/**
* Copyright 2012 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 com.netflix.hystrix.examples.basic;
import static org.junit.Assert.*;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.Future;
import org.junit.Test;
import com.netflix.hystrix.HystrixCollapser;
import com.netflix.hystrix.HystrixCommand;
import com.netflix.hystrix.HystrixCommandGroupKey;
import com.netflix.hystrix.HystrixCommandKey;
import com.netflix.hystrix.HystrixEventType;
import com.netflix.hystrix.HystrixRequestLog;
import com.netflix.hystrix.strategy.concurrency.HystrixRequestContext;
/**
* Sample {@link HystrixCollapser} that automatically batches multiple requests to execute()/queue()
* into a single {@link HystrixCommand} execution for all requests within the defined batch (time or size).
*/
public class CommandCollapserGetValueForKey extends HystrixCollapser<List<String>, String, Integer> {
private final Integer key;
public CommandCollapserGetValueForKey(Integer key) {
this.key = key;
}
@Override
public Integer getRequestArgument() {
return key;
}
@Override
protected HystrixCommand<List<String>> createCommand(final Collection<CollapsedRequest<String, Integer>> requests) {
return new BatchCommand(requests);
}
@Override
protected void mapResponseToRequests(List<String> batchResponse, Collection<CollapsedRequest<String, Integer>> requests) {
int count = 0;
for (CollapsedRequest<String, Integer> request : requests) {
request.setResponse(batchResponse.get(count++));
}
}
private static final class BatchCommand extends HystrixCommand<List<String>> {
private final Collection<CollapsedRequest<String, Integer>> requests;
private BatchCommand(Collection<CollapsedRequest<String, Integer>> requests) {
super(Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("ExampleGroup"))
.andCommandKey(HystrixCommandKey.Factory.asKey("GetValueForKey")));
this.requests = requests;
}
@Override
protected List<String> run() {
ArrayList<String> response = new ArrayList<String>();
for (CollapsedRequest<String, Integer> request : requests) {
// artificial response for each argument received in the batch
response.add("ValueForKey: " + request.getArgument());
}
return response;
}
}
public static class UnitTest {
@Test
public void testCollapser() throws Exception {
HystrixRequestContext context = HystrixRequestContext.initializeContext();
try {
Future<String> f1 = new CommandCollapserGetValueForKey(1).queue();
Future<String> f2 = new CommandCollapserGetValueForKey(2).queue();
Future<String> f3 = new CommandCollapserGetValueForKey(3).queue();
Future<String> f4 = new CommandCollapserGetValueForKey(4).queue();
assertEquals("ValueForKey: 1", f1.get());
assertEquals("ValueForKey: 2", f2.get());
assertEquals("ValueForKey: 3", f3.get());
assertEquals("ValueForKey: 4", f4.get());
int numExecuted = HystrixRequestLog.getCurrentRequest().getExecutedCommands().size();
System.err.println("num executed: " + numExecuted);
// assert that the batch command 'GetValueForKey' was in fact executed and that it executed only
// once or twice (due to non-determinism of scheduler since this example uses the real timer)
if (numExecuted > 2) {
fail("some of the commands should have been collapsed");
}
System.err.println("HystrixRequestLog.getCurrentRequest().getExecutedCommands(): " + HystrixRequestLog.getCurrentRequest().getExecutedCommands());
System.err.println("HystrixRequestLog.getCurrentRequest().getAllExecutedCommands(): " + HystrixRequestLog.getCurrentRequest().getAllExecutedCommands());
int numLogs = 0;
for (HystrixCommand<?> command : HystrixRequestLog.getCurrentRequest().getExecutedCommands()) {
numLogs++;
// assert the command is the one we're expecting
assertEquals("GetValueForKey", command.getCommandKey().name());
System.err.println(command.getCommandKey().name() + " => command.getExecutionEvents(): " + command.getExecutionEvents());
// confirm that it was a COLLAPSED command execution
assertTrue(command.getExecutionEvents().contains(HystrixEventType.COLLAPSED));
assertTrue(command.getExecutionEvents().contains(HystrixEventType.SUCCESS));
}
assertEquals(numExecuted, numLogs);
} finally {
context.shutdown();
}
}
}
}