1.什么是Lucene？
作为一个开放源代码项目，Lucene从问世之后，引发了开放源代码社群的巨大反响，程序员们不仅使用它构建具体的全文检索应用，而且将之集成到各种系统软件中去，以及构建Web应用，甚至某些商业软件也采用了Lucene作为其内部全文检索子系统的核心。apache软件基金会的网站使用了Lucene作为全文检索的引擎，IBM的开源软件eclipse的2.1版本中也采用了Lucene作为帮助子系统的全文索引引擎，相应的IBM的商业软件Web Sphere中也采用了Lucene。Lucene以其开放源代码的特性、优异的索引结构、良好的系统架构获得了越来越多的应用。
Lucene作为一个全文检索引擎，其具有如下突出的优点：
（1）索引文件格式独立于应用平台。Lucene定义了一套以8位字节为基础的索引文件格式，使得兼容系统或者不同平台的应用能够共享建立的索引文件。
（2）在传统全文检索引擎的倒排索引的基础上，实现了分块索引，能够针对新的文件建立小文件索引，提升索引速度。然后通过与原有索引的合并，达到优化的目的。
（3）优秀的面向对象的系统架构，使得对于Lucene扩展的学习难度降低，方便扩充新功能。
（4）设计了独立于语言和文件格式的文本分析接口，索引器通过接受Token流完成索引文件的创立，用户扩展新的语言和文件格式，只需要实现文本分析的接口。
（5）已经默认实现了一套强大的查询引擎，用户无需自己编写代码即使系统可获得强大的查询能力，Lucene的查询实现中默认实现了布尔操作、模糊查询（Fuzzy Search）、分组查询等等。
2.什么是solr？
为什么要solr：
1、solr是将整个索引操作功能封装好了的搜索引擎系统(企业级搜索引擎产品)
2、solr可以部署到单独的服务器上(WEB服务)，它可以提供服务，我们的业务系统就只要发送请求，接收响应即可，降低了业务系统的负载
3、solr部署在专门的服务器上，它的索引库就不会受业务系统服务器存储空间的限制
4、solr支持分布式集群，索引服务的容量和能力可以线性扩展
solr的工作机制：
1、solr就是在lucene工具包的基础之上进行了封装，而且是以web服务的形式对外提供索引功能
2、业务系统需要使用到索引的功能（建索引，查索引）时，只要发出http请求，并将返回数据进行解析即可
Solr 是Apache下的一个顶级开源项目，采用Java开发，它是基于Lucene的全文搜索服务器。Solr提供了比Lucene更为丰富的查询语言，同时实现了可配置、可扩展，并对索引、搜索性能进行了优化。
Solr可以独立运行，运行在Jetty、Tomcat等这些Servlet容器中，Solr 索引的实现方法很简单，用 POST 方法向 Solr 服务器发送一个描述 Field 及其内容的 XML 文档，Solr根据xml文档添加、删除、更新索引 。Solr 搜索只需要发送 HTTP GET 请求，然后对 Solr 返回Xml、json等格式的查询结果进行解析，组织页面布局。Solr不提供构建UI的功能，Solr提供了一个管理界面，通过管理界面可以查询Solr的配置和运行情况。
3.lucene和solr的关系
solr是门户，lucene是底层基础，solr和lucene的关系正如hadoop和hdfs的关系。那么solr是怎么调用到lucene的呢？
我们以查询为例，来看一下整个过程，导入过程可以参考:
solr源码分析之数据导入DataImporter追溯
4.solr是怎么调用到lucene？
4.1.准备工作
lucene-solr本地调试方法
使用内置jetty启动main方法。
4.2 进入Solr-admin：http://localhost:8983/solr/
创建一个new_core集合
4.3 进入http://localhost:8983/solr/#/new_core/query
选择一个field进行查询
4.4 入口是SolrDispatchFilter，整个流程如流程图所示
从上面的流程图可以看出，solr采用filter的模式(如struts2,springmvc使用servlet模式)，然后以容器的方式来封装各种Handler，Handler负责处理各种请求，最终调用的是lucene的底层实现。
注意：solr没有使用lucene本身的QueryParser，而是自己重写了这个组件。
4.4.1 SolrDispatchFilter入口
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain, boolean retry) throws IOException, ServletException {
if (!(request instanceof HttpServletRequest)) return;
try {
if (cores == null || cores.isShutDown()) {
try {
init.await();
} catch (InterruptedException e) { //well, no wait then
} final String msg = "Error processing the request. CoreContainer is either not initialized or shutting down."; if (cores == null || cores.isShutDown()) { log.error(msg); throw new UnavailableException(msg); } } AtomicReference<ServletRequest> wrappedRequest = new AtomicReference<>(); if (!authenticateRequest(request, response, wrappedRequest)) { // the response and status code have already been // sent return; } if (wrappedRequest.get() != null) { request = wrappedRequest.get(); } request = closeShield(request, retry); response = closeShield(response, retry); if (cores.getAuthenticationPlugin() != null) { log.debug("User principal: {}", ((HttpServletRequest) request).getUserPrincipal()); } // No need to even create the HttpSolrCall object if this path is excluded. if (excludePatterns != null) { String requestPath = ((HttpServletRequest) request).getServletPath(); String extraPath = ((HttpServletRequest) request).getPathInfo(); if (extraPath != null) { // In embedded mode, servlet path is empty - include all post-context path here for // testing requestPath += extraPath; } for (Pattern p : excludePatterns) { Matcher matcher = p.matcher(requestPath); if (matcher.lookingAt()) { chain.doFilter(request, response); return; } } } HttpSolrCall call = getHttpSolrCall((HttpServletRequest) request, (HttpServletResponse) response, retry); ExecutorUtil.setServerThreadFlag(Boolean.TRUE); try { Action result = call.call(); //1 switch (result) { case PASSTHROUGH: chain.doFilter(request, response); break; case RETRY: doFilter(request, response, chain, true); break; case FORWARD: request.getRequestDispatcher(call.getPath()).forward(request, response); break; } } finally { call.destroy(); ExecutorUtil.setServerThreadFlag(null); } } finally { consumeInputFully((HttpServletRequest) request); } }
红色部分的调用
4.4.2 HttpSolrCall
/**
* This method processes the request.
*/
public Action call() throws IOException {
MDCLoggingContext.reset();
MDCLoggingContext.setNode(cores);
if (cores == null) {
sendError(503, "Server is shutting down or failed to initialize");
return RETURN;
}
if (solrDispatchFilter.abortErrorMessage != null) {
sendError(500, solrDispatchFilter.abortErrorMessage); return RETURN; } try { init();//1 /* Authorize the request if 1. Authorization is enabled, and 2. The requested resource is not a known static file */ if (cores.getAuthorizationPlugin() != null && shouldAuthorize()) { AuthorizationContext context = getAuthCtx(); log.debug("AuthorizationContext : {}", context); AuthorizationResponse authResponse = cores.getAuthorizationPlugin().authorize(context); if (authResponse.statusCode == AuthorizationResponse.PROMPT.statusCode) { Map<String, String> headers = (Map) getReq().getAttribute(AuthenticationPlugin.class.getName()); if (headers != null) { for (Map.Entry<String, String> e : headers.entrySet()) response.setHeader(e.getKey(), e.getValue()); } log.debug("USER_REQUIRED "+req.getHeader("Authorization")+" "+ req.getUserPrincipal()); } if (!(authResponse.statusCode == HttpStatus.SC_ACCEPTED) && !(authResponse.statusCode == HttpStatus.SC_OK)) { log.info("USER_REQUIRED auth header {} context : {} ", req.getHeader("Authorization"), context); sendError(authResponse.statusCode, "Unauthorized request, Response code: " + authResponse.statusCode); return RETURN; } } HttpServletResponse resp = response; switch (action) { case ADMIN: handleAdminRequest(); return RETURN; case REMOTEQUERY: remoteQuery(coreUrl + path, resp); return RETURN; case PROCESS: final Method reqMethod = Method.getMethod(req.getMethod()); HttpCacheHeaderUtil.setCacheControlHeader(config, resp, reqMethod); // unless we have been explicitly told not to, do cache validation // if we fail cache validation, execute the query if (config.getHttpCachingConfig().isNever304() || !HttpCacheHeaderUtil.doCacheHeaderValidation(solrReq, req, reqMethod, resp)) { SolrQueryResponse solrRsp = new SolrQueryResponse(); /* even for HEAD requests, we need to execute the handler to * ensure we don't get an error (and to make sure the correct * QueryResponseWriter is selected and we get the correct * Content-Type) */ SolrRequestInfo.setRequestInfo(new SolrRequestInfo(solrReq, solrRsp)); execute(solrRsp); //2 HttpCacheHeaderUtil.checkHttpCachingVeto(solrRsp, resp, reqMethod); Iterator<Map.Entry<String, String>> headers = solrRsp.httpHeaders(); while (headers.hasNext()) { Map.Entry<String, String> entry = headers.next(); resp.addHeader(entry.getKey(), entry.getValue()); } QueryResponseWriter responseWriter = getResponseWriter(); if (invalidStates != null) solrReq.getContext().put(CloudSolrClient.STATE_VERSION, invalidStates); writeResponse(solrRsp, responseWriter, reqMethod); } return RETURN; default: return action; } } catch (Throwable ex) { sendError(ex); // walk the the entire cause chain to search for an Error Throwable t = ex; while (t != null) { if (t instanceof Error) { if (t != ex) { log.error("An Error was wrapped in another exception - please report complete stacktrace on SOLR-6161", ex); } throw (Error) t; } t = t.getCause(); } return RETURN; } finally { MDCLoggingContext.clear(); } }
