On Fri, Oct 30, 2009 at 3:17 PM, Antoine Labour <[email protected]> wrote:
> On Fri, Oct 30, 2009 at 3:12 PM, Jeremy Orlow <[email protected]> wrote: > >> I've spent a good deal of this week trying to track down what turned out >> to be a simple but fairly common problem: I forgot virtual dispatch only >> partially works in destructors. There have been several email threads about >> this, but it still bites us form time to time, so I thought it was worth >> another reminder. >> >> >> Details: >> I subclassed ChromeThread which subclasses base::Thread. base::Thread >> calls CleanUp on the thread right before termination. CleanUp is virtual. >> Both ChromeThread and my class override CleanUp(). base::Thread calls >> Stop() in its destructor to stop the thread (if it hasn't already been >> stopped). But by the time you hit destruction, the vtable is no longer >> available and thus the destructor of base::Thread (and anything it calls) >> does NOT have access to the vtable of ChromeThread (or my class). So, if >> you don't explicitly call Stop(), your subclass's CleanUp method will NOT be >> called. Thus the thread was going away without my CleanUp method ever being >> called. >> >> Obviously this affects more than just base::Thread. And this is also how >> you can hit errors with pure virtual methods being called. >> >> J >> > > Suggestion: don't call CleanUp in the destructor, but check that someone > did. > I assume you mean Stop()? The problem is when you have a class like ChromeThread inherit from base::Thread and then call Stop() in its destructor and then have someone else subclass ChromeThread and expect its CleanUp to be called. On Fri, Oct 30, 2009 at 3:16 PM, Adam Barth <[email protected]> wrote: > I'm sorry for introducing this pattern in base::Thread. It's bitten > use several times over the course of the project. If you see a better > design, please don't hesitate to fix it. > > Adam Already filed a bug: http://crbug.com/26365 --~--~---------~--~----~------------~-------~--~----~ Chromium Developers mailing list: [email protected] View archives, change email options, or unsubscribe: http://groups.google.com/group/chromium-dev -~----------~----~----~----~------~----~------~--~---
