https://github.com/alexpanov/retries
Forget about your retry boilerplate
https://github.com/alexpanov/retries
failure retries retry wait
Last synced: 5 days ago
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Forget about your retry boilerplate
- Host: GitHub
- URL: https://github.com/alexpanov/retries
- Owner: alexpanov
- Created: 2015-08-11T09:01:37.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2017-07-07T21:28:02.000Z (almost 8 years ago)
- Last Synced: 2025-04-22T23:06:23.377Z (5 days ago)
- Topics: failure, retries, retry, wait
- Language: Java
- Homepage:
- Size: 60.5 KB
- Stars: 13
- Watchers: 2
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
[](https://travis-ci.org/alexpanov/retries)
[](https://ci.appveyor.com/project/alexpanov/retries/branch/master)
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# Retries
You need to make a call that may fail. You need to wait for a value that meets your criteria. You write your own retry boilerplate. **Why**?
Throw it away. You need not to support it anymore.
## Motivation
Have you ever written a retry/wait code that looks like this?
```java
private String computeWithRetries() {
int numberOfTries = 10;
int sleepTimeout = 1000; // one sec
for (int i = 0; i < numberOfTries; i++) {
try {
String value = computeValue();
} catch (Exception e) {
try {
Thread.sleep(sleepTimeout);
} catch (InterruptedException ie) {
ie.printStackTrace();
}
continue;
}
if (value != null && !value.startsWith("B")) {
return value;
}
}
throw new RuntimeException("Could not compute anything");
}
```
**Ugh**. That's terrible and you know it. It's hard to figure out what's going on, hard to extend, hard to reuse and easy to get it wrong. Luckily, **there is an alternative**.
## Build tools
Add **retries** to your dependencies. Note that *Guava is automatically added too*.
### Maven:
```xml
me.alexpanov
retries
0.0.3
```
### Gradle:
```groovy
compile "me.alexpanov:retries:0.0.3"
```
## Getting started
Create a retryable:
```java
//Nasty call that returns so much nulls
Retryable retryable = new Retryable() {
@Override
public String tryOnce() throws Exception {
return null;
}
};
```
### One call, one failure, ```RetryException``` is thrown
```java
String resultAfterRetries = new Retries(retryable).stopOnMaxFailures(1).perform();
```
Code above will throw a subclass of ```RetryException```:
```
me.alexpanov.retries.FailedToComputeAValueException
```
### Same thing asynchronously, ```java.util.concurrent.ExecutionException``` is thrown
```java
Future resultAfterRetries = new Retries(retryable).stopOnMaxFailures(1).performAsync();
String result = resultAfterRetries.get();
```
Code above will throw an ```ExecutionException``` with a subclass of ```RetryException``` as a cause:
```
me.alexpanov.retries.FailedToComputeAValueException
```
### One call, one failure, default value is returned
```java
String resultAfterRetries = new Retries(retryable).stopOnMaxFailures(1)
.orElse("default value")
.perform();
resultAfterRetries.equals("default value"); //true
```
### Several calls, configured wait timeout
```java
String resultAfterRetries = new Retries(retryable).stopOnMaxFailures(10)
.waitAfterFailureAtLeast(10, TimeUnit.SECONDS)
.orElse("default value")
.perform();
```
### Ignoring results
```java
Predicate startsWithLetterB = new Predicate() {
@Override
public boolean apply(String input) {
return input.startsWith("B");
}
};
String resultAfterRetries = new Retries(retryable).stopOnMaxFailures(2)
.ignoreIfResult(startsWithLetterB)
.perform();
```
### Subscribing to failures for logging etc.
```java
FailureSubscriber logTheError = new FailureSubscriber() {
@Override
public void onFailure(RetryFailure details) {
LOG.info("Failure");
}
};
String resultAfterRetries = new Retries(retryable).stopOnMaxFailures(10)
.onEachFailureDo(logTheError)
.perform();
```
The code above will append a log message each time a call failed (exception, null or skipped result).
## But what about my Callable(s)!?
I got you covered, man.
```java
Retryable retryable = new CallableToRetryable(yourCallable);
```
## Licence
[The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
## Issues
Please feel free to add any issues regarding new functionality, improvements etc. in the [Issues section](https://github.com/alexpanov/retries/issues)