* Re: System calls without error checks in w32 @ 2010-05-31 9:18 grischka 2010-06-05 17:15 ` Jason Rumney 0 siblings, 1 reply; 33+ messages in thread From: grischka @ 2010-05-31 9:18 UTC (permalink / raw To: lennart.borgman; +Cc: emacs-devel > ... For example I know Drew recently wrote about problems when > creating new frames. It is quite hard to both understand what is > happening and what is a bug and what is not. Is there just a bad > timing? A missing hook to proceed the function etc (you may have to > wait until the frame creation is finished)? Typically such problems have to do with the two-thread approach in the "w32" code, which again has to do with emacs unfortunate event system (aka. command_loop) which is not really compatible with GUI backends (w32, gtk). Basically: Replace the command_loop by callbacks, then get rid of the w32-GUI-thread, then watch how the problems disappeared. Magically ;-) --- grischka ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-31 9:18 System calls without error checks in w32 grischka @ 2010-06-05 17:15 ` Jason Rumney 2010-06-07 10:37 ` grischka 0 siblings, 1 reply; 33+ messages in thread From: Jason Rumney @ 2010-06-05 17:15 UTC (permalink / raw To: grischka; +Cc: lennart.borgman, emacs-devel grischka <grishka@gmx.de> writes: > Basically: Replace the command_loop by callbacks, then get rid of the > w32-GUI-thread, then watch how the problems disappeared. Magically ;-) Some problems may disappear, but they will be replaced by many more serious problems; like windows that can't be moved while Lisp code is busy running. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-06-05 17:15 ` Jason Rumney @ 2010-06-07 10:37 ` grischka 2010-06-07 14:54 ` Stephen J. Turnbull 0 siblings, 1 reply; 33+ messages in thread From: grischka @ 2010-06-07 10:37 UTC (permalink / raw To: Jason Rumney; +Cc: lennart.borgman, emacs-devel Jason Rumney wrote: > grischka <grishka@gmx.de> writes: > >> Basically: Replace the command_loop by callbacks, then get rid of the >> w32-GUI-thread, then watch how the problems disappeared. Magically ;-) > > Some problems may disappear, but they will be replaced by many more > serious problems; like windows that can't be moved while Lisp code is > busy running. XEmacs uses the same thread for lisp and gui and doesn't have any such problem. --- grischka ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-06-07 10:37 ` grischka @ 2010-06-07 14:54 ` Stephen J. Turnbull 2010-06-07 15:23 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: Stephen J. Turnbull @ 2010-06-07 14:54 UTC (permalink / raw To: grischka; +Cc: emacs-devel, lennart.borgman, Jason Rumney grischka writes: > XEmacs uses the same thread for lisp and gui and doesn't have any > such problem. XEmacs has such a hairy event loop that it is no longer supported by X.org. You may not want to go there. http://bugs.freedesktop.org/show_bug.cgi?id=13471 https://trac.macports.org/ticket/18491 http://bugs.freedesktop.org/show_bug.cgi?id=20048 ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-06-07 14:54 ` Stephen J. Turnbull @ 2010-06-07 15:23 ` Lennart Borgman 2010-06-07 17:21 ` grischka 2010-06-07 19:56 ` Stefan Monnier 0 siblings, 2 replies; 33+ messages in thread From: Lennart Borgman @ 2010-06-07 15:23 UTC (permalink / raw To: Stephen J. Turnbull; +Cc: grischka, emacs-devel, Jason Rumney On Mon, Jun 7, 2010 at 4:54 PM, Stephen J. Turnbull <stephen@xemacs.org> wrote: > grischka writes: > > > XEmacs uses the same thread for lisp and gui and doesn't have any > > such problem. > > XEmacs has such a hairy event loop that it is no longer supported by > X.org. You may not want to go there. > > http://bugs.freedesktop.org/show_bug.cgi?id=13471 > https://trac.macports.org/ticket/18491 > http://bugs.freedesktop.org/show_bug.cgi?id=20048 ;-) I guess the idea of having two event loops/thread is not in itself bad. If the gui thread is never blocked it can be used to convey status information at least to the user. (You can put these in temporary windows inside the frame for example.) But sometimes I wonder wheter all windows really runs in the gui threads. And why does not C-g break all looping, even those in timers (like fontification)? And is it the same trouble on other platfoms or is it just the w32 port that has this? And moreover I wonder wether all messages really reach their destinations or if something is blocking them in certain situations. (Again, why is not C-g handled in the case above?) And what is blocking Emacs during the time when a new frame is created? Why is not that done asynchronously? ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-06-07 15:23 ` Lennart Borgman @ 2010-06-07 17:21 ` grischka 2010-06-07 17:30 ` Lennart Borgman 2010-06-07 19:56 ` Stefan Monnier 1 sibling, 1 reply; 33+ messages in thread From: grischka @ 2010-06-07 17:21 UTC (permalink / raw To: Lennart Borgman; +Cc: Stephen J. Turnbull, emacs-devel, Jason Rumney Lennart Borgman wrote: > I guess the idea of having two event loops/thread is not in itself > bad. If the gui thread is never blocked it can be used to convey > status information at least to the user. (You can put these in > temporary windows inside the frame for example.) Since this is Emacs you'd probably want to format your status info in Lisp. Bye nice idea and welcome to thread hell. > But sometimes I wonder wheter all windows really runs in the gui > threads. And why does not C-g break all looping, even those in timers > (like fontification)? And is it the same trouble on other platfoms or > is it just the w32 port that has this? > > And moreover I wonder wether all messages really reach their > destinations or if something is blocking them in certain situations. > (Again, why is not C-g handled in the case above?) > > And what is blocking Emacs during the time when a new frame is > created? Why is not that done asynchronously? > I guess there are some people wondering sometimes about something. Thread bugs typically show up sometimes. And typically you'll find nobody who wants to look at them. --- grischka ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-06-07 17:21 ` grischka @ 2010-06-07 17:30 ` Lennart Borgman 2010-06-07 18:54 ` grischka 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-06-07 17:30 UTC (permalink / raw To: grischka; +Cc: Stephen J. Turnbull, emacs-devel, Jason Rumney On Mon, Jun 7, 2010 at 7:21 PM, grischka <grishka@gmx.de> wrote: > Lennart Borgman wrote: >> >> I guess the idea of having two event loops/thread is not in itself >> bad. If the gui thread is never blocked it can be used to convey >> status information at least to the user. (You can put these in >> temporary windows inside the frame for example.) > > Since this is Emacs you'd probably want to format your status info > in Lisp. Bye nice idea and welcome to thread hell. I see no reason to format it in Lisp. Or rather my idea is that the status information is formated by the lisp thread in advance and sent to the gui thread in a non-lisp format. Then the gui thread can offer that information without contactinog the lisp thread. Displaying that information is just a matter of formatting a native w32 window with it. Similar things can of course be done on other platforms, but this part of the code is necessary platform specif (at least in the core parts of it). > I guess there are some people wondering sometimes about something. > Thread bugs typically show up sometimes. And typically you'll find > nobody who wants to look at them. Looking at this kind of bugs is hard and requires that you have a good enough picture of the message queue system. And just guessing what to look at is difficult. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-06-07 17:30 ` Lennart Borgman @ 2010-06-07 18:54 ` grischka 2010-06-08 0:32 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: grischka @ 2010-06-07 18:54 UTC (permalink / raw To: Lennart Borgman; +Cc: Stephen J. Turnbull, emacs-devel, Jason Rumney Lennart Borgman wrote: > On Mon, Jun 7, 2010 at 7:21 PM, grischka <grishka@gmx.de> wrote: >> Lennart Borgman wrote: >>> I guess the idea of having two event loops/thread is not in itself >>> bad. If the gui thread is never blocked it can be used to convey >>> status information at least to the user. (You can put these in >>> temporary windows inside the frame for example.) > >> Since this is Emacs you'd probably want to format your status info >> in Lisp. Bye nice idea and welcome to thread hell. > > I see no reason to format it in Lisp. Or rather my idea is that the > status information is formated by the lisp thread in advance and sent > to the gui thread in a non-lisp format. Then the gui thread can offer > that information without contactinog the lisp thread. But then what is the benefit from that additional effort of preparing and sending a "non-lisp" representation forth and back, except to satisfy the requirements of having two threads? Have only one thread and you can format and display the info in one go. Simple, reliable, conclusive. --- grischka ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-06-07 18:54 ` grischka @ 2010-06-08 0:32 ` Lennart Borgman 2010-06-08 0:34 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-06-08 0:32 UTC (permalink / raw To: grischka; +Cc: Stephen J. Turnbull, emacs-devel, Jason Rumney On Mon, Jun 7, 2010 at 8:54 PM, grischka <grishka@gmx.de> wrote: > Lennart Borgman wrote: >> >> On Mon, Jun 7, 2010 at 7:21 PM, grischka <grishka@gmx.de> wrote: >>> >>> Lennart Borgman wrote: >>>> >>>> I guess the idea of having two event loops/thread is not in itself >>>> bad. If the gui thread is never blocked it can be used to convey >>>> status information at least to the user. (You can put these in >>>> temporary windows inside the frame for example.) >> >>> Since this is Emacs you'd probably want to format your status info >>> in Lisp. Bye nice idea and welcome to thread hell. >> >> I see no reason to format it in Lisp. Or rather my idea is that the >> status information is formated by the lisp thread in advance and sent >> to the gui thread in a non-lisp format. Then the gui thread can offer >> that information without contactinog the lisp thread. > > But then what is the benefit from that additional effort of preparing > and sending a "non-lisp" representation forth and back, except to satisfy > the requirements of having two threads? Have only one thread and you > can format and display the info in one go. Simple, reliable, conclusive. I suppose the rational for having two threads is that basic gui operations should not be stalled by lisp computations. I do not know how it is actually implemented now in Emacs but with two threads you can post messages between them to coordinate them without interrupting the gui handling badly. Here is an example: - the user resize the frame during a lisp computation. The resizing happens then entirely in the gui thread. - When resizing is finished the gui thread can send a message telling that to the lisp queue. - The lisp queue can then handle this when it has time to do that and ask the system for the new frame size. - The gui thread can also send resizing messages during resizing which the lisp thread can safely ignore if it is occupied since the information is available later. The gui thread can send a message to the lisp thread when resizing is finished and tell that resizing has been done. The ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-06-08 0:32 ` Lennart Borgman @ 2010-06-08 0:34 ` Lennart Borgman 0 siblings, 0 replies; 33+ messages in thread From: Lennart Borgman @ 2010-06-08 0:34 UTC (permalink / raw To: grischka; +Cc: Stephen J. Turnbull, emacs-devel, Jason Rumney > - The gui thread can also send resizing messages during resizing which > the lisp thread can safely ignore if it is occupied since the > information is available later. > The gui thread can send a message to the lisp thread when resizing is > finished and tell that resizing has been done. The A shit, this is how firefox sometimes handle input when GDI resources are exhausted. You have to guess the end part of the message for now ... ;-) ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-06-07 15:23 ` Lennart Borgman 2010-06-07 17:21 ` grischka @ 2010-06-07 19:56 ` Stefan Monnier 2010-06-07 23:35 ` Lennart Borgman 1 sibling, 1 reply; 33+ messages in thread From: Stefan Monnier @ 2010-06-07 19:56 UTC (permalink / raw To: Lennart Borgman; +Cc: Stephen J. Turnbull, Jason Rumney, grischka, emacs-devel > threads. And why does not C-g break all looping, even those in timers > (like fontification)? That is simply because timer code is normally run in a way that's completely hidden from the user, so if the user happens to hit C-g while a timer is running, it's probably not because he wants to interrupt the timer, but rather because he wants to interrupt the thing he's currently doing. Timers (and fontification, post-command-hook, ...) should run quickly, or otherwise re-enable interrupts using with-local-quit. Stefan ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-06-07 19:56 ` Stefan Monnier @ 2010-06-07 23:35 ` Lennart Borgman 0 siblings, 0 replies; 33+ messages in thread From: Lennart Borgman @ 2010-06-07 23:35 UTC (permalink / raw To: Stefan Monnier; +Cc: Stephen J. Turnbull, Jason Rumney, grischka, emacs-devel On Mon, Jun 7, 2010 at 9:56 PM, Stefan Monnier <monnier@iro.umontreal.ca> wrote: >> threads. And why does not C-g break all looping, even those in timers >> (like fontification)? > > That is simply because timer code is normally run in a way that's > completely hidden from the user, so if the user happens to hit C-g while > a timer is running, it's probably not because he wants to interrupt the > timer, but rather because he wants to interrupt the thing he's > currently doing. Hm, I always hit C-g to interrupt something that Emacs is doing... ;-) How about some convention: Three C-g within three seconds will stop running timers too? > Timers (and fontification, post-command-hook, ...) should run quickly, > or otherwise re-enable interrupts using with-local-quit. Thanks, I see, that is an idea. I had forgotten about it. ^ permalink raw reply [flat|nested] 33+ messages in thread
* System calls without error checks in w32 @ 2010-05-29 2:38 Lennart Borgman 2010-05-29 17:43 ` Eli Zaretskii 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-05-29 2:38 UTC (permalink / raw To: Emacs-Devel devel There is a lot of system calls in the w32 without error checking. This makes things harder than they should be. How about adding something like DebPrint (("error w32_creatwindow.AjdustRectangle => %d\n", GetLastError ())); to all of them? Is there anyone who has anything against this? ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-29 2:38 Lennart Borgman @ 2010-05-29 17:43 ` Eli Zaretskii 2010-05-29 18:42 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: Eli Zaretskii @ 2010-05-29 17:43 UTC (permalink / raw To: Lennart Borgman; +Cc: emacs-devel > From: Lennart Borgman <lennart.borgman@gmail.com> > Date: Sat, 29 May 2010 04:38:24 +0200 > > There is a lot of system calls in the w32 without error checking. ??? "A lot"? Please give examples of those. > How about adding something like > > DebPrint (("error w32_creatwindow.AjdustRectangle => %d\n", > GetLastError ())); > > to all of them? Is there anyone who has anything against this? What for? ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-29 17:43 ` Eli Zaretskii @ 2010-05-29 18:42 ` Lennart Borgman 2010-05-29 19:35 ` Eli Zaretskii 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-05-29 18:42 UTC (permalink / raw To: Eli Zaretskii; +Cc: emacs-devel On Sat, May 29, 2010 at 7:43 PM, Eli Zaretskii <eliz@gnu.org> wrote: >> From: Lennart Borgman <lennart.borgman@gmail.com> >> Date: Sat, 29 May 2010 04:38:24 +0200 >> >> There is a lot of system calls in the w32 without error checking. > > ??? "A lot"? Please give examples of those. There is a lot of them in w32fns.c. I expect the same for other files with w32 system calls. Here are some I found: CreateFontIndirect DestroyCaret ExtTextOut GetForeGroundWindow GetKeyboardState GetKeyboardState GetModuleHandle GetProcAddress GetTextExtentPoint32 GetWindowPlacement GetWindowRect KillTimer LocalFree PostMessage PostThreadMessage RegisterHotKey ReleaseCapture SelectObject SetWindowLong A few of them does not return errors, but return value may have to be checked anyway. I probably missed some (and did I add the GetWindowPlacement code?). >> How about adding something like >> >> DebPrint (("error w32_creatwindow.AjdustRectangle => %d\n", >> GetLastError ())); >> >> to all of them? Is there anyone who has anything against this? > > What for? I have for several years complained about frequent crashes. They are quite irritating actually. I have to reboot quite often too, maybe because of errors in the system calls (some resource is leaking). Menus often stops working. Difficult to track down, and even more so without knowing if some bad system calls where involved. Emacs can totally hang. Or it can loop without yeilding. At least the first one can be a bad system call. