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@ -1749,33 +1749,6 @@
"review",
"code"
]
},
{
"login": "interactwithankush",
"name": "interactwithankush",
"avatar_url": "https://avatars.githubusercontent.com/u/18613127?v=4",
"profile": "https://github.com/interactwithankush",
"contributions": [
"code"
]
},
{
"login": "yuhangbin",
"name": "CharlieYu",
"avatar_url": "https://avatars.githubusercontent.com/u/17566866?v=4",
"profile": "https://github.com/yuhangbin",
"contributions": [
"code"
]
},
{
"login": "Leisterbecker",
"name": "Leisterbecker",
"avatar_url": "https://avatars.githubusercontent.com/u/20650323?v=4",
"profile": "https://github.com/Leisterbecker",
"contributions": [
"code"
]
}
],
"contributorsPerLine": 7,

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@ -10,7 +10,7 @@
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<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
[![All Contributors](https://img.shields.io/badge/all_contributors-195-orange.svg?style=flat-square)](#contributors-)
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<br/>
@ -322,9 +322,6 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://www.linkedin.com/in/abhinav-vashisth-06613b208/"><img src="https://avatars.githubusercontent.com/u/89785800?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Abhinav Vashisth</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vashisthabhinav" title="Documentation">📖</a></td>
<td align="center"><a href="http://no website"><img src="https://avatars.githubusercontent.com/u/47126749?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kevin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AKevinyl3" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/Shrirang97"><img src="https://avatars.githubusercontent.com/u/28738668?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Shrirang</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AShrirang97" title="Reviewed Pull Requests">👀</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=Shrirang97" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/interactwithankush"><img src="https://avatars.githubusercontent.com/u/18613127?v=4?s=100" width="100px;" alt=""/><br /><sub><b>interactwithankush</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=interactwithankush" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/yuhangbin"><img src="https://avatars.githubusercontent.com/u/17566866?v=4?s=100" width="100px;" alt=""/><br /><sub><b>CharlieYu</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yuhangbin" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Leisterbecker"><img src="https://avatars.githubusercontent.com/u/20650323?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Leisterbecker</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Leisterbecker" title="Code">💻</a></td>
</tr>
</table>

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@ -18,10 +18,10 @@ couldn't otherwise because of incompatible interfaces.
## Explanation
Real-world example
Real world example
> Consider that you have some pictures on your memory card and you need to transfer them to your computer. To transfer them, you need some kind of adapter that is compatible with your computer ports so that you can attach a memory card to your computer. In this case card reader is an adapter.
> Another example would be the famous power adapter; a three-legged plug can't be connected to a two-pronged outlet, it needs to use a power adapter that makes it compatible with the two-pronged outlets.
> Consider that you have some pictures in your memory card and you need to transfer them to your computer. In order to transfer them you need some kind of adapter that is compatible with your computer ports so that you can attach memory card to your computer. In this case card reader is an adapter.
> Another example would be the famous power adapter; a three legged plug can't be connected to a two pronged outlet, it needs to use a power adapter that makes it compatible with the two pronged outlet.
> Yet another example would be a translator translating words spoken by one person to another
In plain words
@ -36,7 +36,7 @@ Wikipedia says
Consider a captain that can only use rowing boats and cannot sail at all.
First, we have interfaces `RowingBoat` and `FishingBoat`
First we have interfaces `RowingBoat` and `FishingBoat`
```java
public interface RowingBoat {
@ -68,7 +68,7 @@ public class Captain {
}
```
Now let's say the pirates are coming and our captain needs to escape but there is only a fishing boat available. We need to create an adapter that allows the captain to operate the fishing boat with his rowing boat skills.
Now let's say the pirates are coming and our captain needs to escape but there is only fishing boat available. We need to create an adapter that allows the captain to operate the fishing boat with his rowing boat skills.
```java
@Slf4j
@ -100,10 +100,10 @@ captain.row();
## Applicability
Use the Adapter pattern when
* You want to use an existing class, and its interface does not match the one you need
* You want to create a reusable class that cooperates with unrelated or unforeseen classes, that is, classes that don't necessarily have compatible interfaces
* You need to use several existing subclasses, but it's impractical to adapt their interface by subclassing everyone. An object adapter can adapt the interface of its parent class.
* Most of the applications using third-party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code.
* you want to use an existing class, and its interface does not match the one you need
* you want to create a reusable class that cooperates with unrelated or unforeseen classes, that is, classes that don't necessarily have compatible interfaces
* you need to use several existing subclasses, but it's impractical to adapt their interface by subclassing every one. An object adapter can adapt the interface of its parent class.
* most of the applications using third party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code.
## Tutorials
@ -114,17 +114,17 @@ Use the Adapter pattern when
## Consequences
Class and object adapters have different trade-offs. A class adapter
* Adapts Adaptee to Target by committing to a concrete Adaptee class. As a consequence, a class adapter wont work when we want to adapt a class and all its subclasses.
* Lets Adapter override some of Adaptees behavior since Adapter is a subclass of Adaptee.
* Introduces only one object, and no additional pointer indirection is needed to get to the adaptee.
* adapts Adaptee to Target by committing to a concrete Adaptee class. As a consequence, a class adapter wont work when we want to adapt a class and all its subclasses.
* lets Adapter override some of Adaptees behavior, since Adapter is a subclass of Adaptee.
* introduces only one object, and no additional pointer indirection is needed to get to the adaptee.
An object adapter
* Lets a single Adapter work with many Adaptees—that is, the Adaptee itself and all of its subclasses (if any). The Adapter can also add functionality to all Adaptees at once.
* Makes it harder to override Adaptee behavior. It will require subclassing Adaptee and making the Adapter refer to the subclass rather than the Adaptee itself.
* lets a single Adapter work with many Adaptees—that is, the Adaptee itself and all of its subclasses (if any). The Adapter can also add functionality to all Adaptees at once.
* makes it harder to override Adaptee behavior. It will require subclassing Adaptee and making Adapter refer to the subclass rather than the Adaptee itself.
## Real-world examples
## Known uses
* [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29)
* [java.util.Collections#list()](https://docs.oracle.com/javase/8/docs/api/java/util/Collections.html#list-java.util.Enumeration-)

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@ -33,7 +33,7 @@ import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.verify;
/**
* Tests for the adapter pattern.
* Test class
*/
class AdapterPatternTest {

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@ -33,7 +33,9 @@ import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
class AppTest {
/**
* Check whether the execution of the main method in {@link App}
* Issue: Add at least one assertion to this test case.
*
* Solution: Inserted assertion to check whether the execution of the main method in {@link App}
* throws an exception.
