423633 - nsComponentManager/nsGenericModule/nsGenericFactory aren't quite threadsafe

Status: RESOLVED WORKSFORME

(Core :: XPCOM, defect)

Description

[timeless]

Attachment: try to ensure genericmodule/genericfactory are threadsafe

component manager (threadsafe [by contract]) exposes nsIFactories via:
f=Components.manager.getClassObjectByContractID("@mozilla.org/storage/service;1",Components.interfaces.nsIFactory);

the standard nsIFactory is:
nsGenericFactory (threadsafe [by contract])
that comes from:
nsGenericModule (threadsafe [by contract])

unfortunately it's possible to call f.createInstance() from multiple threads and if mConstructor isn't threadsafe (and making it threadsafe seems like an unreasonable burden)

this does make a few changes:
1. you're only allowed to call SetComponentInfo once (currently the code lets you try to call it multiple times, although the results are not threadsafe)
2. you can't recursively use nsGenericFactory::CreateInstance, doing this makes absolutely no sense, and supporting it is expensive.

the locks for nsGenericFactory are only created/used if the component is marked as threadsafe. This should hopefully speed the fast path and save on allocations (although having mBusy+mLock isn't quite free).

the locks for nsGenericModule are always used

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The bug assignee is inactive on Bugzilla, so the assignee is being reset.

Comment 2

[Andrew McCreight [:mccr8]]

nsGenericFactory no longer exists.