X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/954b8ae60391d18b87a604e7919c87c0c6ae208b..2cd31b57b27edc34515b11f4023201d96fec0b37:/docs/latex/wx/thread.tex?ds=sidebyside

diff --git a/docs/latex/wx/thread.tex b/docs/latex/wx/thread.tex
index 8910946811..001281e5fd 100644
--- a/docs/latex/wx/thread.tex
+++ b/docs/latex/wx/thread.tex
@@ -8,6 +8,25 @@ 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.
 
+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.
@@ -26,17 +45,24 @@ 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}
 
@@ -58,21 +84,62 @@ One of:
 
 \membersection{wxThread::Delete}\label{wxthreaddelete}
 
-\func{\void}{Delete}{\void}
+\func{void}{Delete}{\void}
+
+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.
 
-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.
+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 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::GetCPUCount}\label{wxthreadgetcpucount}
 
-\membersection{wxThread::GetID}\label{wxthreadgetid}
+\func{static int}{GetCPUCount}{\void}
 
-\constfunc{unsigned long}{GetID}{\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).
@@ -83,7 +150,7 @@ thread throughout the system during its existence (i.e. the thread identifiers m
 
 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
@@ -98,9 +165,15 @@ The following priorities are already defined:
 
 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.
 
@@ -125,6 +198,10 @@ be used with extreme care (and not used at all whenever possible)!} The resource
 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}
@@ -132,11 +209,27 @@ may become inconsistent. Use \helpref{Delete()}{wxthreaddelete} instead.
 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}
 
@@ -155,16 +248,43 @@ The following priorities are already defined:
 
 \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
@@ -174,8 +294,19 @@ is undefined.
 
 \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.
+