其中 1初始化，2.执行请求调用
4.4.3 获取Handler
protected void init() throws Exception {
// check for management path
String alternate = cores.getManagementPath();
if (alternate != null && path.startsWith(alternate)) {
path = path.substring(0, alternate.length());
}
// unused feature ?
int idx = path.indexOf(':');
if (idx > 0) { // save the portion after the ':' for a 'handler' path parameter path = path.substring(0, idx); } // Check for container handlers handler = cores.getRequestHandler(path); if (handler != null) { solrReq = SolrRequestParsers.DEFAULT.parse(null, path, req); solrReq.getContext().put(CoreContainer.class.getName(), cores); requestType = RequestType.ADMIN; action = ADMIN; return; } // Parse a core or collection name from the path and attempt to see if it's a core name idx = path.indexOf("/", 1); if (idx > 1) { origCorename = path.substring(1, idx); // Try to resolve a Solr core name core = cores.getCore(origCorename); if (core != null) { path = path.substring(idx); } else { if (cores.isCoreLoading(origCorename)) { // extra mem barriers, so don't look at this before trying to get core throw new SolrException(ErrorCode.SERVICE_UNAVAILABLE, "SolrCore is loading"); } // the core may have just finished loading core = cores.getCore(origCorename); if (core != null) { path = path.substring(idx); } else { if (!cores.isZooKeeperAware()) { core = cores.getCore(""); } } } } if (cores.isZooKeeperAware()) { // init collectionList (usually one name but not when there are aliases) String def = core != null ? core.getCoreDescriptor().getCollectionName() : origCorename; collectionsList = resolveCollectionListOrAlias(queryParams.get(COLLECTION_PROP, def)); // &collection= takes precedence if (core == null) { // lookup core from collection, or route away if need to String collectionName = collectionsList.isEmpty() ? null : collectionsList.get(0); // route to 1st //TODO try the other collections if can't find a local replica of the first? (and do to V2HttpSolrCall) boolean isPreferLeader = (path.endsWith("/update") || path.contains("/update/")); core = getCoreByCollection(collectionName, isPreferLeader); // find a local replica/core for the collection if (core != null) { if (idx > 0) { path = path.substring(idx); } } else { // if we couldn't find it locally, look on other nodes if (idx > 0) { extractRemotePath(collectionName, origCorename); if (action == REMOTEQUERY) { path = path.substring(idx); return; } } //core is not available locally or remotely autoCreateSystemColl(collectionName); if (action != null) return; } } } // With a valid core... if (core != null) { MDCLoggingContext.setCore(core); config = core.getSolrConfig(); // get or create/cache the parser for the core SolrRequestParsers parser = config.getRequestParsers(); // Determine the handler from the url path if not set // (we might already have selected the cores handler) extractHandlerFromURLPath(parser); if (action != null) return; // With a valid handler and a valid core... if (handler != null) { // if not a /select, create the request if (solrReq == null) { solrReq = parser.parse(core, path, req); } invalidStates = checkStateVersionsAreValid(solrReq.getParams().get(CloudSolrClient.STATE_VERSION)); addCollectionParamIfNeeded(getCollectionsList()); action = PROCESS; return; // we are done with a valid handler } } log.debug("no handler or core retrieved for " + path + ", follow through..."); action = PASSTHROUGH; }
