поточно-безопасное управление списком таймеров (thread-safe timer list management)
Имя (Name)
pmWebTimerRegister, pmWebTimerRelease,
pmWebTimerSetMetricRegistry - thread-safe timer list management
Синопсис C (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
Описание (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 pmWebTimerSetMetricRegistry, 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 values, 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 pointer to an libpcp_mmv(3)
registry that has been suitably initialized by the calling
application. This registry 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).
Возвращаемое значение (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).
Диагностика (Diagnostic)
On failure a negative PMAPI error code is returned in all cases.
Смотри также (See also)
pmproxy(1), mmv_stats_registry(3), PMAPI(3) and PMWEBAPI(3).
