Nsv incr - Revision history

Dossy at 14:44, 27 June 2006

2006-06-27T14:44:30Z

Josephbui: Added an example

2006-06-21T20:31:54Z

Added an example

WikiSysop: imported from WiKit id 842

2004-10-26T11:39:11Z

imported from WiKit id 842

New page

Man page: http://aolserver.com/docs/tcl/nsv_incr.html

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'''NAME'''

: nsv_incr - Increment the value of the element in the nsv array ''arrayName'' specified by ''key''

'''SYNOPSIS'''

: '''nsv_incr''' ''arrayName'' ''key'' ''?increment?''

'''DESCRIPTION'''

: If ''increment'' is supplied then its value (which must be an integer) is added to the value of the element ''key''; otherwise 1 is added to the value of the element ''key''. Unlike the TCL equivalent if ''key'' does not exists it is created. Returns the new value of the element specified by ''key''. Internally interlocked so it is thread safe, no mutex required.

'''EXAMPLES'''

% nsv_incr shared_array foo
1
% nsv_incr shared_array foo -1
0

'''SEE ALSO'''

: [[Thread-shared Variables]]

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[[Category Documentation]] - [[Category Core Tcl API]]

@@ Line 23: / Line 23: @@
 Is this a good implementation with behavior similar to using ns_mutex or ns_critsec, except that later threads do not wait for the first thread to exit the script?
      # Return value 1 indicates that the call was executed normally
@@ Line 80: / Line 82: @@
 : [[Thread-shared Variables]]
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+[[Category:Documentation]]
+[[Category:Core Tcl API]]

← Older revision		Revision as of 20:31, 21 June 2006
Line 21:		Line 21:
	% nsv_incr shared_array foo -1		% nsv_incr shared_array foo -1
	0		0
		+
		+	Is this a good implementation with behavior similar to using ns_mutex or ns_critsec, except that later threads do not wait for the first thread to exit the script?
		+
		+	# Return value 1 indicates that the call was executed normally
		+	# Return value 0 indicates that another thread was executing
		+	# the code so this thread was excluded
		+
		+	proc write_special_file {data} {
		+	if {[nsv_incr one_thread_at_a_time $key] == 1} {
		+	set had_error [catch {
		+	set handle [open special_file w]
		+	puts $handle $data
		+	close $handle
		+	} message]
		+	nsv_set one_thread_at_a_time $key 0
		+	if {$had_error} {
		+	error $message
		+	}
		+	return 1
		+	} else {
		+	return 0
		+	}
		+	}
		+
		+	proc read_special_file {result_varname} {
		+	if {[nsv_incr one_thread_at_a_time $key] == 1} {
		+	upvar $result_varname result
		+	set had_error [catch {
		+	set handle [open special_file r]
		+	set result [read $handle]
		+	close $handle
		+	} message]
		+	nsv_set one_thread_at_a_time $key 0
		+	if {$had_error} {
		+	error $message
		+	}
		+	return 1
		+	} else {
		+	return 0
		+	}
		+	}
		+
		+	proc change_special_file {data result_varname} {
		+	if {[nsv_incr one_thread_at_a_time $key] == 1} {
		+	upvar $result_varname result
		+	# BOTH READ AND WRITE CALLS WILL DO NOTHING
		+	read_special_file result
		+	write_special_file $data
		+	nsv_set one_thread_at_a_time $key 0
		+	return 1
		+	} else {
		+	return 0
		+	}
		+	}

	'''SEE ALSO'''		'''SEE ALSO'''