4.4.4 CoreContainer
public SolrRequestHandler getRequestHandler(String path) {
return RequestHandlerBase.getRequestHandler(path, containerHandlers);
}
4.4.5 RequestHandlerBase
/**
* Get the request handler registered to a given name.
*
* This function is thread safe.
*/
public static SolrRequestHandler getRequestHandler(String handlerName, PluginBag<SolrRequestHandler> reqHandlers) {
if(handlerName == null) return null;
SolrRequestHandler handler = reqHandlers.get(handlerName);
int idx = 0;
if(handler == null) {
for (; ; ) {
idx = handlerName.indexOf('/', idx+1); if (idx > 0) { String firstPart = handlerName.substring(0, idx); handler = reqHandlers.get(firstPart); if (handler == null) continue; if (handler instanceof NestedRequestHandler) { return ((NestedRequestHandler) handler).getSubHandler(handlerName.substring(idx)); } } else { break; } } } return handler; }
4.4.6HttpSolrCall
protected void execute(SolrQueryResponse rsp) {
// a custom filter could add more stuff to the request before passing it on.
// for example: sreq.getContext().put( "HttpServletRequest", req );
// used for logging query stats in SolrCore.execute()
solrReq.getContext().put("webapp", req.getContextPath());
solrReq.getCore().execute(handler, solrReq, rsp);
}
4.4.7 SolrCore
public void execute(SolrRequestHandler handler, SolrQueryRequest req, SolrQueryResponse rsp) {
if (handler==null) {
String msg = "Null Request Handler '" +
req.getParams().get(CommonParams.QT) + "'";
if (log.isWarnEnabled()) log.warn(logid + msg + ":" + req);
throw new SolrException(ErrorCode.BAD_REQUEST, msg); } preDecorateResponse(req, rsp); if (requestLog.isDebugEnabled() && rsp.getToLog().size() > 0) { // log request at debug in case something goes wrong and we aren't able to log later requestLog.debug(rsp.getToLogAsString(logid)); } // TODO: this doesn't seem to be working correctly and causes problems with the example server and distrib (for example /spell) // if (req.getParams().getBool(ShardParams.IS_SHARD,false) && !(handler instanceof SearchHandler)) // throw new SolrException(SolrException.ErrorCode.BAD_REQUEST,"isShard is only acceptable with search handlers"); handler.handleRequest(req,rsp); postDecorateResponse(handler, req, rsp); if (rsp.getToLog().size() > 0) { if (requestLog.isInfoEnabled()) { requestLog.info(rsp.getToLogAsString(logid)); } if (log.isWarnEnabled() && slowQueryThresholdMillis >= 0) { final long qtime = (long) (req.getRequestTimer().getTime()); if (qtime >= slowQueryThresholdMillis) { log.warn("slow: " + rsp.getToLogAsString(logid)); } } } }
4.4.8 RequestHandlerBase
@Override
public void handleRequest(SolrQueryRequest req, SolrQueryResponse rsp) {
requests.inc();
Timer.Context timer = requestTimes.time();
try {
if(pluginInfo != null && pluginInfo.attributes.containsKey(USEPARAM)) req.getContext().put(USEPARAM,pluginInfo.attributes.get(USEPARAM));
