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.
\func{}{wxThread}{\void}
-Default constructor: it doesn't create nor starts the thread.
+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.
\membersection{wxThread::\destruct{wxThread}}
\func{}{\destruct{wxThread}}{\void}
-wxThread destructor is private, so you can not call it directly - i.e., deleting
-wxThread objects is forbidden. Instead, you should use \helpref{Delete}{wxthreaddelete} or
-\helpref{Kill}{wxthreadkill} methods. This also means that thread objects should
-eb {\bf always} allocated on the heap (i.e. with {\it new}) because the functions
-mentioned above will try to reclaim the storage from the heap.
+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{void}{Delete}{\void}
-This function should be called to terminate this thread. Unlike \helpref{Kill}{wxthreadkill}, it
-gives the target thread the time to terminate gracefully. Because of this, however, this function
-may not return immediately and if the thread is "hung" won't return at all. Also, message processing
-is not stopped during this function execution, so the message handlers may be called from inside
-it.
+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.
+
+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!
+
+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).
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.
+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.
+
+For detached threads Delete() will also delete the C++ thread object, but it
+will not do this for joinable ones.
+
+This function can only be called from another thread context.
\membersection{wxThread::Entry}\label{wxthreadentry}
-\func{virtual void *}{Entry}{\void}
+\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 but is currently ignored in
-wxWindows implementation (this will change in near future).
+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::GetCPUCount}\label{wxthreadgetcpucount}
+
+\func{static int}{GetCPUCount}{\void}
+
+Returns the number of system CPUs or -1 if the value is unknown.
-\membersection{wxThread::GetID}\label{wxthreadgetid}
+\wxheading{See also}
+
+\helpref{SetConcurrency}{wxthreadsetconcurrency}
+
+\membersection{wxThread::GetId}\label{wxthreadgetid}
-\constfunc{unsigned long}{GetID}{\void}
+\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).
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
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}
-\constfunc{bool}{IsMain}{\void}
+\func{static bool}{IsMain}{\void}
Returns TRUE if the calling thread is the main application thread.
allocated to the thread will not be freed and the state of the C runtime library
may become inconsistent. Use \helpref{Delete()}{wxthreaddelete} instead.
+For detached threads Kill() will also delete the associated C++ object.
+
+This function can only be called from another thread context.
+
\membersection{wxThread::OnExit}\label{wxthreadonexit}
\func{void}{OnExit}{\void}
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 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}
-Runs the thread.
+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::Sleep}\label{wxthreadsleep}
-\func{\void}{Sleep}{\param{unsigned long }{milliseconds}}
+\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{wxThread *}{This}{\void}
+\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
\membersection{wxThread::Yield}\label{wxthreadyield}
-\func{\void}{Yield}{\void}
+\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.
projects / wxWidgets.git / blobdiff