some fixes for the --repeat_latched option

[1r0b1n0]

This should fix some problems with #1850 :
1
The repeat_latched member variable bool was left in an uninitialized/random state.
On my machine, even without specifying "--repeat_latched", it was sometimes activated.

2
When repeating the latched messages in splitted bags, these should still be published as latched.

Steps to reproduce :
Start the following in several terminals :

• roscore
• publish a latched topic : rostopic pub -l /chatter_latched std_msgs/String "data: 'blabla'"
• publish a periodic topic : rostopic pub -r 2 /periodic std_msgs/Empty
• launch a rosbag record : rosrun rosbag record -a --repeat-latched --duration 5 --split

after ~15 seconds stop all the nodes and the rosbag record

without the fix : when playing a splitted bag rosrun rosbag play [...]_1.bag -s 2 : running rostopic echo /chatter_latched will show nothing

with this fix : when playing a splitted bag rosrun rosbag play [...]_1.bag -s 2 : running rostopic echo /chatter_latched will show the message, because it is latched

[tkazik]

Nice catch, thx a lot!
My 2c: I guess I would prefer the initialization to set the repeat_latched to true. As such, every bag is "contained" in itself by default.
Or are there points against that?

ros_comm/tools/rosbag/src/recorder.cpp

Line 100 in 785826e

repeat_latched(false),

[1r0b1n0]

Hi,
I agree in my opinion the better choice would be to enable repeat_latched by default.
In this case the "--repeat-latched" option can be removed/ignored.

[Martin-Oehler]

Can this be merged please? It contains essential fixes.

[romainreignier]

Hi @mjcarroll what do you think about this?
Should we enable repeat-latched by default and remove the argument or keep the choice?
At least, the uninitialized variable issue should be merged, this is a bugfix. Do you want a separate PR?

[mjcarroll]

At least, the uninitialized variable issue should be merged, this is a bugfix. Do you want a separate PR?

Yes please, I have no issues with that part. I'll need a moment to think about the other part.

[1r0b1n0]

I created #2314 that will only fix the undefined variable.

[romainreignier]

This PR has now been updated to only include the connection_header when writing a latched topic to a bag file. This allows to keep the latched info so rosbag play can publish it as latched.