1598529 - Empty Base Profiler profile makes Gecko Profiler profile JSON ill-formed

Status: RESOLVED FIXED

(Core :: Gecko Profiler, defect, P2)

Description

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

When Gecko Profiler grabs a Base Profiler profile, it assumes that it is empty if the string is totally empty:
https://searchfox.org/mozilla-central/rev/581466eef9269afb03d8a0dba2f50215f3a9026c/tools/profiler/core/platform.cpp#3985
However an empty profile results in a JSON with 1 character -- a newline.

Comment 1

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

... And that caused Gecko Profiler to just blindly "splice" this non-empty looking string into its profile, so the JSON looked like: [ <valid JSON here>, ] -- Notice the missing object after the comma.

Comment 2

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

Attachment: Bug 1598529 - Empty JSON profiles may in fact contain 1 character - r?gregtatum

JSON profiles from the Base Profiler were assumed to be empty if they contained
zero characters, but in fact they contain one character (a single newline).

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1e969b7c2352
Empty JSON profiles may in fact contain 1 character - r=gregtatum

Comment 4

[Narcis Beleuzu [:NarcisB]]

Backed out for causing MinGW bustages on GeckoProfiler.

Backout link: https://hg.mozilla.org/integration/autoland/rev/bf317b52fd44acd12845db1b4dc5d54bb3d08b4a
Log link: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=278302910&repo=autoland&lineNumber=80555

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/6aa8b2b48eb4
Empty JSON profiles may in fact contain 1 character - r=gregtatum

Comment 6

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/6aa8b2b48eb4

Comment 7

[Catalin Sasca, Desktop Test Engineering [:csasca]]

Hi Gerald, is qa needed here? If so, could you provide us with some steps? Thanks!

Comment 8

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

No qa needed, thank you.