define _HPUX_SOURCE under HP-UX, otherwise many things are not defined in standard...

[wxWidgets.git] / docs / latex / wx / tthreads.tex

diff --git a/docs/latex/wx/tthreads.tex b/docs/latex/wx/tthreads.tex
index a034599c70f758e31828f86a157b0f3ddbf35a47..29b0eb9e254ee03bdc0e2505e428afb54366b33b 100644 (file)
--- a/docs/latex/wx/tthreads.tex
+++ b/docs/latex/wx/tthreads.tex
@@ -4,15 +4,18 @@ Classes: \helpref{wxThread}{wxthread}, \helpref{wxMutex}{wxmutex},
 \helpref{wxCriticalSection}{wxcriticalsection}, 
 \helpref{wxCondition}{wxcondition}
 
-wxWindows provides a complete set of classes encapsulating objects necessary in
+wxWidgets provides a complete set of classes encapsulating objects necessary in
 multithreaded (MT) programs: the \helpref{thread}{wxthread} class itself and different
 synchronization objects: \helpref{mutexes}{wxmutex} and 
 \helpref{critical sections}{wxcriticalsection} with 
-\helpref{conditions}{wxcondition}.
+\helpref{conditions}{wxcondition}. The thread API in 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 an untrivial undertaking especially for large
+thread API), however it is still an 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
@@ -21,8 +24,9 @@ new thread for each new client), but in others it might be a very poor choice
 (example: launching a separate thread when doing a long computation to show a
 progress dialog). Other implementation choices are available: for the progress
 dialog example it is far better to do the calculations in the 
-\helpref{idle handler}{wxidleevent} or call \helpref{wxYield()}{wxyield}
-periodically to update the screen.
+\helpref{idle handler}{wxidleevent} or even simply do everything at once
+but call \helpref{wxWindow::Update()}{wxwindowupdate} periodically to update
+the screen.
 
 If you do decide to use threads in your application, it is strongly recommended
 that no more than one thread calls GUI functions. The thread sample shows that
@@ -34,9 +38,16 @@ more robust and will undoubtedly save you countless problems (example: under
 Win32 a thread can only access GDI objects such as pens, brushes, \&c created by
 itself and not by the other threads).
 
-Final note: in the current release of wxWindows, there are no specific
-facilities for communicating between the threads. However, the usual 
-\helpref{ProcessEvent()}{wxevthandlerprocessevent} function may be used for
-thread communication too - but you should provide your own synchronisation
-mechanism if you use it (e.g. just use a critical section before sending a
-message) because there is no built-in synchronisation.
+For communication between secondary threads and the main thread, you may use 
+\helpref{wxEvtHandler::AddPendingEvent}{wxevthandleraddpendingevent}
+or its short version \helpref{wxPostEvent}{wxpostevent}. These functions
+have thread safe implementation so that they can be used as they are for
+sending events from one thread to another. However there is no built in method
+to send messages to the worker threads and you will need to use the available
+synchronization classes to implement the solution which suits your needs
+yourself. In particular, please note that it is \emph{not} enough to derive
+your class from \helpref{wxThread}{wxthread} and 
+\helpref{wxEvtHandler}{wxevthandler} to send messages to it: in fact, this does
+\emph{not} work at all.
+
+