DDevelopment & Design

The hidden benefit of writing short methods

A method should do only one thingQuoting Uncle Bob:The first rule of functions is that they should be small. The second rule of functions is that they should be smaller than that. Functions should not be 100 lines long. Functions should hardly ever be …

A method should do only one thing

Quoting Uncle Bob:

The first rule of functions is that they should be small. The second rule of functions is that they should be smaller than that. Functions should not be 100 lines long. Functions should hardly ever be 20 lines long.

From one of Martin Thompson’s presentations I have learned another – more easily available and intuitive – method of judging wether a method is small enough. What you are supposed to do is to physically cover the part of your screen on which the method is displayed with your hand. If you can’t do that, then it means that your method probably is not small enough and you should consider refactoring it.

The obvious advantages that you gain by following these rules are improved readability and maintainability of your code.

But there is one – less obvious – benefit of writing short methods

And that is that Java HotSpot VM’s JIT compiler uses a compilation technique which is called inlining. 
What the compiler does is it substitutes the body of a method into places where this method is invoked thus saving the cost of calling the method. 
Current default for HotSpot is set at 35 bytes, which means that the compiler will inline a method if it contains less than 35 bytes of bytecode.

How do I know the bytecode size of a given method?

The easiest way is to dump the class file containing your method with:
javap -c mypackage.MyClass

which returns bytecode of decompiled class and the size of each method (well actually the size is equal to the byte offset of the last instruction – you can read more about javap HERE).

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DDevelopment & Design

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DDevelopment & Design

Grails with Spock unit test + IntelliJ IDEA = No thread-bound request found

During my work with Grails project using Spock test in IntelliJ IDEA I've encountered this error:

java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
 at org.springframework.web.context.request.RequestContextHolder.currentRequestAttributes(RequestContextHolder.java:131)
 at org.codehaus.groovy.grails.plugins.web.api.CommonWebApi.currentRequestAttributes(CommonWebApi.java:205)
 at org.codehaus.groovy.grails.plugins.web.api.CommonWebApi.getParams(CommonWebApi.java:65)
... // and few more lines of stacktrace ;)

It occurred when I tried to debug one of test from IDEA level. What is interesting, this error does not happen when I'm running all test using grails test-app for instance.

So what was the issue? With little of reading and tip from Tomek Kalkosiński (http://refaktor.blogspot.com/) it turned out that our test was missing @TestFor annotation and adding it solved all problems.

This annotation, according to Grails docs (link), indicates Spock what class is being tested and implicitly creates field with given type in test class. It is somehow strange as problematic test had explicitly and "manually" created field with proper controller type. Maybe there is a problem with mocking servlet requests?