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-29 18:42 ` Lennart Borgman @ 2010-05-29 19:35 ` Eli Zaretskii 2010-05-29 20:02 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: Eli Zaretskii @ 2010-05-29 19:35 UTC (permalink / raw To: Lennart Borgman; +Cc: emacs-devel > From: Lennart Borgman <lennart.borgman@gmail.com> > Date: Sat, 29 May 2010 20:42:40 +0200 > Cc: emacs-devel@gnu.org > > CreateFontIndirect > DestroyCaret > ExtTextOut > GetForeGroundWindow > GetKeyboardState > GetKeyboardState > GetModuleHandle > GetProcAddress > GetTextExtentPoint32 > GetWindowPlacement > GetWindowRect > KillTimer > LocalFree > PostMessage > PostThreadMessage > RegisterHotKey > ReleaseCapture > SelectObject > SetWindowLong > > A few of them does not return errors, but return value may have to be > checked anyway. If you can suggest what to do when any of these fails, please do. > >> DebPrint (("error w32_creatwindow.AjdustRectangle => %d\n", > >> GetLastError ())); > >> > >> to all of them? Is there anyone who has anything against this? > > > > What for? > > > I have for several years complained about frequent crashes. They are > quite irritating actually. > > I have to reboot quite often too, maybe because of errors in the > system calls (some resource is leaking). > > Menus often stops working. Difficult to track down, and even more so > without knowing if some bad system calls where involved. > > Emacs can totally hang. Or it can loop without yeilding. At least the > first one can be a bad system call. I don't see how any of these problems could be solved by using DebPrint. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-29 19:35 ` Eli Zaretskii @ 2010-05-29 20:02 ` Lennart Borgman 2010-05-29 21:25 ` Eli Zaretskii 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-05-29 20:02 UTC (permalink / raw To: Eli Zaretskii; +Cc: emacs-devel On Sat, May 29, 2010 at 9:35 PM, Eli Zaretskii <eliz@gnu.org> wrote: >> From: Lennart Borgman <lennart.borgman@gmail.com> >> Date: Sat, 29 May 2010 20:42:40 +0200 >> Cc: emacs-devel@gnu.org >> >> CreateFontIndirect >> DestroyCaret >> ExtTextOut >> GetForeGroundWindow >> GetKeyboardState >> GetKeyboardState >> GetModuleHandle >> GetProcAddress >> GetTextExtentPoint32 >> GetWindowPlacement >> GetWindowRect >> KillTimer >> LocalFree >> PostMessage >> PostThreadMessage >> RegisterHotKey >> ReleaseCapture >> SelectObject >> SetWindowLong >> >> A few of them does not return errors, but return value may have to be >> checked anyway. I looked a bit more. There are many more that could be checked, but are not checked now. > If you can suggest what to do when any of these fails, please do. I have already made the suggestion below. I do not mean adding it everywhere where checks are missing, that would be a lot of job in the current state of the code. However adding this kind of output when hunting for a problem could be very helpful. >> >> DebPrint (("error w32_creatwindow.AjdustRectangle => %d\n", >> >> GetLastError ())); >> >> >> >> to all of them? Is there anyone who has anything against this? >> > >> > What for? >> >> >> I have for several years complained about frequent crashes. They are >> quite irritating actually. >> >> I have to reboot quite often too, maybe because of errors in the >> system calls (some resource is leaking). >> >> Menus often stops working. Difficult to track down, and even more so >> without knowing if some bad system calls where involved. >> >> Emacs can totally hang. Or it can loop without yeilding. At least the >> first one can be a bad system call. > > I don't see how any of these problems could be solved by using > DebPrint. Why not? The latest crash fixes I sent in was about missing checks. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-29 20:02 ` Lennart Borgman @ 2010-05-29 21:25 ` Eli Zaretskii 2010-05-29 21:30 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: Eli Zaretskii @ 2010-05-29 21:25 UTC (permalink / raw To: Lennart Borgman; +Cc: emacs-devel > From: Lennart Borgman <lennart.borgman@gmail.com> > Date: Sat, 29 May 2010 22:02:24 +0200 > Cc: emacs-devel@gnu.org > > > If you can suggest what to do when any of these fails, please do. > > > I have already made the suggestion below. How in the world outputting an error message would help here? ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-29 21:25 ` Eli Zaretskii @ 2010-05-29 21:30 ` Lennart Borgman 2010-05-30 3:02 ` Eli Zaretskii 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-05-29 21:30 UTC (permalink / raw To: Eli Zaretskii; +Cc: emacs-devel On Sat, May 29, 2010 at 11:25 PM, Eli Zaretskii <eliz@gnu.org> wrote: >> From: Lennart Borgman <lennart.borgman@gmail.com> >> Date: Sat, 29 May 2010 22:02:24 +0200 >> Cc: emacs-devel@gnu.org >> >> > If you can suggest what to do when any of these fails, please do. >> >> >> I have already made the suggestion below. > > How in the world outputting an error message would help here? You mean instead of fixing the error directly? It is just a first step of course. The error message might also be interesting in itself. It can for example tell about resources lack etc. The API descriptions does not always tell the whole story. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-29 21:30 ` Lennart Borgman @ 2010-05-30 3:02 ` Eli Zaretskii 2010-05-30 3:26 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: Eli Zaretskii @ 2010-05-30 3:02 UTC (permalink / raw To: Lennart Borgman; +Cc: emacs-devel > From: Lennart Borgman <lennart.borgman@gmail.com> > Date: Sat, 29 May 2010 23:30:21 +0200 > Cc: emacs-devel@gnu.org > > On Sat, May 29, 2010 at 11:25 PM, Eli Zaretskii <eliz@gnu.org> wrote: > >> From: Lennart Borgman <lennart.borgman@gmail.com> > >> Date: Sat, 29 May 2010 22:02:24 +0200 > >> Cc: emacs-devel@gnu.org > >> > >> > If you can suggest what to do when any of these fails, please do. > >> > >> > >> I have already made the suggestion below. > > > > How in the world outputting an error message would help here? > > You mean instead of fixing the error directly? It is just a first step > of course. > > The error message might also be interesting in itself. It can for > example tell about resources lack etc. The API descriptions does not > always tell the whole story. Checking values returned by system calls is necessary to avoid working with invalid objects returned by a failed system call. I thought you were talking about this. But it turns out you are talking about something else altogether: how to debug possible failures in some APIs. That is a different story and it requires different solutions. Please take a look at xdisp.c and friends, which have special debugging code inside #ifdef GLYPH_DEBUG. In any case, the solution you suggest is not a good one, because it obfuscates the source code and makes it harder to read and understand. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-30 3:02 ` Eli Zaretskii @ 2010-05-30 3:26 ` Lennart Borgman 2010-05-30 17:36 ` Eli Zaretskii 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-05-30 3:26 UTC (permalink / raw To: Eli Zaretskii; +Cc: emacs-devel On Sun, May 30, 2010 at 5:02 AM, Eli Zaretskii <eliz@gnu.org> wrote: > > In any case, the solution you suggest is not a good one, because it > obfuscates the source code and makes it harder to read and understand. Are you saying that checking the return values of system calls should be avoided because it makes the code to difficult to read? I can't imagine you mean that. What do you mean? Exactly what in my suggestion makes the code to hard to read? How can the check be made more readable? (I can't see how GLYPH_DEBUG style handling of it applies here.) Remember that what I suggest is basically if (bad_return_value) DebPrint (("error this_function.ApiFunction => %d", bad_return_value)); It can be visually more appealing with a macro, something like W32DEBPRINT (this_function, ApiFunction, bad_return_value, 0); Is that what you mean? This is of course what I meant, but my C fu is low, and so my C language. So we might misunderstand each other. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-30 3:26 ` Lennart Borgman @ 2010-05-30 17:36 ` Eli Zaretskii 2010-05-30 18:02 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: Eli Zaretskii @ 2010-05-30 17:36 UTC (permalink / raw To: Lennart Borgman; +Cc: emacs-devel > From: Lennart Borgman <lennart.borgman@gmail.com> > Date: Sun, 30 May 2010 05:26:32 +0200 > Cc: emacs-devel@gnu.org > > On Sun, May 30, 2010 at 5:02 AM, Eli Zaretskii <eliz@gnu.org> wrote: > > > > In any case, the solution you suggest is not a good one, because it > > obfuscates the source code and makes it harder to read and understand. > > > Are you saying that checking the return values of system calls should > be avoided because it makes the code to difficult to read? No. > Remember that what I suggest is basically > > if (bad_return_value) DebPrint (("error this_function.ApiFunction > => %d", bad_return_value)); What purpose does this serve? This isn't "checking return values for errors", because this has no effect for the majority of users who don't run Emacs under a debugger. Their Emacs will still crash if it hits bad_return_value. I thought you were arguing for making the Emacs code more robust in the face of possible failures of the APIs it calls. If you want more debugging aids, I don't object, but then I have no interest in such additions, either. Typically, such additions are only good as long as you debug some specific problem, so keeping them in the code after that is waste of bytes. > W32DEBPRINT (this_function, ApiFunction, bad_return_value, 0); This is even worse, because it's impossible to understand what this does without looking up the magical W32DEBPRINT macro. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-30 17:36 ` Eli Zaretskii @ 2010-05-30 18:02 ` Lennart Borgman 2010-05-30 19:24 ` Juanma Barranquero 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-05-30 18:02 UTC (permalink / raw To: Eli Zaretskii; +Cc: emacs-devel On Sun, May 30, 2010 at 7:36 PM, Eli Zaretskii <eliz@gnu.org> wrote: >> >> On Sun, May 30, 2010 at 5:02 AM, Eli Zaretskii <eliz@gnu.org> wrote: >> > >> > In any case, the solution you suggest is not a good one, because it >> > obfuscates the source code and makes it harder to read and understand. >> >> >> Are you saying that checking the return values of system calls should >> be avoided because it makes the code to difficult to read? > > No. Fine. >> Remember that what I suggest is basically >> >> if (bad_return_value) DebPrint (("error this_function.ApiFunction >> => %d", bad_return_value)); > > What purpose does this serve? This isn't "checking return values for > errors", because this has no effect for the majority of users who > don't run Emacs under a debugger. The debugger of course does not have an effect on those users. But what do you want to say? My intention is to get a chance to know why a system call failed. That is a way to find those errors that are a bit harder to find than those you may see directly by inspecting the code. > Their Emacs will still crash if it > hits bad_return_value. I thought you were arguing for making the > Emacs code more robust in the face of possible failures of the APIs it > calls. Yes, of course, that should be done at the same time. > If you want more debugging aids, I don't object, but then I have no > interest in such additions, either. Typically, such additions are > only good as long as you debug some specific problem, so keeping them > in the code after that is waste of bytes. It seems like you think that problems with system calls are just like any other problem in the code. For problem in Emacs code itself your strategy here is of course good. System calls, however is like a black box. You have to follow the rules for calling the black box, but do not know exactly what is inside, you can only watch the outcome to learn more. One example of this is when I see Emacs going totally weird. That happens quite often and I am not sure what is happening. It might in my cases be problems with edebug or it might be problems with the system calls that makes the depends on resource exhaustion in the black system box. To be able to fix it I need some kind of logging of the system calls. So I really prefer that those debug calls for check system calls are there permanently. >> W32DEBPRINT (this_function, ApiFunction, bad_return_value, 0); > > This is even worse, because it's impossible to understand what this > does without looking up the magical W32DEBPRINT macro. I think it has some advantages, actually. It is easy to see and distinguish from the normal code. It can be a null op in non-debugging compilations. And it is very easy to understand immediately once you have looked up the magical W32DEBPRINT - which is quite easy to do with Emacs tools. But maybe you meant something else? ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-30 18:02 ` Lennart Borgman @ 2010-05-30 19:24 ` Juanma Barranquero 2010-05-30 22:37 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: Juanma Barranquero @ 2010-05-30 19:24 UTC (permalink / raw To: Lennart Borgman; +Cc: Eli Zaretskii, emacs-devel On Sun, May 30, 2010 at 20:02, Lennart Borgman <lennart.borgman@gmail.com> wrote: > My intention is to get a chance to know why a system call failed. That > is a way to find those errors that are a bit harder to find than those > you may see directly by inspecting the code. If you have DebPrint for every system call, and some of them return trivial errors, debugging will sometimes be harder just because of the noise. > System calls, however is like a black box. You have to follow the > rules for calling the black box, but do not know exactly what is > inside, you can only watch the outcome to learn more. I think you'll see that many system calls won't ever return an error (because the error conditions are pretty infrequent). Some of them will, for example system calls related to file manipulation (because of nonexistent or nonaccesible files, etc.); it would be interesting to know how many of those don't have already checking in place. > One example of this is when I see Emacs going totally weird. That > happens quite often and I am not sure what is happening. It might in > my cases be problems with edebug or it might be problems with the > system calls that makes the depends on resource exhaustion in the > black system box. Does that happen to you with your patched Emacs, or unpatched? Because I see occasional crashes, but not nearly as frequently as it seems to happen to you (not by a loooong shot), and I have not seem "weird" behavior (unresponsive Emacs, looping, etc.) perhaps for years. > To be able to fix it I need some kind of logging of > the system calls. Because you somehow assume that the trouble is likely related to bad system calls; most Emacs bugs aren't. >> This is even worse, because it's impossible to understand what this >> does without looking up the magical W32DEBPRINT macro. > > > I think it has some advantages, actually. It is easy to see and > distinguish from the normal code. It can be a null op in non-debugging > compilations. IMHO is horribly ugly. If you're going to have error checks, better to have them on the clear. Juanma ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-30 19:24 ` Juanma Barranquero @ 2010-05-30 22:37 ` Lennart Borgman 2010-05-30 23:03 ` Juanma Barranquero 2010-05-31 3:05 ` Eli Zaretskii 0 siblings, 2 replies; 33+ messages in thread From: Lennart Borgman @ 2010-05-30 22:37 UTC (permalink / raw To: Juanma Barranquero; +Cc: Eli Zaretskii, emacs-devel On Sun, May 30, 2010 at 9:24 PM, Juanma Barranquero <lekktu@gmail.com> wrote: > On Sun, May 30, 2010 at 20:02, Lennart Borgman > <lennart.borgman@gmail.com> wrote: > >> My intention is to get a chance to know why a system call failed. That >> is