This PR was squashed before being merged into the master branch (closes #5381).

Commits
-------

0f3126f Added lockExists to Store interface, fixed locking bugs, added tests.

Discussion
----------

Added lockExists to Store interface, fixed locking bugs, added tests.

While working on Drupal's HttpCache implementation, I discovered that the base HttpCache class does an is_file to check for a lock, which assumes a file-based cache is being used. This seems like a mistake since the rest of the Store interface is easily swappable. I added a lockExists method so that this is properly abstracted.

I also noticed there were no tests for the change I made, so I added some very basic locking tests. While adding those I found that the existing lock method is a bit broken. This line here:

```php
<?php

if (false !== $lock = @fopen($path = $this->getPath($this->getCacheKey($request).'.lck'), 'x')) {
```

will return false if the file couldn't be written for any reason, but the rest of the method assumes that if $lock == false, the lock exists already. So if the file couldnt be written due to the parent directory not existing, $path will be returned as if it exists, which is clearly not the desired behavior.

I changed this to return false if the file couldnt be written and doesn't exist, $path if it exists, and true if the lock was created. It still doesn't feel great to have bool|string return values, but that's the best I could come up with atm. I also added a check for the parent directory that creates it if it doesn't exist. The new tests fail without it.

I also broke out that code a bit as it was very difficult to read.

---------------------------------------------------------------------------

by henrikbjorn at 2012-08-30T09:11:16Z

Symfony have a editorconfig file which set the correct indentation settings. http://editorconfig.org/

---------------------------------------------------------------------------

by msonnabaum at 2012-08-30T13:00:20Z

Updated based on stof's feedback.

---------------------------------------------------------------------------

by msonnabaum at 2012-08-30T13:21:40Z

Fixed based on code style feedback.

---------------------------------------------------------------------------

by jonathaningram at 2012-09-05T12:29:47Z

@msonnabaum, this seems to be distantly related to my recent PR too: #5376.

---------------------------------------------------------------------------

by stof at 2012-10-13T20:35:55Z

@fabpot anything left to merge this ?

---------------------------------------------------------------------------

by catch56 at 2012-10-23T16:42:10Z

This looks great to me, Couldn't find anything to complain about.

This PR was merged into the 2.0 branch.

Commits
-------

a094f7e Add check to Store::unlock to ensure file exists

Discussion
----------

[2.0] [HttpKernel] Add check to Store::unlock to ensure file exists

Bug fix: yes
Feature addition: no
Backwards compatibility break: no
Symfony2 tests pass: yes

I was seeing this error in my logs when using an `AppCache`:

```
Error 2: /var/www/beta.example.com/shared/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/HttpCache/Store.php line 92: unlink(/var/www/beta.example.com/releases/20120827020525/app/cache/beta/http_cache/md/c2/88/66a911b5266a57bdd55131a47895b8861dfd.lck): No such file or directory
```

It was only occurring when the `http_cache` file was being primed (i.e. first load).

I've added a simple check to ensure that the file is a valid file before trying to unlink. I also added a missing `@return` docblock. Note: I've chosen to return `false` if the file does not exist as this seems to be the behaviour of the `purge` method.

---------------------------------------------------------------------------

by jonathaningram at 2012-08-29T06:46:52Z

@henrikbjorn done and rebased. Thanks.

---------------------------------------------------------------------------

by jonathaningram at 2012-09-17T22:38:47Z

@henrikbjorn any news on this one? It's currently not possible to use the HTTP Cache without the first request failing.

---------------------------------------------------------------------------

by jonathaningram at 2012-09-25T01:28:38Z

ping @fabpot sorry to keep pushing this, but any chance you could take a look at this?