docs/latex/wx/thread.tex

   1 \section{\class{wxThread}}\label{wxthread}
   2
   3 A thread is basically a path of execution through a program. Threads are also
   4 sometimes calls {\it light-wight processes}, but the fundamental difference
   5 between threads and processes is that memory spaces of different processes are
   6 separated while all threads share the same address space. While it makes it
   7 much easier to share common data between several threads, it also makes much
   8 easier to shoot oneself in a leg, so careful use of synchronization objects
   9 such as \helpref{mutexes}{wxmutex} and/or \helpref{critical sections}{wxcriticalsection} is recommended.
  10
  11 \wxheading{Derived from}
  12
  13 None.
  14
  15 \wxheading{See also}
  16
  17 \helpref{wxMutex}{wxmutex}, \helpref{wxCondition}{wxcondition}, \helpref{wxCriticalSection}{wxarraywxcriticalsection}
  18
  19 \latexignore{\rtfignore{\wxheading{Members}}}
  20
  21 \membersection{wxThread::wxThread}\label{wxthreadctor}
  22
  23 \func{}{wxThread}{\void}
  24
  25 Default constructor: it doesn't create nor starts the thread.
  26
  27 \membersection{wxThread::\destruct{wxThread}}
  28
  29 \func{}{\destruct{wxThread}}{\void}
  30
  31 wxThread destructor is private, so you can not call it directly - i.e., deleting
  32 wxThread objects is forbidden. Instead, you should use \helpref{Delete}{wxthreaddelete} or
  33 \helpref{Kill}{wxthreadkill} methods. This also means that thread objects should
  34 eb {\bf always} allocated on the heap (i.e. with {\it new}) because the functions
  35 mentioned above will try to reclaim the storage from the heap.
  36
  37 \membersection{wxThread::Create}\label{wxthreadcreate}
  38
  39 \func{wxThreadError}{Create}{\void}
  40
  41 Creates a new thread. The thread object is created in the suspended state, you
  42 should call \helpref{Run}{wxthreadrun} to start running it.
  43
  44 \wxheading{Return value}
  45
  46 One of:
  47
  48 \twocolwidtha{7cm}
  49 \begin{twocollist}\itemsep=0pt
  50 \twocolitem{{\bf wxTHREAD\_NO\_ERROR}}{There was no error.}
  51 \twocolitem{{\bf wxTHREAD\_NO\_RESOURCE}}{There were insufficient resources to create a new thread.}
  52 \twocolitem{{\bf wxTHREAD\_RUNNING}}{The thread is already running.}
  53 \end{twocollist}
  54
  55 \membersection{wxThread::Delete}\label{wxthreaddelete}
  56
  57 \func{\void}{Delete}{\void}
  58
  59 This function should be called to terminate this thread. Unlike \helpref{Kill}{wxthreadkill}, it
  60 gives the target thread the time to terminate gracefully. Because of this, however, this function
  61 may not return immediately and if the thread is "hung" won't return at all. Also, message processing
  62 is not stopped during this function execution, so the message handlers may be called from inside
  63 it.
  64
  65 Delete() may be called for thread in any state: running, paused or even not yet created. Moreover,
  66 it must be called if \helpref{Create}{wxthreadcreate} or \helpref{Run}{wxthreadrun} fail to free
  67 the memory occupied by the thread object.
  68
  69 \membersection{wxThread::GetID}\label{wxthreadgetid}
  70
  71 \constfunc{unsigned long}{GetID}{\void}
  72
  73 Gets the thread identifier: this is a platform dependent number which uniquely identifies the
  74 thread throughout the system during its existence (i.e. the thread identifiers may be reused).