*/

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@ -4,7 +4,6 @@ title: Claim Check Pattern
folder: cloud-claim-check-pattern
permalink: /patterns/cloud-claim-check-pattern/
categories: Cloud
language: en
tags:
- Cloud distributed
- Microservices

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@ -36,6 +36,9 @@ public class Wizard {
private final Deque<Runnable> undoStack = new LinkedList<>();
private final Deque<Runnable> redoStack = new LinkedList<>();
public Wizard() {
}
/**
* Cast spell.
*/

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@ -90,13 +90,6 @@ public class Commander {
private static final Logger LOG = LoggerFactory.getLogger(Commander.class);
//we could also have another db where it stores all orders
private static final String ORDER_ID = "Order {}";
private static final String REQUEST_ID = " request Id: {}";
private static final String ERROR_CONNECTING_MSG_SVC =
": Error in connecting to messaging service ";
private static final String TRY_CONNECTING_MSG_SVC =
": Trying to connect to messaging service..";
Commander(EmployeeHandle empDb, PaymentService paymentService, ShippingService shippingService,
MessagingService messagingService, QueueDatabase qdb, int numOfRetries,
long retryDuration, long queueTime, long queueTaskTime, long paymentTime,
@ -125,17 +118,17 @@ public class Commander {
Retry.Operation op = (l) -> {
if (!l.isEmpty()) {
if (DatabaseUnavailableException.class.isAssignableFrom(l.get(0).getClass())) {
LOG.debug(ORDER_ID + ": Error in connecting to shipping service, "
+ "trying again..", order.id);
LOG.debug("Order " + order.id + ": Error in connecting to shipping service, "
+ "trying again..");
} else {
LOG.debug(ORDER_ID + ": Error in creating shipping request..", order.id);
LOG.debug("Order " + order.id + ": Error in creating shipping request..");
}
throw l.remove(0);
}
String transactionId = shippingService.receiveRequest(order.item, order.user.address);
//could save this transaction id in a db too
LOG.info(ORDER_ID + ": Shipping placed successfully, transaction id: {}",
order.id, transactionId);
LOG.info("Order " + order.id + ": Shipping placed successfully, transaction id: "
+ transactionId);
LOG.info("Order has been placed and will be shipped to you. Please wait while we make your"
+ " payment... ");
sendPaymentRequest(order);
@ -145,19 +138,19 @@ public class Commander {
LOG.info("Shipping is currently not possible to your address. We are working on the problem"
+ " and will get back to you asap.");
finalSiteMsgShown = true;
LOG.info(ORDER_ID + ": Shipping not possible to address, trying to add problem "
+ "to employee db..", order.id);
LOG.info("Order " + order.id + ": Shipping not possible to address, trying to add problem "
+ "to employee db..");
employeeHandleIssue(o);
} else if (ItemUnavailableException.class.isAssignableFrom(err.getClass())) {
LOG.info("This item is currently unavailable. We will inform you as soon as the item "
+ "becomes available again.");
finalSiteMsgShown = true;
LOG.info(ORDER_ID + ": Item {}" + " unavailable, trying to add "
+ "problem to employee handle..", order.id, order.item);
LOG.info("Order " + order.id + ": Item " + order.item + " unavailable, trying to add "
+ "problem to employee handle..");
employeeHandleIssue(o);
} else {
LOG.info("Sorry, there was a problem in creating your order. Please try later.");
LOG.error(ORDER_ID + ": Shipping service unavailable, order not placed..", order.id);
LOG.error("Order " + order.id + ": Shipping service unavailable, order not placed..");
finalSiteMsgShown = true;
}
};
@ -171,7 +164,7 @@ public class Commander {
if (order.paid.equals(PaymentStatus.TRYING)) {
order.paid = PaymentStatus.NOT_DONE;
sendPaymentFailureMessage(order);
LOG.error(ORDER_ID + ": Payment time for order over, failed and returning..", order.id);
LOG.error("Order " + order.id + ": Payment time for order over, failed and returning..");
} //if succeeded or failed, would have been dequeued, no attempt to make payment
return;
}
@ -180,18 +173,17 @@ public class Commander {
Retry.Operation op = (l) -> {
if (!l.isEmpty()) {
if (DatabaseUnavailableException.class.isAssignableFrom(l.get(0).getClass())) {
LOG.debug(ORDER_ID + ": Error in connecting to payment service,"
+ " trying again..", order.id);
LOG.debug("Order " + order.id + ": Error in connecting to payment service,"
+ " trying again..");
} else {
LOG.debug(ORDER_ID + ": Error in creating payment request..", order.id);
LOG.debug("Order " + order.id + ": Error in creating payment request..");
}
throw l.remove(0);
}
if (order.paid.equals(PaymentStatus.TRYING)) {
var transactionId = paymentService.receiveRequest(order.price);
order.paid = PaymentStatus.DONE;
LOG.info(ORDER_ID + ": Payment successful, transaction Id: {}",
order.id, transactionId);
LOG.info("Order " + order.id + ": Payment successful, transaction Id: " + transactionId);
if (!finalSiteMsgShown) {
LOG.info("Payment made successfully, thank you for shopping with us!!");
finalSiteMsgShown = true;
@ -207,7 +199,7 @@ public class Commander {
+ "Meanwhile, your order has been converted to COD and will be shipped.");
finalSiteMsgShown = true;
}
LOG.error(ORDER_ID + ": Payment details incorrect, failed..", order.id);
LOG.error("Order " + order.id + ": Payment details incorrect, failed..");
o.paid = PaymentStatus.NOT_DONE;
sendPaymentFailureMessage(o);
} else {
@ -217,7 +209,7 @@ public class Commander {
+ "asap. Don't worry, your order has been placed and will be shipped.");
finalSiteMsgShown = true;
}
LOG.warn(ORDER_ID + ": Payment error, going to queue..", order.id);
LOG.warn("Order " + order.id + ": Payment error, going to queue..");
sendPaymentPossibleErrorMsg(o);
}
if (o.paid.equals(PaymentStatus.TRYING) && System
@ -242,7 +234,7 @@ public class Commander {
if (System.currentTimeMillis() - qt.order.createdTime >= this.queueTime) {
// since payment time is lesser than queuetime it would have already failed..
