NAME

       pmWebTimerRegister, pmWebTimerRelease, pmWebTimerSetMetricRegistry - thread-safe timer list management

C SYNOPSIS

       #include <pcp/pmwebapi.h>

       typedef void (*pmWebTimerCallBack)(void *data);
       int pmWebTimerRegister(pmWebTimerCallBack callback, void *data);

       int pmWebTimerRelease(int seq);
       int pmWebTimerSetMetricRegistry(struct mmv_registry *registry);
       cc ... -lpcp_web

DESCRIPTION

       The pmWebTimerRegister and related API functions provide a convenient thread-safe API for applications to
       manage  a list of timer driven callbacks.  On the first call to pmWebTimerRegister or pmWebTimerSetMetri‐
       cRegistry, an internal timer is set up and initialized to fire every 1.0 seconds.  Each  time  the  timer
       fires,  all  currently registered callback functions will be called serially with the opaque data pointer
       that was supplied when each function was registered.  The pmWebTimerCallBack typedef provides a  suitable
       callback function prototype.

       All  registered callback functions should be non-blocking and execute quickly and synchronously.  Typical
       callback functions include refreshing instrumentation, calculating and updating performance  metric  val‐
       ues, periodic garbage collection and any other local function that requires regular execution.

       The pmWebTimerSetMetricRegistry function provides a convenient way for an application to pass in a point‐
       er to an libpcp_mmv(3) registry that has been suitably initialized by the calling application.  This reg‐
       istry   will   be  used  to  dynamically  create  six  server  resource  metrics  named  NAME.mem.datasz,
       NAME.mem.maxrss, NAME.cpu.total, NAME.cpu.sys, NAME.cpu.user and NAME.pid, where NAME  is  the  root  PCP
       PMNS(5)  name  set  up  by the calling application.  These metrics should be reasonably self explanatory;
       they provide resource usage metrics from the calling application / server and use getrusage(2),  times(2)
       and getpid(2).

RETURN VALUE

       The pmWebTimerRegister function returns a positive integer handle that may be subsequently used in a call
       to pmWebTimerRelease to remove a timer from the internal timer list.  When a timer is removed with a call
       to  pmWebTimerRelease,  the  internal  data structures are freed.  The caller however, is responsible for
       freeing the associated data (since it may or may not be dynamically allocated).

DIAGNOSTICS

       On failure a negative PMAPI error code is returned in all cases.

SEE ALSO

       pmproxy(1), mmv_stats_registry(3), PMAPI(3) and PMWEBAPI(3).

Performance Co-Pilot                                   PCP                                 PMWEBTIMERREGISTER(3)