a way to find those errors that are a bit harder to find than those >> you may see directly by inspecting the code. > > If you have DebPrint for every system call, and some of them return > trivial errors, debugging will sometimes be harder just because of the > noise. Yes, my intention was not to add them everywhere, only on interesting places. > I think you'll see that many system calls won't ever return an error > (because the error conditions are pretty infrequent). Some of them > will, for example system calls related to file manipulation (because > of nonexistent or nonaccesible files, etc.); it would be interesting > to know how many of those don't have already checking in place. On a quick look I got the impression that file calls are better handled than GUI system calls. >> One example of this is when I see Emacs going totally weird. That >> happens quite often and I am not sure what is happening. It might in >> my cases be problems with edebug or it might be problems with the >> system calls that makes the depends on resource exhaustion in the >> black system box. > > Does that happen to you with your patched Emacs, or unpatched? It happens to me with my patched Emacs because that is the one I am using. I only use unpatched Emacs for bug testing etc. > Because > I see occasional crashes, but not nearly as frequently as it seems to > happen to you (not by a loooong shot), and I have not seem "weird" > behavior (unresponsive Emacs, looping, etc.) perhaps for years. All I know is that some system resources seems to be exhausted. What I directly can see without digging is that GDI are exhausted (these are shown in Windows Task Manager). explorer.exe are owning a lot of them, which I believe means it is system windows like menus that are badly handled. However if Emacs is the culprit or windows itself I do not know. (I am using sticky keys and I think it is related to that.) >> To be able to fix it I need some kind of logging of >> the system calls. > > Because you somehow assume that the trouble is likely related to bad > system calls; most Emacs bugs aren't. That is surely true, but I am not comfortable with how threads are integrated (i.e. it is not visible enough IMO). I wonder if there are any troubles there. Those threads of course communicate through system calls. I might have fixed some of the problems with related to frames which calls crashes, but there might be more. Menus are rather often broken. I can see that in my patched version because menus are more easily accessed there. I surely And I wonder why Emacs sometimes seems to hang temporarily when frame related operations are going on. Is something going wrong? And the inability to stop Emacs sometimes is quite disturbing. What is going on there? Why does not the GUI thread get resources? Or is it given resources but a block occur in some other way? Is GUI messages not checked when looping? >>> This is even worse, because it's impossible to understand what this >>> does without looking up the magical W32DEBPRINT macro. >> >> >> I think it has some advantages, actually. It is easy to see and >> distinguish from the normal code. It can be a null op in non-debugging >> compilations. > > IMHO is horribly ugly. If you're going to have error checks, better to > have them on the clear. So both you and Eli think that way is ugly. I am a bit surprised (but I accept it of course). This type of entering the checks is very similar to what `assert' does in Emacs. Does that mean you think `assert' is very ugly too or is there some difference I am missing? ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-30 22:37 ` Lennart Borgman @ 2010-05-30 23:03 ` Juanma Barranquero 2010-05-30 23:28 ` Lennart Borgman 2010-05-31 3:05 ` Eli Zaretskii 1 sibling, 1 reply; 33+ messages in thread From: Juanma Barranquero @ 2010-05-30 23:03 UTC (permalink / raw To: Lennart Borgman; +Cc: Eli Zaretskii, emacs-devel On Mon, May 31, 2010 at 00:37, Lennart Borgman <lennart.borgman@gmail.com> wrote: > Yes, my intention was not to add them everywhere, only on interesting places. It didn't seem so in your first message. > On a quick look I got the impression that file calls are better > handled than GUI system calls. Likely because file calls are much more likely to fail. > It happens to me with my patched Emacs because that is the one I am > using. I only use unpatched Emacs for bug testing etc. Why don't you add these checks to your patched Emacs and see what comes of it? > That is surely true, but I am not comfortable with how threads are > integrated (i.e. it is not visible enough IMO). I wonder if there are > any troubles there. Those threads of course communicate through system > calls. Do you wonder where "there are any troubles there", or do you suspect that there are troubles? > I might have fixed some of the problems with related to frames which > calls crashes, but there might be more. Well, perhaps you've fixed them, but as I've said, your Emacs seem to crash more often than most others ;-) > And I wonder why Emacs sometimes seems to hang temporarily when frame > related operations are going on. Is something going wrong? You'd have to be a bit more specific... > And the inability to stop Emacs sometimes is quite disturbing. What is > going on there? Why does not the GUI thread get resources? Or is it > given resources but a block occur in some other way? Is GUI messages > not checked when looping? Also here. > This type of entering the checks is very > similar to what `assert' does in Emacs. Does that mean you think > `assert' is very ugly too or is there some difference I am missing? No, I quite like asserts. The difference is than assert is assert (some test) There's nothing to understand there. It passes, or it fails. W32DEBPRINT has four arguments; at the very least, if would make more sense to do W32DEBPRINT (this_function, ApiFunction (args) != bad_return_value) or somesuch, and, at that point, you're just reinventing assert, which seems pointless. Anyway, my feeling is that it makes much more sense to check return codes *to do something* about them in the case of failure, that just to print a message which will be helpful or not, depending of how frequent / how informative they are. So if you're really interested in doing this, I'd suggest looking at specific unchecked syscalls and trying to determine if something (could / need to) be done in case of error. And then send patches ;-) Juanma ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-30 23:03 ` Juanma Barranquero @ 2010-05-30 23:28 ` Lennart Borgman 2010-05-31 0:10 ` Juanma Barranquero 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-05-30 23:28 UTC (permalink / raw To: Juanma Barranquero; +Cc: Eli Zaretskii, emacs-devel On Mon, May 31, 2010 at 1:03 AM, Juanma Barranquero <lekktu@gmail.com> wrote: > On Mon, May 31, 2010 at 00:37, Lennart Borgman > <lennart.borgman@gmail.com> wrote: > >> Yes, my intention was not to add them everywhere, only on interesting places. > > It didn't seem so in your first message. Maybe not, but perhaps even more so from the reply ;-) >> On a quick look I got the impression that file calls are better >> handled than GUI system calls. > > Likely because file calls are much more likely to fail. That is not what I think. I think instead that the consequences of failing file calls are more visible and therefor much easier to catch. And it looks to me from the code that the knowledge of other system calls is less or at least more problematic to handle. At least on the w32 side. And it is not surprising since we are few here looking at that code. That is also one reason for adding debug calls since it can give more knowledge of what is going on in that code. >> It happens to me with my patched Emacs because that is the one I am >> using. I only use unpatched Emacs for bug testing etc. > > Why don't you add these checks to your patched Emacs and see what comes of it? It takes me quite a lot of time to take care of all the patches. There does not seem to be much interest or time to fix many of the issues and then I have to keep them in my patched version. I am trying to minimize that work. Also it is much more trouble making a patch later if I have a lot of small patches that