/**
* 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.apache;
import com.google.common.collect.ImmutableList;
import com.netflix.servo.Metric;
import com.netflix.servo.annotations.DataSourceType;
import com.netflix.servo.monitor.MonitorConfig;
import com.netflix.servo.publish.BaseMetricPoller;
import com.netflix.servo.tag.BasicTag;
import com.netflix.servo.tag.Tag;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Collections;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Base class for simple pollers that do not benefit from filtering in advance.
* Sub-classes implement {@link #pollImpl} to return a list and all filtering
* will be taken care of by the provided implementation of {@link #poll}.
*/
public class ApacheStatusPoller extends BaseMetricPoller {
private final StatusFetcher fetcher;
private static final List<Metric> EMPTY_LIST = Collections.emptyList();
/**
* Mechanism used to fetch a status page.
*/
public interface StatusFetcher {
/**
* Return the apache status page as an {@link InputStream}.
*/
InputStream fetchStatus() throws IOException;
}
/**
* Simple class to fetch a status page using the {@link java.net.URL} class.
*/
public static class URLStatusFetcher implements StatusFetcher {
private final URL url;
/**
* Fetch an apache status page using the given URL passed as a String.
*/
public URLStatusFetcher(String url) throws MalformedURLException {
this(new URL(url));
}
/**
* Fetch an apache status page using the given URL.
*/
public URLStatusFetcher(URL url) {
this.url = url;
}
@Override
public InputStream fetchStatus() throws IOException {
final URLConnection con = url.openConnection();
con.setConnectTimeout(1000);
con.setReadTimeout(2000);
return con.getInputStream();
}
}
private static class StatusPageParser {
private static final Pattern INVALID_CHARS = Pattern.compile("[^a-zA-Z0-9_\\-\\.]");
private static final Pattern STAT_LINE = Pattern.compile("^([^:]+): (\\S+)$");
private static final char[] SCOREBOARD_CHARS = {
'_', 'S', 'R', 'W', 'K', 'D', 'C', 'L', 'G', 'I', '.', '*'};
private static final Tag CLASS_TAG = new BasicTag("class", "ApacheStatusPoller");
/**
* Metrics that should not be included. These can be confusing for end users.
*/
private static final List<String> BLACKLISTED_METRICS = ImmutableList.of("CPULoad");
private static final int ASCII_CHARS = 128;
private static final String SCOREBOARD = "Scoreboard";
private static String getScoreboardName(char c) {
switch (c) {
case '_':
return "WaitingForConnection";
case 'S':
return "StartingUp";
case 'R':
return "ReadingRequest";
case 'W':
return "SendingReply";
case 'K':
return "Keepalive";
case 'D':
return "DnsLookup";
case 'C':
return "ClosingConnection";
case 'L':
return "Logging";
case 'G':
return "GracefullyFinishing";
case 'I':
return "IdleCleanupOfWorker";
case '.':
return "OpenSlotWithNoCurrentProcess";
default:
return "UnknownState";
}
}
static List<Metric> parseStatLine(String line, long timestamp) {
final Matcher m = STAT_LINE.matcher(line);
if (!m.matches()) {
return EMPTY_LIST;
}
final String name = INVALID_CHARS.matcher(m.group(1)).replaceAll("_");
if (BLACKLISTED_METRICS.contains(name)) {
return EMPTY_LIST;
}
final double value = Double.parseDouble(m.group(2));
final Tag metricType = (name.startsWith("Total") || name.startsWith("Uptime"))
? DataSourceType.COUNTER : DataSourceType.GAUGE;
final MonitorConfig monitorConfig = MonitorConfig.builder(name)
.withTag(metricType)
.withTag(CLASS_TAG)
.build();
Metric metric = new Metric(monitorConfig, timestamp, value);
return ImmutableList.of(metric);
}
/*
* "_" Waiting for Connection,
* "S" Starting up,
* "R" Reading Request,
* "W" Sending Reply,
* "K" Keepalive (read),
* "D" DNS Lookup,
* "C" Closing connection,
* "L" Logging,
* "G" Gracefully finishing,
* "I" Idle cleanup of worker,
* ." Open slot with no current process (ignored)
*/
static List<Metric> parseScoreboardLine(String line, long timestamp) {
final Matcher m = STAT_LINE.matcher(line);
if (!m.matches()) {
return EMPTY_LIST;
}
final char[] scoreboard = m.group(2).toCharArray();
final double[] tally = new double[ASCII_CHARS];
for (final char item : SCOREBOARD_CHARS) {
tally[item] = 0;
}
for (final char item : scoreboard) {
final int idx = item % ASCII_CHARS;
tally[idx]++;
}
ImmutableList.Builder<Metric> builder = ImmutableList.builder();
for (final char item : SCOREBOARD_CHARS) {
if (item == '.') { // Open slots are not particularly useful to track
continue;
}
final double value = tally[item];
final String state = getScoreboardName(item);
final MonitorConfig monitorConfig = MonitorConfig.builder(SCOREBOARD)
.withTag(DataSourceType.GAUGE)
.withTag(CLASS_TAG)
.withTag("state", state)
.build();
final Metric metric = new Metric(monitorConfig, timestamp, value);
builder.add(metric);
}
return builder.build();
}
static List<Metric> parse(InputStream input, long timestamp) throws IOException {
final BufferedReader reader = new BufferedReader(new InputStreamReader(input, "UTF-8"));
final ImmutableList.Builder<Metric> metricsBuilder = ImmutableList.builder();
try {
String line;
while ((line = reader.readLine()) != null) {
if (line.startsWith(SCOREBOARD)) {
metricsBuilder.addAll(parseScoreboardLine(line, timestamp));
} else {
metricsBuilder.addAll(parseStatLine(line, timestamp));
}
}
} finally {
reader.close();
}
return metricsBuilder.build();
}
}
/**
* Create a new ApacheStatusPoller with a given mechanism to fetch the status page.
* @param fetcher The {@link StatusFetcher} that will be used to refresh the metrics.
*/
public ApacheStatusPoller(StatusFetcher fetcher) {
this.fetcher = fetcher;
}
List<Metric> pollImpl(boolean reset, long timestamp) {
try {
InputStream statusStream = fetcher.fetchStatus();
try {
return StatusPageParser.parse(statusStream, timestamp);
} finally {
statusStream.close();
}
} catch (IOException e) {
logger.error("Could not fetch status page", e);
return EMPTY_LIST;
}
}
/**
* {@inheritDoc}
*/
@Override
public List<Metric> pollImpl(boolean reset) {
return pollImpl(reset, System.currentTimeMillis());
}
}