/** {@inheritDoc} */
public List<Metric> poll(MetricFilter filter, boolean reset) {
refreshMonitorCache(filter);
List<Monitor<?>> monitors = cachedMonitors.get();
List<Metric> metrics = Lists.newArrayListWithCapacity(monitors.size());
for (Monitor<?> monitor : monitors) {
Object v = getValue(monitor, reset);
if (v != null) {
long now = System.currentTimeMillis();
metrics.add(new Metric(monitor.getConfig(), now, v));
}
}
return metrics;
}
private Object getValue(Monitor<?> monitor, boolean reset) {
try {
if (limiter != null) {
final MonitorValueCallable c = new MonitorValueCallable(monitor);
return limiter.callWithTimeout(c, 1, TimeUnit.SECONDS, true);
} else {
return monitor.getValue();
}
} catch (UncheckedTimeoutException e) {
LOGGER.warn("timeout trying to get value for {}", monitor.getConfig());
} catch (Exception e) {
LOGGER.warn("failed to get value for " + monitor.getConfig(), e);
}
return null;
}
private void getMonitors(List<Monitor<?>> monitors, MetricFilter filter, Monitor<?> monitor) {
if (monitor instanceof CompositeMonitor<?>) {
for (Monitor<?> m : ((CompositeMonitor<?>) monitor).getMonitors()) {
getMonitors(monitors, filter, m);
}
} else if (filter.matches(monitor.getConfig())) {
monitors.add(monitor);
}
}
private void refreshMonitorCache(MetricFilter filter) {
final long age = System.currentTimeMillis() - cacheLastUpdateTime.get();
if (age > cacheTTL) {
List<Monitor<?>> monitors = Lists.newArrayList();
for (Monitor<?> monitor : registry.getRegisteredMonitors()) {
try {
getMonitors(monitors, filter, monitor);
} catch (Exception e) {
LOGGER.warn("failed to get monitors for composite " + monitor.getConfig(), e);
}
}
cacheLastUpdateTime.set(System.currentTimeMillis());
cachedMonitors.set(monitors);
LOGGER.debug(
"cache refreshed, {} monitors matched filter, previous age {} seconds",
monitors.size(),
age / 1000);
} else {
LOGGER.debug(
"cache age of {} seconds is within ttl of {} seconds", age / 1000, cacheTTL / 1000);
}
}
public Object call() throws Exception {
return monitor.getValue();
}