SolrPluginUtils.setDefaults(this, req, defaults, appends, invariants); req.getContext().remove(USEPARAM); rsp.setHttpCaching(httpCaching); handleRequestBody( req, rsp ); // count timeouts NamedList header = rsp.getResponseHeader(); if(header != null) { Object partialResults = header.get(SolrQueryResponse.RESPONSE_HEADER_PARTIAL_RESULTS_KEY); boolean timedOut = partialResults == null ? false : (Boolean)partialResults; if( timedOut ) { numTimeouts.mark(); rsp.setHttpCaching(false); } } } catch (Exception e) { boolean incrementErrors = true; boolean isServerError = true; if (e instanceof SolrException) { SolrException se = (SolrException)e; if (se.code() == SolrException.ErrorCode.CONFLICT.code) { incrementErrors = false; } else if (se.code() >= 400 && se.code() < 500) { isServerError = false; } } else { if (e instanceof SyntaxError) { isServerError = false; e = new SolrException(SolrException.ErrorCode.BAD_REQUEST, e); } } rsp.setException(e); if (incrementErrors) { SolrException.log(log, e); numErrors.mark(); if (isServerError) { numServerErrors.mark(); } else { numClientErrors.mark(); } } } finally { long elapsed = timer.stop(); totalTime.inc(elapsed); } }
4.4.9 SearchHandler
@Override
public void handleRequestBody(SolrQueryRequest req, SolrQueryResponse rsp) throws Exception
{
List<SearchComponent> components = getComponents();
ResponseBuilder rb = new ResponseBuilder(req, rsp, components);
if (rb.requestInfo != null) {
rb.requestInfo.setResponseBuilder(rb);
}
boolean dbg = req.getParams().getBool(CommonParams.DEBUG_QUERY, false); rb.setDebug(dbg); if (dbg == false){//if it's true, we are doing everything anyway. SolrPluginUtils.getDebugInterests(req.getParams().getParams(CommonParams.DEBUG), rb); } final RTimerTree timer = rb.isDebug() ? req.getRequestTimer() : null; final ShardHandler shardHandler1 = getAndPrepShardHandler(req, rb); // creates a ShardHandler object only if it's needed if (timer == null) { // non-debugging prepare phase for( SearchComponent c : components ) { c.prepare(rb); //1 } } else { // debugging prepare phase RTimerTree subt = timer.sub( "prepare" ); for( SearchComponent c : components ) { rb.setTimer( subt.sub( c.getName() ) ); c.prepare(rb); rb.getTimer().stop(); } subt.stop(); } if (!rb.isDistrib) { // a normal non-distributed request long timeAllowed = req.getParams().getLong(CommonParams.TIME_ALLOWED, -1L); if (timeAllowed > 0L) { SolrQueryTimeoutImpl.set(timeAllowed); } try { // The semantics of debugging vs not debugging are different enough that // it makes sense to have two control loops if(!rb.isDebug()) { // Process for( SearchComponent c : components ) { c.process(rb); //2 } } else { // Process RTimerTree subt = timer.sub( "process" ); for( SearchComponent c : components ) { rb.setTimer( subt.sub( c.getName() ) ); c.process(rb); rb.getTimer().stop(); } subt.stop(); // add the timing info if (rb.isDebugTimings()) { rb.addDebugInfo("timing", timer.asNamedList() ); } } } catch (ExitableDirectoryReader.ExitingReaderException ex) { log.warn( "Query: " + req.getParamString() + "; " + ex.getMessage()); SolrDocumentList r = (SolrDocumentList) rb.rsp.getResponse(); if(r == null) r = new SolrDocumentList(); r.setNumFound(0); rb.rsp.addResponse(r); if(rb.isDebug()) { NamedList debug = new NamedList(); debug.add("explain", new NamedList()); rb.rsp.add("debug", debug); } rb.rsp.getResponseHeader().add(SolrQueryResponse.RESPONSE_HEADER_PARTIAL_RESULTS_KEY, Boolean.TRUE); } finally { SolrQueryTimeoutImpl.reset(); } } else { // a distributed request if (rb.outgoing == null) { rb.outgoing = new LinkedList<>(); } rb.finished = new ArrayList<>(); int nextStage = 