acs::LockfreeCache method eval (public)

 <instance of acs::LockfreeCache> eval -key key  \
    [ -no_cache no_cache ] [ -no_empty ] \
    [ -from_cache_indicator from_cache_indicator ] cmd

Defined in

Use the "prefix" to determine whether the cache is per-thread or per-request.

Switches:

-key (required)

key for caching, should start with package-key and a dot to avoid name clashes

-no_cache (optional)

list of returned values that should not be cached

-no_empty (optional, defaults to "false")

don't cache empty values. This flag is deprecated, one should use the no_cache flag instead.

-from_cache_indicator (optional)

variable name to indicate whether the returned value was from cache or not

Parameters:

cmd (required)

command to be executed.

Returns:

return the last value set (don't use "return").

Testcases:

No testcase defined.

Source code:

if {[info exists from_cache_indicator]} {
    :upvar $from_cache_indicator from_cache
}

#if {![info exists ${:prefix}]} {
#    ns_log notice "### exists ${:prefix} ==> 0"
#} else {
#    ns_log notice "### [list dict exists [set ${:prefix}] $key] ==>  [dict exists [set ${:prefix}] $key]"
#}

if {![info exists ${:prefix}] || ![dict exists [set ${:prefix}] $key]} {
    #ns_log notice "### call cmd <$cmd>"
    set from_cache 0
    set value [:uplevel $cmd]
    if {$no_empty} {
        ad_log warning "no_empty flag is deprecated and will be dropped in the future."
        lappend no_cache ""
    }
    if {[info exists no_cache] && $value in $no_cache} {
        #ns_log notice "### cache eval $key returns <$value> without caching"
        return $value
    }
    #if {$value eq "0"} {
    #    ns_log notice "### cache eval $key returns <$value> with caching"
    #}
    dict set ${:prefix} $key $value
    #ns_log notice "### [list dict set ${:prefix} $key $value]"
} else {
    set from_cache 1
    set value [dict get [set ${:prefix}] $key]
}
#ns_log notice "### will return [list dict get ${:prefix} $key]"
return $value

XQL Not present:

Generic, PostgreSQL, Oracle