[foreign] RFR 8216284: Make sure test jars are deleted before/after tests

[Jorn Vernee]

> PS. I guess the issue of deleting jar file-in-use is Windows specific.
> That's why it was never seen on other platforms.

Yeah, I've noticed that the Windows file system can be a little more 
strict in some cases. Guess Mac/Linux don't care since it's the same 
process trying to delete the file.

Thanks for the review!
Jorn

Sundararajan Athijegannathan schreef op 2019-01-09 03:28:
> This change looks good.
> 
> PS. I guess the issue of deleting jar file-in-use is Windows specific.
> That's why it was never seen on other platforms.
> 
> -Sundar
> 
> On 08/01/19, 9:28 PM, Jorn Vernee wrote:
>> Hi,
>> 
>> I was seeing some errors while running the JextractToolProviderTest 
>> test, but the test still passed. The errors were from the test jars 
>> not being able to be deleted because some process was using the file. 
>> It turns out this was due to JextractToolRunner::loadClass creating a 
>> URLClassLoader to load classes from the jar, but the classloader never 
>> being closed causing the file to still be in use when trying to delete 
>> it. This was throwing IOExceptions which were being printed, but 
>> otherwise ignored.
>> 
>> With all the errors being thrown and ignored I wasn't sure whether I 
>> could trust the outcome of the test. Different tests could also 
>> possibly interfere with each other if they use the same jar file name 
>> and the jar doesn't get deleted after each test.
>> 
>> I've solved the problem by replacing the loadClass method with a 
>> classLoader method which returns an AutoCloseable Loader through which 
>> the classes can be loaded. The close() method on Loader closes the 
>> class loader. I have also turned the errors I was seeing into hard 
>> errors to make sure that the tests fail if an IOException occurs 
>> unexpectedly. To make that possible I switched 
>> JextractToolRunner::deleteFile to using Files.deleteIfExtists instead 
>> of delete so that an error will not occur when it is called at the 
>> start of a test but there's nothing to delete.
>> 
>> JextractToolRunner::classLoader is called with a list of Paths to use 
>> as class path entries e.g.:
>> 
>>     Path helloJar = getOutputFilePath("hello.jar");
>>     deleteFile(helloJar); // make sure jar does not exist at start of 
>> test
>>     Path helloH = getInputFilePath("hello.h");
>>     run("-o", helloJar.toString(), helloH.toString()).checkSuccess(); 
>> // create the jar
>>     try(Loader loader = classLoader(helloJar)) {
>>         // ... do tests
>>     } finally { // class loader is closed after try-block
>>         deleteFile(helloJar); // now succeeds to delete jar
>>     }
>> 
>> I've replaced calls to loadClass with calls to Loader::loadClass, also 
>> adding a call to JextractToolRunner::classLoader to the enclosing 
>> try-blocks. I've also made sure jars are being deleted before /after a 
>> test in some places where that was not being done.
>> 
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8216284
>> Webrev: 
>> http://cr.openjdk.java.net/~jvernee/panama/webrevs/8216284/webrev.03/
>> 
>> Thanks,
>> Jorn