JarCastingStatus
dropwizard-petite
This library provides an integration for the awesome Jodd Petite and dropwizard. It provides a light weight dependency injection, similarly to Spring but with a much smaller footprint and better error messages.
It also comes with an optional implementation (MonitoredPetiteContainer) that adds metrics to PetiteContainer, so you can monitor the cost of running Petite in your application. By default it's disabled and works exactly as if you implemented it yourself.
Jodd Petite by default will make your beans singleton, which is perfect for most of DAOs and resource classes.
Supported versions:
| Dropwizard-petite | Dropwizard | Jodd Petite |
|---|---|---|
| - | 0.9.X | 0.0.1 |
| - | 1.X.X | 1.0.0 |
| - | 1.1.x | 1.1.4 |
| 1.3.8 | 1.3.8 | 5.0.6 |
Maven
The library is available at the maven central, so just add dependency to pom.xml:
<dependencies>
<dependency>
<groupId>com.github.mtakaki</groupId>
<artifactId>dropwizard-petite</artifactId>
<version>1.3.8</version>
</dependency>
</dependencies>
How to use it
Bundle
public class TestApplication extends Application<TestConfiguration> {
// Adding hibernate just to show how to register the SessionFactory.
private final HibernateBundle<TestConfiguration> hibernate = new HibernateBundle<TestConfiguration>(
TestEntity.class) {
@Override
public DataSourceFactory getDataSourceFactory(
final TestConfiguration configuration) {
return configuration.getDatabase();
}
};
// This is the Jodd Petite bundle.
private final PetiteBundle<TestConfiguration> petite = new PetiteBundle<TestConfiguration>() {
@Override
protected PetiteConfiguration getConfiguration(final TestConfiguration configuration) {
return configuration.getPetite();
}
};
@Override
public void initialize(final Bootstrap<TestConfiguration> bootstrap) {
bootstrap.addBundle(this.hibernate);
bootstrap.addBundle(this.petite);
}
@Override
public void run(final TestConfiguration configuration, final Environment environment)
throws Exception {
// Registering the SessionFactory to the container because SessionFactory is not annotated
// with @PetiteBean.
this.petite.getPetiteContainer().addBean(SessionFactory.class.getName(),
this.hibernate.getSessionFactory());
// Here we're asking the Petite container to get/build the resource.
environment.jersey().register(this.petite.getPetiteContainer().getBean(TestResource.class));
}
}
Beans
To expose your class as a bean you will need to annotate it with @PetiteBean and the constructor with @PetiteInject, although the latter is optional as Petite can figure it out automatically. Commonly you would annotate your DAO and Resource classes, like this:
@PetiteBean
public class TestDAO extends AbstractDAO<Test> {
@PetiteInject
public TestDAO(SessionFactory sessionFactory) {
super(sessionFactory);
}
}
The DAO class depends on having the SessionFactory registered in the container, otherwise it won't find it when calling the constructor.
The Resource class:
@PetiteBean
public class TestResource {
private final TestEntityDAO dao;
@PetiteInject
public TestResource(TestEntityDAO dao) {
this.dao = dao;
}
}
Configuration
The bundle comes with PetiteConfiguration, so your configuration will look like this:
public class TestConfiguration extends Configuration {
private final PetiteConfiguration petite = new PetiteConfiguration();
public PetiteConfiguration getPetite() {
return this.petite;
}
}
And the YAML will look like this:
petite:
useFullTypeNames: true
automagicConfigurator: true
registerSelf: true
useMetrics: true
useFullTypeNames, will make the container use the full class name, rather than just thegetSimpleName(). This is very useful to avoid class names collision.automagicConfigurator, will make the container automatically look for beans in the class path. If this is not configured, you will need to manually register your beans.registerSelf, will register the container into itself.useMetrics, will use theMonitoredPetiteContainerand will push metrics for the methodsgetBean()andaddBean().
Metrics
These metrics will show up if you setup the useMetrics settings to true (it's default to false). This will show up exactly the overhead of using Jodd Petite.
