From 63ef86c21f091321ecac9bef4d9de8134f028279 Mon Sep 17 00:00:00 2001
From: Daria Volvenkova <d.volvenkova@corp.mail.ru>
Date: Thu, 20 Apr 2017 18:32:02 +0300
Subject: Initialization of transliterators optimized.

---
 coding/transliteration.cpp | 56 +++++++++++++++++++++++++++++++++++-----------
 coding/transliteration.hpp |  8 ++-----
 2 files changed, 45 insertions(+), 19 deletions(-)

(limited to 'coding')

diff --git a/coding/transliteration.cpp b/coding/transliteration.cpp
index ca2f84e643..618c602471 100644
--- a/coding/transliteration.cpp
+++ b/coding/transliteration.cpp
@@ -3,21 +3,35 @@
 
 #include "base/logging.hpp"
 
-#include <cstring>
-
 #include "3party/icu/common/unicode/uclean.h"
 #include "3party/icu/common/unicode/unistr.h"
 #include "3party/icu/common/unicode/utypes.h"
 #include "3party/icu/i18n/unicode/translit.h"
 #include "3party/icu/i18n/unicode/utrans.h"
 
+#include "std/unique_ptr.hpp"
+
+#include <atomic>
+#include <cstring>
+#include <mutex>
+
+struct Transliteration::TransliteratorInfo
+{
+  TransliteratorInfo()
+    : m_initialized(false)
+  {}
+
+  std::atomic<bool> m_initialized;
+  std::mutex m_mutex;
+  std::unique_ptr<Transliterator> m_transliterator;
+};
+
 Transliteration::~Transliteration()
 {
   // The use of u_cleanup() just before an application terminates is optional,
   // but it should be called only once for performance reasons.
   // The primary benefit is to eliminate reports of memory or resource leaks originating
   // in ICU code from the results generated by heap analysis tools.
-  // http://www.icu-project.org/apiref/icu4c/uclean_8h.html#a93f27d0ddc7c196a1da864763f2d8920
   m_transliterators.clear();
   u_cleanup();
 }
@@ -30,6 +44,9 @@ Transliteration & Transliteration::Instance()
 
 void Transliteration::Init(std::string const & icuDataDir)
 {
+  // This function should be called at most once in a process,
+  // before the first ICU operation that will require the loading of an ICU data file.
+  // This function is not thread-safe. Use it before calling ICU APIs from multiple threads.
   u_setDataDirectory(icuDataDir.c_str());
 
   for (auto const & lang : StringUtf8Multilang::GetSupportedLanguages())
@@ -37,14 +54,7 @@ void Transliteration::Init(std::string const & icuDataDir)
     if (strlen(lang.m_transliteratorId) == 0 || m_transliterators.count(lang.m_transliteratorId) != 0)
       continue;
 
-    UErrorCode status = U_ZERO_ERROR;
-    std::unique_ptr<Transliterator> transliterator(
-          Transliterator::createInstance(lang.m_transliteratorId, UTRANS_FORWARD, status));
-
-    if (transliterator != nullptr)
-       m_transliterators.emplace(lang.m_transliteratorId, std::move(transliterator));
-    else
-      LOG(LWARNING, ("Cannot create transliterator \"", lang.m_transliteratorId, "\", icu error =", status));
+    m_transliterators.emplace(lang.m_transliteratorId, make_unique<TransliteratorInfo>());
   }
 }
 
@@ -58,15 +68,35 @@ bool Transliteration::Transliterate(std::string const & str, int8_t langCode, st
   if (transliteratorId.empty())
     return false;
 
-  auto const & it = m_transliterators.find(transliteratorId);
+  auto it = m_transliterators.find(transliteratorId);
   if (it == m_transliterators.end())
   {
     LOG(LWARNING, ("Transliteration failed, unknown transliterator \"", transliteratorId, "\""));
     return false;
   }
 
+  if (!it->second->m_initialized)
+  {
+    std::lock_guard<std::mutex> lock(it->second->m_mutex);
+    if (!it->second->m_initialized)
+    {
+      UErrorCode status = U_ZERO_ERROR;
+      UnicodeString translitId(it->first.c_str());
+
+      it->second->m_transliterator.reset(Transliterator::createInstance(translitId, UTRANS_FORWARD, status));
+
+      if (it->second->m_transliterator == nullptr)
+        LOG(LWARNING, ("Cannot create transliterator \"", it->first, "\", icu error =", status));
+
+      it->second->m_initialized = true;
+    }
+  }
+
+  if (it->second->m_transliterator == nullptr)
+    return false;
+
   UnicodeString ustr(str.c_str());
-  it->second->transliterate(ustr);
+  it->second->m_transliterator->transliterate(ustr);
 
   if (ustr.isEmpty())
     return false;
diff --git a/coding/transliteration.hpp b/coding/transliteration.hpp
index cc3f97eb4d..088f870b56 100644
--- a/coding/transliteration.hpp
+++ b/coding/transliteration.hpp
@@ -4,11 +4,6 @@
 #include <memory>
 #include <string>
 
-namespace icu
-{
-class Transliterator;
-}
-
 class Transliteration
 {
 public:
@@ -23,5 +18,6 @@ public:
 private:
   Transliteration() = default;
 
-  std::map<std::string, std::unique_ptr<icu::Transliterator>> m_transliterators;
+  struct TransliteratorInfo;
+  std::map<std::string, std::unique_ptr<TransliteratorInfo>> m_transliterators;
 };
-- 
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