Close proposal on membership change

[ethanfrey]

Based on #156 (merge that first)
Addresses #141 (just the simple solution to show hooks, need a second PR to close issue)

• Register callback hooks in all tests
• Implement member changed hook handler
• Test proper handling of simple solution: If an "update group" event comes in while there is an open proposal, force close all open proposals
• Improve implementation efficiency (don't iterate over all proposals ever made to find open proposals)

We just need to optimize the query (add secondary index to proposals map), otherwise this is ready to review

[maurolacy]

lgtm.

[maurolacy]

This is becoming complex, but at the same time, more and more useful.

It just occurred to me that it would be nice for flex multisigs to request the hook directly to their group, on creation. But, now that I think of it, this has security concerns... I wonder if this is related to the "listeners" functionality... it would require something like a "publish & subscribe" contract / functionality.

[ethanfrey]

It just occurred to me that it would be nice for flex multisigs to request the hook directly to their group, on creation. But, now that I think of it, this has security concerns... I wonder if this is related to the "listeners" functionality... it would require something like a "publish & subscribe" contract / functionality.

Yeah, I assume an external administrator to set up all contracts. Most of these steps need admin access anyway and it is hard to write robust init scripts as contracts.

The "listener", light weight pub-sub solution that runs outside of the TX would open up a lot of doors. But that begs a lot of questions. Notably, who pays the gas and where we enforce limits

[maurolacy]

The "listener", light weight pub-sub solution that runs outside of the TX would open up a lot of doors. But that begs a lot of questions. Notably, who pays the gas and where we enforce limits

Yes... besides gas, I can think of timeouts, retries, blacklists, whitelists, evictions / purging, priorities, ...