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Tamaya OSGI Configuration Injector

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/*
 * 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.tamaya.osgi.injection;

import org.apache.tamaya.osgi.TamayaConfigPlugin;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.ServiceReference;
import org.osgi.service.cm.ConfigurationAdmin;
import org.osgi.util.tracker.ServiceTracker;

import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Supplier;
import java.util.logging.Logger;

/**
 * Class that monitors services and configures them if they have {@code Tamaya-Config = true} in the
 * service settings.
 */
public class TamayaOSGIInjector{
    /** The logger. */
    private static final Logger LOG = Logger.getLogger(TamayaConfigPlugin.class.getName());
    /** The bundle context. */
    private BundleContext context;
    /** OSGI Config manager. */
    private ConfigurationAdmin cm;
    /** The service tracker. */
    private ServiceTracker tracker;
    /** The cached injectors. */
    private static final Map INJECTORS = new ConcurrentHashMap<>();

    /**
     * Creates a new injector.
     * @param context thge bundle contex, not null.
     */
    public TamayaOSGIInjector(BundleContext context) {
        this.context = Objects.requireNonNull(context);
        ServiceReference cmRef = context.getServiceReference(ConfigurationAdmin.class);
        this.cm = Objects.requireNonNull(context.getService(cmRef));
    }

    /**
     * Starts the injector by registering the servidce tracker for all type of services. Injection is performed on
     * service creation and modification.
     */
    public void start(){
        tracker = new ServiceTracker(context, Object.class.getName(), null) {
            @Override
            public Object addingService(ServiceReference reference) {
                LOG.info("Checking service for configuration: " + reference);
                Object service =  super.addingService(reference);
                if(isInjectionEnabled(reference)) {
                    String pid = (String)reference.getProperty(Constants.SERVICE_PID);
                    if(pid==null){
                        pid = reference.getBundle().getSymbolicName();
                    }
                    OSGIConfigurationInjector injector = getInjector(pid, reference.getBundle().getLocation());
                    injector.configure(service);
                }
                return service;
            }

            @Override
            public void modifiedService(ServiceReference reference, Object service) {
                super.modifiedService(reference, service);
                if(isInjectionEnabled(reference)) {
                    String pid = (String)reference.getProperty(Constants.SERVICE_PID);
                    if(pid==null){
                        pid = reference.getBundle().getSymbolicName();
                    }
                    OSGIConfigurationInjector injector = getInjector(pid, reference.getBundle().getLocation());
                    injector.configure(service);
                }
            }
        };
        tracker.open(true);
    }

    /**
     * Stops the service tracker listening.
     */
    public void stop(){
        if(tracker!=null){
            tracker.close();
            tracker = null;
        }
    }

    /**
     * Get or createObject an injector for injecting OSGI configuration using Tamaya's injection API.
     * @param pid the PID, not nbull.
     * @param location the optional location.
     * @return a injector, never null.
     */
    private OSGIConfigurationInjector getInjector(String pid, String location){
        String key = location==null?pid.trim():pid.trim()+"::"+location.trim();
        OSGIConfigurationInjector injector = INJECTORS.get(key);
        if(injector==null){
            injector = new OSGIConfigurationInjector(cm, pid, location);
            INJECTORS.put(key, injector);
        }
        return injector;
    }

    /**
     * Checks if injection is enabled on the given service.
     * @param reference the service reference, not null.
     * @return true, if injection is enabled.
     */
    static boolean isInjectionEnabled(ServiceReference reference){
        String enabledVal = (String)reference.getProperty(ConfigInjectionService.TAMAYA_INJECTION_ENABLED_PROP);
        if(enabledVal!=null){
            enabledVal = enabledVal.toLowerCase(Locale.ENGLISH);
            switch(enabledVal){
                case "true":
                case "yes":
                case "on":
                    return true;
                default:
                    return false;
            }
        }
        return isInjectionEnabled(reference.getBundle());
    }

    /**
     * Checks if injection is enabled on the given bundle.
     * @param bundle the bundle, not null.
     * @return true, if injection is enabled.
     */
    static boolean isInjectionEnabled(Bundle bundle){
        String enabledVal = bundle.getHeaders().get(ConfigInjectionService.TAMAYA_INJECTION_ENABLED_MANIFEST);
        if(enabledVal!=null){
            enabledVal = enabledVal.toLowerCase(Locale.ENGLISH);
            switch(enabledVal){
                case "true":
                case "yes":
                case "on":
                    return true;
                default:
                    return false;
            }
        }
        return false;
    }

     T configure(String pid, String location, T instance) {
        return getInjector(pid, location).configure(instance);
    }

     Supplier getConfiguredSupplier(String pid, String location, Supplier supplier) {
        return getInjector(pid, location).getConfiguredSupplier(supplier);
    }

     T createTemplate(String pid, String location, Class templateType) {
        return getInjector(pid, location).createTemplate(templateType);
    }
}
    

    

    

            

    

            



    
    






    
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