Incomplete generation when running two fastddsgen in parallel

[iamsergio]

Given this folder structure:

.
|-- idl1/
|   `-- HelloWorld.idl
|-- idl2/
|   `-- HelloWorld.idl
`-- repro.sh

Where HelloWorld.idl is:

struct HelloWorld
{
    string text;
};

And repro.sh is:

rm -rf generated1 generated2
mkdir generated1 generated2
fastddsgen -d generated1 idl1/HelloWorld.idl &
fastddsgen -d generated2 idl2/HelloWorld.idl
wait

ls -lh generated1/idl1/HelloWorld.hpp
ls -lh generated2/idl2/HelloWorld.hpp

Running the above repro.sh results in an incomplete idl1/HelloWorld.hpp

-rw-r--r-- 1 ubuntu ubuntu 1.6K Oct 23 10:18 generated1/idl1/HelloWorld.hpp
-rw-r--r-- 1 ubuntu ubuntu 4.4K Oct 23 10:18 generated2/idl2/HelloWorld.hpp

I'm guessing fastddsgen saves some temporary state based on the filename and there's a clash.

This is however surprising from a user perspective, as both input and output absolute paths are different.

Having two IDL files with the same name in unrelated applications isn’t unusual, and CMake might call fastddsgen in parallel

[MiguelCompany]

There is an additional argument -t <dir> for the path where temporary files are written.
This is used when calling the preprocessor before the IDLs are actually processed.

If your IDL files don't have preprocessor directives (like #include, #define, etc), you have the alternative of disabling the preprocessor with -ppDisable

[MiKom]

Maybe if user doesn't specify the temp directory, fastddsgen should use one of java.nio.file.Files.createTempDirectory() functions to guarantee a unique temp directory?