Context propagation update (OTEP 66) (#720)

* Initial Propagators refactor.

* Add tests for the new propagators changes.

* Make the SDK compile/pass.

* Make the OT shim compile/pass.

* Make contrib components compile/pass.

* Improvement over Span/SpanContext handling in Context.

* Add Span.setParent(Context) overload.

* Do not provide default values for Span/SpanContext keys in Context.

* Improve the Context's active state handling.

* Rename DistributedContext to CorrelationContext.

* Improve names for correlationcontext's ContextUtils methods.

* Don't provide an automatic default for current CorrelationContext.

* Improve the client-server example after the recent changes.

* Adds CorrelationContext.Builder.setParent(Context) overload.

* s/be/become.

* Fix javadoc.

* No need to use diamond.

* Simply import withScopedContext().

* Fix the API/SDK build.

* Remove the builder from the Propagators interface.

* Fix name.

* Use Collections.emptyList() directly.

* Rename Propagators to ContextPropagators.

* Move context/ members in api/ to context_prop/

* Add check/tests for null scoped Contexts.

* Rename ContextUtils classes to better alternatives.

* Update the context* util classes.

* Make the code compile after the latest master merge.

* Cache the fields() in our default composite propagator.

* Remove the overloads of setParent(Context) for now.

* Use DefaultSpan for the tests instead of calling getTracerProvider()

* Fix the sdk testbed artifact build.

* Make the B3 propagator comply with the new propagator API.

* Simplify the HttpTraceContextTest tests.

* Simplify the ContextUtils* classes handling of default values.

* Minor nit.

* Update api/src/main/java/io/opentelemetry/OpenTelemetry.java

Co-Authored-By: Giovanni Liva <giovanni.liva@dynatrace.com>

* Annotate ContextPropagators with ThreadSafe instead of Immutable.

* Do not use the fully qualified ContextUtils identifier.

* Remove SpanContext support from TracingContextUtils.

* Rever to using non-defaulted key for TracingContextUtils.

* Revert the default keys for CorrelationsContextUtils.

Co-authored-by: Giovanni Liva <giovanni.liva@dynatrace.com>

api/src/jmh/java/io/opentelemetry/trace/propagation/HttpTraceContextExtractBenchmark.java

@@ -16,8 +16,10 @@
 
 package io.opentelemetry.trace.propagation;
 
+import io.grpc.Context;
 import io.opentelemetry.context.propagation.HttpTextFormat.Getter;
-import io.opentelemetry.trace.SpanContext;
+import io.opentelemetry.trace.Span;
+import io.opentelemetry.trace.TracingContextUtils;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
@@ -69,8 +71,9 @@ public void setup() {
   @Measurement(iterations = 15, time = 1)
   @OutputTimeUnit(TimeUnit.NANOSECONDS)
   @Warmup(iterations = 5, time = 1)
-  public SpanContext measureExtract() {
-    return httpTraceContext.extract(carrier, getter);
+  public Span measureExtract() {
+    return TracingContextUtils.getSpan(
+        httpTraceContext.extract(Context.current(), carrier, getter));
   }
 
   @TearDown(Level.Iteration)

api/src/jmh/java/io/opentelemetry/trace/propagation/HttpTraceContextInjectBenchmark.java

@@ -16,12 +16,15 @@
 
 package io.opentelemetry.trace.propagation;
 
+import io.grpc.Context;
 import io.opentelemetry.context.propagation.HttpTextFormat.Setter;
+import io.opentelemetry.trace.DefaultSpan;
 import io.opentelemetry.trace.SpanContext;
 import io.opentelemetry.trace.SpanId;
 import io.opentelemetry.trace.TraceFlags;
 import io.opentelemetry.trace.TraceId;
 import io.opentelemetry.trace.TraceState;
+import io.opentelemetry.trace.TracingContextUtils;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
@@ -69,7 +72,9 @@ public void set(Map<String, String> carrier, String key, String value) {
   @OutputTimeUnit(TimeUnit.NANOSECONDS)
   @Warmup(iterations = 5, time = 1)
   public Map<String, String> measureInject() {
-    httpTraceContext.inject(contextToTest, carrier, setter);
+    Context context =
+        TracingContextUtils.withSpan(DefaultSpan.create(contextToTest), Context.current());
+    httpTraceContext.inject(context, carrier, setter);
     return carrier;
   }
 

api/src/main/java/io/opentelemetry/OpenTelemetry.java

@@ -16,10 +16,13 @@
 
 package io.opentelemetry;
 
