X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/e14dccff1c43da7efdba7fcf63bdfb4bab22a428..a6f3598d2b1fbfe82147ad5ae18f7d63484be406:/docs/latex/wx/thread.tex diff --git a/docs/latex/wx/thread.tex b/docs/latex/wx/thread.tex index fab79009fc..89bc18dd24 100644 --- a/docs/latex/wx/thread.tex +++ b/docs/latex/wx/thread.tex @@ -1,34 +1,49 @@ \section{\class{wxThread}}\label{wxthread} -A wxThread manages a system thread, code which executes as a mini-process within the application. +A thread is basically a path of execution through a program. Threads are also +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 +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. \wxheading{Derived from} None. +\wxheading{Include files} + + + \wxheading{See also} -\helpref{wxMutex}{wxmutex}, \helpref{wxCondition}{wxcondition} +\helpref{wxMutex}{wxmutex}, \helpref{wxCondition}{wxcondition}, \helpref{wxCriticalSection}{wxcriticalsection} \latexignore{\rtfignore{\wxheading{Members}}} -\membersection{wxThread::wxThread}\label{wxthreadconstr} +\membersection{wxThread::wxThread}\label{wxthreadctor} \func{}{wxThread}{\void} -Default constructor. +Default constructor: it doesn't create nor starts the thread. \membersection{wxThread::\destruct{wxThread}} \func{}{\destruct{wxThread}}{\void} -Destroys the wxThread object. +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. \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} @@ -36,39 +51,41 @@ One of: \twocolwidtha{7cm} \begin{twocollist}\itemsep=0pt -\twocolitem{{\bf THREAD\_NO\_ERROR}}{There was no error.} -\twocolitem{{\bf THREAD\_NO\_RESOURCE}}{There were insufficient resources to create a new thread.} -\twocolitem{{\bf THREAD\_RUNNING}}{The thread is already running.} +\twocolitem{{\bf wxTHREAD\_NO\_ERROR}}{There was no error.} +\twocolitem{{\bf wxTHREAD\_NO\_RESOURCE}}{There were insufficient resources to create a new thread.} +\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. +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. -\membersection{wxThread::Destroy}\label{wxthreaddestroy} +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. -\func{wxThreadError}{Destroy}{\void} +\membersection{wxThread::Entry}\label{wxthreadentry} -Destroys the thread immediately unless the application has specified deferral via \helpref{wxThread::DeferDestroy}{deferdestroy}. +\func{virtual void *}{Entry}{\void} -\wxheading{Return value} +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. -One of: - -\twocolwidtha{7cm} -\begin{twocollist}\itemsep=0pt -\twocolitem{{\bf THREAD\_NO\_ERROR}}{There was no error.} -\twocolitem{{\bf THREAD\_NOT\_RUNNING}}{The thread is not running.} -\end{twocollist} +The returned value is the thread exit code but is currently ignored in +wxWindows implementation (this will change in near future). \membersection{wxThread::GetID}\label{wxthreadgetid} \constfunc{unsigned long}{GetID}{\void} -Gets the thread identifier. +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} @@ -89,25 +106,47 @@ The following priorities are already defined: \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::IsMain}\label{wxthreadismain} \constfunc{bool}{IsMain}{\void} -Returns TRUE if the thread is the main application thread. +Returns TRUE if the calling thread is the main application thread. + +\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} -\membersection{wxThread::Join}\label{wxthreadjoin} +Returns TRUE if the thread is running. -\func{void*}{Join}{\void} +\membersection{wxThread::Kill}\label{wxthreadkill} -Waits for the termination of the thread. Returns a platform-specific exit code. TODO +\func{wxThreadError}{Kill}{\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. \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. + +\membersection{wxThread::Run}\label{wxthreadrun} + +\func{wxThreadError}{Run}{\void} + +Runs the thread. \membersection{wxThread::SetPriority}\label{wxthreadsetpriority} @@ -124,8 +163,29 @@ The following priorities are already defined: \twocolitem{{\bf WXTHREAD\_MAX\_PRIORITY}}{100} \end{twocollist} +\membersection{wxThread::Sleep}\label{wxthreadsleep} + +\func{\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::This}\label{wxthreadthis} + +\func{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}. -%%% Local Variables: -%%% mode: latex -%%% TeX-master: "referenc" -%%% End: