Insertions not processed if done at t=0 with world paused

[osrf-migration]

Original report (archived issue) by Deanna Hood (Bitbucket: d_hood).

The original report had attachments: gazebo_7-7_state.log, gazebo_7-8_state.log

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Since gazebo 7.8, log files for ARIAC are not inserting the robot arm correctly.
The insertion of the model is done with a call to spawn_urdf from gazebo_ros, while the world is paused.

@nkoenig suspects the line that only processes insertions if t!=0 from this PR: https://osrf-migration.github.io/gazebo-gh-pages/#!/osrf/gazebo/pull-requests/2715/add-log-record-filter-options/diff#Lgazebo/physics/World.ccT2560 (if (this->dataPtr->logLastStateTime != common::Time::Zero) at time of writing in case that link gets outdated)

I have attached un-compressed log files from both 7.7 and 7.8. <insertions> tag is missing in 7.8.

Moving forward for ARIAC, we are going to pin our gazebo version to 7.7, so a fix is not needed urgently.

[osrf-migration]

Original comment by Louise Poubel (Bitbucket: chapulina, GitHub: chapulina).

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• set component to "util::Logging-Playback"

[osrf-migration]

Original comment by Deanna Hood (Bitbucket: d_hood).

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Reverting https://osrf-migration.github.io/gazebo-gh-pages/#!/osrf/gazebo/pull-requests/2715 fixes the issue. I tried to revert different parts of that PR but I wasn't able to narrow it down any.

https://osrf-migration.github.io/gazebo-gh-pages/#!/osrf/gazebo/issues/2136/gz-log-echo-renders-state-log-unplayable (#2136) is a similar issue (also from ARIAC), where the default filter of gz log --echo stripped the insertion tag from the log file. Since https://osrf-migration.github.io/gazebo-gh-pages/#!/osrf/gazebo/pull-requests/2715 applies the default filter at sim time, it would make sense that it has the same side effect of removing the insertion tag. However, merging https://osrf-migration.github.io/gazebo-gh-pages/#!/osrf/gazebo/pull-requests/2608 didn't seem to fix the issue for me (hopefully I just messed up something in my testing procedure).

Steps to reproduce:

1. roslaunch osrf_gear sample_environment.launch (ARIAC 2017) or roslaunch osrf_gear sample_environment.launch state_logging:=true (ARIAC 2018)
2. move something (anything) around in the simulation so that another logging is triggered, and close the simulation.
3. roslaunch osrf_gear gear_playback.launch will start the previously recorded log file paused (add state_log_path:=<absolute_path> to use a different one).
4. Play the log file, and if it gives [Err] [World.cc:2180] Unable to find model[robot] then it hasn't been fixed.

[osrf-migration]

Original comment by Nate Koenig (Bitbucket: Nathan Koenig).

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This can also be reproduced with stand-alone gazebo by:

1. gazebo -r -u
2. Insert double pendulum
3. Play
4. Quit

The recorded log file will miss the double pendulum insertion.

[osrf-migration]

Original comment by Nate Koenig (Bitbucket: Nathan Koenig).

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Fixed in pull request #2890

[osrf-migration]

Original comment by Nate Koenig (Bitbucket: Nathan Koenig).

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• changed state from "new" to "resolved"

Resolved in pull request #2890