dev/core#1222 Clear static DAO cache when writing to DAO

[colemanw]

Overview

This addresses the problem raised in https://lab.civicrm.org/dev/core/issues/1222

Before

Stale data in cache would persist even after dao items were updated.

After

Static cache cleared whenever updating or deleting a dao object.

[civibot]

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[eileenmcnaughton]

@colemanw this makes sense but I'm not sure about the removals of ->free()

We have done this in most places in the code but we left it in those few places in the DAO where db actions are taken (rather than it being an attempt to clean up memory).

Merging this would remove from delete & setFieldValue but not save. In the case of setFieldValue it still gets called in ->save() but I think we should keep the ->free() call in delete in this PR & consider it separately since I think it needs more thought about whether we might be leaving something cached that we shouldn't

[colemanw]

@eileenmcnaughton ok I've dialed back removals of free() to just the one in getFieldValue

[eileenmcnaughton]

Thanks I think this is good now