// additional check not needed
LOG.trace(ORDER_ID + ": Queue time for order over, failed..", qt.order.id);
LOG.trace("Order " + qt.order.id + ": Queue time for order over, failed..");
return;
} else if (qt.taskType.equals(TaskType.PAYMENT) && !qt.order.paid.equals(PaymentStatus.TRYING)
|| qt.taskType.equals(TaskType.MESSAGING) && (qt.messageType == 1
@ -250,30 +242,30 @@ public class Commander {
|| qt.order.messageSent.equals(MessageSent.PAYMENT_FAIL)
|| qt.order.messageSent.equals(MessageSent.PAYMENT_SUCCESSFUL))
|| qt.taskType.equals(TaskType.EMPLOYEE_DB) && qt.order.addedToEmployeeHandle) {
LOG.trace(ORDER_ID + ": Not queueing task since task already done..", qt.order.id);
LOG.trace("Order " + qt.order.id + ": Not queueing task since task already done..");
return;
}
var list = queue.exceptionsList;
Thread t = new Thread(() -> {
Retry.Operation op = (list1) -> {
if (!list1.isEmpty()) {
LOG.warn(ORDER_ID + ": Error in connecting to queue db, trying again..", qt.order.id);
LOG.warn("Order " + qt.order.id + ": Error in connecting to queue db, trying again..");
throw list1.remove(0);
}
queue.add(qt);
queueItems++;
LOG.info(ORDER_ID + ": {}" + " task enqueued..", qt.order.id, qt.getType());
LOG.info("Order " + qt.order.id + ": " + qt.getType() + " task enqueued..");
tryDoingTasksInQueue();
};
Retry.HandleErrorIssue<QueueTask> handleError = (qt1, err) -> {
if (qt1.taskType.equals(TaskType.PAYMENT)) {
qt1.order.paid = PaymentStatus.NOT_DONE;
sendPaymentFailureMessage(qt1.order);
LOG.error(ORDER_ID + ": Unable to enqueue payment task,"
+ " payment failed..", qt1.order.id);
LOG.error("Order " + qt1.order.id + ": Unable to enqueue payment task,"
+ " payment failed..");
}
LOG.error(ORDER_ID + ": Unable to enqueue task of type {}"
+ ", trying to add to employee handle..", qt1.order.id, qt1.getType());
LOG.error("Order " + qt1.order.id + ": Unable to enqueue task of type " + qt1.getType()
+ ", trying to add to employee handle..");
employeeHandleIssue(qt1.order);
};
var r = new Retry<>(op, handleError, numOfRetries, retryDuration,
@ -336,7 +328,7 @@ public class Commander {
private void sendSuccessMessage(Order order) {
if (System.currentTimeMillis() - order.createdTime >= this.messageTime) {
LOG.trace(ORDER_ID + ": Message time for order over, returning..", order.id);
LOG.trace("Order " + order.id + ": Message time for order over, returning..");
return;
}
var list = messagingService.exceptionsList;
@ -362,8 +354,8 @@ public class Commander {
&& System.currentTimeMillis() - o.createdTime < messageTime) {
var qt = new QueueTask(order, TaskType.MESSAGING, 2);
updateQueue(qt);
LOG.info(ORDER_ID + ": Error in sending Payment Success message, trying to"
+ " queue task and add to employee handle..", order.id);
LOG.info("Order " + order.id + ": Error in sending Payment Success message, trying to"
+ " queue task and add to employee handle..");
employeeHandleIssue(order);
}
}
@ -372,11 +364,11 @@ public class Commander {
return (l) -> {
if (!l.isEmpty()) {
if (DatabaseUnavailableException.class.isAssignableFrom(l.get(0).getClass())) {
LOG.debug(ORDER_ID + ERROR_CONNECTING_MSG_SVC
+ "(Payment Success msg), trying again..", order.id);
LOG.debug("Order " + order.id + ": Error in connecting to messaging service "
+ "(Payment Success msg), trying again..");
} else {
LOG.debug(ORDER_ID + ": Error in creating Payment Success"
+ " messaging request..", order.id);
LOG.debug("Order " + order.id + ": Error in creating Payment Success"
+ " messaging request..");
}
throw l.remove(0);
}
@ -384,15 +376,15 @@ public class Commander {
&& !order.messageSent.equals(MessageSent.PAYMENT_SUCCESSFUL)) {
var requestId = messagingService.receiveRequest(2);
order.messageSent = MessageSent.PAYMENT_SUCCESSFUL;
LOG.info(ORDER_ID + ": Payment Success message sent,"
+ REQUEST_ID, order.id, requestId);
LOG.info("Order " + order.id + ": Payment Success message sent,"
+ " request Id: " + requestId);
}
};
}
private void sendPaymentFailureMessage(Order order) {
if (System.currentTimeMillis() - order.createdTime >= this.messageTime) {
LOG.trace(ORDER_ID + ": Message time for order over, returning..", order.id);
LOG.trace("Order " + order.id + ": Message time for order over, returning..");
return;
}
var list = messagingService.exceptionsList;
@ -420,8 +412,8 @@ public class Commander {
&& System.currentTimeMillis() - o.createdTime < messageTime) {
var qt = new QueueTask(order, TaskType.MESSAGING, 0);
updateQueue(qt);
LOG.warn(ORDER_ID + ": Error in sending Payment Failure message, "
+ "trying to queue task and add to employee handle..", order.id);
LOG.warn("Order " + order.id + ": Error in sending Payment Failure message, "
+ "trying to queue task and add to employee handle..");
employeeHandleIssue(o);
}
}
@ -429,11 +421,11 @@ public class Commander {
private void handlePaymentFailureRetryOperation(Order order, List<Exception> l) throws Exception {
if (!l.isEmpty()) {
if (DatabaseUnavailableException.class.isAssignableFrom(l.get(0).getClass())) {
LOG.debug(ORDER_ID + ERROR_CONNECTING_MSG_SVC
+ "(Payment Failure msg), trying again..", order.id);
LOG.debug("Order " + order.id + ": Error in connecting to messaging service "
+ "(Payment Failure msg), trying again..");
} else {
LOG.debug(ORDER_ID + ": Error in creating Payment Failure"
+ " message request..", order.id);
LOG.debug("Order " + order.id + ": Error in creating Payment Failure"
+ " message request..");
}
throw l.remove(0);
}
@ -441,8 +433,8 @@ public class Commander {
&& !order.messageSent.equals(MessageSent.PAYMENT_SUCCESSFUL)) {
var requestId = messagingService.receiveRequest(0);
order.messageSent = MessageSent.PAYMENT_FAIL;
LOG.info(ORDER_ID + ": Payment Failure message sent successfully,"
+ REQUEST_ID, order.id, requestId);
LOG.info("Order " + order.id + ": Payment Failure message sent successfully,"
+ " request Id: " + requestId);
}
}
@ -477,7 +469,7 @@ public class Commander {
var qt = new QueueTask(order, TaskType.MESSAGING, 1);
updateQueue(qt);
LOG.warn("Order " + order.id + ": Error in sending Payment Error message, "
+ "trying to queue task and add to employee handle..");
+ "trying to queue task and add to employee handle..");
employeeHandleIssue(o);
}
}
@ -486,11 +478,11 @@ public class Commander {
throws Exception {
if (!l.isEmpty()) {
if (DatabaseUnavailableException.class.isAssignableFrom(l.get(0).getClass())) {
LOG.debug(ORDER_ID + ERROR_CONNECTING_MSG_SVC
+ "(Payment Error msg), trying again..", order.id);
LOG.debug("Order " + order.id + ": Error in connecting to messaging service "
+ "(Payment Error msg), trying again..");
} else {
LOG.debug(ORDER_ID + ": Error in creating Payment Error"
+ " messaging request..", order.id);
LOG.debug("Order " + order.id + ": Error in creating Payment Error"
