Update publisher creation/destruction API documentation. #252
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| * Otherwise, it will proceed despite errors, freeing as many resources as it can, including | ||
| * the publisher handle. Usage of a deallocated publisher handle is undefined behavior. | ||
| * | ||
| * \pre Given node must be the one the publisher was registered with. |
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This makes me wonder, why don't we keep a reference to the node in the publisher?
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I understand what you mean, but I think the scope of that suggestion is a little broader than the goal of this PR.
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Yeap, not planning to address it here. Just wondering why we seemingly introduce a point of failure for no apparent reason.
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I'm not sure, but I think it might encourage the caller to make sure they keep the node around (as you need it to call fini on the publisher, so it's obvious it needs to be kept around), but I don't actually remember the logic behind it. Obviously if they just follow the docs, then this would not be a useful argument.
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Thanks for the insight. We can revisit at a later point in time. I wasn't planning to change it here anyways.
rmw/include/rmw/rmw.h
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| * arguments for now. | ||
| * This function can fail, and therefore return `NULL`, if: | ||
| * - node is not a valid non-null handle for this rmw implementation, | ||
| * as returned by `rmw_create_node()`, or it is associated to a shutdown context |
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Behavior on a shutdown context was not specified. I think this makes sense.
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I'm not sure if it makes sense.
One of the possible paths to fix ros2/rclcpp#1139 is to reduce the side-effects that calling shutdown has, and this will go against that.
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Oof, that's a long winded discussion. Short term, I don't mind as long as behavior is specified.
Skimming through that thread though, this comment seems to suggest this is the current expected behavior, nevermind future changes.
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Skimming through that thread though, this comment seems to suggest this is the current expected behavior, nevermind future changes.
I think that we have settled in that PR that we want to avoid that behavior in the future.
Currently, that behavior is only enforced in rcl in "some parts" of the API (not everywhere, some things continue working after shutdown).
IMO, we should avoid introducing similar checks in rcl, it will make change to happen much more difficult in the future.
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We can settle over there, as I disagree with some of the arguments.
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Sure, but this PR shouldn't be blocked waiting on that decision.
Currently, none of the rmw implementations are checking if shutdown has already been called.
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Fair point. I do want to speed things up.
rmw/include/rmw/rmw.h
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| * arguments for now. | ||
| * This function can fail, and therefore return `NULL`, if: | ||
| * - node is not a valid non-null handle for this rmw implementation, | ||
| * as returned by `rmw_create_node()`, or it is associated to a shutdown context |
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I'm not sure if it makes sense.
One of the possible paths to fix ros2/rclcpp#1139 is to reduce the side-effects that calling shutdown has, and this will go against that.
| * Otherwise, it will proceed despite errors, freeing as many resources as it can, including | ||
| * the publisher handle. Usage of a deallocated publisher handle is undefined behavior. | ||
| * | ||
| * \pre Given node must be the one the publisher was registered with. |
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I understand what you mean, but I think the scope of that suggestion is a little broader than the goal of this PR.
Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>
Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>
Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>
Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>
Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>
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Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>
Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>
Precisely what the title says.