Breakpoints are not able to move to different sources on update

[connor4312]

See microsoft/vscode-js-debug#277 (comment). Tl;dr is that in a new debug session, the 'same' sources can get assigned different source references. Although we can use extra information in the adapterData of the source to reconcile the breakpoint to the correct place, updating the source referenced in the breakpoints changed event doesn't appear to have an effect.

[isidorn]

I acknowledge this limitation.
Breakpoint currently do not support this, the only update from the session they respect are in this interface. So the fix would be that breakpoints also allow the uri to be updated via the update event (which the DAP supports).
Let me know if this is important for your scenario and I can look into it next milestone potentially.

Code pointer

vscode/src/vs/workbench/contrib/debug/common/debugModel.ts

Line 599 in af69a4f

public uri: uri,

[connor4312]

Not super high priority but I would prefer this to get fixed before js-debug exits preview, so within the next two milestones probably.

[isidorn]

Ok, makes sense. Let's assign to February and try to get it in then.

[connor4312]

Played around with this, where we derive the sourceReference from a hash of the original source data: microsoft/vscode-js-debug#277 (comment)

However it looks like even if the source reference and paths is the same between sessions, VS Code still treats them as separate files. So then it looks like unless the source reference is 0 they're always different, I don't think there's any way to implement this correctly at the moment.

Here's a log of a restarted debug session:

A set breakpoint from first session being restored: 
{"command":"setBreakpoints","arguments":{"source":{"name":"extension.js","path":"/Users/copeet/.vscode-insiders/extensions/samverschueren.final-newline-0.3.2/out/extension.js","sourceReference":257145157},"lines":[23],"breakpoints":[{"line":23}],"sourceModified":false},"type":"request","seq":3}

Load the same source again--everything identical:
{"seq":264,"type":"event","event":"loadedSource","body":{"reason":"new","source":{"name":"extension.js","path":"/Users/copeet/.vscode-insiders/extensions/samverschueren.final-newline-0.3.2/out/extension.js","sourceReference":257145157}}}

Getting the paused stacktrace: 
{"seq":376,"type":"response","request_seq":11,"command":"stackTrace","success":true,"body":{"stackFrames":[{"id":56,"name":"_onWillDocumentSave","line":23,"column":18,"source":{"name":"extension.js","path":"/Users/copeet/.vscode-insiders/extensions/samverschueren.final-newline-0.3.2/out/extension.js","sourceReference":257145157},"presentationHint":"normal"}],"totalFrames":31}}

Then vscode thinks ref 257145157 is a new file from the one I have open in the editor already and requests its contents:
{"command":"source","arguments":{"sourceReference":257145157,"source":{"path":"/Users/copeet/.vscode-insiders/extensions/samverschueren.final-newline-0.3.2/out/extension.js","sourceReference":257145157}},"type":"request","seq":8}

Swapping back to the old source requests it again:
{"command":"source","arguments":{"sourceReference":257145157,"source":{"name":"extension.js","path":"/Users/copeet/.vscode-insiders/extensions/samverschueren.final-newline-0.3.2/out/extension.js","sourceReference":257145157}},"type":"request","seq":19}

[isidorn]

@connor4312 I pushed a potential fix for this. Please try it out and let me know how it goes.
I changed two things:

1. When a source gets opened in the editor ignore the query (which has the source). That way mutiple sessions should open the same file hopefully
2. Breakpoints now allow for hte update event to change their Source

[connor4312]

Works beautifully, thank you!

[isidorn]

Good to know, thanks!

[isidorn]

@connor4312 actually my change to ignore the query when opening the source is BAD. @weinand just found a regression.
I forgot that later on we are reliying on decoding the session id and the reference from the source uri query. Thus we can not do that. So I reverted my commit
Code pointer where we relly on the session id

vscode/src/vs/workbench/contrib/debug/common/debugContentProvider.ts

Line 84 in df59697

session = this.debugService.getModel().getSession(data.sessionId);

So across sessions the sources with sourceRef != 0 will always be different.

[connor4312]

Hm, okay. Well if the breakpoint can still move to a different Source it will still be better than it was--just confusing if the user kept the file from the previous session open in their editor.

[isidorn]

Yeah, breakpoints can still move to a different Source I did not revert that. That part is perfectly fine.