+import io.opentelemetry.context.propagation.ContextPropagators;
+import io.opentelemetry.context.propagation.DefaultContextPropagators;
 import io.opentelemetry.correlationcontext.CorrelationContextManager;
 import io.opentelemetry.correlationcontext.DefaultCorrelationContextManager;
 import io.opentelemetry.correlationcontext.DefaultCorrelationContextManagerProvider;
 import io.opentelemetry.correlationcontext.spi.CorrelationContextManagerProvider;
+import io.opentelemetry.internal.Utils;
 import io.opentelemetry.metrics.DefaultMeterProvider;
 import io.opentelemetry.metrics.DefaultMetricsProvider;
 import io.opentelemetry.metrics.Meter;
@@ -29,6 +32,7 @@
 import io.opentelemetry.trace.DefaultTracerProvider;
 import io.opentelemetry.trace.Tracer;
 import io.opentelemetry.trace.TracerProvider;
+import io.opentelemetry.trace.propagation.HttpTraceContext;
 import io.opentelemetry.trace.spi.TraceProvider;
 import java.util.ServiceLoader;
 import javax.annotation.Nullable;
@@ -53,6 +57,9 @@ public final class OpenTelemetry {
   private final MeterProvider meterProvider;
   private final CorrelationContextManager contextManager;
 
+  private volatile ContextPropagators propagators =
+      DefaultContextPropagators.builder().addHttpTextFormat(new HttpTraceContext()).build();
+
   /**
    * Returns a singleton {@link TracerProvider}.
    *
@@ -90,6 +97,35 @@ public static CorrelationContextManager getCorrelationContextManager() {
     return getInstance().contextManager;
   }
 
+  /**
+   * Returns a {@link ContextPropagators} object, which can be used to access the set of registered
+   * propagators for each supported format.
+   *
+   * @return registered propagators container, defaulting to a {@link ContextPropagators} object
+   *     with {@link HttpTraceContext} registered.
+   * @throws IllegalStateException if a specified manager (via system properties) could not be
+   *     found.
+   * @since 0.3.0
+   */
+  public static ContextPropagators getPropagators() {
+    return getInstance().propagators;
+  }
+
+  /**
+   * Sets the {@link ContextPropagators} object, which can be used to access the set of registered
+   * propagators for each supported format.
+   *
+   * @param propagators the {@link ContextPropagators} object to be registered.
+   * @throws IllegalStateException if a specified manager (via system properties) could not be
+   *     found.
+   * @throws NullPointerException if {@code propagators} is {@code null}.
+   * @since 0.3.0
+   */
+  public static void setPropagators(ContextPropagators propagators) {
+    Utils.checkNotNull(propagators, "propagators");
+    getInstance().propagators = propagators;
+  }
+
   /** Lazy loads an instance. */
   private static OpenTelemetry getInstance() {
     if (instance == null) {

api/src/main/java/io/opentelemetry/correlationcontext/CorrelationContextManager.java

@@ -17,7 +17,6 @@
 package io.opentelemetry.correlationcontext;
 
 import io.opentelemetry.context.Scope;
-import io.opentelemetry.context.propagation.HttpTextFormat;
 import javax.annotation.concurrent.ThreadSafe;
 
 /**
@@ -63,53 +62,4 @@ public interface CorrelationContextManager {
    * @since 0.1.0
    */
   Scope withContext(CorrelationContext distContext);
-
-  /**
-   * Returns the {@link HttpTextFormat} for this implementation.
-   *
-   * <p>Usually this will be the W3C Correlation Context as the HTTP text format. For more details,
-   * see <a href="https://github.com/w3c/correlation-context">correlation-context</a>.
-   *
-   * <p>Example of usage on the client:
-   *
-   * <pre>{@code
-   * private static final CorrelationContextManager contextManager =
-   *     OpenTelemetry.getCorrelationContextManager();
-   * private static final HttpTextFormat textFormat = contextManager.getHttpTextFormat();
-   *
-   * private static final HttpTextFormat.Setter setter =
-   *     new HttpTextFormat.Setter<HttpURLConnection>() {
-   *       public void put(HttpURLConnection carrier, String key, String value) {
-   *         carrier.setRequestProperty(field, value);
-   *       }
-   *     };
-   *
-   * void makeHttpRequest() {
-   *   HttpURLConnection connection =
-   *       (HttpURLConnection) new URL("http://myserver").openConnection();
-   *   textFormat.inject(contextManager.getCurrentContext(), connection, httpURLConnectionSetter);
-   *   // Send the request, wait for response and maybe set the status if not ok.
-   * }
-   * }</pre>
-   *
-   * <p>Example of usage on the server:
-   *
-   * <pre>{@code
-   * private static final CorrelationContextManager contextManager =
-   *     OpenTelemetry.getCorrelationContextManager();
-   * private static final HttpTextFormat textFormat = contextManager.getHttpTextFormat();
-   * private static final HttpTextFormat.Getter<HttpRequest> getter = ...;
-   *
-   * void onRequestReceived(HttpRequest request) {
-   *   CorrelationContext distContext = textFormat.extract(request, getter);
-   *   try (Scope s = contextManager.withContext(distContext)) {
-   *     // Handle request and send response back.
-   *   }
-   * }
-   * }</pre>
-   *
-   * @return the {@code HttpTextFormat} for this implementation.
-   * @since 0.1.0
-   */
-  HttpTextFormat<CorrelationContext> getHttpTextFormat();
 }

