Github user sjcorbett commented on the issue:
https://github.com/apache/brooklyn-server/pull/520
@neykov looks good. I'm going to merge this. Could I ask you to add a
couple of lines describing the new feature to the section on latches in the
docs (https://brooklyn.apache.org/v/latest/yaml/advanced-example.html#latches)?
One final thought for future work is how to improve behaviour when the user
does something they shouldn't do. For example, if someone deployed this
(totally not contrived!) example:
```yaml
services:
- type: org.apache.brooklyn.entity.software.base.VanillaSoftwareProcess
brooklyn.initializers:
- type: org.apache.brooklyn.core.sensor.MaxConcurrencySensor
brooklyn.config:
name: my-latch
latch.concurrency.max: 1
targetType: org.apache.brooklyn.core.sensor.ReleaseableLatch
brooklyn.config:
launch.command: sleep 2
checkRunning.command: true
install.latch: $brooklyn:self().attributeWhenReady("my-latch")
start.latch: $brooklyn:self().attributeWhenReady("my-latch")
stop.latch: $brooklyn:self().attributeWhenReady("my-latch")
```
They'll get an application that is stuck starting forever and that can't be
stopped either. We could consider having a (long) timeout on the `acquire` or
perhaps more interesting would be to have reentrant latches. Some strong
wording in the documentation that this is a bad idea would be sufficient for
the moment.
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