0; do { rb.stage = nextStage; nextStage = ResponseBuilder.STAGE_DONE; // call all components for( SearchComponent c : components ) { // the next stage is the minimum of what all components report nextStage = Math.min(nextStage, c.distributedProcess(rb)); } // check the outgoing queue and send requests while (rb.outgoing.size() > 0) { // submit all current request tasks at once while (rb.outgoing.size() > 0) { ShardRequest sreq = rb.outgoing.remove(0); sreq.actualShards = sreq.shards; if (sreq.actualShards==ShardRequest.ALL_SHARDS) { sreq.actualShards = rb.shards; } sreq.responses = new ArrayList<>(sreq.actualShards.length); // presume we'll get a response from each shard we send to // TODO: map from shard to address[] for (String shard : sreq.actualShards) { ModifiableSolrParams params = new ModifiableSolrParams(sreq.params); params.remove(ShardParams.SHARDS); // not a top-level request params.set(DISTRIB, "false"); // not a top-level request params.remove("indent"); params.remove(CommonParams.HEADER_ECHO_PARAMS); params.set(ShardParams.IS_SHARD, true); // a sub (shard) request params.set(ShardParams.SHARDS_PURPOSE, sreq.purpose); params.set(ShardParams.SHARD_URL, shard); // so the shard knows what was asked if (rb.requestInfo != null) { // we could try and detect when this is needed, but it could be tricky params.set("NOW", Long.toString(rb.requestInfo.getNOW().getTime())); } String shardQt = params.get(ShardParams.SHARDS_QT); if (shardQt != null) { params.set(CommonParams.QT, shardQt); } else { // for distributed queries that don't include shards.qt, use the original path // as the default but operators need to update their luceneMatchVersion to enable // this behavior since it did not work this way prior to 5.1 String reqPath = (String) req.getContext().get(PATH); if (!"/select".equals(reqPath)) { params.set(CommonParams.QT, reqPath); } // else if path is /select, then the qt gets passed thru if set } shardHandler1.submit(sreq, shard, params); } } // now wait for replies, but if anyone puts more requests on // the outgoing queue, send them out immediately (by exiting // this loop) boolean tolerant = rb.req.getParams().getBool(ShardParams.SHARDS_TOLERANT, false); while (rb.outgoing.size() == 0) { ShardResponse srsp = tolerant ? shardHandler1.takeCompletedIncludingErrors(): shardHandler1.takeCompletedOrError(); if (srsp == null) break; // no more requests to wait for // Was there an exception? if (srsp.getException() != null) { // If things are not tolerant, abort everything and rethrow if(!tolerant) { shardHandler1.cancelAll(); if (srsp.getException() instanceof SolrException) { throw (SolrException)srsp.getException(); } else { throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, srsp.getException()); } } else { if(rsp.getResponseHeader().get(SolrQueryResponse.RESPONSE_HEADER_PARTIAL_RESULTS_KEY) == null) { rsp.getResponseHeader().add(SolrQueryResponse.RESPONSE_HEADER_PARTIAL_RESULTS_KEY, Boolean.TRUE); } } } rb.finished.add(srsp.getShardRequest()); // let the components see the responses to the request for(SearchComponent c : components) { c.handleResponses(rb, srsp.getShardRequest()); } } } for(SearchComponent c : components) { c.finishStage(rb); } //3 // we are done when the next stage is MAX_VALUE } while (nextStage != Integer.MAX_VALUE); } // SOLR-5550: still provide shards.info if requested even for a short circuited distrib request if(!rb.isDistrib && req.getParams().getBool(ShardParams.SHARDS_INFO, false) && rb.shortCircuitedURL != null) { NamedList<Object> shardInfo = new SimpleOrderedMap<Object>(); SimpleOrderedMap<Object> nl = new SimpleOrderedMap<Object>(); if (rsp.getException() != null) { Throwable cause = rsp.getException(); if (cause instanceof SolrServerException) { cause = ((SolrServerException)cause).getRootCause(); } else { if (cause.getCause() != null) { cause = cause.getCause(); } } nl.add("error", cause.toString() ); StringWriter trace = new StringWriter(); cause.printStackTrace(new PrintWriter(trace)); nl.add("trace", trace.toString() ); } else { nl.add("numFound", rb.getResults().docList.matches()); nl.add("maxScore", rb.getResults().docList.maxScore()); } nl.add("shardAddress", rb.shortCircuitedURL); nl.add("time", req.getRequestTimer().getTime()); // elapsed time of this request so far int pos = rb.shortCircuitedURL.indexOf("://"); String shardInfoName = pos != -1 ? rb.shortCircuitedURL.substring(pos+3) : rb.shortCircuitedURL; shardInfo.add(shardInfoName, nl); rsp.getValues().add(ShardParams.SHARDS_INFO,shardInfo); } }
4.4.10 QueryComponent
/**
* Actually run the query
*/
@Override
public void process(ResponseBuilder rb) throws IOException
{
LOG.debug("process: {}", rb.req.getParams());
SolrQueryRequest req = rb.req;
SolrParams params = req.getParams();
if (!params.getBool(COMPONENT_NAME, true)) { return; } StatsCache statsCache = req.getCore().getStatsCache(); int purpose = params.getInt(ShardParams.SHARDS_PURPOSE, ShardRequest.PURPOSE_GET_TOP_IDS); if ((purpose & ShardRequest.PURPOSE_GET_TERM_STATS) != 0) { SolrIndexSearcher searcher = req.getSearcher(); statsCache.returnLocalStats(rb, searcher); return; } // check if we need to update the local copy of global dfs if ((purpose & ShardRequest.PURPOSE_SET_TERM_STATS) != 0) { // retrieve from request and update local cache statsCache.receiveGlobalStats(req); } // Optional: This could also be implemented by the top-level searcher sending // a filter that lists the ids... that would be transparent to // the request handler, but would be more expensive (and would preserve score // too if desired). if (doProcessSearchByIds(rb)) { return; } // -1 as flag if not set. long timeAllowed = params.getLong(CommonParams.TIME_ALLOWED, -1L); if (null != rb.getCursorMark() && 0 < timeAllowed) { // fundamentally incompatible throw new SolrException(SolrException.ErrorCode.BAD_REQUEST, "Can not search using both " + CursorMarkParams.CURSOR_MARK_PARAM + " and " + CommonParams.TIME_ALLOWED); } QueryCommand cmd = rb.getQueryCommand(); cmd.setTimeAllowed(timeAllowed); req.getContext().put(SolrIndexSearcher.STATS_SOURCE, statsCache.get(req)); QueryResult result = new QueryResult(); cmd.setSegmentTerminateEarly(params.getBool(CommonParams.SEGMENT_TERMINATE_EARLY, CommonParams.SEGMENT_TERMINATE_EARLY_DEFAULT)); if (cmd.getSegmentTerminateEarly()) { result.setSegmentTerminatedEarly(Boolean.FALSE); } // // grouping / field collapsing // GroupingSpecification groupingSpec = rb.getGroupingSpec(); if (groupingSpec != null) { cmd.setSegmentTerminateEarly(false); // not supported, silently ignore any segmentTerminateEarly flag try { if (params.getBool(GroupParams.GROUP_DISTRIBUTED_FIRST, false)) { doProcessGroupedDistributedSearchFirstPhase(rb, cmd, result); return; } else if (params.getBool(GroupParams.GROUP_DISTRIBUTED_SECOND, false)) { doProcessGroupedDistributedSearchSecondPhase(rb, cmd, result); return; } doProcessGroupedSearch(rb, cmd, result); return; } catch (SyntaxError e) { throw new SolrException(SolrException.ErrorCode.BAD_REQUEST, e); } } // normal search result doProcessUngroupedSearch(rb, cmd, result); }
