Remove CIVICRM_SUPPORT_MULTIPLE_LOCKS and make it always enabled if available

[mattwire]

Overview

This is in use on all my production sites, @eileenmcnaughton uses it and I believe others do as well. Adding the define was just to be really careful in case it could cause any issues - but it's been there a year now and time to go.

Before

You have to enable the CIVICRM_SUPPORT_MULTIPLE_LOCKS define to use multiple locks on modern versions of MySQL/MariaDB.

After

Multiple locks used by default - so less sites fall over when sending mailings.

Technical Details

Comments

@eileenmcnaughton @seamuslee001 per comments on #15588

[civibot]

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[eileenmcnaughton]

Test fail is unrelated. As Matt says we have been successfully using this in production & discussed removing it now that it has been tested. Merging

[mfb]

I have a site using multiple locks on MySQL 5.6 via custom lock subsystem. The supportsMultipleLocks() method is only used by CRM/Core/Lock.php so it's fine if it returns incorrect info, since nothing will be calling it. I guess we could assume no extensions call this method either.

[eileenmcnaughton]

I suspect extensions don't acquire locks very much but that they should do it more. Still it won't affect mysql 5.6 because there is a version compare in there too

[mfb]

I suspect extensions don't acquire locks very much but that they should do it more. Still it won't affect mysql 5.6 because there is a version compare in there too

Not sure what you mean - what I'm saying is my custom lock does support locks on MySQL 5.6 but there's no way to say so. But I don't think this matters, assuming the only code using this method is the built-in lock, which I'm not using. It's just a bit confusing because this code is CRM_Utils_SQL so theoretically some other code could call it.

[eileenmcnaughton]

Well hopefully extensions aren't using CRM_Utils_SQL & are using the api instead. If they access core functions directly all bets are off

[mfb]

ok I thought maybe CRM_Utils_SQL is the api and extensions could call something like CRM_Utils_SQL::supportsFullGroupBy()

[eileenmcnaughton]

Hmm - it's not really intended to be the api although as an extension writer I'd take a risk on calling that function in tested code I would understand it's clearly an 'own-risk' thing to do