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/*
* Copyright © 2016-2017 European Support Limited
*
* 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 org.openecomp.sdc.logging;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.UUID;
import java.util.concurrent.atomic.AtomicLong;
import java.util.prefs.BackingStoreException;
import java.util.prefs.Preferences;
/**
* Collect information the is required for logging, but should not concern the business code of an application. For
* example, host name and IP address.
*
* @author evitaliy
* @since 04 Mar 2018
*/
@SuppressWarnings({"UseOfSystemOutOrSystemErr", "CallToPrintStackTrace", "squid:S106", "squid:S1148"})
public class GlobalLoggingContext {
// should be cashed to avoid low-level call, but with a timeout to account for IP or FQDN changes
private static final HostAddressCache HOST_ADDRESS_CACHE = new HostAddressCache();
@SuppressWarnings("squid:S1075")
private static final String INSTANCE_UUID_PREFERENCES_PATH = "/logging/instance/uuid";
private static final String INSTANCE_ID;
static {
INSTANCE_ID = readInstanceId();
}
private GlobalLoggingContext() {
// prevent instantiation
}
/**
* A unique ID of the logging entity. Is useful to distinguish between different nodes of the same application. It
* is assumed, that the node can be re-started, in which case the unique ID must be retained.
*
* @return unique logging entity ID
*/
public static String getInstanceId() {
return INSTANCE_ID;
}
/**
* Local host address as returned by Java runtime. A value of host address will be cached for the interval specified
* in {@link HostAddressCache#REFRESH_TIME}
*
* @return local host address, may be null if could not be read for some reason
*/
public static InetAddress getHostAddress() {
return HOST_ADDRESS_CACHE.get();
}
private static String readInstanceId() {
try {
// On Linux, by default this will be ~/.java/.userPrefs/prefs.xml
final Preferences preferences = Preferences.userRoot();
String existingId = preferences.get(INSTANCE_UUID_PREFERENCES_PATH, null);
if (existingId != null) {
return existingId;
}
String newId = UUID.randomUUID().toString();
preferences.put(INSTANCE_UUID_PREFERENCES_PATH, newId);
preferences.flush();
return newId;
} catch (BackingStoreException e) {
e.printStackTrace();
// don't fail if there's a problem to use the store for some unexpected reason
return UUID.randomUUID().toString();
}
}
private static class HostAddressCache {
private static final long REFRESH_TIME = 60000L;
private final AtomicLong lastUpdated = new AtomicLong(0L);
private InetAddress hostAddress;
InetAddress get() {
long current = System.currentTimeMillis();
if (current - lastUpdated.get() > REFRESH_TIME) {
synchronized (this) {
try {
// set now to register the attempt even if failed
lastUpdated.set(current);
hostAddress = InetAddress.getLocalHost();
} catch (UnknownHostException e) {
e.printStackTrace(); // can't really use logging
hostAddress = null;
}
}
}
return hostAddress;
}
}
}
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