| /* |
| * 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.htrace.core; |
| |
| import java.lang.reflect.Constructor; |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| /** |
| * A {@link SpanReceiver} builder. It reads a {@link SpanReceiver} class name from the provided |
| * configuration using the {@link #SPAN_RECEIVER_CONF_KEY} key. Unqualified class names |
| * are interpreted as members of the {@code org.apache.htrace.impl} package. The {@link #build()} |
| * method constructs an instance of that class, initialized with the same configuration. |
| */ |
| public class SpanReceiverBuilder { |
| private static final Log LOG = LogFactory.getLog(SpanReceiverBuilder.class); |
| |
| public final static String SPAN_RECEIVER_CONF_KEY = "span.receiver"; |
| private final static String DEFAULT_PACKAGE = "org.apache.htrace.core"; |
| private final static ClassLoader classLoader = |
| SpanReceiverBuilder.class.getClassLoader(); |
| private final HTraceConfiguration conf; |
| private boolean logErrors; |
| private String spanReceiverClass; |
| |
| public SpanReceiverBuilder(HTraceConfiguration conf) { |
| this.conf = conf; |
| reset(); |
| } |
| |
| /** |
| * Set this builder back to defaults. Any previous calls to {@link #spanReceiverClass(String)} |
| * are overridden by the value provided by configuration. |
| * @return This instance |
| */ |
| public SpanReceiverBuilder reset() { |
| this.logErrors = true; |
| this.spanReceiverClass = this.conf.get(SPAN_RECEIVER_CONF_KEY); |
| return this; |
| } |
| |
| /** |
| * Override the {@code SpanReceiver} class name provided in configuration with a new value. |
| * @return This instance |
| */ |
| public SpanReceiverBuilder spanReceiverClass(final String spanReceiverClass) { |
| this.spanReceiverClass = spanReceiverClass; |
| return this; |
| } |
| |
| /** |
| * Configure whether we should log errors during build(). |
| * @return This instance |
| */ |
| public SpanReceiverBuilder logErrors(boolean logErrors) { |
| this.logErrors = logErrors; |
| return this; |
| } |
| |
| private void logError(String errorStr) { |
| if (!logErrors) { |
| return; |
| } |
| LOG.error(errorStr); |
| } |
| |
| private void logError(String errorStr, Throwable e) { |
| if (!logErrors) { |
| return; |
| } |
| LOG.error(errorStr, e); |
| } |
| |
| public SpanReceiver build() { |
| SpanReceiver spanReceiver = newSpanReceiver(); |
| if (LOG.isTraceEnabled()) { |
| LOG.trace("Created new span receiver of type " + |
| ((spanReceiver == null) ? "(none)" : |
| spanReceiver.getClass().getName())); |
| } |
| return spanReceiver; |
| } |
| |
| private SpanReceiver newSpanReceiver() { |
| if ((this.spanReceiverClass == null) || |
| this.spanReceiverClass.isEmpty()) { |
| LOG.debug("No span receiver class specified."); |
| return null; |
| } |
| String str = spanReceiverClass; |
| if (!str.contains(".")) { |
| str = DEFAULT_PACKAGE + "." + str; |
| } |
| Class cls = null; |
| try { |
| cls = classLoader.loadClass(str); |
| } catch (ClassNotFoundException e) { |
| logError("SpanReceiverBuilder cannot find SpanReceiver class " + str + |
| ": disabling span receiver."); |
| return null; |
| } |
| Constructor<SpanReceiver> ctor = null; |
| try { |
| ctor = cls.getConstructor(HTraceConfiguration.class); |
| } catch (NoSuchMethodException e) { |
| logError("SpanReceiverBuilder cannot find a constructor for class " + |
| str + "which takes an HTraceConfiguration. Disabling span " + |
| "receiver."); |
| return null; |
| } |
| try { |
| LOG.debug("Creating new instance of " + str + "..."); |
| return ctor.newInstance(conf); |
| } catch (ReflectiveOperationException e) { |
| logError("SpanReceiverBuilder reflection error when constructing " + str + |
| ". Disabling span receiver.", e); |
| return null; |
| } catch (Throwable e) { |
| logError("SpanReceiverBuilder constructor error when constructing " + str + |
| ". Disabling span receiver.", e); |
| return null; |
| } |
| } |
| } |