api/src/main/java/io/opentelemetry/correlationcontext/DefaultCorrelationContextManager.java

@@ -17,10 +17,7 @@
 package io.opentelemetry.correlationcontext;
 
 import io.opentelemetry.context.Scope;
-import io.opentelemetry.context.propagation.HttpTextFormat;
 import io.opentelemetry.internal.Utils;
-import java.util.Collections;
-import java.util.List;
 import javax.annotation.concurrent.Immutable;
 import javax.annotation.concurrent.ThreadSafe;
 
@@ -33,8 +30,6 @@
 public final class DefaultCorrelationContextManager implements CorrelationContextManager {
   private static final DefaultCorrelationContextManager INSTANCE =
       new DefaultCorrelationContextManager();
-  private static final HttpTextFormat<CorrelationContext> HTTP_TEXT_FORMAT =
-      new NoopHttpTextFormat();
 
   /**
    * Returns a {@code CorrelationContextManager} singleton that is the default implementation for
@@ -62,11 +57,6 @@ public Scope withContext(CorrelationContext distContext) {
     return CorrelationsContextUtils.currentContextWith(distContext);
   }
 
-  @Override
-  public HttpTextFormat<CorrelationContext> getHttpTextFormat() {
-    return HTTP_TEXT_FORMAT;
-  }
-
   @Immutable
   private static final class NoopCorrelationContextBuilder implements CorrelationContext.Builder {
     @Override
@@ -82,10 +72,10 @@ public CorrelationContext.Builder setNoParent() {
 
     @Override
     public CorrelationContext.Builder put(
-        EntryKey key, EntryValue value, EntryMetadata tagMetadata) {
+        EntryKey key, EntryValue value, EntryMetadata entryMetadata) {
       Utils.checkNotNull(key, "key");
       Utils.checkNotNull(value, "value");
-      Utils.checkNotNull(tagMetadata, "tagMetadata");
+      Utils.checkNotNull(entryMetadata, "entryMetadata");
       return this;
     }
 
@@ -100,26 +90,4 @@ public CorrelationContext build() {
       return EmptyCorrelationContext.getInstance();
     }
   }
-
-  @Immutable
-  private static final class NoopHttpTextFormat implements HttpTextFormat<CorrelationContext> {
-    @Override
-    public List<String> fields() {
-      return Collections.emptyList();
-    }
-
-    @Override
-    public <C> void inject(CorrelationContext distContext, C carrier, Setter<C> setter) {
-      Utils.checkNotNull(distContext, "distContext");
-      Utils.checkNotNull(carrier, "carrier");
-      Utils.checkNotNull(setter, "setter");
-    }
-
-    @Override
-    public <C> CorrelationContext extract(C carrier, Getter<C> getter) {
-      Utils.checkNotNull(carrier, "carrier");
-      Utils.checkNotNull(getter, "getter");
-      return EmptyCorrelationContext.getInstance();
-    }
-  }
 }

api/src/main/java/io/opentelemetry/trace/DefaultTracer.java

@@ -18,10 +18,9 @@
 
 import io.opentelemetry.common.AttributeValue;
 import io.opentelemetry.context.Scope;
-import io.opentelemetry.context.propagation.HttpTextFormat;
 import io.opentelemetry.internal.Utils;
-import io.opentelemetry.trace.propagation.HttpTraceContext;
 import java.util.Map;
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 
 /**
@@ -32,7 +31,6 @@
 @ThreadSafe
 public final class DefaultTracer implements Tracer {
   private static final DefaultTracer INSTANCE = new DefaultTracer();
-  private static final HttpTextFormat<SpanContext> HTTP_TEXT_FORMAT = new HttpTraceContext();
 
   /**
    * Returns a {@code Tracer} singleton that is the default implementations for {@link Tracer}.
@@ -56,30 +54,24 @@ public Scope withSpan(Span span) {
 
