fixed bug in mouse handling

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

diff --git a/docs/latex/wx/thread.tex b/docs/latex/wx/thread.tex
index b2ba8022337320caec30c8696968a5b7b7d274af..e531599ce22aae2f518e58994f8a282d9ed3ad08 100644 (file)
--- a/docs/latex/wx/thread.tex
+++ b/docs/latex/wx/thread.tex
@@ -1,41 +1,82 @@
 \section{\class{wxThread}}\label{wxthread}
 
 A thread is basically a path of execution through a program. Threads are also
 \section{\class{wxThread}}\label{wxthread}
 
 A thread is basically a path of execution through a program. Threads are also

-sometimes calls {\it light-wight processes}, but the fundamental difference
+sometimes called {\it light-weight processes}, but the fundamental difference

 between threads and processes is that memory spaces of different processes are
 separated while all threads share the same address space. While it makes it
 much easier to share common data between several threads, it also makes much
 between threads and processes is that memory spaces of different processes are
 separated while all threads share the same address space. While it makes it
 much easier to share common data between several threads, it also makes much

-easier to shoot oneself in a leg, so careful use of synchronization objects
-such as \helpref{mutexes}{wxmutex} and/or \helpref{critical 
-sections}{wxcriticalsection} is recommended.
+easier to shoot oneself in the foot, so careful use of synchronization objects
+such as \helpref{mutexes}{wxmutex} and/or \helpref{critical sections}{wxcriticalsection} is recommended.
+
+There are two types of threads in wxWindows: {\it detached} and {\it joinable}
+ones, just as in POSIX thread API (but unlike Win32 threads where all threads
+are joinable). The difference between the two is that only joinbale threads
+can return a return code - it is returned by Wait() function. The detached
+threads (default) can not be waited for.
+
+You shouldn't hurry to create all the threads joinable, however, because this
+has a disadvantage as well: you {\bf must} Wait() for a joinable thread of the
+system resources used by it will never be freed and you also must delete the
+corresponding wxThread object yourself, while detached threads are of the
+"fire-and-forget" kind: you only have to start a detached thread and it will
+terminate and destroy itself.
+
+This means, of course, that all detached threads {\bf must} be created on the
+heap because the thread will call {\tt delete this;} upon termination. The
+joinable threads may be created on stack (don't create global thread objects
+because they allocate memory in their constructor which is a badthing to do),
+although usually they will be created on the heap as well.

 
 \wxheading{Derived from}
 
 None.
 
 
 \wxheading{Derived from}
 
 None.
 

+\wxheading{Include files}
+
+<wx/thread.h>
+

 \wxheading{See also}
 
 \wxheading{See also}
 

-\helpref{wxMutex}{wxmutex}, \helpref{wxCondition}{wxcondition}
+\helpref{wxMutex}{wxmutex}, \helpref{wxCondition}{wxcondition}, \helpref{wxCriticalSection}{wxcriticalsection}

 
 \latexignore{\rtfignore{\wxheading{Members}}}
 
 
 \latexignore{\rtfignore{\wxheading{Members}}}
 

-\membersection{wxThread::wxThread}\label{wxthreadconstr}
+\membersection{wxThread::wxThread}\label{wxthreadctor}
+
+\func{}{wxThread}{\param{wxThreadKind }{kind = wxTHREAD\_DETACHED}}

 
 

-\func{}{wxThread}{\void}
+Constructor creates a new detached (default) or joinable C++ thread object. It
+does not create (or starts execution of) the real thread - for this you should
+use \helpref{Create}{wxthreadcreate} and \helpref{Run}{wxthreadrun} methods.

 
 

-Default constructor.
+The possible values for {\it kind} parameters are:
+\twocolwidtha{7cm}
+\begin{twocollist}\itemsep=0pt
+\twocolitem{{\bf wxTHREAD\_DETACHED}}{Create a detached thread.}
+\twocolitem{{\bf wxTHREAD\_JOINABLE}}{Create a joinable thread}
+\end{twocollist}

 
 \membersection{wxThread::\destruct{wxThread}}
 
 \func{}{\destruct{wxThread}}{\void}
 
 
 \membersection{wxThread::\destruct{wxThread}}
 
 \func{}{\destruct{wxThread}}{\void}
 

-Destroys the wxThread object.
+Destructor frees the ressources associated with the thread. Notice that you
+should never delete a detached thread - you may only call 
+\helpref{Delete}{wxthreaddelete} on it or wait until it terminates (and auto
+destructs) itself. Because the detached threads delete themselves, they can
+only be allocated on the heap.
+
+The joinable threads, however, may and should be deleted explicitly and 
+\helpref{Delete}{wxthreaddelete} and \helpref{Kill}{wxthreadkill} functions
+will not delete the C++ thread object. It is also safe to allocate them on
+stack.

