src/main/java/org/apache/sling/featureflags/impl/FeatureManager.java - sling-org-apache-sling-featureflags - Git at Google

 /*
  * 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.sling.featureflags.impl;

 import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 import javax.servlet.Filter;
 import javax.servlet.FilterChain;
 import javax.servlet.FilterConfig;
 import javax.servlet.Servlet;
 import javax.servlet.ServletConfig;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import org.apache.sling.api.request.ResponseUtil;
 import org.apache.sling.featureflags.Feature;
 import org.apache.sling.featureflags.Features;
 import org.osgi.framework.Constants;
 import org.osgi.service.component.annotations.Component;
 import org.osgi.service.component.annotations.ConfigurationPolicy;
 import org.osgi.service.component.annotations.Reference;
 import org.osgi.service.component.annotations.ReferenceCardinality;
 import org.osgi.service.component.annotations.ReferencePolicy;
 import org.osgi.service.http.whiteboard.HttpWhiteboardConstants;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 /**
  * This service implements the feature handling. It keeps track of all
  * {@link Feature} services.
  */
 @Component(service = {Features.class, Filter.class, Servlet.class},
            configurationPolicy = ConfigurationPolicy.IGNORE,
            property = {
                    HttpWhiteboardConstants.HTTP_WHITEBOARD_CONTEXT_SELECT + "=(" + HttpWhiteboardConstants.HTTP_WHITEBOARD_CONTEXT_NAME + "=org.apache.sling)",
                    HttpWhiteboardConstants.HTTP_WHITEBOARD_FILTER_PATTERN + "=/",
                    "felix.webconsole.label=features",
                    "felix.webconsole.title=Features",
                    "felix.webconsole.category=Sling",
                    Constants.SERVICE_RANKING + ":Integer=16384",
                    Constants.SERVICE_VENDOR + "=The Apache Software Foundation"
            })
 public class FeatureManager implements Features, Filter, Servlet {

     private final Logger logger = LoggerFactory.getLogger(this.getClass());

     private final ThreadLocal<ExecutionContextImpl> perThreadClientContext = new ThreadLocal<ExecutionContextImpl>();

     private final Map<String, List<FeatureDescription>> allFeatures = new HashMap<String, List<FeatureDescription>>();

     private Map<String, Feature> activeFeatures = Collections.emptyMap();

     private ServletConfig servletConfig;

     //--- Features

     @Override
     public Feature[] getFeatures() {
         final Map<String, Feature> activeFeatures = this.activeFeatures;
         return activeFeatures.values().toArray(new Feature[activeFeatures.size()]);
     }

     @Override
     public Feature getFeature(final String name) {
         return this.activeFeatures.get(name);
     }

     @Override
     public boolean isEnabled(final String featureName) {
         final Feature feature = this.getFeature(featureName);
         if (feature != null) {
             return getCurrentExecutionContext().isEnabled(feature);
         }
         return false;
     }

     //--- Filter

     @Override
     public void init(final FilterConfig filterConfig) {
         // nothing to do
     }

     @Override
     public void doFilter(final ServletRequest request,
             final ServletResponse response,
             final FilterChain chain)
     throws IOException, ServletException {
         this.pushContext((HttpServletRequest) request);
         try {
             chain.doFilter(request, response);
         } finally {
             this.popContext();
         }
     }

     @Override
     public void destroy() {
         // method shared by Servlet and Filter interface
         this.servletConfig = null;
     }

     //--- Servlet

     @Override
     public void init(final ServletConfig config) {
         this.servletConfig = config;
     }

     @Override
     public ServletConfig getServletConfig() {
         return this.servletConfig;
     }

     @Override
     public String getServletInfo() {
         return "Features";
     }

     @Override
     public void service(ServletRequest req, ServletResponse res) throws IOException {
         if ("GET".equals(((HttpServletRequest) req).getMethod())) {
             final PrintWriter pw = res.getWriter();
             final Feature[] features = getFeatures();
             if (features == null || features.length == 0) {
                 pw.println("<p class='statline ui-state-highlight'>No Features currently defined</p>");
             } else {
                 pw.printf("<p class='statline ui-state-highlight'>%d Feature(s) currently defined</p>%n",
                     features.length);
                 pw.println("<table class='nicetable'>");
                 pw.println("<tr><th>Name</th><th>Description</th><th>Enabled</th></tr>");
                 final ExecutionContextImpl ctx = getCurrentExecutionContext();
                 for (final Feature feature : features) {
                     pw.printf("<tr><td>%s</td><td>%s</td><td>%s</td></tr>%n", ResponseUtil.escapeXml(feature.getName()),
                             ResponseUtil.escapeXml(feature.getDescription()), ctx.isEnabled(feature));
                 }
                 pw.println("</table>");
             }
         } else {
             ((HttpServletResponse) res).sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
             res.flushBuffer();
         }
     }

