reduce timeout when acquring lock

[skshetry]

Previously, it'd sleep for 5s. Now, it should retry 6 times
before timing out.

Also reduced the timeout to 3s.

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[efiop]

delay is clearly incorrect terminology 🙂 Let's just

Suggested change

	retries = 6
	delay = DEFAULT_TIMEOUT / retries
	lock_retry = retry(retries, LockError, timeout=delay)(self._do_lock)
	lock_retry = retry(RETRIES, LockError, timeout=TIMEOUT)(self._do_lock)

with, e.g.

TIMEOUT = 0.1
RETRIES = 50

and then just patch for tests as needed.

[skshetry]

Why do you think so?
From funcy's documentation:

There will be a delay in timeout seconds between tries

[efiop]

@skshetry Precisely because it is called timeout and not delay. Dividing stuff is not obvious, better to keep explicit TIMEOUT and RETRIES (and not hardcode it).

[skshetry]

Looks like timeout has two different meanings? I was only familiar with one.

[efiop]

@skshetry They are pretty much the same, but you are thinking about the total lock timeout, while I'm talking about this particular piece of code, where timeout is about the time between tries. In the future there might be a total-timeout CLI option, but right now I'm just concerned about this piece of code.

[skshetry]

@efiop, HardlinkLock uses DEFAULT_TIMEOUT as well. I don't want to have two different timeouts, so I'd have to do something like following:

Suggested change

	retries = 6
	delay = DEFAULT_TIMEOUT / retries
	lock_retry = retry(retries, LockError, timeout=delay)(self._do_lock)
	delay = DEFAULT_TIMEOUT / RETRIES
	lock_retry = retry(RETRIES, LockError, timeout=delay)(self._do_lock)

which is no different from this PR. Also, I want to mock as less as possible, and just mocking total timeout is enough for the tests.