diff options
Diffstat (limited to 'api/src/main/java/io/opencensus/tags/Tags.java')
-rw-r--r-- | api/src/main/java/io/opencensus/tags/Tags.java | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/api/src/main/java/io/opencensus/tags/Tags.java b/api/src/main/java/io/opencensus/tags/Tags.java new file mode 100644 index 00000000..07123647 --- /dev/null +++ b/api/src/main/java/io/opencensus/tags/Tags.java @@ -0,0 +1,126 @@ +/* + * 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.internal.DefaultVisibilityForTesting; +import io.opencensus.internal.Provider; +import io.opencensus.tags.propagation.TagPropagationComponent; +import java.util.logging.Level; +import java.util.logging.Logger; +import javax.annotation.Nullable; + +/** + * Class for accessing the default {@link TagsComponent}. + * + * @since 0.8 + */ +public final class Tags { + private static final Logger logger = Logger.getLogger(Tags.class.getName()); + + private static final TagsComponent tagsComponent = + loadTagsComponent(TagsComponent.class.getClassLoader()); + + private Tags() {} + + /** + * Returns the default {@code Tagger}. + * + * @return the default {@code Tagger}. + * @since 0.8 + */ + public static Tagger getTagger() { + return tagsComponent.getTagger(); + } + + /** + * Returns the default {@code TagPropagationComponent}. + * + * @return the default {@code TagPropagationComponent}. + * @since 0.8 + */ + public static TagPropagationComponent getTagPropagationComponent() { + return tagsComponent.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 static TaggingState getState() { + return tagsComponent.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 {@link #getState()} + * has been called, in order to limit changes to the result of {@code getState()}. + * @since 0.8 + */ + @Deprecated + public static void setState(TaggingState state) { + tagsComponent.setState(state); + } + + // Any provider that may be used for TagsComponent can be added here. + @DefaultVisibilityForTesting + static TagsComponent loadTagsComponent(@Nullable ClassLoader classLoader) { + try { + // Call Class.forName with literal string name of the class to help shading tools. + return Provider.createInstance( + Class.forName( + "io.opencensus.impl.tags.TagsComponentImpl", /*initialize=*/ true, classLoader), + TagsComponent.class); + } catch (ClassNotFoundException e) { + logger.log( + Level.FINE, + "Couldn't load full implementation for TagsComponent, now trying to load lite " + + "implementation.", + e); + } + try { + // Call Class.forName with literal string name of the class to help shading tools. + return Provider.createInstance( + Class.forName( + "io.opencensus.impllite.tags.TagsComponentImplLite", + /*initialize=*/ true, + classLoader), + TagsComponent.class); + } catch (ClassNotFoundException e) { + logger.log( + Level.FINE, + "Couldn't load lite implementation for TagsComponent, now using " + + "default implementation for TagsComponent.", + e); + } + return NoopTags.newNoopTagsComponent(); + } +} |