+ " messaging request..");
}
throw l.remove(0);
}
@ -498,28 +490,28 @@ public class Commander {
.equals(MessageSent.NONE_SENT)) {
var requestId = messagingService.receiveRequest(1);
order.messageSent = MessageSent.PAYMENT_TRYING;
LOG.info(ORDER_ID + ": Payment Error message sent successfully,"
+ REQUEST_ID, order.id, requestId);
LOG.info("Order " + order.id + ": Payment Error message sent successfully,"
+ " request Id: " + requestId);
}
}
private void employeeHandleIssue(Order order) {
if (System.currentTimeMillis() - order.createdTime >= this.employeeTime) {
LOG.trace(ORDER_ID + ": Employee handle time for order over, returning..", order.id);
LOG.trace("Order " + order.id + ": Employee handle time for order over, returning..");
return;
}
var list = employeeDb.exceptionsList;
var t = new Thread(() -> {
Retry.Operation op = (l) -> {
if (!l.isEmpty()) {
LOG.warn(ORDER_ID + ": Error in connecting to employee handle,"
+ " trying again..", order.id);
LOG.warn("Order " + order.id + ": Error in connecting to employee handle,"
+ " trying again..");
throw l.remove(0);
}
if (!order.addedToEmployeeHandle) {
employeeDb.receiveRequest(order);
order.addedToEmployeeHandle = true;
LOG.info(ORDER_ID + ": Added order to employee database", order.id);
LOG.info("Order " + order.id + ": Added order to employee database");
}
};
Retry.HandleErrorIssue<Order> handleError = (o, err) -> {
@ -527,8 +519,8 @@ public class Commander {
.currentTimeMillis() - order.createdTime < employeeTime) {
var qt = new QueueTask(order, TaskType.EMPLOYEE_DB, -1);
updateQueue(qt);
LOG.warn(ORDER_ID + ": Error in adding to employee db,"
+ " trying to queue task..", order.id);
LOG.warn("Order " + order.id + ": Error in adding to employee db,"
+ " trying to queue task..");
}
};
var r = new Retry<>(op, handleError, numOfRetries, retryDuration,
@ -546,51 +538,51 @@ public class Commander {
if (queueItems != 0) {
var qt = queue.peek(); //this should probably be cloned here
//this is why we have retry for doTasksInQueue
LOG.trace(ORDER_ID + ": Started doing task of type {}", qt.order.id, qt.getType());
LOG.trace("Order " + qt.order.id + ": Started doing task of type " + qt.getType());
if (qt.getFirstAttemptTime() == -1) {
qt.setFirstAttemptTime(System.currentTimeMillis());
}
if (System.currentTimeMillis() - qt.getFirstAttemptTime() >= queueTaskTime) {
tryDequeue();
LOG.trace(ORDER_ID + ": This queue task of type {}"
+ " does not need to be done anymore (timeout), dequeue..", qt.order.id, qt.getType());
LOG.trace("Order " + qt.order.id + ": This queue task of type " + qt.getType()
+ " does not need to be done anymore (timeout), dequeue..");
} else {
if (qt.taskType.equals(TaskType.PAYMENT)) {
if (!qt.order.paid.equals(PaymentStatus.TRYING)) {
tryDequeue();
LOG.trace(ORDER_ID + ": This payment task already done, dequeueing..", qt.order.id);
LOG.trace("Order " + qt.order.id + ": This payment task already done, dequeueing..");
} else {
sendPaymentRequest(qt.order);
LOG.debug(ORDER_ID + ": Trying to connect to payment service..", qt.order.id);
LOG.debug("Order " + qt.order.id + ": Trying to connect to payment service..");
}
} else if (qt.taskType.equals(TaskType.MESSAGING)) {
if (qt.order.messageSent.equals(MessageSent.PAYMENT_FAIL)
|| qt.order.messageSent.equals(MessageSent.PAYMENT_SUCCESSFUL)) {
tryDequeue();
LOG.trace(ORDER_ID + ": This messaging task already done, dequeue..", qt.order.id);
LOG.trace("Order " + qt.order.id + ": This messaging task already done, dequeue..");
} else if (qt.messageType == 1 && (!qt.order.messageSent.equals(MessageSent.NONE_SENT)
|| !qt.order.paid.equals(PaymentStatus.TRYING))) {
tryDequeue();
LOG.trace(ORDER_ID + ": This messaging task does not need to be done,"
+ " dequeue..", qt.order.id);
LOG.trace("Order " + qt.order.id + ": This messaging task does not need to be done,"
+ " dequeue..");
} else if (qt.messageType == 0) {
sendPaymentFailureMessage(qt.order);
LOG.debug(ORDER_ID + TRY_CONNECTING_MSG_SVC, qt.order.id);
LOG.debug("Order " + qt.order.id + ": Trying to connect to messaging service..");
} else if (qt.messageType == 1) {
sendPaymentPossibleErrorMsg(qt.order);
LOG.debug(ORDER_ID + TRY_CONNECTING_MSG_SVC, qt.order.id);
LOG.debug("Order " + qt.order.id + ": Trying to connect to messaging service..");
} else if (qt.messageType == 2) {
sendSuccessMessage(qt.order);
LOG.debug(ORDER_ID + TRY_CONNECTING_MSG_SVC, qt.order.id);
LOG.debug("Order " + qt.order.id + ": Trying to connect to messaging service..");
}
} else if (qt.taskType.equals(TaskType.EMPLOYEE_DB)) {
if (qt.order.addedToEmployeeHandle) {
tryDequeue();
LOG.trace(ORDER_ID + ": This employee handle task already done,"
+ " dequeue..", qt.order.id);
LOG.trace("Order " + qt.order.id + ": This employee handle task already done,"
+ " dequeue..");
} else {
employeeHandleIssue(qt.order);
LOG.debug(ORDER_ID + ": Trying to connect to employee handle..", qt.order.id);
LOG.debug("Order " + qt.order.id + ": Trying to connect to employee handle..");
}
}
}

View File

@ -1,526 +0,0 @@
package com.iluwatar.commander;
import com.iluwatar.commander.employeehandle.EmployeeDatabase;
import com.iluwatar.commander.employeehandle.EmployeeHandle;
import com.iluwatar.commander.exceptions.DatabaseUnavailableException;
import com.iluwatar.commander.exceptions.ItemUnavailableException;
import com.iluwatar.commander.exceptions.PaymentDetailsErrorException;
import com.iluwatar.commander.exceptions.ShippingNotPossibleException;
import com.iluwatar.commander.messagingservice.MessagingDatabase;
import com.iluwatar.commander.messagingservice.MessagingService;
import com.iluwatar.commander.paymentservice.PaymentDatabase;
import com.iluwatar.commander.paymentservice.PaymentService;
import com.iluwatar.commander.queue.QueueDatabase;
import com.iluwatar.commander.shippingservice.ShippingDatabase;
import com.iluwatar.commander.shippingservice.ShippingService;
import org.junit.jupiter.api.Test;
import org.junit.platform.commons.util.StringUtils;
import java.util.ArrayList;
import java.util.List;
import static org.junit.jupiter.api.Assertions.assertFalse;
class CommanderTest {
private final int numOfRetries = 1;
private final long retryDuration = 1_000;
private long queueTime = 1_00;
private long queueTaskTime = 1_000;
private long paymentTime = 6_000;
private long messageTime = 5_000;
private long employeeTime = 2_000;
private static final List<Exception> exceptionList = new ArrayList<>();
static {
exceptionList.add(new DatabaseUnavailableException());
exceptionList.add(new ShippingNotPossibleException());
exceptionList.add(new ItemUnavailableException());
exceptionList.add(new PaymentDetailsErrorException());
exceptionList.add(new IllegalStateException());
}
private Commander buildCommanderObject() {
return buildCommanderObject(false);
}
private Commander buildCommanderObject(boolean nonPaymentException) {
PaymentService paymentService = new PaymentService
(new PaymentDatabase(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException());
ShippingService shippingService;
MessagingService messagingService;
if (nonPaymentException) {
shippingService = new ShippingService(new ShippingDatabase(), new DatabaseUnavailableException());
messagingService = new MessagingService(new MessagingDatabase(), new DatabaseUnavailableException());
} else {
shippingService = new ShippingService(new ShippingDatabase(), new DatabaseUnavailableException());
messagingService = new MessagingService(new MessagingDatabase(), new DatabaseUnavailableException());
}
var employeeHandle = new EmployeeHandle
(new EmployeeDatabase(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException());
var qdb = new QueueDatabase
(new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException());
return new Commander(employeeHandle, paymentService, shippingService,
messagingService, qdb, numOfRetries, retryDuration,
queueTime, queueTaskTime, paymentTime, messageTime, employeeTime);
}
private Commander buildCommanderObjectVanilla() {
PaymentService paymentService = new PaymentService
(new PaymentDatabase(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException());
var shippingService = new ShippingService(new ShippingDatabase());
var messagingService = new MessagingService(new MessagingDatabase());
var employeeHandle = new EmployeeHandle
(new EmployeeDatabase(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException());
var qdb = new QueueDatabase
(new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException(),
new DatabaseUnavailableException(), new DatabaseUnavailableException());
return new Commander(employeeHandle, paymentService, shippingService,
messagingService, qdb, numOfRetries, retryDuration,
queueTime, queueTaskTime, paymentTime, messageTime, employeeTime);
}
private Commander buildCommanderObjectUnknownException() {
PaymentService paymentService = new PaymentService
(new PaymentDatabase(), new IllegalStateException());
var shippingService = new ShippingService(new ShippingDatabase());
var messagingService = new MessagingService(new MessagingDatabase());
var employeeHandle = new EmployeeHandle
(new EmployeeDatabase(), new IllegalStateException());
var qdb = new QueueDatabase
(new DatabaseUnavailableException(), new IllegalStateException());
return new Commander(employeeHandle, paymentService, shippingService,
messagingService, qdb, numOfRetries, retryDuration,
queueTime, queueTaskTime, paymentTime, messageTime, employeeTime);
}
private Commander buildCommanderObjectNoPaymentException1() {
PaymentService paymentService = new PaymentService
(new PaymentDatabase());
var shippingService = new ShippingService(new ShippingDatabase());
var messagingService = new MessagingService(new MessagingDatabase());
var employeeHandle = new EmployeeHandle
(new EmployeeDatabase(), new IllegalStateException());
var qdb = new QueueDatabase
(new DatabaseUnavailableException(), new IllegalStateException());
return new Commander(employeeHandle, paymentService, shippingService,
messagingService, qdb, numOfRetries, retryDuration,
queueTime, queueTaskTime, paymentTime, messageTime, employeeTime);
}
private Commander buildCommanderObjectNoPaymentException2() {
PaymentService paymentService = new PaymentService
(new PaymentDatabase());
var shippingService = new ShippingService(new ShippingDatabase());
var messagingService = new MessagingService(new MessagingDatabase(), new IllegalStateException());
var employeeHandle = new EmployeeHandle
(new EmployeeDatabase(), new IllegalStateException());
var qdb = new QueueDatabase
(new DatabaseUnavailableException(), new IllegalStateException());
return new Commander(employeeHandle, paymentService, shippingService,
messagingService, qdb, numOfRetries, retryDuration,
queueTime, queueTaskTime, paymentTime, messageTime, employeeTime);
}
private Commander buildCommanderObjectNoPaymentException3() {
PaymentService paymentService = new PaymentService
(new PaymentDatabase());
var shippingService = new ShippingService(new ShippingDatabase());
var messagingService = new MessagingService(new MessagingDatabase(), new DatabaseUnavailableException());
var employeeHandle = new EmployeeHandle
(new EmployeeDatabase(), new IllegalStateException());
var qdb = new QueueDatabase
(new DatabaseUnavailableException(), new IllegalStateException());
return new Commander(employeeHandle, paymentService, shippingService,
messagingService, qdb, numOfRetries, retryDuration,
queueTime, queueTaskTime, paymentTime, messageTime, employeeTime);
}
private Commander buildCommanderObjectWithDB() {
return buildCommanderObjectWithoutDB(false, false, new IllegalStateException());
}
private Commander buildCommanderObjectWithDB(boolean includeException, boolean includeDBException, Exception e) {
var l = includeDBException ? new DatabaseUnavailableException() : e;
PaymentService paymentService;
ShippingService shippingService;
MessagingService messagingService;
EmployeeHandle employeeHandle;
if (includeException) {
paymentService = new PaymentService
(new PaymentDatabase(), l);
shippingService = new ShippingService(new ShippingDatabase(), l);
messagingService = new MessagingService(new MessagingDatabase(), l);
employeeHandle = new EmployeeHandle
(new EmployeeDatabase(), l);
} else {
paymentService = new PaymentService
(null);
shippingService = new ShippingService(null);
messagingService = new MessagingService(null);
employeeHandle = new EmployeeHandle
(null);
}
return new Commander(employeeHandle, paymentService, shippingService,
messagingService, null, numOfRetries, retryDuration,
queueTime, queueTaskTime, paymentTime, messageTime, employeeTime);
}
private Commander buildCommanderObjectWithoutDB() {
return buildCommanderObjectWithoutDB(false, false, new IllegalStateException());
}
private Commander buildCommanderObjectWithoutDB(boolean includeException, boolean includeDBException, Exception e) {
var l = includeDBException ? new DatabaseUnavailableException() : e;
PaymentService paymentService;
ShippingService shippingService;
MessagingService messagingService;
EmployeeHandle employeeHandle;
if (includeException) {
paymentService = new PaymentService
(null, l);
shippingService = new ShippingService(null, l);
messagingService = new MessagingService(null, l);
employeeHandle = new EmployeeHandle
(null, l);
} else {
paymentService = new PaymentService
(null);
shippingService = new ShippingService(null);
messagingService = new MessagingService(null);
employeeHandle = new EmployeeHandle
(null);
}
return new Commander(employeeHandle, paymentService, shippingService,
messagingService, null, numOfRetries, retryDuration,
queueTime, queueTaskTime, paymentTime, messageTime, employeeTime);
}
@Test
void testPlaceOrderVanilla() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
Commander c = buildCommanderObjectVanilla();
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrder() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
Commander c = buildCommanderObject(true);
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrder2() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
Commander c = buildCommanderObject(false);
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderNoException1() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
Commander c = buildCommanderObjectNoPaymentException1();
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderNoException2() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
Commander c = buildCommanderObjectNoPaymentException2();
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderNoException3() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
Commander c = buildCommanderObjectNoPaymentException3();
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderNoException4() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
Commander c = buildCommanderObjectNoPaymentException3();
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
c.placeOrder(order);
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderUnknownException() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
messageTime *= d;
employeeTime *= d;
queueTime *= d;
Commander c = buildCommanderObjectUnknownException();
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderShortDuration() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
messageTime *= d;
employeeTime *= d;
queueTime *= d;
Commander c = buildCommanderObject(true);
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderShortDuration2() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
messageTime *= d;
employeeTime *= d;
queueTime *= d;
Commander c = buildCommanderObject(false);
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderNoExceptionShortMsgDuration() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
messageTime *= d;
employeeTime *= d;
queueTime *= d;
Commander c = buildCommanderObjectNoPaymentException1();
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderNoExceptionShortQueueDuration() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
messageTime *= d;
employeeTime *= d;
queueTime *= d;
Commander c = buildCommanderObjectUnknownException();
var order = new Order(new User("K", "J"), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderWithDatabase() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
messageTime *= d;
employeeTime *= d;
queueTime *= d;
Commander c = buildCommanderObjectWithDB();
var order = new Order(new User("K", null), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderWithDatabaseAndExceptions() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
messageTime *= d;
employeeTime *= d;
queueTime *= d;
for (Exception e : exceptionList) {
Commander c = buildCommanderObjectWithDB(true, true, e);
var order = new Order(new User("K", null), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
c = buildCommanderObjectWithDB(true, false, e);
order = new Order(new User("K", null), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
c = buildCommanderObjectWithDB(false, false, e);
order = new Order(new User("K", null), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
c = buildCommanderObjectWithDB(false, true, e);
order = new Order(new User("K", null), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
}
@Test
void testPlaceOrderWithoutDatabase() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
messageTime *= d;
employeeTime *= d;
queueTime *= d;
Commander c = buildCommanderObjectWithoutDB();
var order = new Order(new User("K", null), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
@Test
void testPlaceOrderWithoutDatabaseAndExceptions() throws Exception {
for (double d = 0.1; d < 2; d = d + 0.1) {
paymentTime *= d;
queueTaskTime *= d;
messageTime *= d;
employeeTime *= d;
queueTime *= d;
for (Exception e : exceptionList) {
Commander c = buildCommanderObjectWithoutDB(true, true, e);
var order = new Order(new User("K", null), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
c = buildCommanderObjectWithoutDB(true, false, e);
order = new Order(new User("K", null), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
c = buildCommanderObjectWithoutDB(false, false, e);
order = new Order(new User("K", null), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
c = buildCommanderObjectWithoutDB(false, true, e);
order = new Order(new User("K", null), "pen", 1f);
for (Order.MessageSent ms : Order.MessageSent.values()) {
c.placeOrder(order);
assertFalse(StringUtils.isBlank(order.id));
}
}
}
}
}

View File

@ -9,10 +9,6 @@ tags:
- Reactive
---
## Name
Event Aggregator
## Intent
A system with lots of objects can lead to complexities when a
client wants to subscribe to events. The client has to find and register for
@ -21,136 +17,6 @@ requires a separate subscription. An Event Aggregator acts as a single source
of events for many objects. It registers for all the events of the many objects
allowing clients to register with just the aggregator.
## Explanation
Real-world example
> King Joffrey sits on the iron throne and rules the seven kingdoms of Westeros. He receives most
> of his critical information from King's Hand, the second in command. King's hand has many
> close advisors himself, feeding him with relevant information about events occurring in the
> kingdom.
In Plain Words
> Event Aggregator is an event mediator that collects events from multiple sources and delivers
> them to registered observers.
**Programmatic Example**
In our programmatic example, we demonstrate the implementation of an event aggregator pattern. Some of
the objects are event listeners, some are event emitters, and the event aggregator does both.
```java
public interface EventObserver {
void onEvent(Event e);
}
public abstract class EventEmitter {
private final Map<Event, List<EventObserver>> observerLists;
public EventEmitter() {
observerLists = new HashMap<>();
}
public final void registerObserver(EventObserver obs, Event e) {
...
}
protected void notifyObservers(Event e) {
...
}
}
```
`KingJoffrey` is listening to events from `KingsHand`.
```java
@Slf4j
public class KingJoffrey implements EventObserver {
@Override
public void onEvent(Event e) {
LOGGER.info("Received event from the King's Hand: {}", e.toString());
}
}
```
`KingsHand` is listening to events from his subordinates `LordBaelish`, `LordVarys`, and `Scout`.
Whatever he hears from them, he delivers to `KingJoffrey`.
