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/*
* 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.common.Scope;
import io.opencensus.internal.NoopScope;
import io.opencensus.internal.Utils;
import io.opencensus.tags.propagation.TagContextBinarySerializer;
import io.opencensus.tags.propagation.TagPropagationComponent;
import java.util.Collections;
import java.util.Iterator;
import javax.annotation.concurrent.Immutable;
import javax.annotation.concurrent.ThreadSafe;
/** No-op implementations of tagging classes. */
final class NoopTags {
private NoopTags() {}
/**
* Returns a {@code TagsComponent} that has a no-op implementation for {@link Tagger}.
*
* @return a {@code TagsComponent} that has a no-op implementation for {@code Tagger}.
*/
static TagsComponent newNoopTagsComponent() {
return new NoopTagsComponent();
}
/**
* Returns a {@code Tagger} that only produces {@link TagContext}s with no tags.
*
* @return a {@code Tagger} that only produces {@code TagContext}s with no tags.
*/
static Tagger getNoopTagger() {
return NoopTagger.INSTANCE;
}
/**
* Returns a {@code TagContextBuilder} that ignores all calls to {@link TagContextBuilder#put}.
*
* @return a {@code TagContextBuilder} that ignores all calls to {@link TagContextBuilder#put}.
*/
static TagContextBuilder getNoopTagContextBuilder() {
return NoopTagContextBuilder.INSTANCE;
}
/**
* Returns a {@code TagContext} that does not contain any tags.
*
* @return a {@code TagContext} that does not contain any tags.
*/
static TagContext getNoopTagContext() {
return NoopTagContext.INSTANCE;
}
/** Returns a {@code TagPropagationComponent} that contains no-op serializers. */
static TagPropagationComponent getNoopTagPropagationComponent() {
return NoopTagPropagationComponent.INSTANCE;
}
/**
* Returns a {@code TagContextBinarySerializer} that serializes all {@code TagContext}s to zero
* bytes and deserializes all inputs to empty {@code TagContext}s.
*/
static TagContextBinarySerializer getNoopTagContextBinarySerializer() {
return NoopTagContextBinarySerializer.INSTANCE;
}
@ThreadSafe
private static final class NoopTagsComponent extends TagsComponent {
private volatile boolean isRead;
@Override
public Tagger getTagger() {
return getNoopTagger();
}
@Override
public TagPropagationComponent getTagPropagationComponent() {
return getNoopTagPropagationComponent();
}
@Override
public TaggingState getState() {
isRead = true;
return TaggingState.DISABLED;
}
@Override
@Deprecated
public void setState(TaggingState state) {
Utils.checkNotNull(state, "state");
Utils.checkState(!isRead, "State was already read, cannot set state.");
}
}
@Immutable
private static final class NoopTagger extends Tagger {
static final Tagger INSTANCE = new NoopTagger();
@Override
public TagContext empty() {
return getNoopTagContext();
}
@Override
public TagContext getCurrentTagContext() {
return getNoopTagContext();
}
@Override
public TagContextBuilder emptyBuilder() {
return getNoopTagContextBuilder();
}
@Override
public TagContextBuilder toBuilder(TagContext tags) {
Utils.checkNotNull(tags, "tags");
return getNoopTagContextBuilder();
}
@Override
public TagContextBuilder currentBuilder() {
return getNoopTagContextBuilder();
}
@Override
public Scope withTagContext(TagContext tags) {
Utils.checkNotNull(tags, "tags");
return NoopScope.getInstance();
}
}
@Immutable
private static final class NoopTagContextBuilder extends TagContextBuilder {
static final TagContextBuilder INSTANCE = new NoopTagContextBuilder();
@Override
public TagContextBuilder put(TagKey key, TagValue value) {
Utils.checkNotNull(key, "key");
Utils.checkNotNull(value, "value");
return this;
}
@Override
public TagContextBuilder remove(TagKey key) {
Utils.checkNotNull(key, "key");
return this;
}
@Override
public TagContext build() {
return getNoopTagContext();
}
@Override
public Scope buildScoped() {
return NoopScope.getInstance();
}
}
@Immutable
private static final class NoopTagContext extends TagContext {
static final TagContext INSTANCE = new NoopTagContext();
// TODO(sebright): Is there any way to let the user know that their tags were ignored?
@Override
protected Iterator<Tag> getIterator() {
return Collections.<Tag>emptySet().iterator();
}
}
@Immutable
private static final class NoopTagPropagationComponent extends TagPropagationComponent {
static final TagPropagationComponent INSTANCE = new NoopTagPropagationComponent();
@Override
public TagContextBinarySerializer getBinarySerializer() {
return getNoopTagContextBinarySerializer();
}
}
@Immutable
private static final class NoopTagContextBinarySerializer extends TagContextBinarySerializer {
static final TagContextBinarySerializer INSTANCE = new NoopTagContextBinarySerializer();
static final byte[] EMPTY_BYTE_ARRAY = {};
@Override
public byte[] toByteArray(TagContext tags) {
Utils.checkNotNull(tags, "tags");
return EMPTY_BYTE_ARRAY;
}
@Override
public TagContext fromByteArray(byte[] bytes) {
Utils.checkNotNull(bytes, "bytes");
return getNoopTagContext();
}
}
}
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