[5.2] Add shared locks to Filesystem and Cache/FileStore

[deadem]

Have a problem with Cache/FileStore on a production server. It periodically fails with unserialize error:

exception 'ErrorException' with message 'unserialize(): Error at offset 282612 of 282614 bytes' in /home/user/xxx/vendor/laravel/framework/src/Illuminate/Cache/FileStore.php:80
Stack trace:
#0 [internal function]: Illuminate\Foundation\Bootstrap\HandleExceptions->handleError(8, 'unserialize(): ...', '/home/user/xxx...', 80, Array)
#1 /home/user/xxx/vendor/laravel/framework/src/Illuminate/Cache/FileStore.php(80): unserialize('O:39:"Illuminat...')
#2 /home/user/xxx/vendor/laravel/framework/src/Illuminate/Cache/FileStore.php(49): Illuminate\Cache\FileStore->getPayload('todayEvents')
#3 /home/user/xxx/vendor/laravel/framework/src/Illuminate/Cache/Repository.php(129): Illuminate\Cache\FileStore->get('todayEvents')
#4 /home/user/xxx/vendor/laravel/framework/src/Illuminate/Cache/Repository.php(288): Illuminate\Cache\Repository->get('todayEvents')
#5 [internal function]: Illuminate\Cache\Repository->remember('todayEvents', 1, Object(Closure))
#6 /home/user/xxx/vendor/laravel/framework/src/Illuminate/Cache/CacheManager.php(296): call_user_func_array(Array, Array)
#7 /home/user/xxx/bootstrap/cache/compiled.php(6222): Illuminate\Cache\CacheManager->__call('remember', Array)
#8 /home/user/xxx/bootstrap/cache/compiled.php(6222): Illuminate\Cache\CacheManager->remember('todayEvents', 1, Object(Closure))
#9 /home/user/xxx/app/Http/Controllers/Controller.php(101): Illuminate\Support\Facades\Facade::__callStatic('remember', Array)
#10 /home/user/xxx/app/Http/Controllers/Controller.php(101): Illuminate\Support\Facades\Cache::remember('todayEvents', 1, Object(Closure))

Cache/FileStore read file from cache when another instance of php script write same file into cache. I've added some locks to read/write from cache.

[GrahamCampbell]

this should be wrapped in a try finally to make sure this gets closed

[deadem]

@GrahamCampbell There is a bug in hhvm 3.6.6. file_put_constnts(..., LOCK_EX) truncates file immediately and then set the lock. facebook/hhvm#5657

Should I replace Filesystem::put with custom code or skip this test on hhvm versions before HHVM-3.10.0?

[GrahamCampbell]

Just skip HHVM.