OsgiNamingHelper.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.camel.core.osgi;

import java.util.concurrent.atomic.AtomicInteger;

import org.apache.camel.CamelContext;
import org.osgi.framework.BundleContext;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A helper to find free names in the OSGi service registry.
 */
public final class OsgiNamingHelper {

    private static final Logger LOG = LoggerFactory.getLogger(OsgiNamingHelper.class);

    private OsgiNamingHelper() {
    }

    /**
     * Checks the OSGi service registry for a free name (uses the counter if there is a clash to find next free name)
     *
     * @param context the bundle context
     * @param prefix  the prefix for the name
     * @param key     the key to use in the OSGi filter; either {@link OsgiCamelContextPublisher#CONTEXT_NAME_PROPERTY}
     *                or {@link OsgiCamelContextPublisher#CONTEXT_MANAGEMENT_NAME_PROPERTY}.
     * @param counter the counter
     * @param checkFirst <tt>true</tt> to check the prefix name as-is before using the counter, <tt>false</tt> the counter is used immediately
     * @return the free name, is never <tt>null</tt>
     */
    public static String findFreeCamelContextName(BundleContext context, String prefix, String key, AtomicInteger counter, boolean checkFirst) {
        String candidate = null;
        boolean clash = false;

        do {
            try {
                clash = false;

                if (candidate == null && checkFirst) {
                    // try candidate as-is
                    candidate = prefix;
                } else {
                    // generate new candidate
                    candidate = prefix + "-" + getNextCounter(counter);
                }
                LOG.trace("Checking OSGi Service Registry for existence of existing CamelContext with name: {}", candidate);

                ServiceReference<?>[] refs = context.getServiceReferences(CamelContext.class.getName(), "(" + key + "=" + candidate + ")");
                if (refs != null && refs.length > 0) {
                    for (ServiceReference<?> ref : refs) {
                        Object id = ref.getProperty(key);
                        if (id != null && candidate.equals(id)) {
                            clash = true;
                            break;
                        }
                    }
                }
            } catch (InvalidSyntaxException e) {
                LOG.debug("Error finding free Camel name in OSGi Service Registry due " + e.getMessage() + ". This exception is ignored.", e);
                break;
            }
        } while (clash);

        LOG.debug("Generated free name for bundle id: {}, clash: {} -> {}", new Object[]{context.getBundle().getBundleId(), clash, candidate});
        return candidate;
    }

    public static int getNextCounter(AtomicInteger counter) {
        // we want to start counting from 1, so increment first
        return counter.incrementAndGet();
    }

}