Merge remote-tracking branch 'aosp/upstream-master' into merge am: dd3cabeacc am: 6fbc3cf5a1

am: 13217871fe

Change-Id: Icfe12d6db2f81a6f5c65241919b1d63fb665ffd6

1 files changed, 64 insertions, 0 deletions

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..6f585a10
--- /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.export.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;
+  }
+}