Handler save_pre doesn't get called for session recovery save #71506

New Issue

Robert Moats · 2019-11-12T02:54:03+01:00

Robert Moats commented

2019-11-12 02:54:03 +01:00

System Information
Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce GTX 980M/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 389.12

Blender Version
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-07-11 13:50, hash: 06312c6d2d
Worked: (optional)

Short description of error
The Python handler save_pre does not get executed when Blender saves the session recovery file on exit. When add-on's are actively using this handler, they are very likely generating or finalizing data that will be saved along with the file. Skipping over this event while such add-ons are active is likely to cause data loss or strange bugs that will be difficult to track down.

Exact steps for others to reproduce the error
Write a simple script that prints something to the console when save_pre is called, then exit Blender with it active. You can launch Blender from a console window to keep the window open after it exits.

#71506.blend

**System Information** Operating system: Windows-10-10.0.18362 64 Bits Graphics card: GeForce GTX 980M/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 389.12 **Blender Version** Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-07-11 13:50, hash: `06312c6d2d` Worked: (optional) **Short description of error** The Python handler `save_pre` does not get executed when Blender saves the session recovery file on exit. When add-on's are actively using this handler, they are very likely generating or finalizing data that will be saved along with the file. Skipping over this event while such add-ons are active is likely to cause data loss or strange bugs that will be difficult to track down. **Exact steps for others to reproduce the error** Write a simple script that prints something to the console when `save_pre` is called, then exit Blender with it active. You can launch Blender from a console window to keep the window open after it exits. [#71506.blend](https://archive.blender.org/developer/F8059541/T71506.blend)

Robert Moats commented

2019-11-12 02:54:04 +01:00

Added subscriber: @CodeRunner

Philipp Oeser commented

2019-11-13 12:31:40 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2019-11-13 12:31:40 +01:00

Can confirm on first sight, not sure if these should be running in these situations, checking...

Philipp Oeser commented

2019-11-13 13:30:54 +01:00

Added subscribers: @Sergey, @ideasman42

Philipp Oeser commented

2019-11-13 13:30:54 +01:00

@Sergey, @ideasman42 : any drawbacks on calling these in WM_exit_ex as well? (see D6243: Fix #71506: Save Handlers not called for session recovery save)

@Sergey, @ideasman42 : any drawbacks on calling these in `WM_exit_ex` as well? (see [D6243: Fix #71506: Save Handlers not called for session recovery save](https://archive.blender.org/developer/D6243))

Campbell Barton commented

2019-11-13 14:26:27 +01:00

@CodeRunner, what are you using this for? It may help is finding a solution.

This is similar to auto-save which also doesn't run the write callbacks.

It's not obvious that it should since there are actions you may only want to run when the user saves their own data (write other files to disk for e.g.) which you wouldn't want to run on auto-save or exit.

While we could have save_for_recovery, save_for_autosave _pre/post, I'd like to know the purpose of adding additional callbacks.

Setting this as a design task.

@CodeRunner, what are you using this for? It may help is finding a solution. This is similar to auto-save which also doesn't run the write callbacks. It's not obvious that it should since there are actions you may only want to run when the user saves their own data (write other files to disk for e.g.) which you wouldn't want to run on auto-save or exit. While we could have `save_for_recovery`, `save_for_autosave` `_pre/post`, I'd like to know the purpose of adding additional callbacks. ---- Setting this as a design task.

Campbell Barton self-assigned this 2019-11-13 14:27:37 +01:00

Robert Moats commented

2019-11-22 16:08:05 +01:00

I'm personally using the callback to move global property data from the add-on preferences group to scene data, so such data will be saved inside the *.blend file.

That aside, I can't imagine a lot of uses for save_pre that would not involve manipulating part of the scene for some purpose that is intended to be saved with it. I would think save_post would be better suited for other types of actions. However, if it is easy to add new callbacks for the specific purpose of manipulating scene data for a save, I can't think of any reason not to.

I'm personally using the callback to move global property data from the add-on preferences group to scene data, so such data will be saved inside the *.blend file. That aside, I can't imagine a lot of uses for `save_pre` that would not involve manipulating part of the scene for some purpose that is intended to be saved with it. I would think `save_post` would be better suited for other types of actions. However, if it is easy to add new callbacks for the specific purpose of manipulating scene data for a save, I can't think of any reason not to.

Robert Moats commented

2019-11-22 16:22:05 +01:00

There appear to be only a couple built-in add-ons using save_pre (blenderkit and measureit), and they both seem to be using it to clean data. I haven't looked very closely at blenderkit, but measureit appears to be manipulating scene data in the handler. However, I'm not very familiar with it, so I'm not sure how critical it would be to skip over the code during the recovery file save. If it is only cleaning unused data, I'm assuming it would not be very noticeable - just accumulated garbage memory/scene-data.

There appear to be only a couple built-in add-ons using `save_pre` (`blenderkit` and `measureit`), and they both seem to be using it to `clean` data. I haven't looked very closely at `blenderkit`, but `measureit` appears to be manipulating scene data in the handler. However, I'm not very familiar with it, so I'm not sure how critical it would be to skip over the code during the recovery file save. If it is only cleaning unused data, I'm assuming it would not be very noticeable - just accumulated garbage memory/scene-data.

Philipp Oeser removed the

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Handler save_pre doesn't get called for session recovery save #71506