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songy23songy23
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Tags: Implementation of w3c correlation context format. (#1810)
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9 files changed

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impl_core/src/main/java/io/opencensus/implcore/tags/propagation/SerializationUtils.java renamed to impl_core/src/main/java/io/opencensus/implcore/tags/propagation/BinarySerializationUtils.java

Lines changed: 2 additions & 2 deletions
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@@ -66,12 +66,12 @@
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* </ul>
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* </ul>
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*/
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final class SerializationUtils {
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final class BinarySerializationUtils {
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private static final TagMetadata METADATA_UNLIMITED_PROPAGATION =
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TagMetadata.create(TagTtl.UNLIMITED_PROPAGATION);
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private SerializationUtils() {}
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private BinarySerializationUtils() {}
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@VisibleForTesting static final int VERSION_ID = 0;
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@VisibleForTesting static final int TAG_FIELD_ID = 0;

‎impl_core/src/main/java/io/opencensus/implcore/tags/propagation/CorrelationContextFormat.java‎

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/*
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* Copyright 2019, OpenCensus Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package io.opencensus.implcore.tags.propagation;
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import static com.google.common.base.Preconditions.checkArgument;
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import static com.google.common.base.Preconditions.checkNotNull;
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import com.google.common.annotations.VisibleForTesting;
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import com.google.common.base.Splitter;
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import io.opencensus.implcore.internal.CurrentState;
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import io.opencensus.implcore.internal.CurrentState.State;
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import io.opencensus.implcore.tags.TagMapImpl;
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import io.opencensus.implcore.tags.TagValueWithMetadata;
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import io.opencensus.tags.InternalUtils;
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import io.opencensus.tags.Tag;
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import io.opencensus.tags.TagContext;
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import io.opencensus.tags.TagKey;
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import io.opencensus.tags.TagMetadata;
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import io.opencensus.tags.TagMetadata.TagTtl;
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import io.opencensus.tags.TagValue;
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import io.opencensus.tags.propagation.TagContextDeserializationException;
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import io.opencensus.tags.propagation.TagContextSerializationException;
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import io.opencensus.tags.propagation.TagContextTextFormat;
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import java.util.Collections;
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import java.util.HashMap;
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import java.util.Iterator;
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import java.util.List;
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import java.util.Map;
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import javax.annotation.Nullable;
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/*>>>
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import org.checkerframework.checker.nullness.qual.NonNull;
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*/
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/**
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* Implementation of the W3C correlation context propagation protocol. See <a
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* href=https://github.com/w3c/correlation-context>w3c/correlation-context</a>.
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*/
53+
final class CorrelationContextFormat extends TagContextTextFormat {
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@VisibleForTesting static final String CORRELATION_CONTEXT = "Correlation-Context";
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private static final List<String> FIELDS = Collections.singletonList(CORRELATION_CONTEXT);
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@VisibleForTesting static final int MAX_NUMBER_OF_TAGS = 180;
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private static final int TAG_SERIALIZED_SIZE_LIMIT = 4096;
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private static final int TAGCONTEXT_SERIALIZED_SIZE_LIMIT = 8192;
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private static final char TAG_KEY_VALUE_DELIMITER = '=';
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private static final char TAG_DELIMITER = ',';
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private static final Splitter TAG_KEY_VALUE_SPLITTER = Splitter.on(TAG_KEY_VALUE_DELIMITER);
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private static final Splitter TAG_SPLITTER = Splitter.on(TAG_DELIMITER);
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// TODO(songya): These constants are for tag metadata. Uncomment them when we decided to support
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// encoding tag metadata.
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private static final char TAG_PROPERTIES_DELIMITER = ';';
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// private static final char TAG_PROPERTIES_KEY_VALUE_DELIMITER = '=';
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@VisibleForTesting
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static final TagMetadata METADATA_UNLIMITED_PROPAGATION =
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TagMetadata.create(TagTtl.UNLIMITED_PROPAGATION);
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private final CurrentState state;
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CorrelationContextFormat(CurrentState state) {
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this.state = state;
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}
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@Override
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public List<String> fields() {
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return FIELDS;
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}
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@Override
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public <C /*>>> extends @NonNull Object*/> void inject(
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TagContext tagContext, C carrier, Setter<C> setter) throws TagContextSerializationException {
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checkNotNull(tagContext, "tagContext");
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checkNotNull(carrier, "carrier");
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checkNotNull(setter, "setter");
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if (State.DISABLED.equals(state.getInternal())) {
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return;
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}
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try {
97+
StringBuilder stringBuilder = new StringBuilder(TAGCONTEXT_SERIALIZED_SIZE_LIMIT);
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int totalChars = 0; // Here chars are equivalent to bytes, since we're using ascii chars.
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int totalTags = 0;
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for (Iterator<Tag> i = InternalUtils.getTags(tagContext); i.hasNext(); ) {
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Tag tag = i.next();
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if (TagTtl.NO_PROPAGATION.equals(tag.getTagMetadata().getTagTtl())) {
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continue;
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}
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if (stringBuilder.length() > 0) {
106+
stringBuilder.append(TAG_DELIMITER);
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}
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totalTags++;
109+
totalChars += encodeTag(tag, stringBuilder);
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}
111+
checkArgument(
112+
totalTags <= MAX_NUMBER_OF_TAGS,
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"Number of tags in the TagContext exceeds limit " + MAX_NUMBER_OF_TAGS);
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// Note per W3C spec, only the length of tag key and value counts towards the total length.
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// Length of properties (a.k.a TagMetadata) does not count.
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checkArgument(
117+
totalChars <= TAGCONTEXT_SERIALIZED_SIZE_LIMIT,
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"Size of TagContext exceeds the maximum serialized size "
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+ TAGCONTEXT_SERIALIZED_SIZE_LIMIT);
120+
setter.put(carrier, CORRELATION_CONTEXT, stringBuilder.toString());
121+
} catch (IllegalArgumentException e) {
122+
throw new TagContextSerializationException("Failed to serialize TagContext", e);
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}
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}
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// Encodes the tag to the given string builder, and returns the length of encoded key-value pair.
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private static int encodeTag(Tag tag, StringBuilder stringBuilder) {
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String key = tag.getKey().getName();
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String value = tag.getValue().asString();
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int charsOfTag = key.length() + value.length();
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// This should never happen with our current constraints (<= 255 chars) on tags.
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checkArgument(
133+
charsOfTag <= TAG_SERIALIZED_SIZE_LIMIT,
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"Serialized size of tag " + tag + " exceeds limit " + TAG_SERIALIZED_SIZE_LIMIT);
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// TODO(songy23): do we want to encode TagMetadata?
137+
stringBuilder.append(key).append(TAG_KEY_VALUE_DELIMITER).append(value);
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return charsOfTag;
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}
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@Override
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public <C /*>>> extends @NonNull Object*/> TagContext extract(C carrier, Getter<C> getter)
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throws TagContextDeserializationException {
144+
checkNotNull(carrier, "carrier");
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checkNotNull(getter, "getter");
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if (State.DISABLED.equals(state.getInternal())) {
147+
return TagMapImpl.EMPTY;
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}
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150+
@Nullable String correlationContext = getter.get(carrier, CORRELATION_CONTEXT);
151+
if (correlationContext == null) {
152+
throw new TagContextDeserializationException(CORRELATION_CONTEXT + " not present.");
153+
}
154+
try {
155+
if (correlationContext.isEmpty()) {
156+
return TagMapImpl.EMPTY;
157+
}
158+
Map<TagKey, TagValueWithMetadata> tags = new HashMap<>();
159+
List<String> stringTags = TAG_SPLITTER.splitToList(correlationContext);
160+
for (String stringTag : stringTags) {
161+
decodeTag(stringTag, tags);
162+
}
163+
return new TagMapImpl(tags);
164+
} catch (IllegalArgumentException e) {
165+
throw new TagContextDeserializationException("Invalid TagContext: " + correlationContext, e);
166+
}
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}
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169+
// Decodes tag key, value and metadata from the encoded string tag, then puts it into the tag map.
170+
// The format of encoded string tag is name1=value1;properties1=p1;properties2=p2.
171+
private static void decodeTag(String stringTag, Map<TagKey, TagValueWithMetadata> tags) {
172+
String keyWithValue;
173+
int firstPropertyIndex = stringTag.indexOf(TAG_PROPERTIES_DELIMITER);
174+
if (firstPropertyIndex != -1) { // Tag with properties.
175+
keyWithValue = stringTag.substring(0, firstPropertyIndex);
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// TODO(songya): support decoding tag properties.
177+
} else { // Tag without properties.
178+
keyWithValue = stringTag;
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}
180+
List<String> keyValuePair = TAG_KEY_VALUE_SPLITTER.splitToList(keyWithValue);
181+
checkArgument(keyValuePair.size() == 2, "Malformed tag " + stringTag);
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TagKey key = TagKey.create(keyValuePair.get(0).trim());
183+
TagValue value = TagValue.create(keyValuePair.get(1).trim());
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TagValueWithMetadata valueWithMetadata =
185+
TagValueWithMetadata.create(value, METADATA_UNLIMITED_PROPAGATION);
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tags.put(key, valueWithMetadata);
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}
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}

