Source code

001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 * 
010 *      http://www.apache.org/licenses/LICENSE-2.0
011 * 
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.oozie.service;
019
020import org.apache.oozie.util.XLog;
021import org.apache.oozie.util.ELEvaluator;
022import org.apache.oozie.ErrorCode;
023import org.apache.hadoop.conf.Configuration;
024
025import java.lang.reflect.Field;
026import java.lang.reflect.Method;
027import java.lang.reflect.Modifier;
028import java.util.ArrayList;
029import java.util.HashMap;
030import java.util.List;
031
032/**
033 * The ELService creates {@link ELEvaluator} instances preconfigured with constants and functions defined in the
034 * configuration. <p/> The following configuration parameters control the EL service: <p/> {@link #CONF_CONSTANTS} list
035 * of constant definitions to be available for EL evaluations. <p/> {@link #CONF_FUNCTIONS} list of function definitions
036 * to be available for EL evalations. <p/> Definitions must be separated by a comma, definitions are trimmed. <p/> The
037 * syntax for a constant definition is <code>PREFIX:NAME=CLASS_NAME#CONSTANT_NAME</code>. <p/> The syntax for a constant
038 * definition is <code>PREFIX:NAME=CLASS_NAME#METHOD_NAME</code>.
039 */
040public class ELService implements Service {
041
042    public static final String CONF_PREFIX = Service.CONF_PREFIX + "ELService.";
043
044    public static final String CONF_CONSTANTS = CONF_PREFIX + "constants.";
045
046    public static final String CONF_EXT_CONSTANTS = CONF_PREFIX + "ext.constants.";
047
048    public static final String CONF_FUNCTIONS = CONF_PREFIX + "functions.";
049
050    public static final String CONF_EXT_FUNCTIONS = CONF_PREFIX + "ext.functions.";
051
052    public static final String CONF_GROUPS = CONF_PREFIX + "groups";
053
054    private final XLog log = XLog.getLog(getClass());
055
056    //<Group Name>, <List of constants>
057    private HashMap<String, List<ELConstant>> constants;
058    //<Group Name>, <List of functions>
059    private HashMap<String, List<ELFunction>> functions;
060
061    private static class ELConstant {
062        private String name;
063        private Object value;
064
065        private ELConstant(String prefix, String name, Object value) {
066            if (prefix.length() > 0) {
067                name = prefix + ":" + name;
068            }
069            this.name = name;
070            this.value = value;
071        }
072    }
073
074    private static class ELFunction {
075        private String prefix;
076        private String name;
077        private Method method;
078
079        private ELFunction(String prefix, String name, Method method) {
080            this.prefix = prefix;
081            this.name = name;
082            this.method = method;
083        }
084    }
085
086    private List<ELService.ELConstant> extractConstants(Configuration conf, String key) throws ServiceException {
087        List<ELService.ELConstant> list = new ArrayList<ELService.ELConstant>();
088        if (conf.get(key, "").trim().length() > 0) {
089            for (String function : conf.getStrings(key)) {
090                String[] parts = parseDefinition(function);
091                list.add(new ELConstant(parts[0], parts[1], findConstant(parts[2], parts[3])));
092                log.trace("Registered prefix:constant[{0}:{1}] for class#field[{2}#{3}]", (Object[]) parts);
093            }
094        }
095        return list;
096    }
097
098    private List<ELService.ELFunction> extractFunctions(Configuration conf, String key) throws ServiceException {
099        List<ELService.ELFunction> list = new ArrayList<ELService.ELFunction>();
100        if (conf.get(key, "").trim().length() > 0) {
101            for (String function : conf.getStrings(key)) {
102                String[] parts = parseDefinition(function);
103                list.add(new ELFunction(parts[0], parts[1], findMethod(parts[2], parts[3])));
104                log.trace("Registered prefix:constant[{0}:{1}] for class#field[{2}#{3}]", (Object[]) parts);
105            }
106        }
107        return list;
108    }
109
110    /**
111     * Initialize the EL service.
112     *
113     * @param services services instance.
114     * @throws ServiceException thrown if the EL service could not be initialized.
