mco-gh / gcslock Goto Github PK

I created a “version” of this where locks can expire (much sooner than after one day):
github.com/ncruces/go-gcp/gmutex

Loosely based on “A robust distributed locking algorithm based on Google Cloud Storage”.

please support Go modules by creating this file here and use SemVer for you git tags.

thx

Steps to reproduce:

1. Create a new bucket
2. Try to lock.
3. Expected: acquire lock. Results in "lock request timed out" because of the underlying GCS response error:

"error": {
"errors": [
{
"domain": "global",
"reason": "conditionNotMet",
"message": "Precondition Failed",
"locationType": "header",
"location": "If-Match"
}
],
"code": 412,
"message": "Precondition Failed"
}
}

Consider a program which runs indefinitely:

1. A gcslock.Lock(l, time.Second) fails, for any reason.
2. The underlying locking goroutine will keep running indefinitely, until it succeeds.

[In the meantime, another path of the program may have successfully acquired and released the lock]

3. At last, the goroutine initially started in step 1 succeeds.
4. Inconsistent state. Next gcslock.Lock will never succeed now, until the lock is removed by an external job.