--- /dev/null
+'\"
+'\" Copyright (c) 2004 Donal K. Fellows
+'\"
+'\" See the file "license.terms" for information on usage and redistribution
+'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+'\"
+.TH Tcl_LimitCheck 3 8.5 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
+.de AP
+.ie !"\\$4"" .TP \\$4
+.el \{\
+. ie !"\\$2"" .TP \\n()Cu
+. el .TP 15
+.\}
+.ta \\n()Au \\n()Bu
+.ie !"\\$3"" \{\
+\&\\$1 \\fI\\$2\\fP (\\$3)
+.\".b
+.\}
+.el \{\
+.br
+.ie !"\\$2"" \{\
+\&\\$1 \\fI\\$2\\fP
+.\}
+.el \{\
+\&\\fI\\$1\\fP
+.\}
+.\}
+..
+.\" # define tabbing values for .AP
+.de AS
+.nr )A 10n
+.if !"\\$1"" .nr )A \\w'\\$1'u+3n
+.nr )B \\n()Au+15n
+.\"
+.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+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
+.de BS
+.br
+.mk ^y
+.nr ^b 1u
+.if n .nf
+.if n .ti 0
+.if n \l'\\n(.lu\(ul'
+.if n .fi
+..
+.\" # BE - end boxed text (draw box now)
+.de BE
+.nf
+.ti 0
+.mk ^t
+.ie n \l'\\n(^lu\(ul'
+.el \{\
+.\" Draw four-sided box normally, but don't draw top of
+.\" box if the box started on an earlier page.
+.ie !\\n(^b-1 \{\
+\h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
+.\}
+.el \}\
+\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
+.\}
+.\}
+.fi
+.br
+.nr ^b 0
+..
+.\" # 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
+.de VE
+.ie n 'mc
+.el \{\
+.ev 2
+.nf
+.ti 0
+.mk ^t
+\h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
+.sp -1
+.fi
+.ev
+.\}
+.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.
+.de ^B
+.ev 2
+'ti 0
+'nf
+.mk ^t
+.if \\n(^b \{\
+.\" Draw three-sided box if this is the box's first page,
+.\" draw two sides but no top otherwise.
+.ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
+.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
+.\}
+.if \\n(^v \{\
+.nr ^x \\n(^tu+1v-\\n(^Yu
+\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
+.\}
+.bp
+'fi
+.ev
+.if \\n(^b \{\
+.mk ^y
+.nr ^b 2
+.\}
+.if \\n(^v \{\
+.mk ^Y
+.\}
+..
+.\" # DS - begin display
+.de DS
+.RS
+.nf
+.sp
+..
+.\" # DE - end display
+.de DE
+.fi
+.RE
+.sp
+..
+.\" # 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
+.de SE
+.fi
+.ft R
+.LP
+See the \\*(So manual entry for details on the standard options.
+..
+.\" # OP - start of full description for a single option
+.de OP
+.LP
+.nf
+.ta 4c
+Command-Line Name: \\fB\\$1\\fR
+Database Name: \\fB\\$2\\fR
+Database Class: \\fB\\$3\\fR
+.fi
+.IP
+..
+.\" # CS - begin code excerpt
+.de CS
+.RS
+.nf
+.ta .25i .5i .75i 1i
+..
+.\" # CE - end code excerpt
+.de CE
+.fi
+.RE
+..
+.\" # UL - underline word
+.de UL
+\\$1\l'|0\(ul'\\$2
+..
+.\" # 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_LimitAddHandler, Tcl_LimitCheck, Tcl_LimitExceeded, Tcl_LimitGetCommands, Tcl_LimitGetGranularity, Tcl_LimitGetTime, Tcl_LimitReady, Tcl_LimitRemoveHandler, Tcl_LimitSetCommands, Tcl_LimitSetGranularity, Tcl_LimitSetTime, Tcl_LimitTypeEnabled, Tcl_LimitTypeExceeded, Tcl_LimitTypeReset, Tcl_LimitTypeSet \- manage and check resource limits on interpreters
+.SH SYNOPSIS
+.nf
+\fB#include <tcl.h>\fR
+.sp
+int
+\fBTcl_LimitCheck\fR(\fIinterp\fR)
+.sp
+int
+\fBTcl_LimitReady\fR(\fIinterp\fR)
+.sp
+int
+\fBTcl_LimitExceeded\fR(\fIinterp\fR)
+.sp
+int
+\fBTcl_LimitTypeExceeded\fR(\fIinterp, type\fR)
+.sp
+int
+\fBTcl_LimitTypeEnabled\fR(\fIinterp, type\fR)
+.sp
+void
+\fBTcl_LimitTypeSet\fR(\fIinterp, type\fR)
+.sp
+void
+\fBTcl_LimitTypeReset\fR(\fIinterp, type\fR)
+.sp
+int
+\fBTcl_LimitGetCommands\fR(\fIinterp\fR)
+.sp
+void
+\fBTcl_LimitSetCommands\fR(\fIinterp, commandLimit\fR)
+.sp
+void
+\fBTcl_LimitGetTime\fR(\fIinterp, timeLimitPtr\fR)
+.sp
+void
+\fBTcl_LimitSetTime\fR(\fIinterp, timeLimitPtr\fR)
+.sp
+int
+\fBTcl_LimitGetGranularity\fR(\fIinterp, type\fR)
+.sp
+void
+\fBTcl_LimitSetGranularity\fR(\fIinterp, type, granularity\fR)
+.sp
+void
+\fBTcl_LimitAddHandler\fR(\fIinterp, type, handlerProc, clientData, deleteProc\fR)
+.sp
+void
+\fBTcl_LimitRemoveHandler\fR(\fIinterp, type, handlerProc, clientData\fR)
+.SH ARGUMENTS
+.AS Tcl_LimitHandlerDeleteProc commandLimit in/out
+.AP Tcl_Interp *interp in
+Interpreter that the limit being managed applies to or that will have
+its limits checked.
+.AP int type in
+The type of limit that the operation refers to. This must be either
+\fBTCL_LIMIT_COMMANDS\fR or \fBTCL_LIMIT_TIME\fR.
+.AP int commandLimit in
+The maximum number of commands (as reported by \fBinfo cmdcount\fR)
+that may be executed in the interpreter.
+.AP Tcl_Time *timeLimitPtr in/out
+A pointer to a structure that will either have the new time limit read
+from (\fBTcl_LimitSetTime\fR) or the current time limit written to
+(\fBTcl_LimitGetTime\fR).
+.AP int granularity in
+Divisor that indicates how often a particular limit should really be
+checked. Must be at least 1.
+.AP Tcl_LimitHandlerProc *handlerProc in
+Function to call when a particular limit is exceeded. If the
+\fIhandlerProc\fR removes or raises the limit during its processing,
+the limited interpreter will be permitted to continue to process after
+the handler returns. Many handlers may be attached to the same
+interpreter limit; their order of execution is not defined, and they
+must be identified by \fIhandlerProc\fR and \fIclientData\fR when they
+are deleted.
+.AP ClientData clientData in
+Arbitrary pointer-sized word used to pass some context to the
+\fIhandlerProc\fR function.
+.AP Tcl_LimitHandlerDeleteProc *deleteProc in
+Function to call whenever a handler is deleted. May be NULL if the
+\fIclientData\fR requires no deletion.
+.BE
+.SH DESCRIPTION
+.PP
+Tcl's interpreter resource limit subsystem allows for close control
+over how much computation time a script may use, and is useful for
+cases where a program is divided into multiple pieces where some parts
+are more trusted than others (e.g. web application servers).
+.PP
+Every interpreter may have a limit on the wall-time for execution, and
+a limit on the number of commands that the interpreter may execute.
+Since checking of these limits is potentially expensive (especially
+the time limit), each limit also has a checking granularity, which is
+a divisor for an internal count of the number of points in the core
+where a check may be performed (which is immediately before executing
+a command and at an unspecified frequency between running commands,
+which can happen in empty-bodied \fBwhile\fR loops).
+.PP
+The final component of the limit engine is a callback scheme which
+allows for notifications of when a limit has been exceeded. These
+callbacks can just provide logging, or may allocate more resources to
+the interpreter to permit it to continue processing longer.
