44 lines
1.5 KiB
Java
44 lines
1.5 KiB
Java
package datadog.trace.bootstrap;
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/** Instrumentation Context API */
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public class InstrumentationContext {
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private InstrumentationContext() {}
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/**
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* Fetch a context instance out of the context store.
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*
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* <p>
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*
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* <p>Conceptually, this can be thought of as a two pass map look up.
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*
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* <p>For example: <em>RunnableState runnableState = get(runnableImpl, Runnable.class,
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* RunnableState.class)</em> --> <em>RunnableState runnableState = (RunnableState)
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* GlobalContextMap.get(Runnable.class).get(runnableImpl)</em>
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*
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* <p>
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*
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* <p>However, the implementation is actually provided by bytecode transformation for performance
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* reasons.
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*
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* <p>
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*
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* <p>Context classes are weakly referenced and will be garbage collected when their corresponding
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* user instance is collected.
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*
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* <p>
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*
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* <p>Instrumenters making this call must define the user-context class relationship in
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* datadog.trace.agent.tooling.Instrumenter.Default#contextStore.
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*
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* @param userInstance The instance to store context on.
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* @param userClass The user class context is attached to.
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* @param contextClass The context class attached to the user class.
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* @param <K> user class
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* @param <V> context class
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* @return The context instance attached to userInstance.
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*/
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public static <K, V> V get(K userInstance, Class<K> userClass, Class<V> contextClass) {
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throw new RuntimeException("calls to this method will be rewritten");
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}
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}
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