diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/Thread.3 | 66 |
1 files changed, 25 insertions, 41 deletions
diff --git a/doc/Thread.3 b/doc/Thread.3 index 984b9fd..72b572d 100644 --- a/doc/Thread.3 +++ b/doc/Thread.3 @@ -5,7 +5,7 @@ '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: Thread.3,v 1.16 2004/04/16 20:44:18 dgp Exp $ +'\" RCS: @(#) $Id: Thread.3,v 1.17 2004/04/26 09:16:50 dkf Exp $ '\" .so man.macros .TH Threads 3 "8.1" Tcl "Tcl Library Procedures" @@ -43,7 +43,7 @@ int int \fBTcl_JoinThread\fR(\fIid, result\fR) .SH ARGUMENTS -.AS Tcl_ThreadDataKey *keyPtr +.AS Tcl_CreateThreadProc *keyPtr .AP Tcl_Condition *condPtr in A condition variable, which must be associated with a mutex lock. .AP Tcl_Mutex *mutexPtr in @@ -88,12 +88,10 @@ when you configure and compile your Tcl core. An important constraint of the Tcl threads implementation is that \fIonly the thread that created a Tcl interpreter can use that interpreter\fR. In other words, multiple threads can not access -the same Tcl interpreter. (However, as was the case in previous -releases, a single thread can safely create and use multiple -interpreters.) -.PP -.VS 8.3.1 -Tcl does provide \fBTcl_CreateThread\fR for creating threads. The +the same Tcl interpreter. (However, a single thread can safely create +and use multiple interpreters.) +.SH DESCRIPTION +Tcl provides \fBTcl_CreateThread\fR for creating threads. The caller can determine the size of the stack given to the new thread and modify the behaviour through the supplied \fIflags\fR. The value \fBTCL_THREAD_STACK_DEFAULT\fR for the \fIstackSize\fR indicates that @@ -110,14 +108,12 @@ contain the functionality to specify the stacksize of a thread. The specified value for the stacksize is ignored on these systems. Windows currently does not support joinable threads. This flag value is therefore ignored on this platform. -.VE .PP Tcl does provide \fBTcl_ExitThread\fR and \fBTcl_FinalizeThread\fR for terminating threads and invoking optional per-thread exit handlers. See the \fBTcl_Exit\fR page for more information on these procedures. .PP -.VS The \fBTcl_JoinThread\fR function is provided to allow threads to wait upon the exit of another thread, which must have been marked as joinable through usage of the \fBTCL_THREAD_JOINABLE\fR-flag during @@ -129,30 +125,24 @@ thread which already exited is possible, the system will retain the necessary information until after the call to \fBTcl_JoinThread\fR. This means that not calling \fBTcl_JoinThread\fR for a joinable thread will cause a memory leak. -.VE .PP +The \fBTcl_GetThreadData\fR call returns a pointer to a block of +thread-private data. Its argument is a key that is shared by all threads +and a size for the block of storage. The storage is automatically +allocated and initialized to all zeros the first time each thread asks for it. +The storage is automatically deallocated by \fBTcl_FinalizeThread\fR. +.SS "SYNCHRONIZATION AND COMMUNICATION" Tcl provides \fBTcl_ThreadQueueEvent\fR and \fBTcl_ThreadAlert\fR for handling event queueing in multithreaded applications. See the \fBNotifier\fR manual page for more information on these procedures. .PP -In this release, the Tcl language itself provides no support for -creating multithreaded scripts (for example, scripts that could spawn -a Tcl interpreter in a separate thread). If you need to add this -feature at this time, see the \fItclThreadTest.c\fR -file in the Tcl source distribution for an experimental implementation -of a Tcl "Thread" package implementing thread creation and management -commands at the script level. - -.SH DESCRIPTION A mutex is a lock that is used to serialize all threads through a piece of code by calling \fBTcl_MutexLock\fR and \fBTcl_MutexUnlock\fR. If one thread holds a mutex, any other thread calling \fBTcl_MutexLock\fR will block until \fBTcl_MutexUnlock\fR is called. -.VS A mutex can be destroyed after its use by calling \fBTcl_MutexFinalize\fR. The result of locking a mutex twice from the same thread is undefined. On some platforms it will result in a deadlock. -.VE The \fBTcl_MutexLock\fR, \fBTcl_MutexUnlock\fR and \fBTcl_MutexFinalize\fR procedures are defined as empty macros if not compiling with threads enabled. .PP @@ -172,40 +162,34 @@ The caller of \fBTcl_ConditionWait\fR should be prepared for spurious notifications by calling \fBTcl_ConditionWait\fR within a while loop that tests some invariant. .PP -.VS A condition variable can be destroyed after its use by calling \fBTcl_ConditionFinalize\fR. .PP The \fBTcl_ConditionNotify\fR, \fBTcl_ConditionWait\fR and \fBTcl_ConditionFinalize\fR procedures are defined as empty macros if not compiling with threads enabled. -.VE -.PP -The \fBTcl_GetThreadData\fR call returns a pointer to a block of -thread-private data. Its argument is a key that is shared by all threads -and a size for the block of storage. The storage is automatically -allocated and initialized to all zeros the first time each thread asks for it. -The storage is automatically deallocated by \fBTcl_FinalizeThread\fR. -.SH INITIALIZATION +.SS INITIALIZATION .PP All of these synchronization objects are self initializing. They are implemented as opaque pointers that should be NULL upon first use. The mutexes and condition variables are -.VS either cleaned up by process exit handlers (if living that long) or explicitly by calls to \fBTcl_MutexFinalize\fR or \fBTcl_ConditionFinalize\fR. -.VE Thread local storage is reclaimed during \fBTcl_FinalizeThread\fR. -.SH "CREATING THREADS" -The API to create threads is not finalized at this time. -There are private facilities to create threads that contain a new -Tcl interpreter, and to send scripts among threads. -Dive into tclThreadTest.c and tclThread.c for examples. +.SH "SCRIPT-LEVEL ACCESS TO THREADS" +.VS 8.5 +Tcl provides no built-in commands for scripts to use to create, +manage, or join threads, nor any script-level access to mutex or +condition variables. It provides such facilities only via C +interfaces, and leaves it up to packages to expose these matters to +the script level. One such package is the \fBThread\fR package. +.VE 8.5 .SH "SEE ALSO" -Tcl_GetCurrentThread, Tcl_ThreadQueueEvent, Tcl_ThreadAlert, -Tcl_ExitThread, Tcl_FinalizeThread, -Tcl_CreateThreadExitHandler, Tcl_DeleteThreadExitHandler +Tcl_GetCurrentThread(3), Tcl_ThreadQueueEvent(3), Tcl_ThreadAlert(3), +Tcl_ExitThread(3), Tcl_FinalizeThread(3), +Tcl_CreateThreadExitHandler(3), Tcl_DeleteThreadExitHandler(3), +\fBThread\fR package .SH KEYWORDS thread, mutex, condition variable, thread local storage |