[Breaking Change] Remove B3Propagator.Builder, add static methods to access possible instances (#2863)

Signed-off-by: Bogdan Drutu <[email protected]>

Author: bogdandrutu

extensions/trace-propagators/src/jmh/java/io/opentelemetry/extension/trace/propagation/PropagatorContextExtractBenchmark.java

@@ -202,7 +202,7 @@ public String get(Map<String, String> carrier, String key) {
           }
         };
 
-    private final B3Propagator b3Propagator = B3Propagator.getInstance();
+    private final B3Propagator b3Propagator = B3Propagator.injectingSingleHeader();
 
     @Override
     protected Context doExtract() {
@@ -253,7 +253,7 @@ public String get(Map<String, String> carrier, String key) {
           }
         };
 
-    private final B3Propagator b3Propagator = B3Propagator.getInstance();
+    private final B3Propagator b3Propagator = B3Propagator.injectingSingleHeader();
 
     @Override
     protected Context doExtract() {

extensions/trace-propagators/src/jmh/java/io/opentelemetry/extension/trace/propagation/PropagatorContextInjectBenchmark.java

@@ -100,7 +100,7 @@ protected void doInject(Context context, Map<String, String> carrier) {
   /** Benchmark for injecting trace context into a single B3 header. */
   public static class B3SingleHeaderContextInjectBenchmark extends AbstractContextInjectBenchmark {
 
-    private final B3Propagator b3Propagator = B3Propagator.getInstance();
+    private final B3Propagator b3Propagator = B3Propagator.injectingSingleHeader();
     private final TextMapSetter<Map<String, String>> setter =
         new TextMapSetter<Map<String, String>>() {
           @Override
@@ -119,8 +119,7 @@ protected void doInject(Context context, Map<String, String> carrier) {
   public static class B3MultipleHeaderContextInjectBenchmark
       extends AbstractContextInjectBenchmark {
 
-    private final B3Propagator b3Propagator =
-        B3Propagator.builder().injectMultipleHeaders().build();
+    private final B3Propagator b3Propagator = B3Propagator.injectingMultiHeaders();
     private final TextMapSetter<Map<String, String>> setter =
         new TextMapSetter<Map<String, String>>() {
           @Override

extensions/trace-propagators/src/main/java/io/opentelemetry/extension/trace/propagation/B3Propagator.java

@@ -27,23 +27,23 @@
  * href=https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/context/api-propagators.md#b3-requirements>B3
  * Requirements</a>
  *
- * <p>To register the default B3 propagator, which injects a single header, use the default instance
+ * <p>To register the default B3 propagator, which injects a single header, use:
  *
  * <pre>{@code
  * OpenTelemetry.setPropagators(
  *   DefaultContextPropagators
  *     .builder()
- *     .addTextMapPropagator(B3Propagator.getInstance())
+ *     .addTextMapPropagator(B3Propagator.injectingSingleHeader())
  *     .build());
  * }</pre>
  *
- * <p>To register a B3 propagator that injects multiple headers, use the builder
+ * <p>To register a B3 propagator that injects multiple headers, use:
  *
  * <pre>{@code
  * OpenTelemetry.setPropagators(
  *   DefaultContextPropagators
  *     .builder()
- *     .addTextMapPropagator(B3Propagator.builder().injectMultipleHeaders().build())
+ *     .addTextMapPropagator(B3Propagator.injectingMultiHeaders())
  *     .build());
  * }</pre>
  */
@@ -68,7 +68,10 @@ public final class B3Propagator implements TextMapPropagator {
       Collections.unmodifiableList(
           Arrays.asList(TRACE_ID_HEADER, SPAN_ID_HEADER, SAMPLED_HEADER, COMBINED_HEADER));
 
-  private static final B3Propagator INSTANCE = B3Propagator.builder().build();
+  private static final B3Propagator SINGLE_HEADER_INSTANCE =
+      new B3Propagator(new B3PropagatorInjectorSingleHeader());
+  private static final B3Propagator MULTI_HEADERS_INSTANCE =
+      new B3Propagator(new B3PropagatorInjectorMultipleHeaders());
 
   private final B3PropagatorExtractor singleHeaderExtractor =
       new B3PropagatorExtractorSingleHeader();
@@ -81,41 +84,27 @@ private B3Propagator(B3PropagatorInjector b3PropagatorInjector) {
   }
 
   /**
-   * Returns a new {@link B3Propagator.Builder} instance for configuring injection option for {@link
-   * B3Propagator}.
+   * Returns an instance of the {@link B3Propagator} that injects multi headers format.
+   *
+   * <p>This instance extracts both formats, in the order: single header, multi header.
+   *
+   * @return an instance of the {@link B3Propagator} that injects multi headers format.
    */
-  public static B3Propagator.Builder builder() {
-    return new Builder();
+  public static B3Propagator injectingMultiHeaders() {
+    return MULTI_HEADERS_INSTANCE;
   }
 
   /**
-   * Enables the creation of an {@link B3Propagator} instance with the ability to switch injector
-   * from single header (default) to multiple headers.
+   * Returns an instance of the {@link B3Propagator} that injects single header format.
+   *
+   * <p>This instance extracts both formats, in the order: single header, multi header.
+   *
+   * <p>This is the default instance for {@link B3Propagator}.
+   *
+   * @return an instance of the {@link B3Propagator} that injects single header format.
    */
-  public static class Builder {
-    private boolean injectSingleHeader;
-
-    private Builder() {
-      injectSingleHeader = true;
-    }
-
-    public Builder injectMultipleHeaders() {
-      this.injectSingleHeader = false;
-      return this;
-    }
-
-    /** Create the {@link B3Propagator} with selected injector type. */
-    public B3Propagator build() {
-      if (injectSingleHeader) {
-        return new B3Propagator(new B3PropagatorInjectorSingleHeader());
-      } else {
-        return new B3Propagator(new B3PropagatorInjectorMultipleHeaders());
-      }
-    }
-  }
-
-  public static B3Propagator getInstance() {
-    return INSTANCE;
+  public static B3Propagator injectingSingleHeader() {
+    return SINGLE_HEADER_INSTANCE;
   }
 
   @Override

extensions/trace-propagators/src/test/java/io/opentelemetry/extension/trace/propagation/B3PropagatorTest.java

@@ -50,8 +50,8 @@ public String get(Map<String, String> carrier, String key) {
           return carrier.get(key);
         }
       };
-  private final B3Propagator b3Propagator = B3Propagator.builder().injectMultipleHeaders().build();
-  private final B3Propagator b3PropagatorSingleHeader = B3Propagator.getInstance();
+  private final B3Propagator b3Propagator = B3Propagator.injectingMultiHeaders();
+  private final B3Propagator b3PropagatorSingleHeader = B3Propagator.injectingSingleHeader();
 
   private static SpanContext getSpanContext(Context context) {
     return Span.fromContext(context).getSpanContext();

opencensus-shim/src/main/java/io/opentelemetry/opencensusshim/OpenTelemetryPropagationComponentImpl.java

@@ -13,7 +13,7 @@
 class OpenTelemetryPropagationComponentImpl extends PropagationComponentImpl {
 
   private final TextFormat b3Format =
-      new OpenTelemetryTextFormatImpl(B3Propagator.builder().injectMultipleHeaders().build());
+      new OpenTelemetryTextFormatImpl(B3Propagator.injectingMultiHeaders());
   private final TextFormat traceContextFormat =
       new OpenTelemetryTextFormatImpl(W3CTraceContextPropagator.getInstance());
 

opencensus-shim/src/test/java/io/opentelemetry/opencensusshim/OpenTelemetryTextFormatImplTest.java

@@ -112,7 +112,7 @@ void testInjectWithDefaultOptions() {
   @Test
   void testInjectAndExtractWithB3() {
     OpenTelemetryTextFormatImpl textFormatImpl =
-        new OpenTelemetryTextFormatImpl(B3Propagator.builder().injectMultipleHeaders().build());
+        new OpenTelemetryTextFormatImpl(B3Propagator.injectingMultiHeaders());
     Map<String, String> carrier = new LinkedHashMap<>();
 
     textFormatImpl.inject(SPAN_CONTEXT, carrier, SETTER);

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/PropagatorConfiguration.java

@@ -62,9 +62,9 @@ private static TextMapPropagator getPropagator(
 
     switch (name) {
       case "b3":
-        return B3Propagator.getInstance();
+        return B3Propagator.injectingSingleHeader();
       case "b3multi":
-        return B3Propagator.builder().injectMultipleHeaders().build();
+        return B3Propagator.injectingMultiHeaders();
       case "jaeger":
         return JaegerPropagator.getInstance();
         // NB: https://github.com/open-telemetry/opentelemetry-specification/pull/1406

sdk-extensions/autoconfigure/src/testFullConfig/java/io/opentelemetry/sdk/autoconfigure/FullConfigTest.java

@@ -120,7 +120,7 @@ void configures() throws Exception {
     List<String> keys = new ArrayList<>();
     keys.addAll(W3CTraceContextPropagator.getInstance().fields());
     keys.addAll(W3CBaggagePropagator.getInstance().fields());
-    keys.addAll(B3Propagator.getInstance().fields());
+    keys.addAll(B3Propagator.injectingSingleHeader().fields());
     keys.addAll(JaegerPropagator.getInstance().fields());
     keys.addAll(OtTracePropagator.getInstance().fields());
     keys.addAll(AwsXrayPropagator.getInstance().fields());