 
 \membersection{wxThread::Create}\label{wxthreadcreate}
 
 \func{wxThreadError}{Create}{\void}
 
 
 \membersection{wxThread::Create}\label{wxthreadcreate}
 
 \func{wxThreadError}{Create}{\void}
 

-Creates a thread control.
+Creates a new thread. The thread object is created in the suspended state, you
+should call \helpref{Run}{wxthreadrun} to start running it.

 
 \wxheading{Return value}
 
 
 \wxheading{Return value}
 


@@ -48,34 +89,79 @@ One of:
 \twocolitem{{\bf wxTHREAD\_RUNNING}}{The thread is already running.}
 \end{twocollist}
 
 \twocolitem{{\bf wxTHREAD\_RUNNING}}{The thread is already running.}
 \end{twocollist}
 

-\membersection{wxThread::DeferDestroy}\label{wxthreaddeferdestroy}
+\membersection{wxThread::Delete}\label{wxthreaddelete}

 
 

-\func{void}{DeferDestroy}{\param{bool}{ defer}}
+\func{void}{Delete}{\void}

 
 

-If {\it defer} is TRUE, defers thread destruction. This function affects the
-calling thread.
+Calling \helpref{Delete}{wxthreaddelete} is a graceful way to terminate the
+thread. It asks the thread to terminate and, if the thread code is well
+written, the thread will terminate after the next call to 
+\helpref{TestDestroy}{wxthreadtestdestroy} which should happen quiet soon.

 
 

-\membersection{wxThread::Destroy}\label{wxthreaddestroy}
+However, if the thread doesn't call \helpref{TestDestroy}{wxthreadtestdestroy} 
+often enough (or at all), the function will not return immediately, but wait
+until the thread terminates. As it may take a long time, the message processing
+is not stopped during this function execution, so the message handlers may be
+called from inside it!

 
 

-\func{wxThreadError}{Destroy}{\void}
+Delete() may be called for thread in any state: running, paused or even not yet
+created. Moreover, it must be called if \helpref{Create}{wxthreadcreate} or 
+\helpref{Run}{wxthreadrun} failed for a detached thread to free the memory
+occupied by the thread object (it will be done in the destructor for joinable
+threads).

 
 

-Destroys the thread immediately unless the application has specified deferral via \helpref{wxThread::DeferDestroy}{wxthreaddeferdestroy}.
+Delete() may be called for thread in any state: running, paused or even not yet created. Moreover,
+it must be called if \helpref{Create}{wxthreadcreate} or \helpref{Run}{wxthreadrun} fail to free
+the memory occupied by the thread object. However, you should not call Delete()
+on a detached thread which already terminated - doing so will probably result
+in a crash because the thread object doesn't exist any more.

 
 

-\wxheading{Return value}
+For detached threads Delete() will also delete the C++ thread object, but it
+will not do this for joinable ones.

 
 

-One of:
+This function can only be called from another thread context.

 
 

-\twocolwidtha{7cm}
-\begin{twocollist}\itemsep=0pt
-\twocolitem{{\bf wxTHREAD\_NO\_ERROR}}{There was no error.}
-\twocolitem{{\bf wxTHREAD\_NOT\_RUNNING}}{The thread is not running.}
-\end{twocollist}
+\membersection{wxThread::Entry}\label{wxthreadentry}
+
+\func{virtual ExitCode}{Entry}{\void}
+
+This is the entry point of the thread. This function is pure virtual and must
+be implemented by any derived class. The thread execution will start here.
+
+The returned value is the thread exit code which is only useful for the
+joinable threads and is the value returned by \helpref{Wait}{wxthreadwait}.
+
+This function is called by wxWindows itself and should never be called
+directly.
+
+\membersection{wxThread::Exit}\label{wxthreadexit}
+
+\func{void}{Exit}{\param{ExitCode }{exitcode = 0}}

 
 

-\membersection{wxThread::GetID}\label{wxthreadgetid}
+This is a protected function of wxThread class and thus can be called only
+from a derived class. It also can be called only in the context of this
+thread, i.e. a thread can only exit from itself, not from another thread.

