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/**
 * Copyright 2013 Netflix, Inc.
 * 

* Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at *

* http://www.apache.org/licenses/LICENSE-2.0 *

* Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.netflix.servo.publish; import com.netflix.servo.DefaultMonitorRegistry; import com.netflix.servo.Metric; import com.netflix.servo.MonitorRegistry; import com.netflix.servo.monitor.BasicCounter; import com.netflix.servo.monitor.CompositeMonitor; import com.netflix.servo.monitor.Counter; import com.netflix.servo.monitor.DynamicCounter; import com.netflix.servo.monitor.Monitor; import com.netflix.servo.monitor.MonitorConfig; import com.netflix.servo.util.Clock; import com.netflix.servo.util.ClockWithOffset; import com.netflix.servo.util.ThreadFactories; import com.netflix.servo.util.TimeLimiter; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.ArrayList; import java.util.List; import java.util.concurrent.Callable; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.ThreadFactory; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicLong; import java.util.concurrent.atomic.AtomicReference; /** * Poller for fetching {@link com.netflix.servo.annotations.Monitor} metrics * from a monitor registry. */ public final class MonitorRegistryMetricPoller implements MetricPoller { private static final Logger LOGGER = LoggerFactory.getLogger(MonitorRegistryMetricPoller.class); private static final String GET_VALUE_ERROR = "servo.getValueError"; private static final Counter TIMEOUT_ERROR = new BasicCounter(MonitorConfig .builder(GET_VALUE_ERROR) .withTag("id", "timeout") .build()); static { DefaultMonitorRegistry.getInstance().register(TIMEOUT_ERROR); } private final MonitorRegistry registry; private final long cacheTTL; private final AtomicReference>> cachedMonitors = new AtomicReference<>(); private final AtomicLong cacheLastUpdateTime = new AtomicLong(0L); // Put limit on fetching the monitor value in-case someone does something silly like call a // remote service inline private final TimeLimiter limiter; private final ExecutorService service; private final Clock clock; /** * Creates a new instance using {@link com.netflix.servo.DefaultMonitorRegistry}. */ public MonitorRegistryMetricPoller() { this(DefaultMonitorRegistry.getInstance(), 0L, TimeUnit.MILLISECONDS, true); } /** * Creates a new instance using the specified registry. * * @param registry registry to query for annotated objects */ public MonitorRegistryMetricPoller(MonitorRegistry registry) { this(registry, 0L, TimeUnit.MILLISECONDS, true, ClockWithOffset.INSTANCE); } /** * Creates a new instance using the specified registry and a time limiter. * * @param registry registry to query for annotated objects * @param cacheTTL how long to cache the filtered monitor list from the registry * @param unit time unit for the cache ttl */ public MonitorRegistryMetricPoller(MonitorRegistry registry, long cacheTTL, TimeUnit unit) { this(registry, cacheTTL, unit, true); } /** * Creates a new instance using the specified registry. * * @param registry registry to query for annotated objects * @param cacheTTL how long to cache the filtered monitor list from the registry * @param unit time unit for the cache ttl * @param useLimiter whether to use a time limiter for getting the values from the monitors */ public MonitorRegistryMetricPoller(MonitorRegistry registry, long cacheTTL, TimeUnit unit, boolean useLimiter) { this(registry, cacheTTL, unit, useLimiter, ClockWithOffset.INSTANCE); } /** * Creates a new instance using the specified registry. * * @param registry registry to query for annotated objects * @param cacheTTL how long to cache the filtered monitor list from the registry * @param unit time unit for the cache ttl * @param useLimiter whether to use a time limiter for getting the values from the monitors * @param clock clock instance to use to get the time */ public MonitorRegistryMetricPoller( MonitorRegistry registry, long cacheTTL, TimeUnit unit, boolean useLimiter, Clock clock) { this.registry = registry; this.cacheTTL = TimeUnit.MILLISECONDS.convert(cacheTTL, unit); this.clock = clock; if (useLimiter) { final ThreadFactory factory = ThreadFactories.withName("ServoMonitorGetValueLimiter-%d"); service = Executors.newSingleThreadExecutor(factory); limiter = new TimeLimiter(service); } else { service = null; limiter = null; } } private Object getValue(Monitor monitor) { try { if (limiter != null) { final MonitorValueCallable c = new MonitorValueCallable(monitor); return limiter.callWithTimeout(c, 1, TimeUnit.SECONDS); } else { return monitor.getValue(); } } catch (TimeLimiter.UncheckedTimeoutException e) { LOGGER.warn("timeout trying to get value for {}", monitor.getConfig()); TIMEOUT_ERROR.increment(); } catch (Exception e) { LOGGER.warn("failed to get value for " + monitor.getConfig(), e); DynamicCounter.increment(GET_VALUE_ERROR, "id", e.getClass().getSimpleName()); } return null; } private void getMonitors(List> 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> monitors = new ArrayList<>(); 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(clock.now()); 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); } } /** * {@inheritDoc} */ public List poll(MetricFilter filter) { return poll(filter, false); } /** * {@inheritDoc} */ public List poll(MetricFilter filter, boolean reset) { refreshMonitorCache(filter); List> monitors = cachedMonitors.get(); List metrics = new ArrayList<>(monitors.size()); for (Monitor monitor : monitors) { Object v = getValue(monitor); if (v != null) { metrics.add(new Metric(monitor.getConfig(), clock.now(), v)); } } return metrics; } /** * Shutsdown the thread executor used for time limiting the get value calls. It is a good idea * to call this and explicitly cleanup the thread. In most cases the threads will be cleaned * up when the executor is garbage collected if shutdown is not called explicitly. */ public void shutdown() { if (service != null) { service.shutdownNow(); } } private static class MonitorValueCallable implements Callable { private final Monitor monitor; MonitorValueCallable(Monitor monitor) { this.monitor = monitor; } public Object call() throws Exception { return monitor.getValue(); } } }