'\" 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 1.14 2002/07/01 18:24:39 jenglish Exp $
-'\"
-'\" The definitions below are for supplemental macros used in Tcl/Tk
-'\" manual entries.
-'\"
-'\" .AP type name in/out ?indent?
-'\" Start paragraph describing an argument to a library procedure.
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-'\" Give maximum sizes of arguments for setting tab stops. Type and
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-'\" Begin code excerpt.
-'\"
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-'\"
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-'\"
-'\" .SE
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-'\"
-'\" .OP cmdName dbName dbClass
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-'\"
-'\" .UL arg1 arg2
-'\" Print arg1 underlined, then print arg2 normally.
-'\"
-'\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
-'\"
-'\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
+.TH Threads 3 "8.1" Tcl "Tcl Library Procedures"
+.\" The -*- nroff -*- definitions below are for supplemental macros used
+.\" in Tcl/Tk manual entries.
+.\"
+.\" .AP type name in/out ?indent?
+.\" Start paragraph describing an argument to a library procedure.
+.\" type is type of argument (int, etc.), in/out is either "in", "out",
+.\" or "in/out" to describe whether procedure reads or modifies arg,
+.\" and indent is equivalent to second arg of .IP (shouldn't ever be
+.\" needed; use .AS below instead)
+.\"
+.\" .AS ?type? ?name?
+.\" Give maximum sizes of arguments for setting tab stops. Type and
+.\" name are examples of largest possible arguments that will be passed
+.\" to .AP later. If args are omitted, default tab stops are used.
+.\"
+.\" .BS
+.\" Start box enclosure. From here until next .BE, everything will be
+.\" enclosed in one large box.
+.\"
+.\" .BE
+.\" End of box enclosure.
+.\"
+.\" .CS
+.\" Begin code excerpt.
+.\"
+.\" .CE
+.\" End code excerpt.
+.\"
+.\" .VS ?version? ?br?
+.\" Begin vertical sidebar, for use in marking newly-changed parts
+.\" of man pages. The first argument is ignored and used for recording
+.\" the version when the .VS was added, so that the sidebars can be
+.\" found and removed when they reach a certain age. If another argument
+.\" is present, then a line break is forced before starting the sidebar.
+.\"
+.\" .VE
+.\" End of vertical sidebar.
+.\"
+.\" .DS
+.\" Begin an indented unfilled display.
+.\"
+.\" .DE
+.\" End of indented unfilled display.
+.\"
+.\" .SO ?manpage?
+.\" Start of list of standard options for a Tk widget. The manpage
+.\" argument defines where to look up the standard options; if
+.\" omitted, defaults to "options". The options follow on successive
+.\" lines, in three columns separated by tabs.
+.\"
+.\" .SE
+.\" End of list of standard options for a Tk widget.
+.\"
+.\" .OP cmdName dbName dbClass
+.\" Start of description of a specific option. cmdName gives the
+.\" option's name as specified in the class command, dbName gives
+.\" the option's name in the option database, and dbClass gives
+.\" the option's class in the option database.
+.\"
+.\" .UL arg1 arg2
+.\" Print arg1 underlined, then print arg2 normally.
+.\"
+.\" .QW arg1 ?arg2?
+.\" Print arg1 in quotes, then arg2 normally (for trailing punctuation).
+.\"
+.\" .PQ arg1 ?arg2?
+.\" Print an open parenthesis, arg1 in quotes, then arg2 normally
+.\" (for trailing punctuation) and then a closing parenthesis.
+.\"
+.\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
.if t .wh -1.3i ^B
.nr ^l \n(.l
.ad b
-'\" # Start an argument description
+.\" # Start an argument description
.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.\}
.ta \\n()Au \\n()Bu
.ie !"\\$3"" \{\
-\&\\$1 \\fI\\$2\\fP (\\$3)
+\&\\$1 \\fI\\$2\\fP (\\$3)
.\".b
.\}
.el \{\
.\}
.\}
..
-'\" # define tabbing values for .AP
+.\" # define tabbing values for .AP
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.nr )A 10n
.if !"\\$1"" .nr )A \\w'\\$1'u+3n
.nr )C \\n()Bu+\\w'(in/out)'u+2n
..
.AS Tcl_Interp Tcl_CreateInterp in/out
-'\" # BS - start boxed text
-'\" # ^y = starting y location
-'\" # ^b = 1
+.\" # BS - start boxed text
+.\" # ^y = starting y location
+.\" # ^b = 1
.de BS
.br
.mk ^y
.if n \l'\\n(.lu\(ul'
.if n .fi
..
-'\" # BE - end boxed text (draw box now)
+.\" # BE - end boxed text (draw box now)
.de BE
.nf
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.br
.nr ^b 0
..