4.4.11 SolrIndexSearcher
private void doProcessUngroupedSearch(ResponseBuilder rb, QueryCommand cmd, QueryResult result) throws IOException {
SolrQueryRequest req = rb.req;
SolrQueryResponse rsp = rb.rsp;
SolrIndexSearcher searcher = req.getSearcher();
searcher.search(result, cmd);
rb.setResult(result);
ResultContext ctx = new BasicResultContext(rb);
rsp.addResponse(ctx);
rsp.getToLog().add("hits", rb.getResults().docList.matches()); if ( ! rb.req.getParams().getBool(ShardParams.IS_SHARD,false) ) { if (null != rb.getNextCursorMark()) { rb.rsp.add(CursorMarkParams.CURSOR_MARK_NEXT, rb.getNextCursorMark().getSerializedTotem()); } } if(rb.mergeFieldHandler != null) { rb.mergeFieldHandler.handleMergeFields(rb, searcher); } else { doFieldSortValues(rb, searcher); } doPrefetch(rb); }
4.4.12SolrIndexSearcher
/**
* Builds the necessary collector chain (via delegate wrapping) and executes the query against it. This method takes
* into consideration both the explicitly provided collector and postFilter as well as any needed collector wrappers
* for dealing with options specified in the QueryCommand.
*/
private void buildAndRunCollectorChain(QueryResult qr, Query query, Collector collector, QueryCommand cmd,
DelegatingCollector postFilter) throws IOException {
EarlyTerminatingSortingCollector earlyTerminatingSortingCollector = null;
if (cmd.getSegmentTerminateEarly()) {
final Sort cmdSort = cmd.getSort();
final int cmdLen = cmd.getLen(); final Sort mergeSort = core.getSolrCoreState().getMergePolicySort(); if (cmdSort == null || cmdLen <= 0 || mergeSort == null || !EarlyTerminatingSortingCollector.canEarlyTerminate(cmdSort, mergeSort)) { log.warn("unsupported combination: segmentTerminateEarly=true cmdSort={} cmdLen={} mergeSort={}", cmdSort, cmdLen, mergeSort); } else { collector = earlyTerminatingSortingCollector = new EarlyTerminatingSortingCollector(collector, cmdSort, cmd.getLen()); } } final boolean terminateEarly = cmd.getTerminateEarly(); if (terminateEarly) { collector = new EarlyTerminatingCollector(collector, cmd.getLen()); } final long timeAllowed = cmd.getTimeAllowed(); if (timeAllowed > 0) { collector = new TimeLimitingCollector(collector, TimeLimitingCollector.getGlobalCounter(), timeAllowed); } if (postFilter != null) { postFilter.setLastDelegate(collector); collector = postFilter; } try { super.search(query, collector); } catch (TimeLimitingCollector.TimeExceededException | ExitableDirectoryReader.ExitingReaderException x) { log.warn("Query: [{}]; {}", query, x.getMessage()); qr.setPartialResults(true); } catch (EarlyTerminatingCollectorException etce) { if (collector instanceof DelegatingCollector) { ((DelegatingCollector) collector).finish(); } throw etce; } finally { if (earlyTerminatingSortingCollector != null) { qr.setSegmentTerminatedEarly(earlyTerminatingSortingCollector.terminatedEarly()); } } if (collector instanceof DelegatingCollector) { ((DelegatingCollector) collector).finish(); } }
5.总结
从solr-lucene架构图所示，solr封装了handler来处理各种请求，底下是SearchComponent，分为pre，process，post三阶段处理，最后调用lucene的底层api。
lucene 底层通过Similarity来完成打分过程，详细 介绍了lucene的底层文件结构，和一步步如何实现打分。
参考资料：
【1】http://www.blogjava.net/hoojo/archive/2012/09/06/387140.html
【2】https://www.cnblogs.com/peaceliu/p/7786851.html