‎impl_core/src/main/java/io/opencensus/implcore/tags/propagation/TagContextBinarySerializerImpl.java‎

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@@ -37,13 +37,13 @@ final class TagContextBinarySerializerImpl extends TagContextBinarySerializer {
3737
public byte[] toByteArray(TagContext tags) throws TagContextSerializationException {
3838
return state.getInternal() == State.DISABLED
3939
? EMPTY_BYTE_ARRAY
40-
: SerializationUtils.serializeBinary(tags);
40+
: BinarySerializationUtils.serializeBinary(tags);
4141
}
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4343
@Override
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public TagContext fromByteArray(byte[] bytes) throws TagContextDeserializationException {
4545
return state.getInternal() == State.DISABLED
4646
? TagMapImpl.EMPTY
47-
: SerializationUtils.deserializeBinary(bytes);
47+
: BinarySerializationUtils.deserializeBinary(bytes);
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}
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}

‎impl_core/src/main/java/io/opencensus/implcore/tags/propagation/TagPropagationComponentImpl.java‎

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@@ -24,9 +24,11 @@
2424
/** Implementation of {@link TagPropagationComponent}. */
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public final class TagPropagationComponentImpl extends TagPropagationComponent {
2626
private final TagContextBinarySerializer tagContextBinarySerializer;
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private final TagContextTextFormat tagContextTextFormat;
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2829
public TagPropagationComponentImpl(CurrentState state) {
2930
tagContextBinarySerializer = new TagContextBinarySerializerImpl(state);
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tagContextTextFormat = new CorrelationContextFormat(state);
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}
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3234
@Override
@@ -36,6 +38,6 @@ public TagContextBinarySerializer getBinarySerializer() {
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3739
@Override
3840
public TagContextTextFormat getCorrelationContextFormat() {
39-
throw new UnsupportedOperationException("not implemented");
41+
return tagContextTextFormat;
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}
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}

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