Merge remote-tracking branch 'upstream/master'

This commit is contained in:
Gopinath Langote 2017-09-13 22:15:26 +05:30
commit 8652d0d32b
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<module>cqrs</module> <module>cqrs</module>
<module>event-sourcing</module> <module>event-sourcing</module>
<module>data-transfer-object</module> <module>data-transfer-object</module>
</modules> <module>throttling</module>
</modules>
<dependencyManagement> <dependencyManagement>
<dependencies> <dependencies>

20
throttling/README.md Normal file
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---
layout: pattern
title: Throttling
folder: throttling
permalink: /patterns/throttling/
tags:
- Java
- Difficulty-Beginner
- Throttling
---
## Intent
Ensure that a given client is not able to access service resources more than the assigned limit.
![alt text](./etc/throttling-patern.png "Throttling pattern")
## Applicability
The Throttling pattern should be used:
* when a service access needs to be restricted to not have high impacts on the performance of the service.
* when multiple clients are consuming the same service resources and restriction has to be made according to the usage per client.

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@startuml
package com.iluwatar.tls {
class App {
- LOGGER : Logger {static}
+ App()
+ main(args : String[]) {static}
- makeServiceCalls(service : B2BService) {static}
}
~class B2BService {
- LOGGER : Logger {static}
- callsCounter : int
- tenant : Tenant
+ B2BService(tenant : Tenant)
+ dummyCustomerApi() : int
+ getCurrentCallsCount() : int
- getRandomCustomerId() : int
}
class Tenant {
- allowedCallsPerSecond : int
- name : String
+ Tenant(name : String, allowedCallsPerSecond : int)
+ getAllowedCallsPerSecond() : int
+ getName() : String
+ setAllowedCallsPerSecond(allowedCallsPerSecond : int)
+ setName(name : String)
}
}
B2BService --> "-tenant" Tenant
@enduml

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throttling/pom.xml Normal file
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<?xml version="1.0" encoding="UTF-8"?>
<!--
The MIT License
Copyright (c) 2014 Ilkka Seppälä
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.17.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>throttling</artifactId>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>
</dependencies>
</project>

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/**
* The MIT License
* Copyright (c) 2014-2016 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.throttling;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.iluwatar.throttling.timer.Throttler;
import com.iluwatar.throttling.timer.ThrottleTimerImpl;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
/**
* Throttling pattern is a design pattern to throttle or limit the use of resources or even a complete service by
* users or a particular tenant. This can allow systems to continue to function and meet service level agreements,
* even when an increase in demand places load on resources.
* <p>
* In this example we have ({@link App}) as the initiating point of the service.
* This is a time based throttling, i.e. only a certain number of calls are allowed per second.
* </p>
* ({@link Tenant}) is the Tenant POJO class with which many tenants can be created
* ({@link B2BService}) is the service which is consumed by the tenants and is throttled.
*/
public class App {
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
/**
* Application entry point
* @param args main arguments
*/
public static void main(String[] args) {
Tenant adidas = new Tenant("Adidas", 5);
Tenant nike = new Tenant("Nike", 6);
ExecutorService executorService = Executors.newFixedThreadPool(2);
executorService.execute(() -> makeServiceCalls(adidas));
executorService.execute(() -> makeServiceCalls(nike));
executorService.shutdown();
try {
executorService.awaitTermination(10, TimeUnit.SECONDS);
} catch (InterruptedException e) {
LOGGER.error("Executor Service terminated: {}", e.getMessage());
}
}
/**
* Make calls to the B2BService dummy API
* @param service an instance of B2BService
*/
private static void makeServiceCalls(Tenant tenant) {
Throttler timer = new ThrottleTimerImpl(10);
B2BService service = new B2BService(timer);
for (int i = 0; i < 20; i++) {
service.dummyCustomerApi(tenant);
// Sleep is introduced to keep the output in check and easy to view and analyze the results.
try {
Thread.sleep(1);
} catch (InterruptedException e) {
LOGGER.error("Thread interrupted: {}", e.getMessage());
}
}
}
}

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/**
* The MIT License
* Copyright (c) 2014 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.throttling;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.iluwatar.throttling.timer.Throttler;
import java.util.concurrent.ThreadLocalRandom;
/**
* A service which accepts a tenant and throttles the resource based on the time given to the tenant.
*/
class B2BService {
private static final Logger LOGGER = LoggerFactory.getLogger(B2BService.class);
public B2BService(Throttler timer) {
timer.start();
}
/**
*
* @return customer id which is randomly generated
*/
public int dummyCustomerApi(Tenant tenant) {
String tenantName = tenant.getName();
int count = CallsCount.getCount(tenantName);
LOGGER.debug("Counter for {} : {} ", tenant.getName(), count);
if (count >= tenant.getAllowedCallsPerSecond()) {
LOGGER.error("API access per second limit reached for: {}", tenantName);
return -1;
}
CallsCount.incrementCount(tenantName);
return getRandomCustomerId();
}
private int getRandomCustomerId() {
return ThreadLocalRandom.current().nextInt(1, 10000);
}
}

