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Extends TextMapGetter with GetAll() method, implement usage in W3CBag…
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…gagePropagator (#6852)

Co-authored-by: Jack Berg <[email protected]>
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jamesmoessis and jack-berg authored Dec 5, 2024
1 parent ee8d735 commit b07dab3
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Expand Up @@ -16,7 +16,9 @@
import io.opentelemetry.context.propagation.TextMapGetter;
import io.opentelemetry.context.propagation.TextMapPropagator;
import io.opentelemetry.context.propagation.TextMapSetter;
import io.opentelemetry.context.propagation.internal.ExtendedTextMapGetter;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import javax.annotation.Nullable;

Expand Down Expand Up @@ -95,6 +97,14 @@ public <C> Context extract(Context context, @Nullable C carrier, TextMapGetter<C
return context;
}

if (getter instanceof ExtendedTextMapGetter) {
return extractMulti(context, carrier, (ExtendedTextMapGetter<C>) getter);
}
return extractSingle(context, carrier, getter);
}

private static <C> Context extractSingle(
Context context, @Nullable C carrier, TextMapGetter<C> getter) {
String baggageHeader = getter.get(carrier, FIELD);
if (baggageHeader == null) {
return context;
Expand All @@ -112,6 +122,33 @@ public <C> Context extract(Context context, @Nullable C carrier, TextMapGetter<C
return context.with(baggageBuilder.build());
}

private static <C> Context extractMulti(
Context context, @Nullable C carrier, ExtendedTextMapGetter<C> getter) {
Iterator<String> baggageHeaders = getter.getAll(carrier, FIELD);
if (baggageHeaders == null) {
return context;
}

boolean extracted = false;
BaggageBuilder baggageBuilder = Baggage.builder();

while (baggageHeaders.hasNext()) {
String header = baggageHeaders.next();
if (header.isEmpty()) {
continue;
}

try {
extractEntries(header, baggageBuilder);
extracted = true;
} catch (RuntimeException expected) {
// invalid baggage header, continue
}
}

return extracted ? context.with(baggageBuilder.build()) : context;
}

private static void extractEntries(String baggageHeader, BaggageBuilder baggageBuilder) {
new Parser(baggageHeader).parseInto(baggageBuilder);
}
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Expand Up @@ -8,14 +8,18 @@
import static java.util.Collections.singletonMap;
import static org.assertj.core.api.Assertions.assertThat;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import io.opentelemetry.api.baggage.Baggage;
import io.opentelemetry.api.baggage.BaggageEntryMetadata;
import io.opentelemetry.context.Context;
import io.opentelemetry.context.propagation.TextMapGetter;
import io.opentelemetry.context.propagation.internal.ExtendedTextMapGetter;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import javax.annotation.Nullable;
import org.junit.jupiter.api.Test;
Expand All @@ -36,6 +40,28 @@ public String get(Map<String, String> carrier, String key) {
}
};

private static final ExtendedTextMapGetter<Map<String, List<String>>> multiGetter =
new ExtendedTextMapGetter<Map<String, List<String>>>() {
@Override
public Iterable<String> keys(Map<String, List<String>> carrier) {
return carrier.keySet();
}

@Nullable
@Override
public String get(Map<String, List<String>> carrier, String key) {
return carrier.getOrDefault(key, Collections.emptyList()).stream()
.findFirst()
.orElse(null);
}

@Override
public Iterator<String> getAll(Map<String, List<String>> carrier, String key) {
List<String> values = carrier.get(key);
return values == null ? Collections.emptyIterator() : values.iterator();
}
};

@Test
void fields() {
assertThat(W3CBaggagePropagator.getInstance().fields()).containsExactly("baggage");
Expand Down Expand Up @@ -421,6 +447,101 @@ void extract_nullGetter() {
.isSameAs(context);
}

@Test
void extract_multiple_headers() {
W3CBaggagePropagator propagator = W3CBaggagePropagator.getInstance();

Context result =
propagator.extract(
Context.root(),
ImmutableMap.of("baggage", ImmutableList.of("k1=v1", "k2=v2")),
multiGetter);

Baggage expectedBaggage = Baggage.builder().put("k1", "v1").put("k2", "v2").build();
assertThat(Baggage.fromContext(result)).isEqualTo(expectedBaggage);
}

@Test
void extract_multiple_headers_duplicate_key() {
W3CBaggagePropagator propagator = W3CBaggagePropagator.getInstance();

Context result =
propagator.extract(
Context.root(),
ImmutableMap.of("baggage", ImmutableList.of("k1=v1", "k1=v2")),
multiGetter);

Baggage expectedBaggage = Baggage.builder().put("k1", "v2").build();
assertThat(Baggage.fromContext(result)).isEqualTo(expectedBaggage);
}

@Test
void extract_multiple_headers_mixed_duplicates_non_duplicates() {
W3CBaggagePropagator propagator = W3CBaggagePropagator.getInstance();

Context result =
propagator.extract(
Context.root(),
ImmutableMap.of("baggage", ImmutableList.of("k1=v1,k2=v0", "k2=v2,k3=v3")),
multiGetter);

Baggage expectedBaggage =
Baggage.builder().put("k1", "v1").put("k2", "v2").put("k3", "v3").build();
assertThat(Baggage.fromContext(result)).isEqualTo(expectedBaggage);
}