are not in the upstream Emacs. I have wasted quite a lot of time on this. One reason is of course that I do not install my patches myself. Maybe it is time to do that instead. Is there any easy way out of the situation that I have my checkout from Launchpad. Can I somehow make bzr aware of that this is really the same thing as on savannah and upload from it? Or should I make a new checkout from savannah and use that just for this? >> That is surely true, but I am not comfortable with how threads are >> integrated (i.e. it is not visible enough IMO). I wonder if there are >> any troubles there. Those threads of course communicate through system >> calls. > > Do you wonder where "there are any troubles there", or do you suspect > that there are troubles? Both ;-) How does blocking interfere with that code? Are the system calls always done in the right thread (or with correct thread communication)? >> I might have fixed some of the problems with related to frames which >> calls crashes, but there might be more. > > Well, perhaps you've fixed them, but as I've said, your Emacs seem to > crash more often than most others ;-) I think I have given the reason for that. So far I have never been able to identify a crash as something depending on my code. And believe it or not that is what I try to investigate first (which makes my quite a bit angry about having to keep them myself)... ;-) >> And I wonder why Emacs sometimes seems to hang temporarily when frame >> related operations are going on. Is something going wrong? > > You'd have to be a bit more specific... I see this when creating a frame in a timer. Or perhaps when fetching info from the web in a timer. I am not sure, but none of these should block. Of course there must not be system calls involved directly. It might be "bad chaining", i.e. code that is unnecessarily waiting for system calls to complete. >> And the inability to stop Emacs sometimes is quite disturbing. What is >> going on there? Why does not the GUI thread get resources? Or is it >> given resources but a block occur in some other way? Is GUI messages >> not checked when looping? > > Also here. Run something in a timer. Try to stop it. >> This type of entering the checks is very >> similar to what `assert' does in Emacs. Does that mean you think >> `assert' is very ugly too or is there some difference I am missing? > > No, I quite like asserts. The difference is than assert is > > assert (some test) > > There's nothing to understand there. It passes, or it fails. > W32DEBPRINT has four arguments; at the very least, if would make more > sense to do > > W32DEBPRINT (this_function, ApiFunction (args) != bad_return_value) > > or somesuch, and, at that point, you're just reinventing assert, which > seems pointless. Oh, the four args where just to make it more easy to understand... ;-) Do you mean there is an assert that can do DebPrint? That would be very nice. > Anyway, my feeling is that it makes much more sense to check return > codes *to do something* about them in the case of failure, that just > to print a message which will be helpful or not, depending of how > frequent / how informative they are. Things sometimes does not go totally wrong with system calls even if something is wrong because the system will try to recover. Looking at the messages might then give some information. The problem as I have seen it (it was a long time since I did something like this) is often that you get too much information so you have to shut down the logging and only have it on for short tests. (That is one reason to keep the debug printing statements, but commented out.) > So if you're really interested in > doing this, I'd suggest looking at specific unchecked syscalls and > trying to determine if something (could / need to) be done in case of > error. And then send patches ;-) Sending patches is much easier if you do not have to remove a lot of things from the diffs. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-30 23:28 ` Lennart Borgman @ 2010-05-31 0:10 ` Juanma Barranquero 2010-05-31 0:58 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: Juanma Barranquero @ 2010-05-31 0:10 UTC (permalink / raw To: Lennart Borgman; +Cc: Eli Zaretskii, emacs-devel On Mon, May 31, 2010 at 01:28, Lennart Borgman <lennart.borgman@gmail.com> wrote: > That is not what I think. I think instead that the consequences of > failing file calls are more visible and therefor much easier to catch. They wouldn't be catched if they didn't happen. If other system calls are causing as many errors as you suggest, it is strange the sparsity of bug reports about them. > And it looks to me from the code that the knowledge of other system > calls is less or at least more problematic to handle. I cannot parse this, sorry. > At least on the > w32 side. And it is not surprising since we are few here looking at > that code. That is also one reason for adding debug calls since it can > give more knowledge of what is going on in that code. Usually, bugs have a tendendy to show up even if you're not looking for them... > It takes me quite a lot of time to take care of all the patches. There > does not seem to be much interest or time to fix many of the issues > and then I have to keep them in my patched version. Here we go again. "Does not seem to be much interest or time" sort of implies that you've done the work of sending patches and they've been summarily rejected. From my recollection, you seem to lose interest quite fast as soon as you fail to immediately convince that they are worthwhile and correct (sorry if this seems an ad hominem; it's not. I'm just describing how I remember past interactions, particularly with respect to emacsclient). > Also it is much more trouble making a patch later if I have a lot of > small patches that are not in the upstream Emacs. That's what branches are for :-) > One reason is of course that I do not install my patches myself. Maybe > it is time to do that instead. Is there any easy way out of the > situation that I have my checkout from Launchpad. Can I somehow make > bzr aware of that this is really the same thing as on savannah and > upload from it? Or should I make a new checkout from savannah and use > that just for this? The latter. But I'd advise against installing these kind of changes without discussing them first with Eli and Jason, which shoulder most of the w32 effort. > Both ;-) Well, if you know there are troubles, you can patch your Emacs and debug them... > How does blocking interfere with that code? Are the system calls > always done in the right thread (or with correct thread > communication)? Again: for specific problems, file bug reports. Perhaps there are really some missing checks on some syscalls, but the fix for your troubles is likely to be more than just calling DebPrint. > I think I have given the reason for that. So far I have never been > able to identify a crash as something depending on my code. Have you been able to identify them as something depending on the trunk code? If so, did you file reports for them? > I see this when creating a frame in a timer. Or perhaps when fetching > info from the web in a timer. I am not sure, but none of these should > block. > Of course there must not be system calls involved directly. It might > be "bad chaining", i.e. code that is unnecessarily waiting for system > calls to complete. Specific examples would help in debugging this. > Oh, the four args where just to make it more easy to understand... ;-) I think you mean s/more/less/. > Do you mean there is an assert that can do DebPrint? That would be very nice. No, I mean that if the syscalls are failing in such a way that there's no fix to be done after the fact, triggering an assert is the Right Thing To Do (that will help detect the problem). > Things sometimes does not go totally wrong with system calls even if > something is wrong because the system will try to recover. Looking at > the messages might then give some information. That is not an argument *for* printing information, is an argument for checking the return code more thoroughly and doing the right thing. > Sending patches is much easier if you do not have to remove a lot of > things from the diffs. Do you really have so