```java
public class KingsHand extends EventEmitter implements EventObserver {
public KingsHand() {
}
public KingsHand(EventObserver obs, Event e) {
super(obs, e);
}
@Override
public void onEvent(Event e) {
notifyObservers(e);
}
}
```
For example, `LordVarys` finds a traitor every Sunday and notifies the `KingsHand`.
```java
@Slf4j
public class LordVarys extends EventEmitter implements EventObserver {
@Override
public void timePasses(Weekday day) {
if (day == Weekday.SATURDAY) {
notifyObservers(Event.TRAITOR_DETECTED);
}
}
}
```
The following snippet demonstrates how the objects are constructed and wired together.
```java
var kingJoffrey = new KingJoffrey();
var kingsHand = new KingsHand();
kingsHand.registerObserver(kingJoffrey, Event.TRAITOR_DETECTED);
kingsHand.registerObserver(kingJoffrey, Event.STARK_SIGHTED);
kingsHand.registerObserver(kingJoffrey, Event.WARSHIPS_APPROACHING);
kingsHand.registerObserver(kingJoffrey, Event.WHITE_WALKERS_SIGHTED);
var varys = new LordVarys();
varys.registerObserver(kingsHand, Event.TRAITOR_DETECTED);
varys.registerObserver(kingsHand, Event.WHITE_WALKERS_SIGHTED);
var scout = new Scout();
scout.registerObserver(kingsHand, Event.WARSHIPS_APPROACHING);
scout.registerObserver(varys, Event.WHITE_WALKERS_SIGHTED);
var baelish = new LordBaelish(kingsHand, Event.STARK_SIGHTED);
var emitters = List.of(
kingsHand,
baelish,
varys,
scout
);
Arrays.stream(Weekday.values())
.<Consumer<? super EventEmitter>>map(day -> emitter -> emitter.timePasses(day))
.forEachOrdered(emitters::forEach);
```
The console output after running the example.
```
18:21:52.955 [main] INFO com.iluwatar.event.aggregator.KingJoffrey - Received event from the King's Hand: Warships approaching
18:21:52.960 [main] INFO com.iluwatar.event.aggregator.KingJoffrey - Received event from the King's Hand: White walkers sighted
18:21:52.960 [main] INFO com.iluwatar.event.aggregator.KingJoffrey - Received event from the King's Hand: Stark sighted
18:21:52.960 [main] INFO com.iluwatar.event.aggregator.KingJoffrey - Received event from the King's Hand: Traitor detected
```
## Class diagram
![alt text](./etc/classes.png "Event Aggregator")
@ -160,13 +26,9 @@ Use the Event Aggregator pattern when
* Event Aggregator is a good choice when you have lots of objects that are
potential event sources. Rather than have the observer deal with registering
with them all, you can centralize the registration logic to the Event
Aggregator. As well as simplifying registration, an Event Aggregator also
Aggregator. As well as simplifying registration, a Event Aggregator also
simplifies the memory management issues in using observers.
## Related patterns
* [Observer](https://java-design-patterns.com/patterns/observer/)
## Credits
* [Martin Fowler - Event Aggregator](http://martinfowler.com/eaaDev/EventAggregator.html)

View File

@ -49,28 +49,13 @@ public class App {
public static void main(String[] args) {
var kingJoffrey = new KingJoffrey();
var kingsHand = new KingsHand();
kingsHand.registerObserver(kingJoffrey, Event.TRAITOR_DETECTED);
kingsHand.registerObserver(kingJoffrey, Event.STARK_SIGHTED);
kingsHand.registerObserver(kingJoffrey, Event.WARSHIPS_APPROACHING);
kingsHand.registerObserver(kingJoffrey, Event.WHITE_WALKERS_SIGHTED);
var varys = new LordVarys();
varys.registerObserver(kingsHand, Event.TRAITOR_DETECTED);
varys.registerObserver(kingsHand, Event.WHITE_WALKERS_SIGHTED);
var scout = new Scout();
scout.registerObserver(kingsHand, Event.WARSHIPS_APPROACHING);
scout.registerObserver(varys, Event.WHITE_WALKERS_SIGHTED);
var baelish = new LordBaelish(kingsHand, Event.STARK_SIGHTED);
var kingsHand = new KingsHand(kingJoffrey);
var emitters = List.of(
kingsHand,
baelish,
varys,
scout
new LordBaelish(kingsHand),
new LordVarys(kingsHand),
new Scout(kingsHand)
);
Arrays.stream(Weekday.values())

View File

@ -31,7 +31,6 @@ import lombok.RequiredArgsConstructor;
@RequiredArgsConstructor
public enum Event {
WHITE_WALKERS_SIGHTED("White walkers sighted"),
STARK_SIGHTED("Stark sighted"),
WARSHIPS_APPROACHING("Warships approaching"),
TRAITOR_DETECTED("Traitor detected");

View File

@ -23,48 +23,31 @@
package com.iluwatar.event.aggregator;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
/**
* EventEmitter is the base class for event producers that can be observed.
*/
public abstract class EventEmitter {
private final Map<Event, List<EventObserver>> observerLists;
private final List<EventObserver> observers;
public EventEmitter() {
observerLists = new HashMap<>();
observers = new LinkedList<>();
}
public EventEmitter(EventObserver obs, Event e) {
public EventEmitter(EventObserver obs) {
this();
registerObserver(obs, e);
registerObserver(obs);
}
/**
* Registers observer for specific event in the related list.
*
* @param obs the observer that observers this emitter
* @param e the specific event for that observation occurs
* */
public final void registerObserver(EventObserver obs, Event e) {
if (!observerLists.containsKey(e)) {
observerLists.put(e, new LinkedList<>());
}
if (!observerLists.get(e).contains(obs)) {
observerLists.get(e).add(obs);
}
public final void registerObserver(EventObserver obs) {
observers.add(obs);
}
protected void notifyObservers(Event e) {
if (observerLists.containsKey(e)) {
observerLists
.get(e)
.forEach(observer -> observer.onEvent(e));
}
observers.forEach(obs -> obs.onEvent(e));
}
public abstract void timePasses(Weekday day);

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@ -31,8 +31,8 @@ public class KingsHand extends EventEmitter implements EventObserver {
public KingsHand() {
}
public KingsHand(EventObserver obs, Event e) {
super(obs, e);
public KingsHand(EventObserver obs) {
super(obs);
}
@Override
@ -42,5 +42,6 @@ public class KingsHand extends EventEmitter implements EventObserver {
@Override
public void timePasses(Weekday day) {
// NOP
}
}

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@ -31,8 +31,8 @@ public class LordBaelish extends EventEmitter {
public LordBaelish() {
}
public LordBaelish(EventObserver obs, Event e) {
super(obs, e);
public LordBaelish(EventObserver obs) {
super(obs);
}
@Override

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@ -23,19 +23,16 @@
package com.iluwatar.event.aggregator;
import lombok.extern.slf4j.Slf4j;
/**
* LordVarys produces events.
