io.micronaut.tracing.instrument.rxjava.RxJava1TracingInstrumentation Maven / Gradle / Ivy

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/*
 * Copyright 2017-2020 original authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.micronaut.tracing.instrument.rxjava;

import io.micronaut.context.annotation.Context;
import io.micronaut.context.annotation.Requires;
import io.micronaut.core.annotation.Internal;
import io.micronaut.scheduling.instrument.InvocationInstrumenter;
import io.micronaut.tracing.instrument.util.TracingInvocationInstrumenterFactory;
import rx.Single;
import rx.functions.Action0;
import rx.functions.Func1;
import rx.plugins.RxJavaHooks;

import javax.annotation.PostConstruct;
import javax.inject.Singleton;

/**
 * Instrumentation for RxJava 1.
 *
 * @author graemerocher
 * @since 1.0
 */
@Singleton
@Context
@Requires(classes = Single.class)
@Requires(beans = TracingInvocationInstrumenterFactory.class)
@Internal
public final class RxJava1TracingInstrumentation {

    /**
     * Instrumentation for RxJava 1 for tracing.
     *
     * @param instrumenter A function that instruments an existing Runnable
     */
    @PostConstruct
    void init(TracingInvocationInstrumenterFactory instrumenter) {
        if (instrumenter != null) {
            Func1 existing = RxJavaHooks.getOnScheduleAction();
            if (existing != null && !(existing instanceof InstrumentScheduleAction)) {
                RxJavaHooks.setOnScheduleAction(action0 ->
                        new InstrumentScheduleAction(instrumenter).call(existing.call(action0))
                );
            } else {
                RxJavaHooks.setOnScheduleAction(new InstrumentScheduleAction(instrumenter));
            }
        }
    }

    /**
     * A function that instruments an existing Runnable with {@link io.micronaut.tracing.instrument.util.TracingRunnable}.
     */
    private static class InstrumentScheduleAction implements Func1 {
        private final TracingInvocationInstrumenterFactory instrumenter;

        InstrumentScheduleAction(TracingInvocationInstrumenterFactory instrumenter) {
            this.instrumenter = instrumenter;
        }

        @Override
        public Action0 call(Action0 action0) {
            final InvocationInstrumenter instrumenter = this.instrumenter.newTracingInvocationInstrumenter();
            if (instrumenter != null) {
                return () -> {
                    try {
                        instrumenter.beforeInvocation();
                        action0.call();
                    } finally {
                        instrumenter.afterInvocation(false);
                    }
                };
            } else {
                return action0;
            }
        }
    }
}