115     */
116    @Override
117    public synchronized void init(Services services) throws ServiceException {
118        log.trace("Constants and functions registration");
119        constants = new HashMap<String, List<ELConstant>>();
120        functions = new HashMap<String, List<ELFunction>>();
121        //Get the list of group names from configuration file
122        // defined in the property tag: oozie.service.ELSerice.groups
123        //String []groupList = services.getConf().get(CONF_GROUPS, "").trim().split(",");
124        String[] groupList = services.getConf().getStrings(CONF_GROUPS, "");
125        //For each group, collect the required functions and constants
126        // and store it into HashMap
127        for (String group : groupList) {
128            List<ELConstant> tmpConstants = new ArrayList<ELConstant>();
129            tmpConstants.addAll(extractConstants(services.getConf(), CONF_CONSTANTS + group));
130            tmpConstants.addAll(extractConstants(services.getConf(), CONF_EXT_CONSTANTS + group));
131            constants.put(group, tmpConstants);
132            List<ELFunction> tmpFunctions = new ArrayList<ELFunction>();
133            tmpFunctions.addAll(extractFunctions(services.getConf(), CONF_FUNCTIONS + group));
134            tmpFunctions.addAll(extractFunctions(services.getConf(), CONF_EXT_FUNCTIONS + group));
135            functions.put(group, tmpFunctions);
136        }
137    }
138
139    /**
140     * Destroy the EL service.
141     */
142    @Override
143    public void destroy() {
144        constants = null;
145        functions = null;
146    }
147
148    /**
149     * Return the public interface for EL service.
150     *
151     * @return {@link ELService}.
152     */
153    @Override
154    public Class<? extends Service> getInterface() {
155        return ELService.class;
156    }
157
158    /**
159     * Return an {@link ELEvaluator} pre-configured with the constants and functions for the specific group of
160     * EL-functions and variables defined in the configuration. If the group name doesn't exist,
161     * IllegalArgumentException is thrown
162     *
163     * @param group: Name of the group of required EL Evaluator.
164     * @return a preconfigured {@link ELEvaluator}.
165     */
166    public ELEvaluator createEvaluator(String group) {
167        ELEvaluator.Context context = new ELEvaluator.Context();
168        boolean groupDefined = false;
169        if (constants.containsKey(group)) {
170            for (ELConstant constant : constants.get(group)) {
171                context.setVariable(constant.name, constant.value);
172            }
173            groupDefined = true;
174        }
175        if (functions.containsKey(group)) {
176            for (ELFunction function : functions.get(group)) {
177                context.addFunction(function.prefix, function.name, function.method);
178            }
179            groupDefined = true;
180        }
181        if (groupDefined == false) {
182            throw new IllegalArgumentException("Group " + group + " is not defined");
183        }
184        return new ELEvaluator(context);
185    }
186
187    private static String[] parseDefinition(String str) throws ServiceException {
188        try {
189            str = str.trim();
190            if (!str.contains(":")) {
191                str = ":" + str;
192            }
193            String[] parts = str.split(":");
194            String prefix = parts[0];
195            parts = parts[1].split("=");
196            String name = parts[0];
197            parts = parts[1].split("#");
198            String klass = parts[0];
199            String method = parts[1];
200            return new String[]{prefix, name, klass, method};
201        }
202        catch (Exception ex) {
203            throw new ServiceException(ErrorCode.E0110, str, ex.getMessage(), ex);
204        }
205    }
206
207    public static Method findMethod(String className, String methodName) throws ServiceException {
208        Method method = null;
209        try {
210            Class klass = Thread.currentThread().getContextClassLoader().loadClass(className);
211            for (Method m : klass.getMethods()) {
212                if (m.getName().equals(methodName)) {
213                    method = m;
214                    break;
215                }
216            }
217            if (method == null) {
218                throw new ServiceException(ErrorCode.E0111, className, methodName);
219            }
220            if ((method.getModifiers() & (Modifier.PUBLIC | Modifier.STATIC)) != (Modifier.PUBLIC | Modifier.STATIC)) {
221                throw new ServiceException(ErrorCode.E0112, className, methodName);
222            }
223        }
224        catch (ClassNotFoundException ex) {
225            throw new ServiceException(ErrorCode.E0113, className);
226        }
227        return method;
228    }
229
230    public static Object findConstant(String className, String constantName) throws ServiceException {
231        try {
232            Class klass = Thread.currentThread().getContextClassLoader().loadClass(className);
233            Field field = klass.getField(constantName);
234            if ((field.getModifiers() & (Modifier.PUBLIC | Modifier.STATIC)) != (Modifier.PUBLIC | Modifier.STATIC)) {
235                throw new ServiceException(ErrorCode.E0114, className, constantName);
236            }
237            return field.get(null);
238        }
239        catch (IllegalAccessException ex) {
240            throw new IllegalArgumentException(ex);
241        }
242        catch (NoSuchFieldException ex) {
243            throw new ServiceException(ErrorCode.E0115, className, constantName);
244        }
245        catch (ClassNotFoundException ex) {
246            throw new ServiceException(ErrorCode.E0113, className);
247        }
248    }
249
250}