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Set promise value after try-catch #1292

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brawner wants to merge 2 commits into from
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Set promise value after try-catch #1292

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eedb3e6
Set promise value after try-catch
brawner Sep 8, 2020
84f383f
Move goal_response_callback earlier
brawner Sep 10, 2020
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18 changes: 10 additions & 8 deletions rclcpp_action/include/rclcpp_action/client.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -370,14 +370,6 @@ class Client : public ClientBase
// Do not use std::make_shared as friendship cannot be forwarded.
std::shared_ptr<GoalHandle> goal_handle(
new GoalHandle(goal_info, options.feedback_callback, options.result_callback));
{
std::lock_guard<std::mutex> guard(goal_handles_mutex_);
goal_handles_[goal_handle->get_goal_id()] = goal_handle;
}
promise->set_value(goal_handle);
if (options.goal_response_callback) {
options.goal_response_callback(future);
}

if (options.result_callback) {
try {
Expand All @@ -387,6 +379,16 @@ class Client : public ClientBase
return;
}
}

{
std::lock_guard<std::mutex> guard(goal_handles_mutex_);
goal_handles_[goal_handle->get_goal_id()] = goal_handle;
}

promise->set_value(goal_handle);
if (options.goal_response_callback) {
options.goal_response_callback(future);

@jacobperron jacobperron Sep 9, 2020

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It was moved in response to #701 (review); if make_result_aware is called first, we risk having the result callback triggered before the goal response callback (unlikely, but I think this is possible if the action server is running in the same process).

@hidmic hidmic Sep 10, 2020 •
edited
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Hmm, reflecting on this, it seems to me that the goal response callback should simply be taking a concrete goal handle instead of a future one. Additionally, failing to make the goal handle result aware should not result in calling code losing access to the goal handle. Getting the future result should throw, but the exception could carry the goal handle (which is still valid) with it.

That's not a fix we can backport though.

@jacobperron jacobperron Sep 10, 2020

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@hidmic I agree with everything you've said. I think it's okay to not backport changes (though maybe we could by supporting two different signatures for the goal response callback).

@brawner brawner Sep 11, 2020

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Adjusted the goal_response_callback signature, but I'm still not decided about what to do exception and goal handle bit.

@jacobperron jacobperron Sep 11, 2020

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I think we can remove the try-catch altogether. I'll open a PR in a moment with a proposed alternative.

@jacobperron jacobperron Sep 11, 2020

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See #1311.

}
});

// TODO(jacobperron): Encapsulate into it's own function and
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