macro sm_agi(agi,agi_failsafe) {

    // extract script name from primary agi for the global breaker variable name
    Set(LOCAL(breaker)=sm_agi_breaker-${CUT(CUT(agi,/,${FIELDQTY(agi,/)}),^,1)});
    Set(SM_AGI_STATUS=);

    if ("${GLOBAL(${breaker})}" == "tripped") {
        // globally lock breaker variable to prevent race condition
        if (${TRYLOCK(${breaker})}) {
            Noop(AGI Breaker '${breaker}' is currently 'tripped'  Checking elapsed time and elapsed calls.);
            if (${${breaker}_calls} > ${SM_AGI_BREAKER_MAX_CALLS} || ${MATH(${STRFTIME(,,%s)}-${${breaker}_timestamp},int)} > ${SM_AGI_BREAKER_MAX_ELAPSED}) {
                System(/bin/echo "AGI breaker '${breaker}' reset on '${SM_NODE}' after '${MATH(${STRFTIME(,,%s)}-${${breaker}_timestamp},int)}' seconds and '${${breaker}_calls}' calls.  Normal call processing has resumed." | mail -s "NOTICE: ${SM_NODE} AGI Breaker '${breaker}' Reset" ${SM_AGI_BREAKER_NOTIFY});
                Set(ARRAY(GLOBAL(${breaker}),GLOBAL(${breaker}_calls),GLOBAL(${breaker}_elapsed))=,,,);
            }
            Set(undef=${UNLOCK(${breaker})});
        }
    }
    if ("${GLOBAL(${breaker})}" != "tripped") {

        // run agi, replacing ^ with ,
        AGI(${REPLACE(agi,^,\,)});

        // the agi should set SM_AGI_STATUS to "FAIL" when it starts and set it to "SUCCESS" just before the AGI exits.   This is because if the AGI fails it won't be able to set the SM_AGI_STATUS variable.
        if ("${SM_AGI_STATUS}" == "SUCCESS") {
            return;
        }
        if ("${SM_AGI_STATUS}" != "FAIL" && "${AGISTATUS}" == "SUCCESS") {
            Set(SM_AGI_STATUS=SUCCESS);
            return;
        }

        // agi failed, trip the circuit breaker
        if (${TRYLOCK(${breaker})}) {
            Set(ARRAY(GLOBAL(${breaker}),GLOBAL(${breaker}_calls),GLOBAL(${breaker}_timestamp))=tripped,1,${STRFTIME(,,%s)});
            Set(undef=${UNLOCK(${breaker})});
        }

        System(/bin/echo "AGI '${agi}' failed on channel '${CHANNEL(name)}' with status '${AGISTATUS}' on '${SM_NODE}', tripping AGI breaker '${breaker}'.  Failsafe mode enabled, AGI breaker will reset after '${SM_AGI_BREAKER_MAX_ELAPSED}' seconds or '${SM_AGI_BREAKER_MAX_CALLS}' calls" | mail -s "ERROR: ${SM_NODE} AGI Breaker '${breaker}' Tripped" ${SM_AGI_BREAKER_NOTIFY});

        Playback(custom/sm_agi_fail);

    }

    // try using the failsafe
    AGI(${REPLACE(agi_failsafe,^,\,)});
    if ("${AGISTATUS}" == "SUCCESS") {
        if (${LOCK(${breaker})}) {
            Set(ARRAY(GLOBAL(${breaker}_calls),SM_AGI_STATUS)=${MATH(${${breaker}_calls}+1,int)},SUCCESS);
            Set(undef=${UNLOCK(${breaker})});
        }
        return;
    }

    System(/bin/echo "Backup AGI '${agi_failsafe}' failed with status '${AGISTATUS}' on '${SM_NODE}'.  This is a critical emergency.  All calls on this node are failing.  Drop whatever you are doing and deal with it." | mail -s "PANIC: ${SM_NODE} AGI FAILED" ${SM_AGI_BREAKER_NOTIFY});

    // both agi and failsafe agi failed. reset the agi breaker for the next call and hope for the best.
    Set(ARRAY(GLOBAL(${breaker}),GLOBAL(${breaker}_calls),GLOBAL(${breaker}_timestamp))=,,,);

    return;

}