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

am: 13217871fe

Change-Id: Icfe12d6db2f81a6f5c65241919b1d63fb665ffd6

1 files changed, 85 insertions, 0 deletions

diff --git a/impl_core/src/main/java/io/opencensus/implcore/tags/TagContextImpl.java b/impl_core/src/main/java/io/opencensus/implcore/tags/TagContextImpl.java
new file mode 100644
index 00000000..f7a8ff82
--- /dev/null
+++ b/impl_core/src/main/java/io/opencensus/implcore/tags/TagContextImpl.java
@@ -0,0 +1,85 @@
+/*
+ * Copyright 2017, 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.tags;
+
+import io.opencensus.tags.Tag;
+import io.opencensus.tags.TagContext;
+import io.opencensus.tags.TagKey;
+import io.opencensus.tags.TagValue;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Map.Entry;
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+public final class TagContextImpl extends TagContext {
+
+  public static final TagContextImpl EMPTY =
+      new TagContextImpl(Collections.<TagKey, TagValue>emptyMap());
+
+  // The types of the TagKey and value must match for each entry.
+  private final Map<TagKey, TagValue> tags;
+
+  public TagContextImpl(Map<? extends TagKey, ? extends TagValue> tags) {
+    this.tags = Collections.unmodifiableMap(new HashMap<TagKey, TagValue>(tags));
+  }
+
+  public Map<TagKey, TagValue> getTags() {
+    return tags;
+  }
+
+  @Override
+  protected Iterator<Tag> getIterator() {
+    return new TagIterator(tags);
+  }
+
+  @Override
+  public boolean equals(@Nullable Object other) {
+    // Directly compare the tags when both objects are TagContextImpls, for efficiency.
+    if (other instanceof TagContextImpl) {
+      return getTags().equals(((TagContextImpl) other).getTags());
+    }
+    return super.equals(other);
+  }
+
+  private static final class TagIterator implements Iterator<Tag> {
+    Iterator<Map.Entry<TagKey, TagValue>> iterator;
+
+    TagIterator(Map<TagKey, TagValue> tags) {
+      iterator = tags.entrySet().iterator();
+    }
+
+    @Override
+    public boolean hasNext() {
+      return iterator.hasNext();
+    }
+
+    @Override
+    public Tag next() {
+      final Entry<TagKey, TagValue> next = iterator.next();
+      return Tag.create(next.getKey(), next.getValue());
+    }
+
+    @Override
+    public void remove() {
+      throw new UnsupportedOperationException("TagIterator.remove()");
+    }
+  }
+}