IAT / guava-retrying

This is a small extension to Google's Guava library to allow for the creation of configurable retrying strategies for an arbitrary function call, such as something that talks to a remote service with flaky uptime.

##What is this? The guava-retrying module provides a general purpose method for retrying arbitrary Java code with specific stop, retry, and exception handling capabilities that are enhanced by Guava's predicate matching.

This is a fork of the excellent RetryerBuilder code posted here by Jean-Baptiste Nizet (JB). I've added a Gradle build for pushing it up to my little corner of Maven Central so that others can easily pull it into their existing projects with minimal effort. It also includes an exponential backoff WaitStrategy that might be useful for situations where more well-behaved service polling is preferred.

##Maven

    <dependency>
      <groupId>com.github.rholder</groupId>
      <artifactId>guava-retrying</artifactId>
      <version>1.0.4</version>
    </dependency>

##Gradle

    compile "com.github.rholder:guava-retrying:1.0.4"

##Quickstart A minimal sample of some of the functionality would look like:

    Callable<Boolean> callable = new Callable<Boolean>() {
        public Boolean call() throws Exception {
            return true; // do something useful here
        }
    };

    Retryer<Boolean> retryer = RetryerBuilder.<Boolean>newBuilder()
            .retryIfResult(Predicates.<Boolean>isNull())
            .retryIfExceptionOfType(IOException.class)
            .retryIfRuntimeException()
            .withStopStrategy(StopStrategies.stopAfterAttempt(3))
            .build();
    try {
        retryer.call(callable);
    } catch (RetryException e) {
        e.printStackTrace();
    } catch (ExecutionException e) {
        e.printStackTrace();
    }

##Exponential Backoff Create a Retryer that retries forever, waiting after every failed retry in increasing exponential backoff intervals until at most 5 minutes. After 5 minutes, retry from then on in 5 minute intervals.

    Retryer<Boolean> retryer = RetryerBuilder.<Boolean>newBuilder()
            .retryIfExceptionOfType(IOException.class)
            .retryIfRuntimeException()
            .withWaitStrategy(WaitStrategies.exponentialWait(100, 5, TimeUnit.MINUTES))
            .withStopStrategy(StopStrategies.neverStop())
            .build();

##Documentation Javadoc can be found here.

##Building from source The guava-retrying module uses a Gradle-based build system. In the instructions below, ./gradlew is invoked from the root of the source tree and serves as a cross-platform, self-contained bootstrap mechanism for the build. The only prerequisites are Git and JDK 1.6+.

check out sources

git clone git://github.com/rholder/guava-retrying.git

compile and test, build all jars

./gradlew build

install all jars into your local Maven cache

./gradlew install

##License The guava-retrying module is released under version 2.0 of the Apache License.

##Contributors

• Jean-Baptiste Nizet (JB)
• Jason Dunkelberger (dirkraft)
• Diwaker Gupta (diwakergupta)