many changes in the w32*.c files that doing a diff is a problem? Perhaps it's time you start calling EmacsW32 a fork ;-) Juanma ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-31 0:10 ` Juanma Barranquero @ 2010-05-31 0:58 ` Lennart Borgman 2010-05-31 2:02 ` Juanma Barranquero 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-05-31 0:58 UTC (permalink / raw To: Juanma Barranquero; +Cc: Eli Zaretskii, emacs-devel On Mon, May 31, 2010 at 2:10 AM, Juanma Barranquero <lekktu@gmail.com> wrote: > On Mon, May 31, 2010 at 01:28, Lennart Borgman > <lennart.borgman@gmail.com> wrote: > >> That is not what I think. I think instead that the consequences of >> failing file calls are more visible and therefor much easier to catch. > > They wouldn't be catched if they didn't happen. If other system calls > are causing as many errors as you suggest, it is strange the sparsity > of bug reports about them. I don't think so. It is just much more difficult to track some of these. For example I know Drew recently wrote about problems when creating new frames. It is quite hard to both understand what is happening and what is a bug and what is not. Is there just a bad timing? A missing hook to proceed the function etc (you may have to wait until the frame creation is finished)? >> And it looks to me from the code that the knowledge of other system >> calls is less or at least more problematic to handle. > > I cannot parse this, sorry. I just mean that the normal C code (i.e. not related to system calls) seems better checked on w32. > Usually, bugs have a tendendy to show up even if you're not looking for them... Maybe you are missing my point. The system tries to stay stable. There are timing issues etc. >> It takes me quite a lot of time to take care of all the patches. There >> does not seem to be much interest or time to fix many of the issues >> and then I have to keep them in my patched version. > > Here we go again. "Does not seem to be much interest or time" sort of > implies that you've done the work of sending patches and they've been > summarily rejected. From my recollection, you seem to lose interest > quite fast as soon as you fail to immediately convince that they are > worthwhile and correct (sorry if this seems an ad hominem; it's not. > I'm just describing how I remember past interactions, particularly > with respect to emacsclient). No. I would rather say I just don't have time then. When I entered this list I went into a long discussion about the problems with printing on the w32 side. I actually felt I wasted a lot of time when I told that the code was in error. Since then I have thought it is less waste of time to keep the patches in my patched version. Now and then I ask if things have changed. If they have not I just skip it, but with some regret about the extra trouble and lost work. >> Also it is much more trouble making a patch later if I have a lot of >> small patches that are not in the upstream Emacs. > > That's what branches are for :-) Yes, it seems easier, but I will have to create quite a few branches for some old patches. And it takes time. >> One reason is of course that I do not install my patches myself. Maybe >> it is time to do that instead. Is there any easy way out of the >> situation that I have my checkout from Launchpad. Can I somehow make >> bzr aware of that this is really the same thing as on savannah and >> upload from it? Or should I make a new checkout from savannah and use >> that just for this? > > The latter. But I'd advise against installing these kind of changes > without discussing them first with Eli and Jason, which shoulder most > of the w32 effort. Thanks. Yes, of course. >> Both ;-) > > Well, if you know there are troubles, you can patch your Emacs and debug them... See above. >> How does blocking interfere with that code? Are the system calls >> always done in the right thread (or with correct thread >> communication)? > > Again: for specific problems, file bug reports. I have done that many times (or sent reports to the list before) but these kind of errors are not easy to track down. And since I have some patches (that correct some bugs, but also makes other bugs more visible) they tend to be dismissed. It is kind of a locked situation. > Perhaps there are > really some missing checks on some syscalls, but the fix for your > troubles is likely to be more than just calling DebPrint. There are a lot of them as I said before. >> I think I have given the reason for that. So far I have never been >> able to identify a crash as something depending on my code. > > Have you been able to identify them as something depending on the > trunk code? If so, did you file reports for them? It seems much more trouble reporting the problems than fixing them. Maybe I should try to make a "system calls fix branch" from savannah and pick them one by one when I have time. >> I see this when creating a frame in a timer. Or perhaps when fetching >> info from the web in a timer. I am not sure, but none of these should >> block. >> Of course there must not be system calls involved directly. It might >> be "bad chaining", i.e. code that is unnecessarily waiting for system >> calls to complete. > > Specific examples would help in debugging this. I have an example where I create a frame contact a web page in pause.el. Is that specific enough? (You have to run my patched code to see it since I can't do the frame manipulation I need without that.) >> Oh, the four args where just to make it more easy to understand... ;-) > > I think you mean s/more/less/. No ;-) >> Do you mean there is an assert that can do DebPrint? That would be very nice. > > No, I mean that if the syscalls are failing in such a way that there's > no fix to be done after the fact, triggering an assert is the Right > Thing To Do (that will help detect the problem). I don't think so. You should most often not crash Emacs because of bad system call return status. You should take a relevant action. >> Things sometimes does not go totally wrong with system calls even if >> something is wrong because the system will try to recover. Looking at >> the messages might then give some information. > > That is not an argument *for* printing information, is an argument for > checking the return code more thoroughly and doing the right thing. Of course, but you may be interested in information about what happened too. >> Sending patches is much easier if you do not have to remove a lot of >> things from the diffs. > > Do you really have so many changes in the w32*.c files that doing a > diff is a problem? Perhaps it's time you start calling EmacsW32 a fork > ;-) Perhaps not, but sometimes it is a bit scary when merging as it was recently when I had some changes to local/global variables. A variant of those are now in Emacs so I can skip worrying about that any more. And the changes that allows better menu handling are also a bit scaring when merging. They are still only in my code. > Juanma ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-31 0:58 ` Lennart Borgman @ 2010-05-31 2:02 ` Juanma Barranquero 2010-05-31 2:36 ` Lennart Borgman 0 siblings, 1 reply; 33+ messages in thread From: Juanma Barranquero @ 2010-05-31 2:02 UTC (permalink / raw To: Lennart Borgman; +Cc: Eli Zaretskii, emacs-devel On Mon, May 31, 2010 at 02:58, Lennart Borgman <lennart.borgman@gmail.com> wrote: > I don't think so. It is just much more difficult to track some of > these. For example I know Drew recently wrote about problems when > creating new frames. It is quite hard to both understand what is > happening and what is a bug and what is not. Well, I'd say that should be the first step... > I just mean that the normal C code (i.e. not related to system calls) > seems better checked on w32. Not sure what do you mean with "better checked". Obviously it is easier to know what one of our own C functions is doing that what a Windows system call does, so it's less likely that a return code from a C function is ignored. > Maybe you are missing my point. The system tries to stay stable. There > are timing issues etc. Maybe. Sometimes it seems like you assume your interlocutor knows it all about the bugs you encounter; I tend to find your descriptions vague and hard