1506718 - Console evaluation fails (JSPropertyProvider)

Status: RESOLVED FIXED

(Core Graveyard :: Web Replay, defect, P1)

Description

[Jason Laster [:jlast]]

STR:

1. go to https://firefox-dev.tools/debugger-examples/examples/todomvc/
2. start recording
3. add a breakpoint in todo-view.js#54 
4. pause at 54
5. evaluate this.$el in the console

> Handler function JSPropertyProvider threw an exception: Error: [Exception... "Factory not registered"  nsresult: "0x80040154 (NS_ERROR_FACTORY_NOT_REGISTERED)"  location: "JS frame :: http://localhost:7999/todomvc/js/views/todo-view.js :: render :: line 54"  data: no]
> Stack: ThrowError@resource://devtools/server/actors/replay/debugger.js:783:17
> _sendRequest@resource://devtools/server/actors/replay/debugger.js:93:7
> _sendRequestAllowDiverge@resource://devtools/server/actors/replay/debugger.js:104:12
> _ensureNames@resource://devtools/server/actors/replay/debugger.js:738:21
> names@resource://devtools/server/actors/replay/debugger.js:750:5
> getProperties@resource://devtools/shared/webconsole/js-property-provider.js:708:19
> getMatchedPropsImpl@resource://devtools/shared/webconsole/js-property-provider.js:582:19
> getMatchedPropsInEnvironment@resource://devtools/shared/webconsole/js-property-provider.js:538:10
> JSPropertyProvider@resource://devtools/shared/webconsole/js-property-provider.js:374:16
> exports.makeInfallible/<@resource://devtools/shared/ThreadSafeDevToolsUtils.js:109:14
> autocomplete@resource://devtools/server/actors/webconsole.js:1208:22
> onPacket@resource://devtools/server/main.js:1324:15
> receiveMessage@resource://devtools/shared/transport/child-transport.js:66:5
> enter@resource://devtools/server/actors/utils/event-loop.js:118:5
> _pushThreadPause@resource://devtools/server/actors/thread.js:188:5
> _pauseAndRespond@resource://devtools/server/actors/thread.js:496:7
> pauseAndRespond@resource://devtools/server/actors/thread.js:743:52
> _makeOnStep/<@resource://devtools/server/actors/thread.js:667:16
> setReplayingOnStep/</<@resource://devtools/server/actors/replay/debugger.js:561:17
> Line: 783, column: 17

Comment 1

[Brian Hackett [Laid off!]]

Attachment: patch

This patch fixes the error logged to the console, and allows autocomplete to work when evaluating things in the console.  I haven't seen the problem of the console going blank when doing this evaluation so don't know if that will be fixed.

When getting names in the environment (presumably to populate data for the autocomplete) we would throw an exception that was originally thrown within the Debugger.Env in the replaying process.  This exception is probably happening because we don't load new JS components after diverging from the recording (if we tried then the whole debugger operation would fail).

This patch avoids throwing exceptions entirely when getting environment names by returning a bogus value.  A (maybe better) alternative would be to handle this separately at call sites in the debugger server, but doing things this way is simpler and is consistent with similar handling in other fallible ReplayDebugger operations.

Comment 2

[Logan Smyth [:loganfsmyth]]

Comment on attachment 9026533 [details] [diff] [review]
patch

Review of attachment 9026533 [details] [diff] [review]:
-----------------------------------------------------------------

Seems reasonable.

Would we want to log what the error is to help tracing issues, or would that already be logged elsewhere or not worth it?

Comment 3

[Brian Hackett [Laid off!]]

(In reply to Logan Smyth [:loganfsmyth] from comment #2)
> Comment on attachment 9026533 [details] [diff] [review]
> patch
> 
> Review of attachment 9026533 [details] [diff] [review]:
> -----------------------------------------------------------------
> 
> Seems reasonable.
> 
> Would we want to log what the error is to help tracing issues, or would that
> already be logged elsewhere or not worth it?

There won't be any logging associated with this.  Would it be OK to just dump() a message to stderr, or is there a better way?

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/3578632557aa
Tolerate exceptions being thrown when getting environment names, r=lsmyth.

Comment 5

[Daniel Varga [:dvarga]]

https://hg.mozilla.org/mozilla-central/rev/3578632557aa