 
 

-\constfunc{unsigned long}{GetID}{\void}
+This function will terminate the OS thread (i.e. stop the associated path of
+execution) and also delete the associated C++ object for detached threads. 
+\helpref{wxThread::OnExit}{wxthreadonexit} will be called just before exiting.

 
 

-Gets the thread identifier.
+\membersection{wxThread::GetCPUCount}\label{wxthreadgetcpucount}
+
+\func{static int}{GetCPUCount}{\void}
+
+Returns the number of system CPUs or -1 if the value is unknown.
+
+\wxheading{See also}
+
+\helpref{SetConcurrency}{wxthreadsetconcurrency}
+
+\membersection{wxThread::GetId}\label{wxthreadgetid}
+
+\constfunc{unsigned long}{GetId}{\void}
+
+Gets the thread identifier: this is a platform dependent number which uniquely identifies the
+thread throughout the system during its existence (i.e. the thread identifiers may be reused).

 
 \membersection{wxThread::GetPriority}\label{wxthreadgetpriority}
 
 
 \membersection{wxThread::GetPriority}\label{wxthreadgetpriority}
 


@@ -83,7 +169,7 @@ Gets the thread identifier.
 
 Gets the priority of the thread, between zero and 100.
 
 
 Gets the priority of the thread, between zero and 100.
 

-The following priorities are already defined:
+The following priorities are defined:

 
 \twocolwidtha{7cm}
 \begin{twocollist}\itemsep=0pt
 
 \twocolwidtha{7cm}
 \begin{twocollist}\itemsep=0pt


@@ -96,25 +182,84 @@ The following priorities are already defined:
 
 \constfunc{bool}{IsAlive}{\void}
 
 
 \constfunc{bool}{IsAlive}{\void}
 

-Returns TRUE if the thread is alive.
+Returns TRUE if the thread is alive (i.e. started and not terminating).
+
+\membersection{wxThread::IsDetached}\label{wxthreadisdetached}
+
+\constfunc{bool}{IsDetached}{\void}
+
+Returns TRUE if the thread is of detached kind, FALSE if it is a joinable one.

 
 \membersection{wxThread::IsMain}\label{wxthreadismain}
 
 
 \membersection{wxThread::IsMain}\label{wxthreadismain}
 

-\constfunc{bool}{IsMain}{\void}
+\func{static bool}{IsMain}{\void}

 
 Returns TRUE if the calling thread is the main application thread.
 
 
 Returns TRUE if the calling thread is the main application thread.
 

-\membersection{wxThread::Join}\label{wxthreadjoin}
+\membersection{wxThread::IsPaused}\label{wxthreadispaused}
+
+\constfunc{bool}{IsPaused}{\void}
+
+Returns TRUE if the thread is paused.
+
+\membersection{wxThread::IsRunning}\label{wxthreadisrunning}
+
+\constfunc{bool}{IsRunning}{\void}
+
+Returns TRUE if the thread is running.
+
+\membersection{wxThread::Kill}\label{wxthreadkill}
+
+\func{wxThreadError}{Kill}{\void}

 
 

-\func{void*}{Join}{\void}
+Immediately terminates the target thread. {\bf This function is dangerous and should
+be used with extreme care (and not used at all whenever possible)!} The resources
+allocated to the thread will not be freed and the state of the C runtime library
+may become inconsistent. Use \helpref{Delete()}{wxthreaddelete} instead.

 
 

-Waits for the termination of the thread. Returns a platform-specific exit code. TODO
+For detached threads Kill() will also delete the associated C++ object,
+however this will not happen for joinable threads and this means that you will
+still have to delete the wxThread object yourself to avoid memory leaks.
+In neither case \helpref{OnExit}{wxthreadonexit} of the dying thread will be
+called, so no thread-specific cleanup will be performed.
+
+This function can only be called from another thread context, i.e. a thread
+can not kill itself.
+
+It is also an error to call this function for a thread which is not running or
+paused (in the latter case, the thread will be resumed first) - if you do it, 
+{\tt wxTHREAD\_NOT\_RUNNING} error will be returned.

