Java tutorial
/* * Licensed 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 com.addthis.hydra.query.web; import java.io.IOException; import java.util.concurrent.TimeUnit; import java.nio.CharBuffer; import com.addthis.basis.kv.KVPairs; import com.addthis.basis.util.CUID; import com.addthis.hydra.data.query.Query; import com.addthis.hydra.data.query.QueryException; import com.google.common.cache.Cache; import com.google.common.cache.CacheBuilder; import org.apache.commons.io.output.StringBuilderWriter; import io.netty.buffer.ByteBuf; import io.netty.buffer.ByteBufUtil; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.http.DefaultHttpContent; import io.netty.handler.codec.http.HttpContent; import io.netty.handler.codec.http.HttpHeaders; import io.netty.handler.codec.http.HttpRequest; import io.netty.handler.codec.http.HttpResponse; import io.netty.handler.codec.http.LastHttpContent; import io.netty.util.CharsetUtil; public class LegacyHandler { // You have 5 minutes to claim your async result, if we ever need to // parametrize this we have created a monster. static final Cache<String, Query> asyncCache = CacheBuilder.newBuilder().expireAfterWrite(5, TimeUnit.MINUTES) .build(); public static Query handleQuery(Query query, KVPairs kv, HttpRequest request, ChannelHandlerContext ctx) throws IOException, QueryException { String async = kv.getValue("async"); if (async == null) { return query; } else if (async.equals("new")) { StringBuilderWriter writer = new StringBuilderWriter(50); HttpResponse response = HttpUtils.startResponse(writer); String asyncUuid = genAsyncUuid(); asyncCache.put(asyncUuid, query); if (query.isTraced()) { Query.emitTrace("async create " + asyncUuid + " from " + query); } writer.write("{\"id\":\"" + asyncUuid + "\"}"); ByteBuf textResponse = ByteBufUtil.encodeString(ctx.alloc(), CharBuffer.wrap(writer.getBuilder()), CharsetUtil.UTF_8); HttpContent content = new DefaultHttpContent(textResponse); response.headers().set(HttpHeaders.Names.CONTENT_LENGTH, textResponse.readableBytes()); if (HttpHeaders.isKeepAlive(request)) { response.headers().set(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.KEEP_ALIVE); } ctx.write(response); ctx.write(content); ChannelFuture lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT); if (!HttpHeaders.isKeepAlive(request)) { lastContentFuture.addListener(ChannelFutureListener.CLOSE); } return null; } else { Query asyncQuery = asyncCache.getIfPresent(async); asyncCache.invalidate(async); if (query.isTraced()) { Query.emitTrace("async restore " + async + " as " + asyncQuery); } if (asyncQuery != null) { return asyncQuery; } else { throw new QueryException("Missing Async Id"); } } } static String genAsyncUuid() { return CUID.createCUID(); } }