*/
@Slf4j
public class LordVarys extends EventEmitter implements EventObserver {
public class LordVarys extends EventEmitter {
public LordVarys() {
}
public LordVarys(EventObserver obs, Event e) {
super(obs, e);
public LordVarys(EventObserver obs) {
super(obs);
}
@Override
@ -44,10 +41,4 @@ public class LordVarys extends EventEmitter implements EventObserver {
notifyObservers(Event.TRAITOR_DETECTED);
}
}
@Override
public void onEvent(Event e) {
notifyObservers(e);
}
}

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@ -31,8 +31,8 @@ public class Scout extends EventEmitter {
public Scout() {
}
public Scout(EventObserver obs, Event e) {
super(obs, e);
public Scout(EventObserver obs) {
super(obs);
}
@Override
@ -40,8 +40,5 @@ public class Scout extends EventEmitter {
if (day == Weekday.TUESDAY) {
notifyObservers(Event.WARSHIPS_APPROACHING);
}
if (day == Weekday.WEDNESDAY) {
notifyObservers(Event.WHITE_WALKERS_SIGHTED);
}
}
}

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@ -31,7 +31,6 @@ import static org.mockito.Mockito.verifyNoMoreInteractions;
import static org.mockito.Mockito.verifyZeroInteractions;
import java.util.Objects;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Supplier;
import org.junit.jupiter.api.Test;
@ -47,7 +46,7 @@ abstract class EventEmitterTest<E extends EventEmitter> {
/**
* Factory used to create a new instance of the test object with a default observer
*/
private final BiFunction<EventObserver, Event, E> factoryWithDefaultObserver;
private final Function<EventObserver, E> factoryWithDefaultObserver;
/**
* Factory used to create a new instance of the test object without passing a default observer
@ -68,7 +67,7 @@ abstract class EventEmitterTest<E extends EventEmitter> {
* Create a new event emitter test, using the given test object factories, special day and event
*/
EventEmitterTest(final Weekday specialDay, final Event event,
final BiFunction<EventObserver, Event, E> factoryWithDefaultObserver,
final Function<EventObserver, E> factoryWithDefaultObserver,
final Supplier<E> factoryWithoutDefaultObserver) {
this.specialDay = specialDay;
@ -130,8 +129,8 @@ abstract class EventEmitterTest<E extends EventEmitter> {
final var observer2 = mock(EventObserver.class);
final var emitter = this.factoryWithoutDefaultObserver.get();
emitter.registerObserver(observer1, event);
emitter.registerObserver(observer2, event);
emitter.registerObserver(observer1);
emitter.registerObserver(observer2);
testAllDays(specialDay, event, emitter, observer1, observer2);
}
@ -147,9 +146,9 @@ abstract class EventEmitterTest<E extends EventEmitter> {
final var observer1 = mock(EventObserver.class);
final var observer2 = mock(EventObserver.class);
final var emitter = this.factoryWithDefaultObserver.apply(defaultObserver, event);
emitter.registerObserver(observer1, event);
emitter.registerObserver(observer2, event);
final var emitter = this.factoryWithDefaultObserver.apply(defaultObserver);
emitter.registerObserver(observer1);
emitter.registerObserver(observer2);
testAllDays(specialDay, event, emitter, defaultObserver, observer1, observer2);
}

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@ -55,11 +55,7 @@ class KingsHandTest extends EventEmitterTest<KingsHand> {
@Test
void testPassThrough() throws Exception {
final var observer = mock(EventObserver.class);
final var kingsHand = new KingsHand();
kingsHand.registerObserver(observer, Event.STARK_SIGHTED);
kingsHand.registerObserver(observer, Event.WARSHIPS_APPROACHING);
kingsHand.registerObserver(observer, Event.TRAITOR_DETECTED);
kingsHand.registerObserver(observer, Event.WHITE_WALKERS_SIGHTED);
final var kingsHand = new KingsHand(observer);
// The kings hand should not pass any events before he received one
verifyZeroInteractions(observer);

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@ -34,9 +34,7 @@ class ScoutTest extends EventEmitterTest<Scout> {
* Create a new test instance, using the correct object factory
*/
public ScoutTest() {
super(Weekday.TUESDAY, Event.WARSHIPS_APPROACHING, Scout::new, Scout::new);
super(Weekday.TUESDAY, Event.WARSHIPS_APPROACHING, Scout::new, Scout::new);
}
}

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@ -96,11 +96,9 @@ public class NioReactor {
* @throws IOException if any I/O error occurs.
*/
public void stop() throws InterruptedException, IOException {
reactorMain.shutdown();
reactorMain.shutdownNow();
selector.wakeup();
if (!reactorMain.awaitTermination(4, TimeUnit.SECONDS)) {
reactorMain.shutdownNow();
}
reactorMain.awaitTermination(4, TimeUnit.SECONDS);
selector.close();
LOGGER.info("Reactor stopped");
}

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@ -64,8 +64,6 @@ public class ThreadPoolDispatcher implements Dispatcher {
@Override
public void stop() throws InterruptedException {
executorService.shutdown();
if (executorService.awaitTermination(4, TimeUnit.SECONDS)) {
executorService.shutdownNow();
}
executorService.awaitTermination(4, TimeUnit.SECONDS);
}
}

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@ -34,11 +34,11 @@ import java.util.HashMap;
public class SpatialPartitionBubbles extends SpatialPartitionGeneric<Bubble> {
private final HashMap<Integer, Bubble> bubbles;
private final QuadTree bubblesQuadTree;
private final QuadTree quadTree;
SpatialPartitionBubbles(HashMap<Integer, Bubble> bubbles, QuadTree bubblesQuadTree) {
SpatialPartitionBubbles(HashMap<Integer, Bubble> bubbles, QuadTree quadTree) {
this.bubbles = bubbles;
this.bubblesQuadTree = bubblesQuadTree;
this.quadTree = quadTree;
}
void handleCollisionsUsingQt(Bubble b) {
@ -46,7 +46,7 @@ public class SpatialPartitionBubbles extends SpatialPartitionGeneric<Bubble> {
// centre of bubble and length = radius of bubble
var rect = new Rect(b.coordinateX, b.coordinateY, 2D * b.radius, 2D * b.radius);
var quadTreeQueryResult = new ArrayList<Point>();
this.bubblesQuadTree.query(rect, quadTreeQueryResult);
this.quadTree.query(rect, quadTreeQueryResult);
//handling these collisions
b.handleCollision(quadTreeQueryResult, this.bubbles);
}