 
 \membersection{wxThread::OnExit}\label{wxthreadonexit}
 
 \func{void}{OnExit}{\void}
 
 
 \membersection{wxThread::OnExit}\label{wxthreadonexit}
 
 \func{void}{OnExit}{\void}
 

-Called when the thread exits. The default implementation calls \helpref{wxThread::Join}{wxthreadjoin}.
+Called when the thread exits. This function is called in the context of the
+thread associated with the wxThread object, not in the context of the main
+thread. This function will not be called if the thread was 
+\helpref{killed}{wxthreadkill}.
+
+This function should never be called directly.
+
+\membersection{wxThread::Pause}\label{wxthreadpause}
+
+\func{wxThreadError}{Pause}{\void}
+
+Suspends the thread. Under some implementations (Win32), the thread is
+suspended immediately, under others it will only be suspended when it calls 
+\helpref{TestDestroy}{wxthreadtestdestroy} for the next time (hence, if the
+thread doesn't call it at all, it won't be suspended).
+
+This function can only be called from another thread context.
+
+\membersection{wxThread::Run}\label{wxthreadrun}
+
+\func{wxThreadError}{Run}{\void}
+
+Starts the thread execution. Should be called after 
+\helpref{Create}{wxthreadcreate}.
+
+This function can only be called from another thread context.

 
 \membersection{wxThread::SetPriority}\label{wxthreadsetpriority}
 
 
 \membersection{wxThread::SetPriority}\label{wxthreadsetpriority}
 


@@ -130,3 +275,67 @@ The following priorities are already defined:
 \twocolitem{{\bf WXTHREAD\_DEFAULT\_PRIORITY}}{50}
 \twocolitem{{\bf WXTHREAD\_MAX\_PRIORITY}}{100}
 \end{twocollist}
 \twocolitem{{\bf WXTHREAD\_DEFAULT\_PRIORITY}}{50}
 \twocolitem{{\bf WXTHREAD\_MAX\_PRIORITY}}{100}
 \end{twocollist}

+
+\membersection{wxThread::Sleep}\label{wxthreadsleep}
+
+\func{static void}{Sleep}{\param{unsigned long }{milliseconds}}
+
+Pauses the thread execution for the given amount of time.
+
+This function should be used instead of \helpref{wxSleep}{wxsleep} by all worker
+(i.e. all except the main one) threads.
+
+\membersection{wxThread::Resume}\label{wxthreadresume}
+
+\func{wxThreadError}{Resume}{\void}
+
+Resumes a thread suspended by the call to \helpref{Pause}{wxthreadpause}.
+
+This function can only be called from another thread context.
+
+\membersection{wxThread::SetConcurrency}\label{wxthreadsetconcurrency}
+
+\func{static bool}{SetConcurrency}{\param{size\_t }{level}}
+
+Sets the thread concurrency level for this process. This is, roughly, the
+number of threads that the system tries to schedule to run in parallel.
+The value of $0$ for {\it level} may be used to set the default one.
+
+Returns TRUE on success or FALSE otherwise (for example, if this function is
+not implemented for this platform (currently everything except Solaris)).
+
+\membersection{wxThread::TestDestroy}\label{wxthreadtestdestroy}
+
+\func{bool}{TestDestroy}{\void}
+
+This function should be periodically called by the thread to ensure that calls
+to \helpref{Pause}{wxthreadpause} and \helpref{Delete}{wxthreaddelete} will
+work. If it returns TRUE, the thread should exit as soon as possible.
+
+\membersection{wxThread::This}\label{wxthreadthis}
+
+\func{static wxThread *}{This}{\void}
+
+Return the thread object for the calling thread. NULL is returned if the calling thread
+is the main (GUI) thread, but \helpref{IsMain}{wxthreadismain} should be used to test
+whether the thread is really the main one because NULL may also be returned for the thread
+not created with wxThread class. Generally speaking, the return value for such thread
+is undefined.
+
+\membersection{wxThread::Yield}\label{wxthreadyield}
+
+\func{void}{Yield}{\void}
+
+Give the rest of the thread time slice to the system allowing the other threads to run.
+See also \helpref{Sleep()}{wxthreadsleep}.
+
+\membersection{wxThread::Wait}\label{wxthreadwait}
+
+\constfunc{ExitCode}{Wait}{\void}
+
+Waits until the thread terminates and returns its exit code or {\tt (ExitCode)-1} on error.
+
+You can only Wait() for joinable (not detached) threads.
+
+This function can only be called from another thread context.
+