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Update lessons #30
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| Original file line number | Diff line number | Diff line change |
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@@ -53,18 +53,19 @@ We can use a global instance returned by `io.opentracing.util.GlobalTracer.get() | |
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| ```java | ||
| import io.opentracing.Span; | ||
| import io.opentracing.Tracer; | ||
| import io.opentracing.util.GlobalTracer; | ||
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| public class Hello { | ||
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| private final Tracer tracer; | ||
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| private Hello(Tracer tracer) { | ||
| this.tracer = tracer; | ||
| } | ||
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| private void sayHello(String helloTo) { | ||
| Span span = tracer.buildSpan("say-hello").start(); | ||
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| String helloStr = String.format("Hello, %s!", helloTo); | ||
| System.out.println(helloStr); | ||
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@@ -85,7 +86,7 @@ public class Hello { | |
| We are using the following basic features of the OpenTracing API: | ||
| * a `tracer` instance is used to create a span builder via `buildSpan()` | ||
| * each `span` is given an _operation name_, `"say-hello"` in this case | ||
| * builder is used to create a span via `start()` | ||
| * each `span` must be finished by calling its `finish()` function | ||
| * the start and end timestamps of the span will be captured automatically by the tracer implementation | ||
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@@ -94,40 +95,38 @@ That's because the function `GlobalTracer.get()` returns a no-op tracer by defau | |
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| ### Initialize a real tracer | ||
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| Let's create an instance of a real tracer, such as Jaeger (https://github.com/jaegertracing/jaeger-client-java). | ||
| Our `pom.xml` already imports Jaeger: | ||
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| ```xml | ||
| <dependency> | ||
| <groupId>io.jaegertracing</groupId> | ||
| <artifactId>jaeger-client</artifactId> | ||
| <version>0.31.0</version> | ||
| </dependency> | ||
| ``` | ||
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| First let's define a helper function that will create a tracer. | ||
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| ```java | ||
| import io.jaegertracing.Configuration; | ||
| import io.jaegertracing.Configuration.ReporterConfiguration; | ||
| import io.jaegertracing.Configuration.SamplerConfiguration; | ||
| import io.jaegertracing.internal.JaegerTracer; | ||
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| public static JaegerTracer initTracer(String service) { | ||
| SamplerConfiguration samplerConfig = new SamplerConfiguration().withType("const").withParam(1); | ||
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There was a problem hiding this comment. How about we use a simple There was a problem hiding this comment. @jpkrohling, I just started learning OpenTracing, so I'm not familiar with "export the relevant env vars", yet. There was a problem hiding this comment. Fair enough. This is particular to Jaeger (not generic OpenTracing), and it might indeed confuse users. For reference, I'm talking about There was a problem hiding this comment. Could you change this to use |
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| ReporterConfiguration reporterConfig = new ReporterConfiguration().withLogSpans(true); | ||
| Configuration config = new Configuration(service).withSampler(samplerConfig).withReporter(reporterConfig); | ||
| return config.getTracer(); | ||
| } | ||
| ``` | ||
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| To use this instance, let's change the main function: | ||
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| ```java | ||
| Tracer tracer = initTracer("hello-world"); | ||
| new Hello(tracer).sayHello(helloTo); | ||
| ``` | ||
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| Note that we are passing a string `hello-world` to the init method. It is used to mark all spans emitted by | ||
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@@ -137,9 +136,9 @@ If we run the program now, we should see a span logged: | |
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| ``` | ||
| $ ./run.sh lesson01.exercise.Hello Bryan | ||
| [lesson01.exercise.Hello.main()] INFO io.jaegertracing.Configuration - Initialized tracer=Tracer(...) | ||
| Hello, Bryan! | ||
| [lesson01.exercise.Hello.main()] INFO io.jaegertracing.reporters.LoggingReporter - Span reported: 76509ca0cd333055:76509ca0cd333055:0:1 - say-hello | ||
| ``` | ||
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| If you have Jaeger backend running, you should be able to see the trace in the UI. | ||
