[demand] Wrap access to `demand.db` with ACID compliant file handler

[agritheory]

It is likely that multiple workers or processes will want to access demand.db at the same time. Multiple reads should be fine, multiple write should not. Using an ACID compliant file handler like ACID files should be a reasonable solution to this that allows us to avoid a DBMS layer.

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For discussion sake, I think it would be appropriate to mention network-friendly implementations of this idea.

• sqlite can be wrapped such that it is accessible from HTTP
  • sqlite can also be wrapped with the postgres wire protocol but this seems to have been deprecated
  • It would also be possible with the ACID approach to use an NFS mount and share the file between know machines/ Frappe runtimes explicitly.
  • It would NOT be appropriate to expose it to a BI platform like Metabase or Frappe Insights, though it may be possible with limited replication techniques, though this defeats the real time intent of the data

[agritheory]

ACID Files does not seem to be maintained. Let's look at Filelock instead

[MyuddinKhatri]

ACID Files does not seem to be maintained. Let's look at Filelock instead

@agritheory I think we can use this frappe has https://github.com/frappe/frappe/blob/develop/frappe/utils/synchronization.py#L18 this seems like a wrapper around filelock.

[agritheory]

@MyuddinKhatri Perfect, let's use that.