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 called {\it light-weight 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 the foot, 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{Include files}
  16
  17 <wx/thread.h>
  18
  19 \wxheading{See also}
  20
  21 \helpref{wxMutex}{wxmutex}, \helpref{wxCondition}{wxcondition}, \helpref{wxCriticalSection}{wxcriticalsection}
  22
  23 \latexignore{\rtfignore{\wxheading{Members}}}
  24
  25 \membersection{wxThread::wxThread}\label{wxthreadctor}
  26
  27 \func{}{wxThread}{\void}
  28
  29 Default constructor: it doesn't create nor starts the thread.
  30
  31 \membersection{wxThread::\destruct{wxThread}}
  32
  33 \func{}{\destruct{wxThread}}{\void}
  34
  35 wxThread destructor is private, so you can not call it directly - i.e., deleting
  36 wxThread objects is forbidden. Instead, you should use \helpref{Delete}{wxthreaddelete} or
  37 \helpref{Kill}{wxthreadkill} methods. This also means that thread objects should
  38 eb {\bf always} allocated on the heap (i.e. with {\it new}) because the functions
  39 mentioned above will try to reclaim the storage from the heap.
  40
  41 \membersection{wxThread::Create}\label{wxthreadcreate}
  42
  43 \func{wxThreadError}{Create}{\void}
  44
  45 Creates a new thread. The thread object is created in the suspended state, you
  46 should call \helpref{Run}{wxthreadrun} to start running it.
  47
  48 \wxheading{Return value}
  49
  50 One of:
  51
  52 \twocolwidtha{7cm}
  53 \begin{twocollist}\itemsep=0pt
  54 \twocolitem{{\bf wxTHREAD\_NO\_ERROR}}{There was no error.}
  55 \twocolitem{{\bf wxTHREAD\_NO\_RESOURCE}}{There were insufficient resources to create a new thread.}
  56 \twocolitem{{\bf wxTHREAD\_RUNNING}}{The thread is already running.}
  57 \end{twocollist}
  58
  59 \membersection{wxThread::Delete}\label{wxthreaddelete}
  60
  61 \func{\void}{Delete}{\void}
  62
  63 This function should be called to terminate this thread. Unlike \helpref{Kill}{wxthreadkill}, it
  64 gives the target thread the time to terminate gracefully. Because of this, however, this function
  65 may not return immediately and if the thread is "hung" won't return at all. Also, message processing
  66 is not stopped during this function execution, so the message handlers may be called from inside
  67 it.
  68
  69 Delete() may be called for thread in any state: running, paused or even not yet created. Moreover,
  70 it must be called if \helpref{Create}{wxthreadcreate} or \helpref{Run}{wxthreadrun} fail to free
  71 the memory occupied by the thread object.
  72
  73 \membersection{wxThread::GetID}\label{wxthreadgetid}
  74
  75 \constfunc{unsigned long}{GetID}{\void}
  76
  77 Gets the thread identifier: this is a platform dependent number which uniquely identifies the
  78 thread throughout the system during its existence (i.e. the thread identifiers may be reused).
  79
  80 \membersection{wxThread::GetPriority}\label{wxthreadgetpriority}
  81
  82 \constfunc{int}{GetPriority}{\void}
  83
  84 Gets the priority of the thread, between zero and 100.
  85
  86 The following priorities are already defined:
  87
  88 \twocolwidtha{7cm}
  89 \begin{twocollist}\itemsep=0pt
  90 \twocolitem{{\bf WXTHREAD\_MIN\_PRIORITY}}{0}
  91 \twocolitem{{\bf WXTHREAD\_DEFAULT\_PRIORITY}}{50}
  92 \twocolitem{{\bf WXTHREAD\_MAX\_PRIORITY}}{100}
  93 \end{twocollist}
  94
  95 \membersection{wxThread::IsAlive}\label{wxthreadisalive}
  96
  97 \constfunc{bool}{IsAlive}{\void}
  98
  99 Returns TRUE if the thread is alive (i.e. started and not terminating).
 100
 101 \membersection{wxThread::IsMain}\label{wxthreadismain}
 102
 103 \constfunc{bool}{IsMain}{\void}
 104
 105 Returns TRUE if the calling thread is the main application thread.
 106
 107 \membersection{wxThread::IsPaused}\label{wxthreadispaused}
 108
 109 \constfunc{bool}{IsPaused}{\void}
 110
 111 Returns TRUE if the thread is paused.
 112
 113 \membersection{wxThread::IsRunning}\label{wxthreadisrunning}
 114
 115 \constfunc{bool}{IsRunning}{\void}
 116
 117 Returns TRUE if the thread is running.
 118
 119 \membersection{wxThread::Kill}\label{wxthreadkill}
 120
 121 \func{wxThreadError}{Kill}{\void}
 122
 123 Immediately terminates the target thread. {\bf This function is dangerous and should
 124 be used with extreme care (and not used at all whenever possible)!} The resources
 125 allocated to the thread will not be freed and the state of the C runtime library
 126 may become inconsistent. Use \helpref{Delete()}{wxthreaddelete} instead.
 127
 128 \membersection{wxThread::OnExit}\label{wxthreadonexit}
 129
 130 \func{void}{OnExit}{\void}
 131
 132 Called when the thread exits. This function is called in the context of the thread
 133 associated with the wxThread object, not in the context of the main thread.
 134
 135 \membersection{wxThread::Run}\label{wxthreadrun}
 136
 137 \func{wxThreadError}{Run}{\void}
 138
 139 Runs the thread.
 140
 141 \membersection{wxThread::SetPriority}\label{wxthreadsetpriority}
 142
 143 \func{void}{SetPriority}{\param{int}{ priority}}
 144
 145 Sets the priority of the thread, between zero and 100. This must be set before the thread is created.
 146
 147 The following priorities are already defined:
 148
 149 \twocolwidtha{7cm}
 150 \begin{twocollist}\itemsep=0pt
 151 \twocolitem{{\bf WXTHREAD\_MIN\_PRIORITY}}{0}
 152 \twocolitem{{\bf WXTHREAD\_DEFAULT\_PRIORITY}}{50}
 153 \twocolitem{{\bf WXTHREAD\_MAX\_PRIORITY}}{100}
 154 \end{twocollist}
 155
 156 \membersection{wxThread::Sleep}\label{wxthreadsleep}
 157
 158 \func{\void}{Sleep}{\param{unsigned long }{milliseconds}}
 159
 160 Pauses the thread execution for the given amount of time.
 161
 162 This function should be used instead of \helpref{wxSleep}{wxsleep} by all worker
 163 (i.e. all except the main one) threads.
 164
 165 \membersection{wxThread::This}\label{wxthreadthis}
 166
 167 \func{wxThread *}{This}{\void}
 168
 169 Return the thread object for the calling thread. NULL is returned if the calling thread
 170 is the main (GUI) thread, but \helpref{IsMain}{wxthreadismain} should be used to test
 171 whether the thread is really the main one because NULL may also be returned for the thread
 172 not created with wxThread class. Generally speaking, the return value for such thread
 173 is undefined.
 174
 175 \membersection{wxThread::Yield}\label{wxthreadyield}
 176
 177 \func{\void}{Yield}{\void}
 178
 179 Give the rest of the thread time slice to the system allowing the other threads to run.
 180 See also \helpref{Sleep()}{wxthreadsleep}.
 181