group_by with not completed observable issue

[diorcety]

I found an potential issue with flat_map operation when source the is a scoped observable using a factory holding a shared pointer.
In this case my shared pointer is not released after the last unsubscribe of the observable returned by flat_map.
I didn't succeed to produce a minimal example that trigger this issue, but a quick and dirty hack seems to solve the issue:
if I "reset" the state_type source (which is manly not used):
this->source = source_type();
my smart pointer is released when I unsubscribe.
Maybe this is an issue on my side, but I go many times through my code, I don't see the issue

[kirkshoop]

Hard to say without specific repro, but I would assume that something has stored the flat_map. the source must stay valid while the flat_map observable exists because it has to assume that subscribe might be called again.

[diorcety]

The source is still valid in the initial variable. I will try harder to create minimal example

[diorcety]

Here the issue:
https://gist.github.com/diorcety/4cbded6fd3583ae001ebc9cf1d3e409d

[diorcety]

Commented on_completed:

Hello, World!
Abcd
Value: 0
Value: 20
Unsubscribe
End of World!

Uncommented

Hello, World!
Abcd
Value: 0
Value: 20
~Abcd
Unsubscribe
End of World!

[diorcety]

The issue is certainly in the group_by not the flat_map

[diorcety]

In both case at the unsubscribe, the hook (held by the lambda) should be released. Because there is no link to the observable anymore

[kirkshoop]

this is probably a bug in the lifetime - possibly introduced by (8065a79#diff-9430ecceb5eeb688548de212b7fd57be)

Pure speculation, but it may be similar to the bug in window_toggle fixed here (b41b15f)

I will add this to the backlog - thank you for the report!

as a workaround until this bug is fixed, adding a take_until before the group_by where the trigger parameter was a subject whose on_next was called each time the cancellation was desired should complete the stream cleanly.

[diorcety]

I was on a old version, seems to be solved in the master