# metrics-clojure / docs / source / gauges.rst

 Steve Losh 660b6b0 2011-11-02 Steve Losh 6eb0284 2011-11-02 Steve Losh 660b6b0 2011-11-02 Steve Losh 6eb0284 2011-11-02 Steve Losh 660b6b0 2011-11-02   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 Gauges ====== Gauges are used to measure the instantaneous value of something. Creating -------- Create your gauge:: (use '[metrics.gauges :only (gauge)]) (def files-open (gauge "files-open" (return-number-of-files-open ...))) That's it. Pretty simple. gauge is a macro. If you need a function instead you can use gauge-fn, but you have to pass it a function, not just a body:: (use '[metrics.gauges :only (gauge-fn)]) (def files-open (gauge-fn "files-open" #(return-number-of-files-open ...))) Writing ------- There is no writing. Gauges execute the form(s) (or function) you passed when creating them every time they're read. You don't need to do anything else. Reading ------- There's only one way to get data from a gauge. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ value ~~~~~~~~~ You can read the value of a gauge at any time with value:: (use '[metrics.gauges :only (value)]) (value files-open) 
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