImplBase}. */
+@RunWith(JUnit4.class)
+public class MetricsComponentImplBaseTest {
+
+  @Test
+  public void getExportComponent() {
+    MetricsComponentImplBase metricsComponentImplBase = new MetricsComponentImplBase();
+    assertThat(metricsComponentImplBase.getExportComponent())
+        .isInstanceOf(ExportComponentImpl.class);
+  }
+}
diff --git a/impl_core/src/test/java/io/opencensus/implcore/metrics/export/ExportComponentImplTest.java b/impl_core/src/test/java/io/opencensus/implcore/metrics/export/ExportComponentImplTest.java
new file mode 100644
index 00000000..fb91641c
--- /dev/null
+++ b/impl_core/src/test/java/io/opencensus/implcore/metrics/export/ExportComponentImplTest.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2018, OpenCensus Authors
+ *
+ * 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 io.opencensus.implcore.metrics.export;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link ExportComponentImpl}. */
+@RunWith(JUnit4.class)
+public class ExportComponentImplTest {
+
+  @Test
+  public void getMetricProducerManager() {
+    ExportComponentImpl exportComponent = new ExportComponentImpl();
+    assertThat(exportComponent.getMetricProducerManager())
+        .isInstanceOf(MetricProducerManagerImpl.class);
+  }
+}
diff --git a/impl_core/src/test/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImplTest.java b/impl_core/src/test/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImplTest.java
new file mode 100644
index 00000000..7f2ec153
--- /dev/null
+++ b/impl_core/src/test/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImplTest.java
@@ -0,0 +1,115 @@
+/*
+ * Copyright 2018, OpenCensus Authors
+ *
+ * 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 io.opencensus.implcore.metrics.export;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import io.opencensus.metrics.MetricProducer;
+import io.opencensus.metrics.export.MetricProducerManager;
+import java.util.Set;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+/** Unit tests for {@link MetricProducerManagerImpl}. */
+@RunWith(JUnit4.class)
+public class MetricProducerManagerImplTest {
+
+  private final MetricProducerManager metricProducerManager = new MetricProducerManagerImpl();
+  @Mock private MetricProducer metricProducer;
+  @Mock private MetricProducer metricProducerOther;
+
+  @Rule public final ExpectedException thrown = ExpectedException.none();
+
+  @Before
+  public void setUp() {
+    MockitoAnnotations.initMocks(this);
+  }
+
+  @Test
+  public void add_DisallowsNull() {
+    thrown.expect(NullPointerException.class);
+    metricProducerManager.add(null);
+  }
+
+  @Test
+  public void add() {
+    metricProducerManager.add(metricProducer);
+    assertThat(metricProducerManager.getAllMetricProducer()).containsExactly(metricProducer);
+  }
+
+  @Test
+  public void add_DuplicateElement() {
+    metricProducerManager.add(metricProducer);
+    Set<MetricProducer> metricProducerSet = metricProducerManager.getAllMetricProducer();
+    assertThat(metricProducerSet).containsExactly(metricProducer);
+    metricProducerManager.add(metricProducer);
+    // Returns the same object.
+    assertThat(metricProducerManager.getAllMetricProducer()).isSameAs(metricProducerSet);
+  }
+
+  @Test
+  public void add_MultipleElements() {
+    metricProducerManager.add(metricProducer);
+    Set<MetricProducer> metricProducerSet = metricProducerManager.getAllMetricProducer();
+    assertThat(metricProducerSet).containsExactly(metricProducer);
+    metricProducerManager.add(metricProducerOther);
+    // Returns the same object.
+    assertThat(metricProducerManager.getAllMetricProducer())
+        .containsExactly(metricProducer, metricProducerOther);
+  }
+
+  @Test
+  public void addAndRemove() {
+    metricProducerManager.add(metricProducer);
+    assertThat(metricProducerManager.getAllMetricProducer()).containsExactly(metricProducer);
+    metricProducerManager.remove(metricProducer);
+    assertThat(metricProducerManager.getAllMetricProducer()).isEmpty();
+  }
+
+  @Test
+  public void remove_DisallowsNull() {
+    thrown.expect(NullPointerException.class);
+    metricProducerManager.remove(null);
+  }
+
+  @Test
+  public void remove_FromEmpty() {
+    metricProducerManager.remove(metricProducer);
+    assertThat(metricProducerManager.getAllMetricProducer()).isEmpty();
+  }
+
+  @Test
+  public void remove_NotPresent() {
+    metricProducerManager.add(metricProducer);
+    Set<MetricProducer> metricProducerSet = metricProducerManager.getAllMetricProducer();
+    assertThat(metricProducerSet).containsExactly(metricProducer);
+    metricProducerManager.remove(metricProducerOther);
+    // Returns the same object.
+    assertThat(metricProducerManager.getAllMetricProducer()).isSameAs(metricProducerSet);
+  }
+
+  @Test
+  public void getAllMetricProducer_empty() {
+    assertThat(metricProducerManager.getAllMetricProducer()).isEmpty();
+  }
+}