feat(Cache): make cache writes more atomic

[rtm-ctrlz]

Running parallel writes to cache may lead to race condition, when .tmp file is already renamed.

I'm getting error during tests via GitLab CI:

• using docker-runners with shared composer cache (by mounting /var/composer/cache)
• 3 parallel jobs (phpstan, phpcs, phpunit)
• each make own composer install
• usually all jobs pass install-phase without errors
• sometimes one of jobs fails to install (see Random failures on CI related to file rename #9568)

May be there is other way:

• to reproduce this race condition (it is necessary?)
• workaround this problem with locks (ex. flock+timeout) - for me using locks is a proper way, but it would be a bit more complicated rather then just using more unique temporary filenames for every file/install.

Closes #9568

[mxr576]

Thanks @rtm-ctrlz for the patch and for confirming that the reported issues exist :)

I compiled a phar from the current state of this PR and testing it in our CI.

composer.phar.txt

[mxr576]

The first build was successful with the code in this PR, but the second failed with this error again. Maybe there is another race condition somewhere or this issue is unrelated?

#9568 (comment)

[mxr576]

Updated my findings in #9568, tl;dr; as of today, it looks to me this PR fixes the random failures caused by race conditions in cache writes.

[rtm-ctrlz]

@stof have a look, please

• temporary files will have .tmp extension
• also catch block will use correct filename

[Seldaek]

Thanks, looks good to me.