Re: review request for 7021582, use try-with-resources in jar/zip implementation and tests

[Xueming Shen]

 Kumar,

Would you please help review the change in your pack code?

Thanks,
-Sherman

On 2011-2-23 22:26, Stuart Marks wrote:

Hi Sherman, all,

Here's a webrev to convert code in the jar/zip implementation files and tests to use the new Java 7 try-with-resources construct.

http://cr.openjdk.java.net/~smarks/reviews/7021582/webrev.0/

There are rather a lot of files, however, most of the changes are pretty straightforward. A typical conversion changes code like this:

    FileInputStream fis = new FileInputStream(filename);
    // use fis
    fis.close();

to this:

    try (FileInputStream fis = new FileInputStream(filename)) {
        // use fis
    }

The majority of the conversions are like the above. However, there are a several places where I had to rearrange things either in order to get them to work at all, to improve robustness, or for general cleanup.

Some of these are marked with "TODO". I will of course remove these comments before committing the changes. Where you see these comments, you might want to give the code a bit more scrutiny.

Specific examples of things to look at follow:

* test/java/util/jar/JarEntry/GetMethodsReturnClones.java

I had to change the ordering of local variable declarations so that the variable was visible where it's used. TWR introduces a nested block, so obviously a local declared within will have to be moved outside in order to be used outside. This occurs in several other places as well. In some cases initialization order was changed. This shouldn't matter, though, since it's things like opening a file vs. allocating an array.

* src/share/classes/com/sun/java/util/jar/pack/Driver.java

I narrowed the scope of the open resource. No sense keeping it open any longer than necessary. This occurs in several other places as well.

* src/share/classes/com/sun/java/util/jar/pack/PackageReader.java
* src/share/classes/com/sun/java/util/jar/pack/PackageWriter.java

These changes rely on recent changes to TWR's handling of null resources. Currently, TWR will avoid calling close if the resource is null. Joe checked in this change just last week. Before that, a null resource would generate an unavoidable NPE when it attempted to call close(). Handling of non-null resources is unchanged.

I don't think the change to null handling is in a promoted build yet. Is it OK to check in code that depends on it? All tests pass, but that just means that the path where the resource is null isn't tested.

* src/share/classes/com/sun/java/util/jar/pack/PropMap.java

Narrowed the scope of catch IOException; should be OK since the code that was migrated out cannot throw IOException.

* src/share/classes/com/sun/java/util/jar/pack/UnpackerImpl.java

This closes its input after successful processing. I changed this so that it also closes its input if an exception is thrown.

* test/java/util/zip/LargeZip.java

I've "unrolled" a cascade of constructors into separate resource variables. This also occurs in several other places. Basically code that used to look like this:

    ZipOutputStream zos = new ZipOutputStream(
        new BufferedOutputStream(
            new FileOutputStream(largeFile)));
    // process zos
    zos.close();

is converted to this:

    try (FileOutputStream fos = new FileOutputStream(largeFile);
         BufferedOutputStream bos = new BufferedOutputStream(fos);
         ZipOutputStream zos = new ZipOutputStream(bos))
    {
        // process zos
    }

I think this more robust, since it closes the FileOutputStream if an exception occurs during the construction of one of the stacked streams, which the original code did not handle. Since the wrapper streams will close their underlying streams, this will result in redundant close() calls. However, close() is supposed to be idempotent so this should be OK.

* test/java/util/zip/ZipFile/DeleteTempJar.java

I'm not sure if this properly handles an IOException caused by HttpExchange.close(). Funny, the method isn't declared to throw IOE, but this test did compile and pass.

* test/java/util/zip/ZipFile/LargeZipFile.java

I changed this to fail the test if close() were to throw IOE. I think this is proper for test code.

* test/java/util/zip/ZipFile/ReadZip.java

I took the liberty of converting the file copying code to use the new java.nio.file.Files utilities. Well, I'm really following Alan's lead here since he's prompted me to do so in other places a couple times already. :-)

Thanks for reviewing!

s'marks