io.reactivex.netty.contexts.ThreadLocalRequestCorrelator Maven / Gradle / Ivy
/*
* Copyright 2014 Netflix, Inc.
*
* 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.reactivex.netty.contexts;
import io.netty.channel.EventLoopGroup;
import io.netty.util.AttributeKey;
import io.netty.util.AttributeMap;
import io.netty.util.DefaultAttributeMap;
import io.reactivex.netty.client.RxClient;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.PrintStream;
import java.util.Stack;
import java.util.concurrent.Callable;
/**
* An implementation of {@link RequestCorrelator} that fetches {@link ContextsContainer} and request Identifer from
* {@link ThreadLocal} variables.
* The usage of this correlator assumes that every {@link EventLoopGroup} used by all {@link RxClient}s in use for
* the propagation of these contexts, uses {@link ContextAwareEventLoopGroup}.
* In case, the application is using any other threadpools, the invariant of the thread state copied from one thread
* to another is maintained.
*
* @author Nitesh Kant
*/
public class ThreadLocalRequestCorrelator implements RequestCorrelator {
private static final Logger logger = LoggerFactory.getLogger(ThreadLocalRequestCorrelator.class);
protected static final ThreadLocal state = new ThreadLocal() {
@Override
protected ThreadStateHolder initialValue() {
return new ThreadStateHolder();
}
};
@Override
public String getRequestIdForClientRequest() {
return state.get().getRequestId();
}
@Override
public ContextsContainer getContextForClientRequest(String requestId) {
return state.get().getContainer();
}
@Override
public void onNewServerRequest(String requestId, ContextsContainer contextsContainer) {
if (null == requestId) {
throw new IllegalArgumentException("Request Id can not be null.");
}
if (null == contextsContainer) {
throw new IllegalArgumentException("Context container can not be null.");
}
state.get().push(new DefaultAttributeMap());
state.get().setRequestId(requestId);
state.get().setContainer(contextsContainer);
}
@Override
public void beforeNewClientRequest(String requestId, ContextsContainer contextsContainer) {
onNewServerRequest(requestId, contextsContainer); // same effect
}
@Override
public void onClientProcessingEnd(String requestId) {
state.get().pop();
}
@Override
public void onServerProcessingEnd(String requestId) {
state.get().pop();
}
public static ContextsContainer getCurrentContextContainer() {
return state.get().getContainer();
}
public static String getCurrentRequestId() {
return state.get().getRequestId();
}
@Override
public Callable makeClosure(final Callable original) {
final AttributeMap currentState = state.get().peek();
return new Callable() {
@Override
public V call() throws Exception {
state.get().push(currentState);
try {
return original.call();
} finally {
state.get().pop();
}
}
};
}
@Override
public Runnable makeClosure(final Runnable original) {
final AttributeMap currentState = state.get().peek();
return new Runnable() {
@Override
public void run() {
state.get().push(currentState);
try {
original.run();
} finally {
state.get().pop();
}
}
};
}
public void dumpThreadState() {
if (logger.isDebugEnabled()) {
ThreadStateHolder threadStateHolder = state.get();
logger.debug("******************** Thread Attributes ********************");
int count = 0;
for (AttributeMap threadAttribute : threadStateHolder.threadAttributes) {
logger.debug("Stack level==> " + ++count);
logger.debug("Request Id: " + threadAttribute.attr(ThreadStateHolder.requestIdKey));
logger.debug("Context container: " + threadAttribute.attr(ThreadStateHolder.containerKey));
}
logger.debug("***********************************************************");
}
}
public void dumpThreadState(PrintStream outputStream) {
ThreadStateHolder threadStateHolder = state.get();
outputStream.println("******************** Thread Attributes ********************");
int count = 0;
for (AttributeMap threadAttribute : threadStateHolder.threadAttributes) {
outputStream.println("Stack level==> " + ++count);
outputStream.println("Request Id: " + threadAttribute.attr(ThreadStateHolder.requestIdKey));
outputStream.println("Context container: " + threadAttribute.attr(ThreadStateHolder.containerKey));
}
outputStream.println("***********************************************************");
}
public static final class ThreadStateHolder {
private static final AttributeKey requestIdKey =
AttributeKey.valueOf("rxnetty-contexts-threadlocal-request-id-key");
private static final AttributeKey containerKey =
AttributeKey.valueOf("rxnetty-contexts-threadlocal-context-container-key");
/**
* This is a stack because the client and server processing can be on the same thread, either by chance or
* just because there is only a single thread in the system.
* This means we can not simply set & unset on start & stop of processing as it can step on other's feet.
* The best way to handle is to use a stack where in states are pushed and popped. If we pop everything, it is
* as good as clear state.
* Here {@link AttributeMap} is used just to have a map that stores multiple objects and still is type safe.
*/
private final Stack threadAttributes = new Stack();
public void push(AttributeMap map) {
threadAttributes.push(map);
}
public AttributeMap pop() {
return threadAttributes.pop();
}
public AttributeMap peek() {
if (isEmpty()) {
return null;
}
return threadAttributes.peek();
}
public boolean isEmpty() {
return threadAttributes.isEmpty();
}
public void setRequestId(String requestId) {
if (!isEmpty()) {
peek().attr(requestIdKey).set(requestId);
}
}
public void setContainer(ContextsContainer container) {
if (!isEmpty()) {
peek().attr(containerKey).set(container);
}
}
public String getRequestId() {
if (isEmpty()) {
return null;
}
return peek().attr(requestIdKey).get();
}
public ContextsContainer getContainer() {
if (isEmpty()) {
return null;
}
return peek().attr(containerKey).get();
}
}
}