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@@ -177,7 +176,7 @@ In the case of `Hello Bryan`, the string `"Bryan"` is a good candidate for a spa | |
| to the whole span and not to a particular moment in time. We can record it like this: | ||
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| ```java | ||
| Span span = tracer.buildSpan("say-hello").start(); | ||
| span.setTag("hello-to", helloTo); | ||
| ``` | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,9 +1,10 @@ | ||
| package lesson01.solution; | ||
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| import com.google.common.collect.ImmutableMap; | ||
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| import io.jaegertracing.internal.JaegerTracer; | ||
| import io.opentracing.Span; | ||
| import io.opentracing.Tracer; | ||
| import lib.Tracing; | ||
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| public class Hello { | ||
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@@ -15,9 +16,9 @@ private Hello(Tracer tracer) { | |
| } | ||
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| private void sayHello(String helloTo) { | ||
| Span span = tracer.buildSpan("say-hello").start(); | ||
| span.setTag("hello-to", helloTo); | ||
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| String helloStr = String.format("Hello, %s!", helloTo); | ||
| span.log(ImmutableMap.of("event", "string-format", "value", helloStr)); | ||
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@@ -31,9 +32,10 @@ public static void main(String[] args) { | |
| if (args.length != 1) { | ||
| throw new IllegalArgumentException("Expecting one argument"); | ||
| } | ||
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| String helloTo = args[0]; | ||
| try (JaegerTracer tracer = Tracing.init("hello-world")) { | ||
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There was a problem hiding this comment. IMO, the tutorial should be using OT's Tracer instead of JaegerTracer as much as possible. The side effect is that, at least for now, we'd need to close the tracer manually (see jaegertracing/jaeger-client-java#544). There was a problem hiding this comment. That said, we could change the tutorial later, once we fix the mentioned issue. There was a problem hiding this comment. I absolutely agree! I have changed the code and lesson01/README.md to reflect this. |
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| new Hello(tracer).sayHello(helloTo); | ||
| } | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,13 +1,14 @@ | ||
| package lesson02.solution; | ||
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| import com.google.common.collect.ImmutableMap; | ||
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| import io.jaegertracing.internal.JaegerTracer; | ||
| import io.opentracing.Scope; | ||
| import io.opentracing.Tracer; | ||
| import lib.Tracing; | ||
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| public class HelloActive { | ||
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| private final Tracer tracer; | ||
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| private HelloActive(Tracer tracer) { | ||
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@@ -17,7 +18,7 @@ private HelloActive(Tracer tracer) { | |
| private void sayHello(String helloTo) { | ||
| try (Scope scope = tracer.buildSpan("say-hello").startActive(true)) { | ||
| scope.span().setTag("hello-to", helloTo); | ||
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| String helloStr = formatString(helloTo); | ||
| printHello(helloStr); | ||
| } | ||
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@@ -42,9 +43,10 @@ public static void main(String[] args) { | |
| if (args.length != 1) { | ||
| throw new IllegalArgumentException("Expecting one argument"); | ||
| } | ||
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| String helloTo = args[0]; | ||
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There was a problem hiding this comment. You'll still need this until we release 0.31.1, which includes the JVM shutdown hook. There was a problem hiding this comment. I have been waiting for opentracing/opentracing-java#250 and opentracing/specification#128 to move forward with the Closeable spec, but it seems this will take a while. I've updated this pull request to upcast to JaegerTracer in a try-resource block. |
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| try (JaegerTracer tracer = Tracing.init("hello-world")) { | ||
| new HelloActive(tracer).sayHello(helloTo); | ||
| } | ||
| } | ||
| } | ||
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0.32.0, otherwise, you'll need to add the
#close()calls. The 0.32.0 implements the "close on JVM shutdown" feature.There was a problem hiding this comment.
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@pavolloffay, is 0.32.0 available on maven central already?
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it should be, if it's not I don't want to redo the release 😢
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It's there, just confirmed :)