net.thisptr.java.prometheus.metrics.agent.config.FileConfigWatcher Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of java-prometheus-metrics-agent Show documentation

Java agent for collecting and reporting metrics to Prometheus

There is a newer version: 0.0.5

Show newest version

package net.thisptr.java.prometheus.metrics.agent.config;

import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
import com.google.common.io.Files;

import net.thisptr.java.prometheus.metrics.agent.utils.MoreValidators;

public class FileConfigWatcher extends Thread implements ConfigWatcher {
	private static final Logger LOG = Logger.getLogger(FileConfigWatcher.class.getName());
	private static final ObjectMapper YAML_MAPPER = new ObjectMapper(new YAMLFactory());

	private final File file;
	private final ConfigWatcher.ConfigListener listener;

	private volatile Config config;
	private volatile byte[] bytes;

	public FileConfigWatcher(final File file, final ConfigWatcher.ConfigListener listener) throws JsonParseException, JsonMappingException, IOException {
		this.file = file;
		this.bytes = Files.toByteArray(file);
		this.config = YAML_MAPPER.readValue(this.bytes, Config.class);
		MoreValidators.validate(this.config);
		this.listener = listener;
		this.setName("Prometheus Metrics Agent " + FileConfigWatcher.class.getSimpleName());
		this.setDaemon(true);
	}

	@Override
	public void run() {
		while (true) {
			try {
				Thread.sleep(1000);
			} catch (final InterruptedException ie) {
				LOG.log(Level.INFO, "Interrupted. Stopping Prometheus Metrics Agent " + FileConfigWatcher.class.getSimpleName() + "...");
				break;
			}

			final byte[] newBytes;
			try {
				newBytes = Files.toByteArray(file);
				if (Arrays.equals(bytes, newBytes))
					continue;
			} catch (final Throwable th) {
				LOG.log(Level.WARNING, "Got exception while reloading " + file.getAbsolutePath() + ".", th);
				continue;
			}

			final Config newConfig;
			try {
				newConfig = YAML_MAPPER.readValue(newBytes, Config.class);
				MoreValidators.validate(newConfig);
			} catch (final Throwable th) {
				LOG.log(Level.WARNING, "Got exception while reloading " + file.getAbsolutePath() + ".", th);
				continue;
			}

			try {
				listener.changed(config, newConfig);
			} catch (final Throwable th) {
				LOG.log(Level.WARNING, "Got exception while reconfiguring from " + file.getAbsolutePath() + ".", th);
			}

			this.config = newConfig;
			this.bytes = newBytes;
		}
	}

	public Config config() {
		return config;
	}

	public void shutdown() {
		this.interrupt();
	}
}