     //--- Feature binding

     // bind method for Feature services
     @Reference(cardinality = ReferenceCardinality.MULTIPLE,
             policy = ReferencePolicy.DYNAMIC)
     private void bindFeature(final Feature f, final Map<String, Object> props) {
         synchronized (this.allFeatures) {
             final String name = f.getName();
             final FeatureDescription info = new FeatureDescription(f, props);

             List<FeatureDescription> candidates = this.allFeatures.get(name);
             if (candidates == null) {
                 candidates = new ArrayList<FeatureDescription>();
                 this.allFeatures.put(name, candidates);
             }
             candidates.add(info);
             Collections.sort(candidates);

             this.calculateActiveProviders();
         }
     }

     // unbind method for Feature services
     @SuppressWarnings("unused")
     private void unbindFeature(final Feature f, final Map<String, Object> props) {
         synchronized (this.allFeatures) {
             final String name = f.getName();
             final FeatureDescription info = new FeatureDescription(f, props);

             final List<FeatureDescription> candidates = this.allFeatures.get(name);
             if (candidates != null) { // sanity check
                 candidates.remove(info);
                 if (candidates.size() == 0) {
                     this.allFeatures.remove(name);
                 }
             }
             this.calculateActiveProviders();
         }
     }

     // calculates map of active features (eliminating Feature name
     // collisions). Must be called while synchronized on this.allFeatures
     private void calculateActiveProviders() {
         final Map<String, Feature> activeMap = new HashMap<String, Feature>();
         for (final Map.Entry<String, List<FeatureDescription>> entry : this.allFeatures.entrySet()) {
             final FeatureDescription desc = entry.getValue().get(0);
             activeMap.put(entry.getKey(), desc.feature);
             if (entry.getValue().size() > 1) {
                 logger.warn("More than one feature service for feature {}", entry.getKey());
             }
         }
         this.activeFeatures = activeMap;
     }

     //--- Client Context management and access

     void pushContext(final HttpServletRequest request) {
         this.perThreadClientContext.set(new ExecutionContextImpl(this, request));
     }

     void popContext() {
         this.perThreadClientContext.set(null);
     }

     ExecutionContextImpl getCurrentExecutionContext() {
         ExecutionContextImpl ctx = this.perThreadClientContext.get();
         return (ctx != null) ? ctx : new ExecutionContextImpl(this, null);
     }

     /**
      * Internal class caching some feature meta data like service id and
      * ranking.
      */
     private final static class FeatureDescription implements Comparable<FeatureDescription> {

         public final int ranking;

         public final long serviceId;

         public final Feature feature;

         public FeatureDescription(final Feature feature, final Map<String, Object> props) {
             this.feature = feature;
             final Object sr = props.get(Constants.SERVICE_RANKING);
             if (sr instanceof Integer) {
                 this.ranking = (Integer) sr;
             } else {
                 this.ranking = 0;
             }
             this.serviceId = (Long) props.get(Constants.SERVICE_ID);
         }

         @Override
         public int compareTo(final FeatureDescription o) {
             if (this.ranking < o.ranking) {
                 return 1;
             } else if (this.ranking > o.ranking) {
                 return -1;
             }
             // If ranks are equal, then sort by service id in descending order.
             return (this.serviceId < o.serviceId) ? -1 : 1;
         }

         @Override
         public boolean equals(final Object obj) {
             if (obj instanceof FeatureDescription) {
                 return ((FeatureDescription) obj).serviceId == this.serviceId;
             }
             return false;
         }

