Java tutorial
// ================================================================================================= // Copyright 2011 Twitter, Inc. // ------------------------------------------------------------------------------------------------- // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this work except in compliance with the License. // You may obtain a copy of the License in the LICENSE file, or 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 com.twitter.common.thrift; import java.net.InetSocketAddress; import java.util.List; import java.util.Map; import java.util.Set; import com.google.common.base.Function; import com.google.common.base.Joiner; import com.google.common.base.Predicate; import com.google.common.base.Strings; import com.google.common.collect.Lists; import org.apache.thrift.TBase; import org.apache.thrift.TFieldIdEnum; import org.apache.thrift.meta_data.FieldMetaData; import com.twitter.thrift.Endpoint; import com.twitter.thrift.ServiceInstance; /** * Utility functions for thrift. * * @author William Farner */ public class Util { public static Function<ServiceInstance, InetSocketAddress> GET_ADDRESS = new Function<ServiceInstance, InetSocketAddress>() { @Override public InetSocketAddress apply(ServiceInstance serviceInstance) { Endpoint endpoint = serviceInstance.getServiceEndpoint(); return InetSocketAddress.createUnresolved(endpoint.getHost(), endpoint.getPort()); } }; public static final Predicate<ServiceInstance> IS_ALIVE = new Predicate<ServiceInstance>() { @Override public boolean apply(ServiceInstance serviceInstance) { switch (serviceInstance.getStatus()) { case ALIVE: return true; // We'll be optimistic here and let MTCP's ranking deal with // unhealthy services in a WARNING state. case WARNING: return true; // Services which are just starting up, on the other hand... are much easier to just not // send requests to. The STARTING state is useful to distinguish from WARNING or ALIVE: // you exist in ZooKeeper, but don't yet serve traffic. case STARTING: default: return false; } } }; /** * Pretty-prints a thrift object contents. * * @param t The thrift object to print. * @return The pretty-printed version of the thrift object. */ public static String prettyPrint(TBase t) { return t == null ? "null" : printTbase(t, 0); } /** * Prints an object contained in a thrift message. * * @param o The object to print. * @param depth The print nesting level. * @return The pretty-printed version of the thrift field. */ private static String printValue(Object o, int depth) { if (o == null) { return "null"; } else if (TBase.class.isAssignableFrom(o.getClass())) { return "\n" + printTbase((TBase) o, depth + 1); } else if (Map.class.isAssignableFrom(o.getClass())) { return printMap((Map) o, depth + 1); } else if (List.class.isAssignableFrom(o.getClass())) { return printList((List) o, depth + 1); } else if (Set.class.isAssignableFrom(o.getClass())) { return printSet((Set) o, depth + 1); } else if (String.class == o.getClass()) { return '"' + o.toString() + '"'; } else { return o.toString(); } } private static final String METADATA_MAP_FIELD_NAME = "metaDataMap"; /** * Prints a TBase. * * @param t The object to print. * @param depth The print nesting level. * @return The pretty-printed version of the TBase. */ private static String printTbase(TBase t, int depth) { List<String> fields = Lists.newArrayList(); for (Map.Entry<? extends TFieldIdEnum, FieldMetaData> entry : FieldMetaData .getStructMetaDataMap(t.getClass()).entrySet()) { @SuppressWarnings("unchecked") Object value = t.getFieldValue(entry.getKey()); fields.add(tabs(depth) + entry.getValue().fieldName + ": " + printValue(value, depth)); } return Joiner.on("\n").join(fields); } /** * Prints a map in a style that is consistent with TBase pretty printing. * * @param map The map to print * @param depth The print nesting level. * @return The pretty-printed version of the map. */ private static String printMap(Map<?, ?> map, int depth) { List<String> entries = Lists.newArrayList(); for (Map.Entry entry : map.entrySet()) { entries.add( tabs(depth) + printValue(entry.getKey(), depth) + " = " + printValue(entry.getValue(), depth)); } return entries.isEmpty() ? "{}" : String.format("{\n%s\n%s}", Joiner.on(",\n").join(entries), tabs(depth - 1)); } /** * Prints a list in a style that is consistent with TBase pretty printing. * * @param list The list to print * @param depth The print nesting level. * @return The pretty-printed version of the list */ private static String printList(List<?> list, int depth) { List<String> entries = Lists.newArrayList(); for (int i = 0; i < list.size(); i++) { entries.add(String.format("%sItem[%d] = %s", tabs(depth), i, printValue(list.get(i), depth))); } return entries.isEmpty() ? "[]" : String.format("[\n%s\n%s]", Joiner.on(",\n").join(entries), tabs(depth - 1)); } /** * Prints a set in a style that is consistent with TBase pretty printing. * * @param set The set to print * @param depth The print nesting level. * @return The pretty-printed version of the set */ private static String printSet(Set<?> set, int depth) { List<String> entries = Lists.newArrayList(); for (Object item : set) { entries.add(String.format("%sItem = %s", tabs(depth), printValue(item, depth))); } return entries.isEmpty() ? "{}" : String.format("{\n%s\n%s}", Joiner.on(",\n").join(entries), tabs(depth - 1)); } private static String tabs(int n) { return Strings.repeat(" ", n); } private Util() { // Utility class. } }