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Allow HystrixFeign.Builder to be used incrementally. #313

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Allow HystrixFeign.Builder to be used incrementally. #313

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6 changes: 3 additions & 3 deletions hystrix/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -74,7 +74,7 @@ GitHub fallback = (owner, repo) -> {
}
};

GitHub github = HystrixFeign.builder()
...
.target(GitHub.class, "https://api.github.com", fallback);
HystrixFeign.Builder builder = HystrixFeign.builder();
...
GitHub github = builder.target(GitHub.class, "https://api.github.com", fallback);

@spencergibb spencergibb Jan 13, 2016

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Because the change is in a terminal method you need it's original type 😞. One option is to move create a fallback() method which could retain the fluent style. Another is to create an AbstractBuilder<B> that returns B from each method allowing downstream builders to have custom terminal methods.

```
168 changes: 27 additions & 141 deletions hystrix/src/main/java/feign/hystrix/HystrixFeign.java
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Expand Up @@ -6,18 +6,10 @@
import java.lang.reflect.Method;
import java.util.Map;

import feign.Client;
import feign.Contract;
import feign.Feign;
import feign.InvocationHandlerFactory;
import feign.Logger;
import feign.Request;
import feign.RequestInterceptor;
import feign.Retryer;
import feign.Target;
import feign.codec.Decoder;
import feign.codec.Encoder;
import feign.codec.ErrorDecoder;

/**
* Allows Feign interfaces to return HystrixCommand or rx.Observable or rx.Single objects. Also
Expand All @@ -30,25 +22,30 @@ public static Builder builder() {
return new Builder();
}

// Doesn't extend Feign.Builder for two reasons:
// * Hide invocationHandlerFactory - as this isn't customizable
// * Provide a path to the new fallback method w/o using covariant return types
public static final class Builder {
private final Feign.Builder delegate = new Feign.Builder();
private Contract contract = new Contract.Default();
// Extends Feign.Builder because downstream projects use it incrementally.
public static final class Builder extends Feign.Builder {

/**
* @see #target(Class, String, Object)
*/
public <T> T target(Target<T> target, final T fallback) {
delegate.invocationHandlerFactory(new InvocationHandlerFactory() {
public Builder() {
// both needed if fallbacks, not used
contract(new HystrixDelegatingContract(new Contract.Default()));
super.invocationHandlerFactory(buildInvocationHandlerFactory(null));
}

private InvocationHandlerFactory buildInvocationHandlerFactory(final Object fallback) {
return new InvocationHandlerFactory() {
@Override
public InvocationHandler create(Target target, Map<Method, MethodHandler> dispatch) {
return new HystrixInvocationHandler(target, dispatch, fallback);
}
});
delegate.contract(new HystrixDelegatingContract(contract));
return delegate.build().newInstance(target);
};
}

/**
* @see #target(Class, String, Object)
*/
public <T> T target(Target<T> target, final T fallback) {
super.invocationHandlerFactory(buildInvocationHandlerFactory(fallback));
return build().newInstance(target);
}

/**
Expand Down Expand Up @@ -79,137 +76,26 @@ public InvocationHandler create(Target target, Map<Method, MethodHandler> dispat
* }
* };
*
* GitHub github = HystrixFeign.builder()
* GitHub github = HystrixFeign.builder(fallback)
* ...
* .target(GitHub.class, "https://api.github.com", fallback);
* .target(GitHub.class, "https://api.github.com");
* }</pre>
*
* @see #target(Target, Object)
*/
public <T> T target(Class<T> apiType, String url, T fallback) {
return target(new Target.HardCodedTarget<T>(apiType, url), fallback);
}

/**
* @see feign.Feign.Builder#contract
*/
public Builder contract(Contract contract) {
this.contract = contract;
return this;
}

/**
* @see feign.Feign.Builder#build
*/
public Feign build() {
delegate.invocationHandlerFactory(new HystrixInvocationHandler.Factory());
delegate.contract(new HystrixDelegatingContract(contract));
return delegate.build();
}

// re-declaring methods in Feign.Builder is same work as covariant overrides,
// but results in less complex bytecode.

/**
* @see feign.Feign.Builder#target(Class, String)
*/
public <T> T target(Class<T> apiType, String url) {
return target(new Target.HardCodedTarget<T>(apiType, url));
}

/**
* @see feign.Feign.Builder#target(Target)
*/
public <T> T target(Target<T> target) {
return build().newInstance(target);
}

/**
* @see feign.Feign.Builder#logLevel
*/
public Builder logLevel(Logger.Level logLevel) {
delegate.logLevel(logLevel);
return this;
}

/**
* @see feign.Feign.Builder#client
*/
public Builder client(Client client) {
delegate.client(client);
@Override
public Feign.Builder invocationHandlerFactory(InvocationHandlerFactory invocationHandlerFactory) {
//TODO: throw exception, log warning or do nothing?

@spencergibb spencergibb Jan 13, 2016

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Since the method can no longer be hidden, what do you think should be done here?

@codefromthecrypt codefromthecrypt Jan 14, 2016

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unsupportedoperationexception

return this;
}

/**
* @see feign.Feign.Builder#retryer
*/
public Builder retryer(Retryer retryer) {
delegate.retryer(retryer);
return this;
}

/**
* @see feign.Feign.Builder#retryer
*/
public Builder logger(Logger logger) {
delegate.logger(logger);
return this;
}

/**
* @see feign.Feign.Builder#encoder
*/
public Builder encoder(Encoder encoder) {
delegate.encoder(encoder);
return this;
}

/**
* @see feign.Feign.Builder#decoder
*/
public Builder decoder(Decoder decoder) {
delegate.decoder(decoder);
return this;
}

/**
* @see feign.Feign.Builder#decode404
*/
public Builder decode404() {
delegate.decode404();
return this;
}

/**
* @see feign.Feign.Builder#errorDecoder
*/
public Builder errorDecoder(ErrorDecoder errorDecoder) {
delegate.errorDecoder(errorDecoder);
return this;
}

/**
* @see feign.Feign.Builder#options
*/
public Builder options(Request.Options options) {
delegate.options(options);
return this;
}

/**
* @see feign.Feign.Builder#requestInterceptor
*/
public Builder requestInterceptor(RequestInterceptor requestInterceptor) {
delegate.requestInterceptor(requestInterceptor);
return this;
}

/**
* @see feign.Feign.Builder#requestInterceptors
* @see feign.Feign.Builder#contract
*/
public Builder requestInterceptors(Iterable<RequestInterceptor> requestInterceptors) {
delegate.requestInterceptors(requestInterceptors);
return this;
public Feign.Builder contract(Contract contract) {
return super.contract(new HystrixDelegatingContract(contract));
}
}
}