Refactor distributed lock, such that they work with async code

[Spacefish]

• Changed the locks from Monitor to SemaphoreSlim which works in async contexts, where the lock is acquired by one thread and released by another
• Moved the lock handling to the MemoryStorageConnection class to avoid spreading state over multiple types
• Added an Disposable Utillity class to have a quickhand for returning disposables

[perrich]

Thank you, I'll try to check and merge your PR tomorrow.

[perrich]

Thanks, seems to work well (not reproduced the sync issue from #31)

[EvheniyHlushko]

`Hangfire.Storage.DistributedLockTimeoutException
Timeout expired. The timeout elapsed prior to obtaining a distributed lock on the 'lock:recurring-job:Test' resource.
   at Hangfire.MemoryStorage.MemoryStorageConnection.AcquireDistributedLock(String resource, TimeSpan timeout)
   at Hangfire.RecurringJobExtensions.AcquireDistributedRecurringJobLock(IStorageConnection connection, String recurringJobId, TimeSpan timeout)
   at Hangfire.RecurringJobManager.AddOrUpdate(String recurringJobId, Job job, String cronExpression, RecurringJobOptions options)
   at Hangfire.RecurringJobManagerExtensions.AddOrUpdate[T](IRecurringJobManager manager, String recurringJobId, Expression`1 methodCall, String cronExpression, RecurringJobOptions options)
   at Hangfire.RecurringJobManagerExtensions.AddOrUpdate[T](IRecurringJobManager manager, String recurringJobId, Expression`1 methodCall, Func`1 cronExpression, RecurringJobOptions options)`

Looks like after these changes on version 1.8 encountering test failures when run in parallel. Everything works in the previous version, 1.7.0.

[perrich]

Seems that you try to execute same named job in the same time. First is not finished and second request is in timeout.
I don't think it's a bug.

[EvheniyHlushko]

Right. I'm using WebApplicationFactory for tests. In Strartup each instance adds a background job. Probably it's because Data are stored in a static way

[Spacefish]

Right. I'm using WebApplicationFactory for tests. In Strartup each instance adds a background job. Probably it's because Data are stored in a static way

yes it uses static variables to store a lot of internal state.. So no separation between different instances.. I tried to make them independent while fixing this synchronization issue, but it would have introduced too many changes / i wasn´t sure if this breaks something else.. The MemoryStorageConnection class is public after all..

Furthemore Hangfire itself uses static classes / advertises the use of static class methods to submit jobs..

I did it now and created a PR:
#43

[EvheniyHlushko]

Built a package based on your PR, still encountering the same issue.

Furthemore Hangfire itself uses static classes / advertises the use of static class methods to submit jobs..

Most likely it's the case
static JobStorage.Current passed to RecurringJobManager constructor