com.netflix.servo.monitor.Pollers Maven / Gradle / Ivy
/**
* 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.monitor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* Poller configuration. This class provides the mechanism
* to know how many pollers will be used, and at their estimated polling intervals.
*/
public final class Pollers {
private Pollers() {
}
/**
* A comma separated list of longs indicating the frequency of the pollers. For example:
* {@code 60000, 10000 }
* indicates that the main poller runs every 60s and a secondary
* poller will run every 10 seconds.
* This is used to deal with monitors that need to get reset after they're polled.
* For example a MinGauge or a MaxGauge.
*/
public static final String POLLERS = System.getProperty("servo.pollers", "60000,10000");
static final long[] DEFAULT_PERIODS = new long[]{60000L, 10000L};
/**
* Polling intervals in milliseconds.
*/
static final long[] POLLING_INTERVALS = parse(POLLERS);
private static final List POLLING_INTERVALS_AS_LIST;
/**
* Get list of polling intervals in milliseconds.
*/
public static List getPollingIntervals() {
return POLLING_INTERVALS_AS_LIST;
}
/**
* Number of pollers that will run.
*/
public static final int NUM_POLLERS = POLLING_INTERVALS.length;
/**
* For debugging. Simple toString for non-empty arrays
*/
private static String join(long[] a) {
assert (a.length > 0);
StringBuilder builder = new StringBuilder();
builder.append(a[0]);
for (int i = 1; i < a.length; ++i) {
builder.append(',');
builder.append(a[i]);
}
return builder.toString();
}
/**
* Parse the content of the system property that describes the polling intervals,
* and in case of errors
* use the default of one poller running every minute.
*/
static long[] parse(String pollers) {
String[] periods = pollers.split(",\\s*");
long[] result = new long[periods.length];
boolean errors = false;
Logger logger = LoggerFactory.getLogger(Pollers.class);
for (int i = 0; i < periods.length; ++i) {
String period = periods[i];
try {
result[i] = Long.parseLong(period);
if (result[i] <= 0) {
logger.error("Invalid polling interval: {} must be positive.", period);
errors = true;
}
} catch (NumberFormatException e) {
logger.error("Cannot parse '{}' as a long: {}", period, e.getMessage());
errors = true;
}
}
if (errors || periods.length == 0) {
logger.info("Using a default configuration for poller intervals: {}",
join(DEFAULT_PERIODS));
return DEFAULT_PERIODS;
} else {
return result;
}
}
static {
List intervals = new ArrayList<>(POLLING_INTERVALS.length);
for (Long interval : POLLING_INTERVALS) {
intervals.add(interval);
}
POLLING_INTERVALS_AS_LIST = Collections.unmodifiableList(intervals);
}
}