Drop unnecessary mutex lock in .event_mgr()

[roncapat]

Description

Closes #991

Is this user-facing behavior change?

Did you use Generative AI?

No

Additional Information

There are two occurrences of such pattern, where an internal shared_ptr<EventsManager> gets copied and returned to the caller. That smart pointer is initialized once in constructor and never re-assigned to point to a different instance. Hence, protecting its copy with the mutex is unnecessary.

[roncapat]

@Yadunund I did a quick search across the repo for trivial cases like this one, and I believe there is another one:

https://github.com/roncapat/rmw_zenoh/blob/cfd6a62215734310656913f312ad6ca96677cf4c/rmw_zenoh_cpp/src/detail/rmw_subscription_data.cpp#L1187-L1191

could you check also this one?

[Yadunund]

@roncapat thanks for catching that too. We can safely get rid of it as GraphCache has a couple different mutexes protecting members

[roncapat]

Is this one already ok or is there any pending action needed from myself? :)

[mergify]

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[jmachowinski]

Pulls: #996
Gist: https://gist.githubusercontent.com/jmachowinski/08a05ed51ffc2ce61ab4d9c4a27af1e5/raw/b8abc708ea87345706e03eb41dfe43ad14d613e0/ros2.repos
BUILD args: --cmake-args -DRMW_IMPLEMENTATION=rmw_zenoh_cpp
TEST args:
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/19782

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[jmachowinski]

Pulls: #996
Gist: https://gist.githubusercontent.com/jmachowinski/885d6de201c4228e4a5d5808071873b6/raw/b8abc708ea87345706e03eb41dfe43ad14d613e0/ros2.repos
BUILD args: --cmake-args -DRMW_IMPLEMENTATION=rmw_zenoh_cpp
TEST args:
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/19813

• Linux
• Linux-aarch64
• Linux-rhel
• Windows