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RESTHeart MongoDB - MongoDB Client Provider
/*-
* ========================LICENSE_START=================================
* restheart-mongoclient-provider
* %%
* Copyright (C) 2014 - 2024 SoftInstigate
* %%
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see }
*/
public class MongoClientSingleton {
private static boolean initialized = false;
private static ConnectionString mongoUri;
private String serverVersion = null;
private static final Logger LOGGER = LoggerFactory.getLogger(MongoClientSingleton.class);
/**
*
* @param uri
*/
public static void init(ConnectionString uri) {
mongoUri = uri;
initialized = true;
}
/**
* @return the initialized
*/
public static boolean isInitialized() {
return initialized;
}
/**
* alias for getInstance()
* @return the MongoClientSingleton
*/
public static MongoClientSingleton get() {
return getInstance();
}
/**
*
* @return
*/
public static MongoClientSingleton getInstance() {
return MongoClientSingletonHolder.INSTANCE;
}
/**
* @return the serverVersion
*/
public String getServerVersion() {
return serverVersion;
}
private MongoClient mclient;
private MongoClientSingleton() {
if (!initialized) {
throw new IllegalStateException("not initialized");
}
}
private void setup() {
if (!initialized) {
throw new IllegalStateException("MongoClientSingleton is not initialized");
}
LOGGER.info("Connecting to MongoDB...");
// TODO add minSize and maxSize to configuration
var settings = MongoClientSettings.builder()
.applyToConnectionPoolSettings((final ConnectionPoolSettings.Builder builder) -> {
// default mongodb values: min=0 and max=100
builder.minSize(0).maxSize(128);
})
.applicationName("restheart (sync)")
.applyConnectionString(mongoUri)
.build();
mclient = MongoClients.create(settings);
// this is the first time we check the connection
if (connected(mclient)) {
// get the db version
try {
var res = mclient.getDatabase("admin").runCommand(new BsonDocument("buildInfo", new BsonInt32(1)));
var _version = res.get("version");
if (_version != null && _version instanceof String) {
serverVersion = (String) _version;
} else {
LOGGER.warn("Cannot get the MongoDB version.");
serverVersion = "?";
}
LOGGER.info("MongoDB version {}", ansi()
.fg(MAGENTA)
.a(getServerVersion())
.reset()
.toString());
if (replicaSet(this.mclient)) {
LOGGER.info("MongoDB is a replica set.");
} else {
LOGGER.warn("MongoDB is a standalone instance.");
}
} catch (Throwable t) {
LOGGER.error(ansi().fg(RED).bold().a("Cannot connect to MongoDB. ").reset().toString()
+ "Check that MongoDB is running and "
+ "the configuration property '/mclient/connection-string' "
+ "is set properly");
serverVersion = "?";
}
} else {
LOGGER.error(ansi().fg(RED).bold().a("Cannot connect to MongoDB. ").reset().toString()
+ "Check that MongoDB is running and "
+ "the configuration property '/mclient/connection-string' "
+ "is set properly");
serverVersion = "?";
}
}
/**
* alias for getClient()
* @return the MongoClient
*/
public MongoClient client() {
return getClient();
}
/**
*
* @return
*/
public MongoClient getClient() {
if (!initialized) {
throw new IllegalStateException("MongoClientSingleton is not initialized");
}
if (this.mclient == null) {
setup();
}
return this.mclient;
}
@Override
public boolean equals(Object obj) {
// it is a singleton!
return obj == null ? false : getClass().getName().equals(obj.getClass().getName());
}
private static class MongoClientSingletonHolder {
private static final MongoClientSingleton INSTANCE;
// make sure the Singleton is a Singleton even in a multi-classloader environment
// credits to https://stackoverflow.com/users/145989/ondra-Žižka
// https://stackoverflow.com/a/47445573/4481670
static {
// There should be just one system class loader object in the whole JVM.
synchronized(ClassLoader.getSystemClassLoader()) {
var sysProps = System.getProperties();
// The key is a String, because the .class object would be different across classloaders.
var singleton = (MongoClientSingleton) sysProps.get(MongoClientSingleton.class.getName());
// Some other class loader loaded MongoClientSingleton earlier.
if (singleton != null) {
INSTANCE = singleton;
}
else {
// Otherwise this classloader is the first one, let's create a singleton.
// Make sure not to do any locking within this.
INSTANCE = new MongoClientSingleton();
System.getProperties().put(MongoClientSingleton.class.getName(), INSTANCE);
}
}
}
}
}