X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/9063ea8ee28601bfa00b6c724847ff22eced970d..afbe906abdf9aa69a56571b8b20b095351dd8f34:/docs/latex/wx/conditn.tex?ds=sidebyside diff --git a/docs/latex/wx/conditn.tex b/docs/latex/wx/conditn.tex index 777a3cd226..88b04eeb28 100644 --- a/docs/latex/wx/conditn.tex +++ b/docs/latex/wx/conditn.tex @@ -5,12 +5,70 @@ objects. They may be used in a multithreaded application to wait until the given condition becomes true which happens when the condition becomes signaled. For example, if a worker thread is doing some long task and another thread has -to wait until it's finished, the latter thread will wait on the condition +to wait until it is finished, the latter thread will wait on the condition object and the worker thread will signal it on exit (this example is not perfect because in this particular case it would be much better to just \helpref{Wait()}{wxthreadwait} for the worker thread, but if there are several worker threads it already makes much more sense). +Note that a call to \helpref{Signal()}{wxconditionsignal} may happen before the +other thread calls \helpref{Wait()}{wxconditionwait} but, in marked contrast +with the pthread conditions, this will still work as the missed signals are +queued and \helpref{Wait()}{wxconditionwait} simply returns immediately if +there are ny pending signals. + +However, the calls to \helpref{Broadcast()}{wxconditionbroadcast} are {\bf not} +queued and so it will only wake up the threads already waiting on the +condition. Accordingly, you will probably want to use a mutex to ensure that +the thread(s) you want to be waken up have indeed started to wait before +calling \helpref{Broadcast()}{wxconditionbroadcast}. + +\wxheading{Example} + +This example shows how a main thread may launch a worker thread and wait until +it starts running: + +\begin{verbatim} +class MyWaitingThread : public wxThread +{ +public: + MyWaitingThread(wxCondition *condition) + { + m_condition = condition; + + Create(); + } + + virtual ExitCode Entry() + { + // let the main thread know that we started running + m_condition->Signal(); + + ... do our job ... + + return 0; + } + +private: + wxCondition *m_condition; +}; + +int main() +{ + wxCondition condition; + MyWaitingThread *thread - new MyWaitingThread(&condition); + + thread->Run(); + + // wait until the thread really starts running + condition.Wait(); + + ... + + return 0; +} +\end{verbatim} + \wxheading{Derived from} None. @@ -51,18 +109,16 @@ Signals the object. \membersection{wxCondition::Wait}\label{wxconditionwait} -\func{void}{Wait}{\param{wxMutex\&}{ mutex}} +\func{void}{Wait}{\void} Waits indefinitely. -\func{bool}{Wait}{\param{wxMutex\&}{ mutex}, \param{unsigned long}{ sec}, \param{unsigned long}{ nsec}} +\func{bool}{Wait}{\param{unsigned long}{ sec}, \param{unsigned long}{ nsec}} Waits until a signal is raised or the timeout has elapsed. \wxheading{Parameters} -\docparam{mutex}{wxMutex object.} - \docparam{sec}{Timeout in seconds} \docparam{nsec}{Timeout nanoseconds component (added to {\it sec}).}