+.PP
+When a limit is exceeded (and the callbacks have run; the order of
+execution of the callbacks is unspecified) execution in the limited
+interpreter is stopped by raising an error and setting a flag that
+prevents the \fBcatch\fR command in that interpreter from trapping
+that error. It is up to the context that started execution in that
+interpreter (typically the main interpreter) to handle the error.
+.SH "LIMIT CHECKING API"
+.PP
+To check the resource limits for an interpreter, call
+\fBTcl_LimitCheck\fR, which returns \fBTCL_OK\fR if the limit was not
+exceeded (after processing callbacks) and \fBTCL_ERROR\fR if the limit was
+exceeded (in which case an error message is also placed in the
+interpreter result). That function should only be called when
+\fBTcl_LimitReady\fR returns non-zero so that granularity policy is
+enforced. This API is designed to be similar in usage to
+\fBTcl_AsyncReady\fR and \fBTcl_AsyncInvoke\fR.
+.PP
+When writing code that may behave like \fBcatch\fR in respect of
+errors, you should only trap an error if \fBTcl_LimitExceeded\fR
+returns zero. If it returns non-zero, the interpreter is in a
+limit-exceeded state and errors should be allowed to propagate to the
+calling context. You can also check whether a particular type of
+limit has been exceeded using \fBTcl_LimitTypeExceeded\fR.
+.SH "LIMIT CONFIGURATION"
+.PP
+To check whether a limit has been set (but not whether it has actually
+been exceeded) on an interpreter, call \fBTcl_LimitTypeEnabled\fR with
+the type of limit you want to check. To enable a particular limit
+call \fBTcl_LimitTypeSet\fR, and to disable a limit call
+\fBTcl_LimitTypeReset\fR.
+.PP
+The level of a command limit may be set using
+\fBTcl_LimitSetCommands\fR, and retrieved using
+\fBTcl_LimitGetCommands\fR. Similarly for a time limit with
+\fBTcl_LimitSetTime\fR and \fBTcl_LimitGetTime\fR respectively, but
+with that API the time limit is copied from and to the Tcl_Time
+structure that the \fItimeLimitPtr\fR argument points to.
+.PP
+The checking granularity for a particular limit may be set using
+\fBTcl_LimitSetGranularity\fR and retrieved using
+\fBTcl_LimitGetGranularity\fR. Note that granularities must always be
+positive.
+.SS "LIMIT CALLBACKS"
+.PP
+To add a handler callback to be invoked when a limit is exceeded, call
+\fBTcl_LimitAddHandler\fR. The \fIhandlerProc\fR argument describes
+the function that will actually be called; it should have the
+following prototype:
+.PP
+.CS
+typedef void \fBTcl_LimitHandlerProc\fR(
+ ClientData \fIclientData\fR,
+ Tcl_Interp *\fIinterp\fR);
+.CE
+.PP
+The \fIclientData\fR argument to the handler will be whatever is
+passed to the \fIclientData\fR argument to \fBTcl_LimitAddHandler\fR,
+and the \fIinterp\fR is the interpreter that had its limit exceeded.
+.PP
+The \fIdeleteProc\fR argument to \fBTcl_LimitAddHandler\fR is a
+function to call to delete the \fIclientData\fR value. It may be
+\fBTCL_STATIC\fR or NULL if no deletion action is necessary, or
+\fBTCL_DYNAMIC\fR if all that is necessary is to free the structure with
+\fBTcl_Free\fR. Otherwise, it should refer to a function with the
+following prototype:
+.PP
+.CS
+typedef void \fBTcl_LimitHandlerDeleteProc\fR(
+ ClientData \fIclientData\fR);
+.CE
+.PP
+A limit handler may be deleted using \fBTcl_LimitRemoveHandler\fR; the
+handler removed will be the first one found (out of the handlers added
+with \fBTcl_LimitAddHandler\fR) with exactly matching \fItype\fR,
+\fIhandlerProc\fR and \fIclientData\fR arguments. This function
+always invokes the \fIdeleteProc\fR on the \fIclientData\fR (unless
+the \fIdeleteProc\fR was NULL or \fBTCL_STATIC\fR).
+.SH KEYWORDS
+interpreter, resource, limit, commands, time, callback
OSDN Git Service