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/**
* The MIT License
* Copyright (c) 2014 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.throttling;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
/**
* A class to keep track of the counter of different Tenants
* @author drastogi
*
*/
public final class CallsCount {
private static Map<String, Integer> tenantCallsCount = new ConcurrentHashMap<>();
/**
* Add a new tenant to the map.
* @param tenantName name of the tenant.
*/
public static void addTenant(String tenantName) {
if (!tenantCallsCount.containsKey(tenantName)) {
tenantCallsCount.put(tenantName, 0);
}
}
/**
* Increment the count of the specified tenant.
* @param tenantName name of the tenant.
*/
public static void incrementCount(String tenantName) {
tenantCallsCount.put(tenantName, tenantCallsCount.get(tenantName) + 1);
}
/**
*
* @param tenantName name of the tenant.
* @return the count of the tenant.
*/
public static int getCount(String tenantName) {
return tenantCallsCount.get(tenantName);
}
/**
* Resets the count of all the tenants in the map.
*/
public static void reset() {
for (Entry<String, Integer> e : tenantCallsCount.entrySet()) {
tenantCallsCount.put(e.getKey(), 0);
}
}
}

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/**
* The MIT License
* Copyright (c) 2014 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.throttling;
import java.security.InvalidParameterException;
/**
* A Pojo class to create a basic Tenant with the allowed calls per second.
*/
public class Tenant {
private String name;
private int allowedCallsPerSecond;
/**
*
* @param name Name of the tenant
* @param allowedCallsPerSecond The number of calls allowed for a particular tenant.
* @throws InvalidParameterException If number of calls is less than 0, throws exception.
*/
public Tenant(String name, int allowedCallsPerSecond) {
if (allowedCallsPerSecond < 0) {
throw new InvalidParameterException("Number of calls less than 0 not allowed");
}
this.name = name;
this.allowedCallsPerSecond = allowedCallsPerSecond;
CallsCount.addTenant(name);
}
public String getName() {
return name;
}
public int getAllowedCallsPerSecond() {
return allowedCallsPerSecond;
}
}

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/**
* The MIT License
* Copyright (c) 2014 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/**
*
*/
package com.iluwatar.throttling.timer;
import java.util.Timer;
import java.util.TimerTask;
import com.iluwatar.throttling.CallsCount;
/**
* Implementation of throttler interface. This class resets the counter every second.
* @author drastogi
*
*/
public class ThrottleTimerImpl implements Throttler{
private int throttlePeriod;
public ThrottleTimerImpl(int throttlePeriod) {
this.throttlePeriod = throttlePeriod;
}
/**
* A timer is initiated with this method. The timer runs every second and resets the
* counter.
*/
public void start() {
new Timer(true).schedule(new TimerTask() {
@Override
public void run() {
CallsCount.reset();
}
}, 0, throttlePeriod);
}
}

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/**
* The MIT License
* Copyright (c) 2014 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/**
*
*/
package com.iluwatar.throttling.timer;
/**
* An interface for defining the structure of different types of throttling ways.
* @author drastogi
*
*/
public interface Throttler {
void start();
}

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/**
* The MIT License
* Copyright (c) 2014 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.throttling;
import org.junit.Test;
/**
* Application test
*/
public class AppTest {
@Test
public void test() {
final String[] args = {};
App.main(args);
}
}

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/**
* The MIT License
* Copyright (c) 2014 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.throttling;
import org.junit.Assert;
import org.junit.Test;
import com.iluwatar.throttling.timer.ThrottleTimerImpl;
import com.iluwatar.throttling.timer.Throttler;
/**
* B2BServiceTest class to test the B2BService
*/
public class B2BServiceTest {
@Test
public void dummyCustomerApiTest() {
Tenant tenant = new Tenant("testTenant", 2);
Throttler timer = new ThrottleTimerImpl(10);
B2BService service = new B2BService(timer);
for (int i = 0; i < 5; i++) {
service.dummyCustomerApi(tenant);
}
int counter = CallsCount.getCount(tenant.getName());
Assert.assertTrue("Counter limit must be reached", counter == 2);
}
}

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/**
* The MIT License
* Copyright (c) 2014 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.throttling;
import org.junit.Test;
import com.iluwatar.throttling.Tenant;
import java.security.InvalidParameterException;
/**
* TenantTest to test the creation of Tenant with valid parameters.
*/
public class TenantTest {
@Test(expected = InvalidParameterException.class)
public void constructorTest() {
Tenant tenant = new Tenant("FailTenant", -1);
}
}