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remove mention of wxMutexGuiEnter/leave from the multithreading topic overview; document that wxMutexGuiEnter only works for wxMSW as the code seems to confirm this (see #10366)

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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58683 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Francesco Montorsi 2009-02-05 18:24:27 +00:00
parent 06f89fe437
commit ae93dddfaf
2 changed files with 28 additions and 19 deletions
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37
docs/doxygen/overviews/thread.h
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@ -6,6 +6,11 @@
// Licence: wxWindows license
/////////////////////////////////////////////////////////////////////////////
/*
NOTE: we explicitely don't name wxMutexGUIEnter() and wxMutexGUILeave()
as they're not safe. See also ticket #10366.
*/
/**
@page overview_thread Multithreading
@ -20,27 +25,29 @@ wxWidgets resembles to POSIX1.c threads API (a.k.a. pthreads), although several
functions have different names and some features inspired by Win32 thread API
are there as well.
These classes will hopefully make writing MT programs easier and they also
provide some extra error checking (compared to the native (be it Win32 or
Posix) thread API), however it is still a non-trivial undertaking especially
for large projects. Before starting an MT application (or starting to add MT
These classes hopefully make writing MT programs easier and they also
provide some extra error checking (compared to the native - be it Win32 or
Posix - thread API), however it is still a non-trivial undertaking especially
for large projects.
Before starting an MT application (or starting to add MT
features to an existing one) it is worth asking oneself if there is no easier
and safer way to implement the same functionality. Of course, in some
situations threads really make sense (classical example is a server application
which launches a new thread for each new client), but in others it might be an
overkill. On the other hand, the recent evolution of the computer hardware shows
and safer way to implement the same functionality.
Of course, in some situations threads really make sense (classical example is a
server application which launches a new thread for each new client), but in others
it might be an overkill.
On the other hand, the recent evolution of the computer hardware shows
an important trend towards multi-core systems, which are better exploited using
multiple threads (e.g. you may want to split a long task among as many threads
as many CPU (cores) the system reports; see wxThread::GetCPUCount).
To implement non-blocking operations without using multiple threads you have
two other possible implementation choices:
- using wxIdleEvent (e.g. to perform a long calculation while updating a progress dialog)
- simply do everything at once but call wxWindow::Update() periodically to update the screen.
To implement non-blocking operations @e without using multiple threads you have
two possible implementation choices:
- use wxIdleEvent (e.g. to perform a long calculation while updating a progress dialog)
- do everything at once but call wxWindow::Update() or wxApp::YieldFor(wxEVT_CATEGORY_UI)
periodically to update the screen.
Even if there are the ::wxMutexGuiEnter and ::wxMutexGuiLeave functions which allows
to use GUI functions from multiple threads, if you do decide to use threads in your
application, it is strongly recommended that <b>no more than one calls GUI functions</b>.
If instead you choose to use threads in your application, it is strongly recommended
that <b>no secondary threads call GUI functions</b>.
The design which uses one GUI thread and several worker threads which communicate
with the main one using @b events is much more robust and will undoubtedly save you
countless problems (example: under Win32 a thread can only access GDI objects such

10
interface/wx/thread.h
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@ -863,9 +863,9 @@ enum
as MFC.
A workaround for some wxWidgets ports is calling wxMutexGUIEnter()
before any GUI calls and then calling wxMutexGUILeave() afterwords. However,
the recommended way is to simply process the GUI calls in the main thread
through an event that is posted by wxQueueEvent().
before any GUI calls and then calling wxMutexGUILeave() afterwords.
However, the recommended way is to simply process the GUI calls in the main
thread through an event that is posted by wxQueueEvent().
This does not imply that calls to these classes are thread-safe, however,
as most wxWidgets classes are not thread-safe, including wxString.
@ -1620,6 +1620,8 @@ public:
*/
bool wxIsMainThread();
/**
This function must be called when any thread other than the main GUI thread
wants to get access to the GUI library. This function will block the
@ -1645,7 +1647,7 @@ bool wxIsMainThread();
@endcode
This function is only defined on platforms which support preemptive
threads.
threads and only works under some ports (wxMSW currently).
@note Under GTK, no creation of top-level windows is allowed in any thread
but the main one.