{
"timers" : {
"com.github.mtakaki.dropwizard.petite.MonitoredPetiteContainer.addBean" : {
"count" : 2,
"max" : 0.006725265,
"mean" : 0.003824707,
"min" : 9.241490000000001E-4,
"p50" : 0.006725265,
"p75" : 0.006725265,
"p95" : 0.006725265,
"p98" : 0.006725265,
"p99" : 0.006725265,
"p999" : 0.006725265,
"stddev" : 0.002900558,
"m15_rate" : 0.4,
"m1_rate" : 0.4,
"m5_rate" : 0.4,
"mean_rate" : 0.2675745788220869,
"duration_units" : "seconds",
"rate_units" : "calls/second"
},
"com.github.mtakaki.dropwizard.petite.MonitoredPetiteContainer.getBean" : {
"count" : 2,
"max" : 0.00296589,
"mean" : 0.0029420970000000003,
"min" : 0.002918304,
"p50" : 0.00296589,
"p75" : 0.00296589,
"p95" : 0.00296589,
"p98" : 0.00296589,
"p99" : 0.00296589,
"p999" : 0.00296589,
"stddev" : 2.3793E-5,
"m15_rate" : 0.4,
"m1_rate" : 0.4,
"m5_rate" : 0.4,
"mean_rate" : 0.26755860731761477,
"duration_units" : "seconds",
"rate_units" : "calls/second"
},
"com.github.mtakaki.dropwizard.petite.PetiteConfiguration.automagicConfigurator" : {
"count" : 1,
"max" : 1.683990942,
"mean" : 1.683990942,
"min" : 1.683990942,
"p50" : 1.683990942,
"p75" : 1.683990942,
"p95" : 1.683990942,
"p98" : 1.683990942,
"p99" : 1.683990942,
"p999" : 1.683990942,
"stddev" : 0.0,
"m15_rate" : 0.2,
"m1_rate" : 0.2,
"m5_rate" : 0.2,
"mean_rate" : 0.13377928037494183,
"duration_units" : "seconds",
"rate_units" : "calls/second"
}
}
Debugging errors
Null pointer exception when registering resource
If you're getting an NPE when registering your resource, like this:
Exception in thread "main" java.lang.NullPointerException
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:210)
at io.dropwizard.jersey.setup.JerseyEnvironment.register(JerseyEnvironment.java:37)
at com.github.mtakaki.test.TestApplication.run(TestApplication.java:90)
at com.github.mtakaki.test.TestApplication.run(TestApplication.java:1)
at io.dropwizard.cli.EnvironmentCommand.run(EnvironmentCommand.java:40)
at io.dropwizard.cli.ConfiguredCommand.run(ConfiguredCommand.java:77)
at io.dropwizard.cli.Cli.run(Cli.java:70)
at io.dropwizard.Application.run(Application.java:80)
at com.github.mtakaki.test.TestApplication.main(TestApplication.java:34)
It means the container could not find your bean. It means that your bean was not registered.
Solutions:
- Set
automagicConfigurator: truein your configuration file. - Manually register the bean into your
PetiteContainer.
Wiring exception
If your application fails to initialize due to a PetiteException and it throws this stack trace:
Exception in thread "main" jodd.petite.PetiteException: Wiring constructor failed. References 'null,sessionFactory,org.hibernate.SessionFactory' not found for constructor: public com.github.mtakaki.test.database.TestDAO(org.hibernate.SessionFactory)
at jodd.petite.PetiteContainer.newBeanInstance(PetiteContainer.java:90)
at jodd.petite.PetiteContainer.getBean(PetiteContainer.java:368)
at jodd.petite.PetiteContainer.getBean(PetiteContainer.java:325)
at jodd.petite.PetiteContainer.newBeanInstance(PetiteContainer.java:87)
at jodd.petite.PetiteContainer.getBean(PetiteContainer.java:368)
at jodd.petite.PetiteContainer.getBean(PetiteContainer.java:314)
at com.github.mtakaki.dropwizard.petite.MonitoredPetiteContainer.getBean(MonitoredPetiteContainer.java:29)
at jodd.petite.PetiteContainer.getBean(PetiteContainer.java:302)
at com.github.mtakaki.dropwizard.petite.MonitoredPetiteContainer.getBean(MonitoredPetiteContainer.java:22)
at com.github.mtakaki.test.TestApplication.run(TestApplication.java:88)
at com.github.mtakaki.test.TestApplication.run(TestApplication.java:1)
at io.dropwizard.cli.EnvironmentCommand.run(EnvironmentCommand.java:40)
at io.dropwizard.cli.ConfiguredCommand.run(ConfiguredCommand.java:77)
at io.dropwizard.cli.Cli.run(Cli.java:70)
at io.dropwizard.Application.run(Application.java:80)
at com.github.mtakaki.test.TestApplication.main(TestApplication.java:32)
It means the SessionFactory has not been added to the container. As the stack trace shows, it tried calling a constructor that receives a SessionFactory but it could not find the bean to call it.
Solution:
- Register the
SessionFactory.SessionFactoryis not part of your project, so you cannot annotate it with@PetiteBean. The solution is to manually add the bean to the container so it can be found when auto-wiring your beans:
@Override
public void run(final TestConfiguration configuration,
final Environment environment) throws Exception {
final PetiteContainer petiteContainer = this.petite.getPetiteContainer();
petiteContainer.addBean(SessionFactory.class.getName(), this.hibernate.getSessionFactory());
}