From 008db4e25d706c4d80d62c862e171575da5cabc6 Mon Sep 17 00:00:00 2001
From: Maneesh P M <manu.pm55@gmail.com>
Date: Wed, 13 Oct 2021 20:52:02 +0530
Subject: [PATCH] Retrieve SuggestionSearcher from LRU Cache

---
 src/server/internalServer.cpp | 23 ++++++++++++++++-------
 src/server/internalServer.h   |  8 ++++++--
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/src/server/internalServer.cpp b/src/server/internalServer.cpp
index f7c76a14c..4e04b2043 100644
--- a/src/server/internalServer.cpp
+++ b/src/server/internalServer.cpp
@@ -151,7 +151,8 @@ InternalServer::InternalServer(Library* library,
   mp_library(library),
   mp_nameMapper(nameMapper ? nameMapper : &defaultNameMapper),
   searcherCache(std::max(getCacheLength("SEARCHER_CACHE_SIZE", mp_library->getBookCount(true, true)*0.1), 1U)),
-  searchCache(std::max(getCacheLength("SEARCH_CACHE_SIZE", SEARCH_CACHE_SIZE), 1U))
+  searchCache(std::max(getCacheLength("SEARCH_CACHE_SIZE", SEARCH_CACHE_SIZE), 1U)),
+  suggestionSearcherCache(std::max(getCacheLength("SUGGESTION_SEARCHER_CACHE_SIZE", mp_library->getBookCount(true, true)*0.1), 1U))
 {}
 
 bool InternalServer::start() {
@@ -356,13 +357,20 @@ std::unique_ptr<Response> InternalServer::build_homepage(const RequestContext& r
  **/
 
 // TODO: retrieve searcher from caching mechanism
-SuggestionsList_t getSuggestions(const zim::Archive* const archive,
-                  const std::string& queryString, int start, int suggestionCount)
+SuggestionsList_t getSuggestions(SuggestionSearcherCache& cache, const zim::Archive* const archive,
+                  const std::string& bookId, const std::string& queryString, int start, int suggestionCount)
 {
   SuggestionsList_t suggestions;
-  auto searcher = zim::SuggestionSearcher(*archive);
+  std::shared_ptr<zim::SuggestionSearcher> searcher;
+  try {
+    searcher = cache.get(bookId);
+  } catch (std::runtime_error&) {
+    searcher = make_shared<zim::SuggestionSearcher>(*archive);
+    cache.put(bookId, searcher);
+  }
+
   if (archive->hasTitleIndex()) {
-    auto search = searcher.suggest(queryString);
+    auto search = searcher->suggest(queryString);
     auto srs = search.getResults(start, suggestionCount);
 
     for (auto it : srs) {
@@ -375,7 +383,7 @@ SuggestionsList_t getSuggestions(const zim::Archive* const archive,
     std::vector<std::string> variants = getTitleVariants(queryString);
     int currCount = 0;
     for (auto it = variants.begin(); it != variants.end() && currCount < suggestionCount; it++) {
-      auto search = searcher.suggest(queryString);
+      auto search = searcher->suggest(queryString);
       auto srs = search.getResults(0, suggestionCount);
       for (auto it : srs) {
         SuggestionItem suggestion(it.getTitle(), kiwix::normalize(it.getTitle()),
@@ -492,7 +500,8 @@ std::unique_ptr<Response> InternalServer::handle_suggest(const RequestContext& r
   bool first = true;
 
   /* Get the suggestions */
-  SuggestionsList_t suggestions = getSuggestions(archive.get(), queryString, start, count);
+  SuggestionsList_t suggestions = getSuggestions(suggestionSearcherCache, archive.get(),
+                                                  bookId, queryString, start, count);
   for(auto& suggestion:suggestions) {
     MustacheData result;
     result.set("label", suggestion.getTitle());
diff --git a/src/server/internalServer.h b/src/server/internalServer.h
index 2973e45a0..db27ea8dd 100644
--- a/src/server/internalServer.h
+++ b/src/server/internalServer.h
@@ -44,6 +44,9 @@ extern "C" {
 namespace kiwix {
 
 typedef kainjow::mustache::data MustacheData;
+typedef LRUCache<string, std::shared_ptr<zim::Searcher>> SearcherCache;
+typedef LRUCache<string, std::shared_ptr<zim::Search>> SearchCache;
+typedef LRUCache<string, std::shared_ptr<zim::SuggestionSearcher>> SuggestionSearcherCache;
 
 class Entry;
 class OPDSDumper;
@@ -115,8 +118,9 @@ class InternalServer {
     Library* mp_library;
     NameMapper* mp_nameMapper;
 
-    LRUCache<string, std::shared_ptr<zim::Searcher>> searcherCache;
-    LRUCache<string, std::shared_ptr<zim::Search>> searchCache;
+    SearcherCache searcherCache;
+    SearchCache searchCache;
+    SuggestionSearcherCache suggestionSearcherCache;
 
     std::string m_server_id;
     std::string m_library_id;