-'\" # VS - start vertical sidebar
-'\" # ^Y = starting y location
-'\" # ^v = 1 (for troff; for nroff this doesn't matter)
+.\" # VS - start vertical sidebar
+.\" # ^Y = starting y location
+.\" # ^v = 1 (for troff; for nroff this doesn't matter)
.de VS
.if !"\\$2"" .br
.mk ^Y
.ie n 'mc \s12\(br\s0
.el .nr ^v 1u
..
-'\" # VE - end of vertical sidebar
+.\" # VE - end of vertical sidebar
.de VE
.ie n 'mc
.el \{\
.\}
.nr ^v 0
..
-'\" # Special macro to handle page bottom: finish off current
-'\" # box/sidebar if in box/sidebar mode, then invoked standard
-'\" # page bottom macro.
+.\" # Special macro to handle page bottom: finish off current
+.\" # box/sidebar if in box/sidebar mode, then invoked standard
+.\" # page bottom macro.
.de ^B
.ev 2
'ti 0
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.\}
..
-'\" # DS - begin display
+.\" # DS - begin display
.de DS
.RS
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.sp
..
-'\" # DE - end display
+.\" # DE - end display
.de DE
.fi
.RE
.sp
..
-'\" # SO - start of list of standard options
+.\" # SO - start of list of standard options
.de SO
+'ie '\\$1'' .ds So \\fBoptions\\fR
+'el .ds So \\fB\\$1\\fR
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 5.5c 11c
.ft B
..
-'\" # SE - end of list of standard options
+.\" # SE - end of list of standard options
.de SE
.fi
.ft R
.LP
-See the \\fBoptions\\fR manual entry for details on the standard options.
+See the \\*(So manual entry for details on the standard options.
..
-'\" # OP - start of full description for a single option
+.\" # OP - start of full description for a single option
.de OP
.LP
.nf
.fi
.IP
..
-'\" # CS - begin code excerpt
+.\" # CS - begin code excerpt
.de CS
.RS
.nf
.ta .25i .5i .75i 1i
..
-'\" # CE - end code excerpt
+.\" # CE - end code excerpt
.de CE
.fi
.RE
..
+.\" # UL - underline word
.de UL
\\$1\l'|0\(ul'\\$2
..
-.TH Threads 3 "8.1" Tcl "Tcl Library Procedures"
+.\" # QW - apply quotation marks to word
+.de QW
+.ie '\\*(lq'"' ``\\$1''\\$2
+.\"" fix emacs highlighting
+.el \\*(lq\\$1\\*(rq\\$2
+..
+.\" # PQ - apply parens and quotation marks to word
+.de PQ
+.ie '\\*(lq'"' (``\\$1''\\$2)\\$3
+.\"" fix emacs highlighting
+.el (\\*(lq\\$1\\*(rq\\$2)\\$3
+..
+.\" # QR - quoted range
+.de QR
+.ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3
+.\"" fix emacs highlighting
+.el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3
+..
+.\" # MT - "empty" string
+.de MT
+.QW ""
+..
.BS
.SH NAME
-Tcl_ConditionNotify, Tcl_ConditionWait, Tcl_ConditionFinalize, Tcl_GetThreadData, Tcl_MutexLock, Tcl_MutexUnlock, Tcl_MutexFinalize, Tcl_CreateThread, Tcl_JoinThread \- Tcl thread support.
+Tcl_ConditionNotify, Tcl_ConditionWait, Tcl_ConditionFinalize, Tcl_GetThreadData, Tcl_MutexLock, Tcl_MutexUnlock, Tcl_MutexFinalize, Tcl_CreateThread, Tcl_JoinThread \- Tcl thread support
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
\fBTcl_MutexFinalize\fR(\fImutexPtr\fR)
.sp
int
-\fBTcl_CreateThread\fR(\fIidPtr, threadProc, clientData, stackSize, flags\fR)
+\fBTcl_CreateThread\fR(\fIidPtr, proc, clientData, stackSize, flags\fR)
.sp
int
\fBTcl_JoinThread\fR(\fIid, result\fR)
.SH ARGUMENTS
-.AS Tcl_ThreadDataKey *keyPtr
+.AS Tcl_CreateThreadProc proc out
.AP Tcl_Condition *condPtr in
A condition variable, which must be associated with a mutex lock.
-.AP Tcl_Condition *mutexPtr in
+.AP Tcl_Mutex *mutexPtr in
A mutex lock.
-.AP Tcl_Time *timePtr in
+.AP "const Tcl_Time" *timePtr in
A time limit on the condition wait. NULL to wait forever.
-Note that a polling value of 0 seconds doesn't make much sense.
+Note that a polling value of 0 seconds does not make much sense.
.AP Tcl_ThreadDataKey *keyPtr in
This identifies a block of thread local storage. The key should be
static and process-wide, yet each thread will end up associating
returned by the operating system.
.AP Tcl_ThreadId id in
Id of the thread waited upon.
