Implementation of BaggagePropagator and BaggageContext #8330
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| Original file line number | Diff line number | Diff line change |
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| package datadog.trace.core.baggage; | ||
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| import datadog.context.Context; | ||
| import datadog.context.propagation.CarrierSetter; | ||
| import datadog.context.propagation.CarrierVisitor; | ||
| import datadog.context.propagation.Propagator; | ||
| import datadog.trace.api.Config; | ||
| import datadog.trace.bootstrap.instrumentation.api.BaggageContext; | ||
| import datadog.trace.core.util.EscapedData; | ||
| import datadog.trace.core.util.PercentEscaper; | ||
| import java.io.UnsupportedEncodingException; | ||
| import java.net.URLDecoder; | ||
| import java.util.Collections; | ||
| import java.util.HashMap; | ||
| import java.util.Map; | ||
| import java.util.function.BiConsumer; | ||
| import javax.annotation.ParametersAreNonnullByDefault; | ||
| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
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| @ParametersAreNonnullByDefault | ||
| public class BaggagePropagator implements Propagator { | ||
| private static final Logger log = LoggerFactory.getLogger(BaggagePropagator.class); | ||
| private static final PercentEscaper UTF_ESCAPER = PercentEscaper.create(); | ||
| static final String BAGGAGE_KEY = "baggage"; | ||
| private final Config config; | ||
| private final boolean injectBaggage; | ||
| private final boolean extractBaggage; | ||
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| public BaggagePropagator(Config config) { | ||
| this.injectBaggage = config.isBaggageInject(); | ||
| this.extractBaggage = config.isBaggageExtract(); | ||
| this.config = config; | ||
| } | ||
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| // use primarily for testing purposes | ||
| public BaggagePropagator(boolean injectBaggage, boolean extractBaggage) { | ||
| this.injectBaggage = injectBaggage; | ||
| this.extractBaggage = extractBaggage; | ||
| config = Config.get(); | ||
| } | ||
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| @Override | ||
| public <C> void inject(Context context, C carrier, CarrierSetter<C> setter) { | ||
| int maxItems = config.getTraceBaggageMaxItems(); | ||
| int maxBytes = config.getTraceBaggageMaxBytes(); | ||
| //noinspection ConstantValue | ||
| if (!this.injectBaggage | ||
| || maxItems == 0 | ||
| || maxBytes == 0 | ||
| || context == null | ||
| || carrier == null | ||
| || setter == null) { | ||
| return; | ||
| } | ||
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| BaggageContext baggageContext = BaggageContext.fromContext(context); | ||
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| if (baggageContext == null) { | ||
| log.debug("BaggageContext instance is missing from the following context {}", context); | ||
| return; | ||
| } | ||
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| String baggageHeader = baggageContext.getW3cBaggageHeader(); | ||
| if (baggageHeader != null) { | ||
| setter.set(carrier, BAGGAGE_KEY, baggageHeader); | ||
| return; | ||
| } | ||
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| int processedBaggage = 0; | ||
| int currentBytes = 0; | ||
| StringBuilder baggageText = new StringBuilder(); | ||
| for (final Map.Entry<String, String> entry : baggageContext.asMap().entrySet()) { | ||
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| // if there are already baggage items processed, add and allocate bytes for a comma | ||
| int extraBytes = 1; | ||
| if (processedBaggage != 0) { | ||
| baggageText.append(','); | ||
| extraBytes++; | ||
| } | ||
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| EscapedData escapedKey = UTF_ESCAPER.escapeKey(entry.getKey()); | ||
| EscapedData escapedVal = UTF_ESCAPER.escapeValue(entry.getValue()); | ||
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| baggageText.append(escapedKey.getData()); | ||
| baggageText.append('='); | ||
| baggageText.append(escapedVal.getData()); | ||
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| processedBaggage++; | ||
| // reached the max number of baggage items allowed | ||
| if (processedBaggage == maxItems) { | ||
| break; | ||
| } | ||
| // Drop newest k/v pair if adding it leads to exceeding the limit | ||
| if (currentBytes + escapedKey.getSize() + escapedVal.getSize() + extraBytes > maxBytes) { | ||
| baggageText.setLength(currentBytes); | ||
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| break; | ||
| } | ||
| currentBytes += escapedKey.getSize() + escapedVal.getSize() + extraBytes; | ||
| } | ||
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| String baggageString = baggageText.toString(); | ||
| baggageContext.setW3cBaggageHeader(baggageString); | ||
| setter.set(carrier, BAGGAGE_KEY, baggageString); | ||
| } | ||
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| @Override | ||
| public <C> Context extract(Context context, C carrier, CarrierVisitor<C> visitor) { | ||