         @Override
         public int hashCode() {
             final int prime = 31;
             int result = 1;
             result = prime * result + (int) (serviceId ^ (serviceId >>> 32));
             return result;
         }
     }
 }
	/*
	* 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.sling.featureflags.impl;

	import java.io.IOException;
	import java.io.PrintWriter;
	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;

	import javax.servlet.Filter;
	import javax.servlet.FilterChain;
	import javax.servlet.FilterConfig;
	import javax.servlet.Servlet;
	import javax.servlet.ServletConfig;
	import javax.servlet.ServletException;
	import javax.servlet.ServletRequest;
	import javax.servlet.ServletResponse;
	import javax.servlet.http.HttpServletRequest;
	import javax.servlet.http.HttpServletResponse;

	import org.apache.sling.api.request.ResponseUtil;
	import org.apache.sling.featureflags.Feature;
	import org.apache.sling.featureflags.Features;
	import org.osgi.framework.Constants;
	import org.osgi.service.component.annotations.Component;
	import org.osgi.service.component.annotations.ConfigurationPolicy;
	import org.osgi.service.component.annotations.Reference;
	import org.osgi.service.component.annotations.ReferenceCardinality;
	import org.osgi.service.component.annotations.ReferencePolicy;
	import org.osgi.service.http.whiteboard.HttpWhiteboardConstants;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;

	/**
	* This service implements the feature handling. It keeps track of all
	* {@link Feature} services.
	*/
	@Component(service = {Features.class, Filter.class, Servlet.class},
	configurationPolicy = ConfigurationPolicy.IGNORE,
	property = {
	HttpWhiteboardConstants.HTTP_WHITEBOARD_CONTEXT_SELECT + "=(" + HttpWhiteboardConstants.HTTP_WHITEBOARD_CONTEXT_NAME + "=org.apache.sling)",
	HttpWhiteboardConstants.HTTP_WHITEBOARD_FILTER_PATTERN + "=/",
	"felix.webconsole.label=features",
	"felix.webconsole.title=Features",
	"felix.webconsole.category=Sling",
	Constants.SERVICE_RANKING + ":Integer=16384",
	Constants.SERVICE_VENDOR + "=The Apache Software Foundation"
	})
	public class FeatureManager implements Features, Filter, Servlet {

	private final Logger logger = LoggerFactory.getLogger(this.getClass());

	private final ThreadLocal<ExecutionContextImpl> perThreadClientContext = new ThreadLocal<ExecutionContextImpl>();

	private final Map<String, List<FeatureDescription>> allFeatures = new HashMap<String, List<FeatureDescription>>();

	private Map<String, Feature> activeFeatures = Collections.emptyMap();

	private ServletConfig servletConfig;

	//--- Features

	@Override
	public Feature[] getFeatures() {
	final Map<String, Feature> activeFeatures = this.activeFeatures;
	return activeFeatures.values().toArray(new Feature[activeFeatures.size()]);
	}

	@Override
	public Feature getFeature(final String name) {
	return this.activeFeatures.get(name);
	}

	@Override
	public boolean isEnabled(final String featureName) {
	final Feature feature = this.getFeature(featureName);
	if (feature != null) {
	return getCurrentExecutionContext().isEnabled(feature);
	}
	return false;
	}

	//--- Filter

	@Override
	public void init(final FilterConfig filterConfig) {
	// nothing to do
	}

	@Override
	public void doFilter(final ServletRequest request,
	final ServletResponse response,
	final FilterChain chain)
	throws IOException, ServletException {
	this.pushContext((HttpServletRequest) request);
	try {
	chain.doFilter(request, response);
	} finally {
	this.popContext();
	}
	}

	@Override
	public void destroy() {
	// method shared by Servlet and Filter interface
	this.servletConfig = null;
	}

	//--- Servlet

	@Override
	public void init(final ServletConfig config) {
	this.servletConfig = config;
	}

	@Override
	public ServletConfig getServletConfig() {
	return this.servletConfig;
	}