   @Override
   public Span.Builder spanBuilder(String spanName) {
-    return NoopSpanBuilder.create(this, spanName);
-  }
-
-  @Override
-  public HttpTextFormat<SpanContext> getHttpTextFormat() {
-    return HTTP_TEXT_FORMAT;
+    return NoopSpanBuilder.create(spanName);
   }
 
   private DefaultTracer() {}
 
   // Noop implementation of Span.Builder.
   private static final class NoopSpanBuilder implements Span.Builder {
-    static NoopSpanBuilder create(Tracer tracer, String spanName) {
-      return new NoopSpanBuilder(tracer, spanName);
+    static NoopSpanBuilder create(String spanName) {
+      return new NoopSpanBuilder(spanName);
     }
 
-    private final Tracer tracer;
     private boolean isRootSpan;
-    private SpanContext spanContext;
+    @Nullable private SpanContext spanContext;
 
     @Override
     public Span startSpan() {
       if (spanContext == null && !isRootSpan) {
-        spanContext = tracer.getCurrentSpan().getContext();
+        spanContext = TracingContextUtils.getCurrentSpan().getContext();
       }
 
       return spanContext != null && !SpanContext.getInvalid().equals(spanContext)
@@ -165,9 +157,8 @@ public NoopSpanBuilder setStartTimestamp(long startTimestamp) {
       return this;
     }
 
-    private NoopSpanBuilder(Tracer tracer, String name) {
+    private NoopSpanBuilder(String name) {
       Utils.checkNotNull(name, "name");
-      this.tracer = tracer;
     }
   }
 }

api/src/main/java/io/opentelemetry/trace/Tracer.java

@@ -18,8 +18,6 @@
 
 import com.google.errorprone.annotations.MustBeClosed;
 import io.opentelemetry.context.Scope;
-import io.opentelemetry.context.propagation.HttpTextFormat;
-import io.opentelemetry.trace.propagation.HttpTraceContext;
 import javax.annotation.concurrent.ThreadSafe;
 
 /**
@@ -152,59 +150,4 @@ public interface Tracer {
    * @since 0.1.0
    */
   Span.Builder spanBuilder(String spanName);
-
-  /**
-   * Returns the {@link HttpTextFormat} for this tracer implementation.
-   *
-   * <p>If no tracer implementation is provided, this defaults to the W3C Trace Context HTTP text
-   * format ({@link HttpTraceContext}). For more details see <a
-   * href="https://w3c.github.io/trace-context/">W3C Trace Context</a>.
-   *
-   * <p>Example of usage on the client:
-   *
-   * <pre>{@code
-   * private static final Tracer tracer = OpenTelemetry.getTracer();
-   * private static final HttpTextFormat textFormat = tracer.getHttpTextFormat();
-   * private static final HttpTextFormat.Setter setter =
-   *         new HttpTextFormat.Setter<HttpURLConnection>() {
-   *   public void put(HttpURLConnection carrier, String key, String value) {
-   *     carrier.setRequestProperty(field, value);
-   *   }
-   * }
-   *
-   * void makeHttpRequest() {
-   *   Span span = tracer.spanBuilder("MyRequest").setSpanKind(Span.Kind.CLIENT).startSpan();
-   *   try (Scope s = tracer.withSpan(span)) {
-   *     HttpURLConnection connection =
-   *         (HttpURLConnection) new URL("http://myserver").openConnection();
-   *     textFormat.inject(span.getContext(), connection, httpURLConnectionSetter);
-   *     // Send the request, wait for response and maybe set the status if not ok.
-   *   }
-   *   span.end();  // Can set a status.
-   * }
-   * }</pre>
-   *
-   * <p>Example of usage on the server:
-   *
-   * <pre>{@code
-   * private static final Tracer tracer = OpenTelemetry.getTracer();
-   * private static final HttpTextFormat textFormat = tracer.getHttpTextFormat();
-   * private static final HttpTextFormat.Getter<HttpRequest> getter = ...;
-   *
-   * void onRequestReceived(HttpRequest request) {
-   *   SpanContext spanContext = textFormat.extract(request, getter);
-   *   Span span = tracer.spanBuilder("MyRequest")
-   *       .setParent(spanContext)
-   *       .setSpanKind(Span.Kind.SERVER).startSpan();
-   *   try (Scope s = tracer.withSpan(span)) {
-   *     // Handle request and send response back.
-   *   }
-   *   span.end()
-   * }
-   * }</pre>
-   *
-   * @return the {@code HttpTextFormat} for this implementation.
-   * @since 0.1.0
-   */
-  HttpTextFormat<SpanContext> getHttpTextFormat();
 }