  75
  76 \membersection{wxThread::GetPriority}\label{wxthreadgetpriority}
  77
  78 \constfunc{int}{GetPriority}{\void}
  79
  80 Gets the priority of the thread, between zero and 100.
  81
  82 The following priorities are already defined:
  83
  84 \twocolwidtha{7cm}
  85 \begin{twocollist}\itemsep=0pt
  86 \twocolitem{{\bf WXTHREAD\_MIN\_PRIORITY}}{0}
  87 \twocolitem{{\bf WXTHREAD\_DEFAULT\_PRIORITY}}{50}
  88 \twocolitem{{\bf WXTHREAD\_MAX\_PRIORITY}}{100}
  89 \end{twocollist}
  90
  91 \membersection{wxThread::IsAlive}\label{wxthreadisalive}
  92
  93 \constfunc{bool}{IsAlive}{\void}
  94
  95 Returns TRUE if the thread is alive (i.e. started and not terminating).
  96
  97 \membersection{wxThread::IsMain}\label{wxthreadismain}
  98
  99 \constfunc{bool}{IsMain}{\void}
 100
 101 Returns TRUE if the calling thread is the main application thread.
 102
 103 \membersection{wxThread::IsPaused}\label{wxthreadispaused}
 104
 105 \constfunc{bool}{IsPaused}{\void}
 106
 107 Returns TRUE if the thread is paused.
 108
 109 \membersection{wxThread::IsRunning}\label{wxthreadisrunning}
 110
 111 \constfunc{bool}{IsRunning}{\void}
 112
 113 Returns TRUE if the thread is running.
 114
 115 \membersection{wxThread::Kill}\label{wxthreadkill}
 116
 117 \func{wxThreadError}{Kill}{\void}
 118
 119 Immediately terminates the target thread. {\bf This function is dangerous and should
 120 be used with extreme care (and not used at all whenever possible)!} The resources
 121 allocated to the thread will not be freed and the state of the C runtime library
 122 may become inconsistent. Use \helpref{Delete()}{wxthreaddelete} instead.
 123
 124 \membersection{wxThread::OnExit}\label{wxthreadonexit}
 125
 126 \func{void}{OnExit}{\void}
 127
 128 Called when the thread exits. This function is called in the context of the thread
 129 associated with the wxThread object, not in the context of the main thread.
 130
 131 \membersection{wxThread::SetPriority}\label{wxthreadsetpriority}
 132
 133 \func{void}{SetPriority}{\param{int}{ priority}}
 134
 135 Sets the priority of the thread, between zero and 100. This must be set before the thread is created.
 136
 137 The following priorities are already defined:
 138
 139 \twocolwidtha{7cm}
 140 \begin{twocollist}\itemsep=0pt
 141 \twocolitem{{\bf WXTHREAD\_MIN\_PRIORITY}}{0}
 142 \twocolitem{{\bf WXTHREAD\_DEFAULT\_PRIORITY}}{50}
 143 \twocolitem{{\bf WXTHREAD\_MAX\_PRIORITY}}{100}
 144 \end{twocollist}
 145
 146 \membersection{wxThread::Sleep}\label{wxthreadsleep}
 147
 148 \func{\void}{Sleep}{\param{unsigned long }{milliseconds}}
 149
 150 Pauses the thread execution for the given amount of time.
 151
 152 This function should be used instead of \helpref{wxSleep}{wxsleep} by all worker
 153 (i.e. all except the main one) threads.
 154
 155 \membersection{wxThread::This}\label{wxthreadthis}
 156
 157 \func{wxThread *}{This}{\void}
 158
 159 Return the thread object for the calling thread. NULL is returned if the calling thread
 160 is the main (GUI) thread, but \helpref{IsMain}{wxthreadismain} should be used to test
 161 whether the thread is really the main one because NULL may also be returned for the thread
 162 not created with wxThread class. Generally speaking, the return value for such thread
 163 is undefined.
 164
 165 \membersection{wxThread::Yield}\label{wxthreadyield}
 166
 167 \func{\void}{Yield}{\void}
 168
 169 Give the rest of the thread time slice to the system allowing the other threads to run.
 170 See also \helpref{Sleep()}{wxthreadsleep}.