snarking on otel's tracer v0.6

Snark.java

import io.opentelemetry.common.AttributeValue;
import io.opentelemetry.exporters.logging.LoggingSpanExporter;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.trace.export.SimpleSpanProcessor;
import io.opentelemetry.trace.Span;
import io.opentelemetry.trace.Tracer;

// This shows how you can add attributes to a span and print it to console using Java's logger.
//
// $ java -cp snark.jar Snark
// Jul 09, 2020 10:09:38 AM io.opentelemetry.exporters.logging.LoggingSpanExporter export
// INFO: span: SpanWrapper{delegate=io.opentelemetry.sdk.trace.RecordEventsReadableSpan@42110406, resolvedLinks=[], resolvedEvents=[], attributes={test questions?=AttributeValueBooleanArray{booleanArrayValue=[false, false, true]}}, totalAttributeCount=2, totalRecordedEvents=0, status=Status{canonicalCode=OK, description=null}}
//
// If you bundle this with maven-shade-library, you'll get all 3MiB of dependencies needed to print
// the above, like I did. Here's what you'll get when you depend on opentelemetry-exporters-logging
//
// \- io.opentelemetry:opentelemetry-exporters-logging:jar:0.6.0:compile
//    \- io.opentelemetry:opentelemetry-sdk:jar:0.6.0:compile
//       +- io.opentelemetry:opentelemetry-api:jar:0.6.0:compile
//       |  \- io.opentelemetry:opentelemetry-context-prop:jar:0.6.0:compile
//       |     \- io.grpc:grpc-context:jar:1.28.0:compile
//       \- com.google.guava:guava:jar:28.2-android:runtime
//          +- com.google.guava:failureaccess:jar:1.0.1:runtime
//          +- com.google.guava:listenablefuture:jar:9999.0-empty-to-avoid-conflict-with-guava:runtime
//          +- com.google.code.findbugs:jsr305:jar:3.0.2:runtime
//          +- org.checkerframework:checker-compat-qual:jar:2.5.5:runtime
//          +- com.google.errorprone:error_prone_annotations:jar:2.3.4:runtime
//          \- com.google.j2objc:j2objc-annotations:jar:1.3:runtime
//
// Here goes..
public class Snark {

  // Some jokes are about "sdk" types and some will say .. oh just use api..
  // 
  // I dare you to find any project that exclusively depends on the "api" and can do anything.
  // I double-dare you to find a second impl of the api
  // 
  // meaning the SDK classes can be assumed present
  public static void main(String[] args) {
    // hmm static registries.. can't find an example of a not-static registry.
    OpenTelemetrySdk.getTracerProvider()
        // I assume this will just change whatever global there is. Handy this is exposed as I was
        // thinking I can add a processor per-request?
        .addSpanProcessor(SimpleSpanProcessor.newBuilder(
            // this is for when you want to see hashCodes of java types in log files...
            // even if this stopped being lazy and used a non-generated toString, something helpful
            // like rendering in json might be thwarted due to the intentional inclusion of various
            // 64-bit numeric types (like both long and double and.. heh.. arrays of them!)
            new LoggingSpanExporter()
        ).build());

    // addSpanProcessor isn't chained, which is ok I guess as it shouldn't be an api anyway
    // odd that I had to change this from TracerSdk to Tracer. Why would you covariantly return
    // a package private type? annoying..
    Tracer tracer =
        OpenTelemetrySdk.getTracerProvider().get("we have to name tracers.. ok");

    // something normalish whew..
    Span span = tracer.spanBuilder("snark attack").startSpan();
    span.setAttribute("string", "sheesh"); // not chained so we can practice semi-colons
    // null allowed because we like to pretend you can win a race. Also allows us to force a cast
    span.setAttribute("string", (String) null);
    // this is one of the more hilarious api choices. what ... tag.. would .. be ..?
    span.setAttribute("test questions?", AttributeValue.arrayAttributeValue(false, false, true));
    span.end(); // start/finish begin/end.. false dichotomy! start/end

    // because shutting down things we didn't start is good
    OpenTelemetrySdk.getTracerProvider().shutdown();
  }
}