| //noinspection ConstantValue | ||
| if (!this.extractBaggage || context == null || carrier == null || visitor == null) { | ||
| return context; | ||
| } | ||
| BaggageContextExtractor baggageContextExtractor = new BaggageContextExtractor(); | ||
| visitor.forEachKeyValue(carrier, baggageContextExtractor); | ||
| BaggageContext extractedContext = baggageContextExtractor.extractedContext; | ||
| if (extractedContext == null) { | ||
| return context; | ||
| } | ||
| return extractedContext.storeInto(context); | ||
| } | ||
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| public static class BaggageContextExtractor implements BiConsumer<String, String> { | ||
| private BaggageContext extractedContext; | ||
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| BaggageContextExtractor() {} | ||
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| /** URL decode value */ | ||
| private String decode(final String value) { | ||
| String decoded = value; | ||
| try { | ||
| decoded = URLDecoder.decode(value, "UTF-8"); | ||
| } catch (final UnsupportedEncodingException | IllegalArgumentException e) { | ||
| log.debug("Failed to decode {}", value); | ||
| } | ||
| return decoded; | ||
| } | ||
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| private Map<String, String> parseBaggageHeaders(String input) { | ||
| Map<String, String> baggage = new HashMap<>(); | ||
| char keyValueSeparator = '='; | ||
| char pairSeparator = ','; | ||
| int start = 0; | ||
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| int pairSeparatorInd = input.indexOf(pairSeparator); | ||
| pairSeparatorInd = pairSeparatorInd == -1 ? input.length() : pairSeparatorInd; | ||
| int kvSeparatorInd = input.indexOf(keyValueSeparator); | ||
| while (kvSeparatorInd != -1) { | ||
| int end = pairSeparatorInd; | ||
| if (kvSeparatorInd > end) { | ||
| log.debug( | ||
| "Dropping baggage headers due to key with no value {}", input.substring(start, end)); | ||
| return Collections.emptyMap(); | ||
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| } | ||
| String key = decode(input.substring(start, kvSeparatorInd).trim()); | ||
| String value = decode(input.substring(kvSeparatorInd + 1, end).trim()); | ||
| if (key.isEmpty() || value.isEmpty()) { | ||
| log.debug("Dropping baggage headers due to empty k/v {}:{}", key, value); | ||
| return Collections.emptyMap(); | ||
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| } | ||
| baggage.put(key, value); | ||
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| kvSeparatorInd = input.indexOf(keyValueSeparator, pairSeparatorInd + 1); | ||
| pairSeparatorInd = input.indexOf(pairSeparator, pairSeparatorInd + 1); | ||
| pairSeparatorInd = pairSeparatorInd == -1 ? input.length() : pairSeparatorInd; | ||
| start = end + 1; | ||
| } | ||
| return baggage; | ||
| } | ||
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| @Override | ||
| public void accept(String key, String value) { | ||
| // Only process tags that are relevant to baggage | ||
| if (key != null && key.equalsIgnoreCase(BAGGAGE_KEY)) { | ||
| Map<String, String> baggage = parseBaggageHeaders(value); | ||
| if (!baggage.isEmpty()) { | ||
| extractedContext = BaggageContext.create(baggage, value); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,36 @@ | ||
| package datadog.trace.core.util; | ||
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| public class EscapedData { | ||
| private String data; | ||
| private int size; | ||
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| public EscapedData(String data, int size) { | ||
| this.data = data; | ||
| this.size = size; | ||
| } | ||
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| public EscapedData() { | ||
| this.data = ""; | ||
| this.size = 0; | ||
| } | ||
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| public String getData() { | ||
| return data; | ||
| } | ||
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| public int getSize() { | ||
| return size; | ||
| } | ||
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| public void setData(String data) { | ||
| this.data = data; | ||
| } | ||
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| public void incrementSize() { | ||
| size++; | ||
| } | ||
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| public void addSize(int delta) { | ||
| size += delta; | ||
| } | ||
| } |
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Don't forget to skip this value from
HttpCodedcreateExtractorandcreateInjectorThere was a problem hiding this comment.
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Neither inject or extract currently have a case handling Baggage!
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The goal is to avoid emitting the following log entries for Baggage propagation style:
"No implementation found to inject propagation style: {}""No implementation found to extract propagation style: {}"It will be misleading during escalation 😓
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Ah that makes sense. I added a case to just break and not add anything!