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

am: 6fbc3cf5a1

Change-Id: I11b0ec1cf561d2a14da78e444b1594f167787fe6

1 files changed, 73 insertions, 0 deletions

diff --git a/api/src/main/java/io/opencensus/tags/TagsComponent.java b/api/src/main/java/io/opencensus/tags/TagsComponent.java
new file mode 100644
index 00000000..d34f1951
--- /dev/null
+++ b/api/src/main/java/io/opencensus/tags/TagsComponent.java
@@ -0,0 +1,73 @@
+/*
+ * 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.tags;
+
+import io.opencensus.tags.propagation.TagPropagationComponent;
+
+/**
+ * Class that holds the implementation for {@link Tagger} and {@link TagPropagationComponent}.
+ *
+ * <p>All objects returned by methods on {@code TagsComponent} are cacheable.
+ *
+ * @since 0.8
+ */
+public abstract class TagsComponent {
+
+  /**
+   * Returns the {@link Tagger} for this implementation.
+   *
+   * @since 0.8
+   */
+  public abstract Tagger getTagger();
+
+  /**
+   * Returns the {@link TagPropagationComponent} for this implementation.
+   *
+   * @since 0.8
+   */
+  public abstract TagPropagationComponent getTagPropagationComponent();
+
+  /**
+   * Returns the current {@code TaggingState}.
+   *
+   * <p>When no implementation is available, {@code getState} always returns {@link
+   * TaggingState#DISABLED}.
+   *
+   * <p>Once {@link #getState()} is called, subsequent calls to {@link #setState(TaggingState)} will
+   * throw an {@code IllegalStateException}.
+   *
+   * @return the current {@code TaggingState}.
+   * @since 0.8
+   */
+  public abstract TaggingState getState();
+
+  /**
+   * Sets the current {@code TaggingState}.
+   *
+   * <p>When no implementation is available, {@code setState} does not change the state.
+   *
+   * @param state the new {@code TaggingState}.
+   * @throws IllegalStateException if {@link #getState()} was previously called.
+   * @deprecated This method is deprecated because other libraries could cache the result of {@link
+   *     #getState()}, use a stale value, and behave incorrectly. It is only safe to call early in
+   *     initialization. This method throws {@link IllegalStateException} after {@code getState()}
+   *     has been called, in order to limit changes to the result of {@code getState()}.
+   * @since 0.8
+   */
+  @Deprecated
+  public abstract void setState(TaggingState state);
+}