util_background_exec (public)

 util_background_exec [ -pass_vars pass_vars ] -name name code_chunk

Defined in packages/acs-tcl/tcl/utilities-procs.tcl

Executes a chunk of code in the background. The code is run exclusively, meaning that no two threads with the same name can run at the same time.

Switches:

-pass_vars

(optional)

Names of variables which you want passed to the code chunk

-name

(required)

The name of the thread. No two chunks with the same name can run at the same time.

Parameters:

code_chunk - The chunk you want executed

Partial Call Graph (max 5 caller/called nodes):

Testcases:

No testcase defined.

Source code:

    ns_log Debug "util_background_exec: Starting, waiting for mutex"

    #    ns_mutex lock [nsv_get util_background_exec_mutex .]

    ns_log Debug "util_background_exec: Got mutex"

    set running_p [nsv_exists util_background_exec $name]
    if { !$running_p } {
        nsv_set util_background_exec [list $name] 1
    }

    #    ns_mutex unlock [nsv_get util_background_exec_mutex .]
    ns_log Debug "util_background_exec: Released mutex"

    if { $running_p } {
        ns_log Notice "util_background_exec: $name is already running, exiting"
        return
    }

    set code {}
    foreach var $pass_vars {
        upvar 1 $var the_var
        if { [array exists the_var] } {
            append code "array set [list $var] [list [array get the_var]]\n"
        } else {
            append code "set [list $var] [list $the_var]\n"
        }
    }

    append code "
        set errno \[catch {
            $code_chunk
        } errmsg\]

        set errinfo {}
        set errcode {}
        if { \$errno == 1 } {
            set errinfo \$::errorInfo
            set errcode \$::errorCode
        }

        if { \$errno == 1 } {
            \# This is an error
            ns_log Error \"util_background_exec: Error in thread named '$name': \$::errorInfo\"
        }

        \# errno = 0 (TCL_OK) or 2 (TCL_RETURN) is considered normal, i.e. first elm is true
        set success_p \[expr { \$errno == 0 || \$errno == 2 }\]
        set result \[list \$success_p \$errmsg \$errno \$errinfo \$errcode]

        ns_log debug \"util_background_exec: Thread named '$name' returned \$result\"

        nsv_unset util_background_exec [list $name]
        nsv_set util_background_exec_result [list $name] \$result

    "
    ns_log Debug "util_background_exec: Scheduling code\n$code"

    ns_schedule_proc -thread -once 1 $code

XQL Not present:

PostgreSQL, Oracle

Generic XQL file:

packages/acs-tcl/tcl/utilities-procs.xql