-.AP Tcl_ThreadCreateProc threadProc in
+.AP Tcl_ThreadCreateProc *proc in
This procedure will act as the \fBmain()\fR of the newly created
thread. The specified \fIclientData\fR will be its sole argument.
.AP ClientData clientData in
-Arbitrary information. Passed as sole argument to the \fIthreadProc\fR.
+Arbitrary information. Passed as sole argument to the \fIproc\fR.
.AP int stackSize in
The size of the stack given to the new thread.
.AP int flags in
-Bitmask containing flags allowing the caller to modify behaviour of
+Bitmask containing flags allowing the caller to modify behavior of
the new thread.
.AP int *result out
The referred storage is used to place the exit code of the thread
Beginning with the 8.1 release, the Tcl core is thread safe, which
allows you to incorporate Tcl into multithreaded applications without
customizing the Tcl core. To enable Tcl multithreading support,
-you must include the \fB--enable-threads\fR option to \fBconfigure\fR
+you must include the \fB\-\|\-enable-threads\fR option to \fBconfigure\fR
when you configure and compile your Tcl core.
.PP
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
+modify the behavior through the supplied \fIflags\fR. The value
\fBTCL_THREAD_STACK_DEFAULT\fR for the \fIstackSize\fR indicates that
the default size as specified by the operating system is to be used
-for the new thread. As for the flags, currently are only the values
-\fBTCL_THREAD_NOFLAGS\fR and \fBTCL_THREAD_JOINABLE\fR defined. The
-first of them invokes the default behaviour with no
-specialties. Using the second value marks the new thread as
-\fIjoinable\fR. This means that another thread can wait for the such
-marked thread to exit and join it.
+for the new thread. As for the flags, currently only the values
+\fBTCL_THREAD_NOFLAGS\fR and \fBTCL_THREAD_JOINABLE\fR are defined. The
+first of them invokes the default behavior with no special settings.
+Using the second value marks the new thread as \fIjoinable\fR. This
+means that another thread can wait for the such marked thread to exit
+and join it.
.PP
-Restrictions: On some unix systems the pthread-library does not
-contain the functionality to specify the stacksize of a thread. The
-specified value for the stacksize is ignored on these systems. Both
-Windows and Macintosh currently do not support joinable threads. This
-flag value is therefore ignored on these platforms.
-.VE
+Restrictions: On some UNIX systems the pthread-library does not
+contain the functionality to specify the stack size of a thread. The
+specified value for the stack size is ignored on these systems.
+Windows currently does not support joinable threads. This
+flag value is therefore ignored on this platform.
.PP
-Tcl does provide \fBTcl_ExitThread\fR and \fBTcl_FinalizeThread\fR
+Tcl provides the \fBTcl_ExitThread\fR and \fBTcl_FinalizeThread\fR functions
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
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
+for handling event queuing 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.
+For declaration of mutexes the \fBTCL_DECLARE_MUTEX\fR macro should be used.
+This macro assures correct mutex handling even when the core is compiled
+without threads enabled.
.PP
A condition variable is used as a signaling mechanism:
a thread can lock a mutex and then wait on a condition variable
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.
+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"
+.PP
+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.
+.SH EXAMPLE
+.PP
+To create a thread with portable code, its implementation function should be
+declared as follows:
+.PP
+.CS
+static \fBTcl_ThreadCreateProc\fR MyThreadImplFunc;
+.CE
+.PP
+It should then be defined like this example, which just counts up to a given
+value and then finishes.
+.PP
+.CS
+static \fBTcl_ThreadCreateType\fR
+MyThreadImplFunc(
+ ClientData clientData)
+{
+ int i, limit = (int) clientData;
+ for (i=0 ; i<limit ; i++) {
+ /* doing nothing at all here */
+ }
+ \fBTCL_THREAD_CREATE_RETURN\fR;
+}
+.CE
+.PP
+To create the above thread, make it execute, and wait for it to finish, we
+would do this:
+.PP
+.CS
+int limit = 1000000000;
+ClientData limitData = (void*)((intptr_t) limit);
+Tcl_ThreadId id; \fI/* holds identity of thread created */\fR
+int result;
+
+if (\fBTcl_CreateThread\fR(&id, MyThreadImplFunc, limitData,
+ \fBTCL_THREAD_STACK_DEFAULT\fR,
+ \fBTCL_THREAD_JOINABLE\fR) != TCL_OK) {
+ \fI/* Thread did not create correctly */\fR
+ return;
+}
+\fI/* Do something else for a while here */\fR
+if (\fBTcl_JoinThread\fR(id, &result) != TCL_OK) {
+ \fI/* Thread did not finish properly */\fR
+ return;
+}
+\fI/* All cleaned up nicely */\fR
+.CE
.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), Thread
.SH KEYWORDS
thread, mutex, condition variable, thread local storage
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