to follow (not necessarily your fault, of course). > When I entered this list I went into a long discussion about the > problems with printing on the w32 side. I actually felt I wasted a lot > of time when I told that the code was in error. Since then I have > thought it is less waste of time to keep the patches in my patched > version. Now and then I ask if things have changed. If they have not I > just skip it, but with some regret about the extra trouble and lost > work. I see no practical difference between my take of the situation (regarding your patches) and yours. > I have done that many times (or sent reports to the list before) but > these kind of errors are not easy to track down. And since I have some > patches (that correct some bugs, but also makes other bugs more > visible) they tend to be dismissed. I don't think so. They aren't dismissed because of your patches, but because they are (at least, some that I've followed) very hard to reproduce in standard Emacs. > It seems much more trouble reporting the problems than fixing them. > Maybe I should try to make a "system calls fix branch" from savannah > and pick them one by one when I have time. Perhaps it'd be a good idea. > I have an example where I create a frame contact a web page in > pause.el. Is that specific enough? (You have to run my patched code to > see it since I can't do the frame manipulation I need without that.) Then, why are you sure the problem isn't in your code? Surely if it is a bug in Emacs there will be a way to show it with the trunk code? > No ;-) Hmm... allow me to disagree ;-) > I don't think so. You should most often not crash Emacs because of bad > system call return status. You should take a relevant action. That's explicit in my comment. If you can take relevant action, do it (not DebPrint, but a really relevant action). If you cannot, and the bug is real, then abort. > Of course, but you may be interested in information about what happened too. While debugging. Not as a general principle. I don't want to run Emacs under GDB for a totally unrelated reason and have a lot of noise. I want that "noise", if it is relevant, to be acted upon. So, instead of just adding lots of DebPrints, it would be more sensible to add them locally for debugging, find what's happening (surely if you have so many troubles, the error output will be abundant) and either fix it or file a bug report for it. > And the changes that allows better menu handling are also a bit > scaring when merging. They are still only in my code. Perhaps the latter is consequence of the former. Juanma ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-31 2:02 ` Juanma Barranquero @ 2010-05-31 2:36 ` Lennart Borgman 2010-05-31 3:06 ` Juanma Barranquero 0 siblings, 1 reply; 33+ messages in thread From: Lennart Borgman @ 2010-05-31 2:36 UTC (permalink / raw To: Juanma Barranquero; +Cc: Eli Zaretskii, emacs-devel On Mon, May 31, 2010 at 4:02 AM, Juanma Barranquero <lekktu@gmail.com> wrote: > On Mon, May 31, 2010 at 02:58, Lennart Borgman > <lennart.borgman@gmail.com> wrote: > >> I don't think so. It is just much more difficult to track some of >> these. For example I know Drew recently wrote about problems when >> creating new frames. It is quite hard to both understand what is >> happening and what is a bug and what is not. > > Well, I'd say that should be the first step... Exactly. That is why debug output might be helpful. >> I just mean that the normal C code (i.e. not related to system calls) >> seems better checked on w32. > > Not sure what do you mean with "better checked". Obviously it is > easier to know what one of our own C functions is doing that what a > Windows system call does, so it's less likely that a return code from > a C function is ignored. Yes, but isn't it a really good reason to always check the return code from system calls? > I see no practical difference between my take of the situation > (regarding your patches) and yours. Maybe it is just me then. But I have thrown away a good deal of them just to get less work (even if some of them were bug fixes). >> I have an example where I create a frame contact a web page in >> pause.el. Is that specific enough? (You have to run my patched code to >> see it since I can't do the frame manipulation I need without that.) > > Then, why are you sure the problem isn't in your code? Surely if it is > a bug in Emacs there will be a way to show it with the trunk code? Because they are not related to that part of the code. >> No ;-) > > Hmm... allow me to disagree ;-) What can I do? ;-) > While debugging. Not as a general principle. I don't want to run Emacs > under GDB for a totally unrelated reason and have a lot of noise. Yes, of course. But keeping a commented out one line debug output call might be quit useful in some places. >> And the changes that allows better menu handling are also a bit >> scaring when merging. They are still only in my code. > > Perhaps the latter is consequence of the former. Yes, I know. ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-31 2:36 ` Lennart Borgman @ 2010-05-31 3:06 ` Juanma Barranquero 0 siblings, 0 replies; 33+ messages in thread From: Juanma Barranquero @ 2010-05-31 3:06 UTC (permalink / raw To: Lennart Borgman; +Cc: Eli Zaretskii, emacs-devel On Mon, May 31, 2010 at 04:36, Lennart Borgman <lennart.borgman@gmail.com> wrote: > Yes, but isn't it a really good reason to always check the return code > from system calls? Yes. Check and *do something* about it. >> Then, why are you sure the problem isn't in your code? Surely if it is >> a bug in Emacs there will be a way to show it with the trunk code? > > Because they are not related to that part of the code. That does not answer the second question. > Yes, of course. But keeping a commented out one line debug output call > might be quit useful in some places. The trick is to find these (supposedly few) "some places". Juanma ^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: System calls without error checks in w32 2010-05-30 22:37 ` Lennart Borgman 2010-05-30 23:03 ` Juanma Barranquero @ 2010-05-31 3:05 ` Eli Zaretskii 1 sibling, 0 replies; 33+ messages in thread From: Eli Zaretskii @ 2010-05-31 3:05 UTC (permalink / raw To: Lennart Borgman; +Cc: lekktu, emacs-devel > From: Lennart Borgman <lennart.borgman@gmail.com> > Date: Mon, 31 May 2010 00:37:26 +0200 > Cc: Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org > > On a quick look I got the impression that file calls are better > handled than GUI system calls. That's because when it happens with files, it's quite clear what to do. But what do you do when you try to display a menu, and the API returns an error? > So both you and Eli think that way is ugly. It obfuscates the source code, that's the main problem. ^ permalink raw reply [flat|nested] 33+ messages in thread
end of thread, other threads:[~2010-06-08 0:34 UTC | newest] Thread overview: 33+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2010-05-31 9:18 System calls without error checks in w32 grischka 2010-06-05 17:15 ` Jason Rumney 2010-06-07 10:37 ` grischka 2010-06-07 14:54 ` Stephen J. Turnbull 2010-06-07 15:23 ` Lennart Borgman 2010-06-07 17:21 ` grischka 2010-06-07 17:30 ` Lennart Borgman 2010-06-07 18:54 ` grischka 2010-06-08 0:32 ` Lennart Borgman 2010-06-08 0:34 ` Lennart Borgman 2010-06-07 19:56 ` Stefan Monnier 2010-06-07 23:35 ` Lennart Borgman -- strict thread matches above, loose matches on Subject: below -- 2010-05-29 2:38 Lennart Borgman 2010-05-29 17:43 ` Eli Zaretskii 2010-05-29 18:42 ` Lennart Borgman 2010-05-29 19:35 ` Eli Zaretskii 2010-05-29 20:02 ` Lennart Borgman 2010-05-29 21:25 ` Eli Zaretskii 2010-05-29 21:30 ` Lennart Borgman 2010-05-30 3:02 ` Eli Zaretskii 2010-05-30 3:26 ` Lennart Borgman 2010-05-30 17:36 ` Eli Zaretskii 2010-05-30 18:02 ` Lennart Borgman 2010-05-30 19:24 ` Juanma Barranquero 2010-05-30 22:37 ` Lennart Borgman 2010-05-30 23:03 ` Juanma Barranquero 2010-05-30 23:28 ` Lennart Borgman 2010-05-31 0:10 ` Juanma Barranquero 2010-05-31 0:58 ` Lennart Borgman 2010-05-31 2:02 ` Juanma Barranquero 2010-05-31 2:36 ` Lennart Borgman 2010-05-31 3:06 ` Juanma Barranquero 2010-05-31 3:05 ` Eli Zaretskii
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