	@Override
	public String getServletInfo() {
	return "Features";
	}

	@Override
	public void service(ServletRequest req, ServletResponse res) throws IOException {
	if ("GET".equals(((HttpServletRequest) req).getMethod())) {
	final PrintWriter pw = res.getWriter();
	final Feature[] features = getFeatures();
	if (features == null \|\| features.length == 0) {
	pw.println("<p class='statline ui-state-highlight'>No Features currently defined</p>");
	} else {
	pw.printf("<p class='statline ui-state-highlight'>%d Feature(s) currently defined</p>%n",
	features.length);
	pw.println("<table class='nicetable'>");
	pw.println("<tr><th>Name</th><th>Description</th><th>Enabled</th></tr>");
	final ExecutionContextImpl ctx = getCurrentExecutionContext();
	for (final Feature feature : features) {
	pw.printf("<tr><td>%s</td><td>%s</td><td>%s</td></tr>%n", ResponseUtil.escapeXml(feature.getName()),
	ResponseUtil.escapeXml(feature.getDescription()), ctx.isEnabled(feature));
	}
	pw.println("</table>");
	}
	} else {
	((HttpServletResponse) res).sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
	res.flushBuffer();
	}
	}

	//--- Feature binding

	// bind method for Feature services
	@Reference(cardinality = ReferenceCardinality.MULTIPLE,
	policy = ReferencePolicy.DYNAMIC)
	private void bindFeature(final Feature f, final Map<String, Object> props) {
	synchronized (this.allFeatures) {
	final String name = f.getName();
	final FeatureDescription info = new FeatureDescription(f, props);

	List<FeatureDescription> candidates = this.allFeatures.get(name);
	if (candidates == null) {
	candidates = new ArrayList<FeatureDescription>();
	this.allFeatures.put(name, candidates);
	}
	candidates.add(info);
	Collections.sort(candidates);

	this.calculateActiveProviders();
	}
	}

	// unbind method for Feature services
	@SuppressWarnings("unused")
	private void unbindFeature(final Feature f, final Map<String, Object> props) {
	synchronized (this.allFeatures) {
	final String name = f.getName();
	final FeatureDescription info = new FeatureDescription(f, props);

	final List<FeatureDescription> candidates = this.allFeatures.get(name);
	if (candidates != null) { // sanity check
	candidates.remove(info);
	if (candidates.size() == 0) {
	this.allFeatures.remove(name);
	}
	}
	this.calculateActiveProviders();
	}
	}

	// calculates map of active features (eliminating Feature name
	// collisions). Must be called while synchronized on this.allFeatures
	private void calculateActiveProviders() {
	final Map<String, Feature> activeMap = new HashMap<String, Feature>();
	for (final Map.Entry<String, List<FeatureDescription>> entry : this.allFeatures.entrySet()) {
	final FeatureDescription desc = entry.getValue().get(0);
	activeMap.put(entry.getKey(), desc.feature);
	if (entry.getValue().size() > 1) {
	logger.warn("More than one feature service for feature {}", entry.getKey());
	}
	}
	this.activeFeatures = activeMap;
	}

	//--- Client Context management and access

	void pushContext(final HttpServletRequest request) {
	this.perThreadClientContext.set(new ExecutionContextImpl(this, request));
	}

	void popContext() {
	this.perThreadClientContext.set(null);
	}

	ExecutionContextImpl getCurrentExecutionContext() {
	ExecutionContextImpl ctx = this.perThreadClientContext.get();
	return (ctx != null) ? ctx : new ExecutionContextImpl(this, null);
	}

	/**
	* Internal class caching some feature meta data like service id and
	* ranking.
	*/
	private final static class FeatureDescription implements Comparable<FeatureDescription> {

	public final int ranking;

	public final long serviceId;

	public final Feature feature;

	public FeatureDescription(final Feature feature, final Map<String, Object> props) {
	this.feature = feature;
	final Object sr = props.get(Constants.SERVICE_RANKING);
	if (sr instanceof Integer) {
	this.ranking = (Integer) sr;
	} else {
	this.ranking = 0;
	}
	this.serviceId = (Long) props.get(Constants.SERVICE_ID);
	}

	@Override
	public int compareTo(final FeatureDescription o) {
	if (this.ranking < o.ranking) {
	return 1;
	} else if (this.ranking > o.ranking) {
	return -1;
	}
	// If ranks are equal, then sort by service id in descending order.
	return (this.serviceId < o.serviceId) ? -1 : 1;
	}

	@Override
	public boolean equals(final Object obj) {
	if (obj instanceof FeatureDescription) {
	return ((FeatureDescription) obj).serviceId == this.serviceId;
	}
	return false;
	}

	@Override
	public int hashCode() {
	final int prime = 31;
	int result = 1;
	result = prime * result + (int) (serviceId ^ (serviceId >>> 32));
	return result;
	}
	}
	}