@Test
void extract_multiple_headers_all_empty() {
W3CBaggagePropagator propagator = W3CBaggagePropagator.getInstance();

Context result =
propagator.extract(
Context.root(), ImmutableMap.of("baggage", ImmutableList.of("", "")), multiGetter);

Baggage expectedBaggage = Baggage.builder().build();
assertThat(Baggage.fromContext(result)).isEqualTo(expectedBaggage);
}

@Test
void extract_multiple_headers_some_empty() {
W3CBaggagePropagator propagator = W3CBaggagePropagator.getInstance();

Context result =
propagator.extract(
Context.root(), ImmutableMap.of("baggage", ImmutableList.of("", "k=v")), multiGetter);

Baggage expectedBaggage = Baggage.builder().put("k", "v").build();
assertThat(Baggage.fromContext(result)).isEqualTo(expectedBaggage);
}

@Test
void extract_multiple_headers_all_invalid() {
W3CBaggagePropagator propagator = W3CBaggagePropagator.getInstance();

Context result =
propagator.extract(
Context.root(),
ImmutableMap.of("baggage", ImmutableList.of("!@#$%^", "key=va%lue")),
multiGetter);

Baggage expectedBaggage = Baggage.builder().build();
assertThat(Baggage.fromContext(result)).isEqualTo(expectedBaggage);
}

@Test
void extract_multiple_headers_some_invalid() {
W3CBaggagePropagator propagator = W3CBaggagePropagator.getInstance();

Context result =
propagator.extract(
Context.root(),
ImmutableMap.of("baggage", ImmutableList.of("k1=v1", "key=va%lue", "k2=v2")),
multiGetter);

Baggage expectedBaggage = Baggage.builder().put("k1", "v1").put("k2", "v2").build();
assertThat(Baggage.fromContext(result)).isEqualTo(expectedBaggage);
}

@Test
void inject_noBaggage() {
W3CBaggagePropagator propagator = W3CBaggagePropagator.getInstance();
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@@ -0,0 +1,44 @@
/*
* Copyright The OpenTelemetry Authors
* SPDX-License-Identifier: Apache-2.0
*/

package io.opentelemetry.context.propagation.internal;

import io.opentelemetry.context.propagation.TextMapGetter;
import java.util.Collections;
import java.util.Iterator;
import javax.annotation.Nullable;

/**
* Extends {@link TextMapGetter} to return possibly multiple values for a given key.
*
* <p>This class is internal and experimental. Its APIs are unstable and can change at any time. Its
* APIs (or a version of them) may be promoted to the public stable API in the future, but no
* guarantees are made.
*
* @param <C> carrier of propagation fields, such as an http request.
*/
public interface ExtendedTextMapGetter<C> extends TextMapGetter<C> {
/**
* If implemented, returns all values for a given {@code key} in order, or returns an empty list.
*
* <p>The default method returns the first value of the given propagation {@code key} as a
* singleton list, or returns an empty list.
*
* <p>This class is internal and is hence not for public use. Its APIs are unstable and can change
* at any time.
*
* @param carrier carrier of propagation fields, such as an http request.
* @param key the key of the field.
* @return all values for a given {@code key} in order, or returns an empty list. Default method
* wraps {@code get()} as an {@link Iterator}.
*/
default Iterator<String> getAll(@Nullable C carrier, String key) {
String first = get(carrier, key);
if (first == null) {
return Collections.emptyIterator();
}
return Collections.singleton(first).iterator();
}
}
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@@ -0,0 +1,70 @@
/*
* Copyright The OpenTelemetry Authors
* SPDX-License-Identifier: Apache-2.0
*/

package io.opentelemetry.context.propagation.internal;

import static org.assertj.core.api.AssertionsForClassTypes.assertThat;

import com.google.common.collect.ImmutableList;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import javax.annotation.Nullable;
import org.junit.jupiter.api.Test;

class ExtendedTextMapGetterTest {

final ExtendedTextMapGetter<Void> nullGet =
new ExtendedTextMapGetter<Void>() {
@Override
public Iterable<String> keys(Void carrier) {
return ImmutableList.of("key");
}

@Nullable
@Override
public String get(@Nullable Void carrier, String key) {
return null;
}
};

final ExtendedTextMapGetter<Void> nonNullGet =
new ExtendedTextMapGetter<Void>() {
@Override
public Iterable<String> keys(Void carrier) {
return ImmutableList.of("key");
}

@Override
public String get(@Nullable Void carrier, String key) {
return "123";
}
};

@Test
void extendedTextMapGetterdefaultMethod_returnsEmpty() {
Iterator<String> result = nullGet.getAll(null, "key");
assertThat(result).isNotNull();
List<String> values = iterToList(result);
assertThat(values).isEqualTo(Collections.emptyList());
}

@Test
void extendedTextMapGetterdefaultMethod_returnsSingleVal() {
Iterator<String> result = nonNullGet.getAll(null, "key");
assertThat(result).isNotNull();
List<String> values = iterToList(result);
assertThat(values).isEqualTo(Collections.singletonList("123"));
}

private static <T> List<T> iterToList(Iterator<T> iter) {
List<T> list = new ArrayList<>();
while (iter.hasNext()) {
list.add(iter.next());
}
return list;
}
}

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