From ea00efe391274efcae7d3d4bff464fd84f17ee4e Mon Sep 17 00:00:00 2001
From: vng <viktor.govako@gmail.com>
Date: Sun, 4 Mar 2012 14:35:52 +0300
Subject: [PATCH] [search] Avoid many search threads waiting in search mutex.

---
 search/search_engine.cpp | 14 +++++++++++++-
 search/search_engine.hpp |  4 +++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/search/search_engine.cpp b/search/search_engine.cpp
index f89c0742e0..ef85d26ff3 100644
--- a/search/search_engine.cpp
+++ b/search/search_engine.cpp
@@ -129,7 +129,6 @@ void Engine::Search(SearchParams const & params, m2::RectD const & viewport)
 
   {
     threads::MutexGuard guard(m_updateMutex);
-
     m_params = params;
     m_viewport = viewport;
   }
@@ -153,12 +152,25 @@ void Engine::SetViewportAsync(m2::RectD const & viewport, m2::RectD const & near
 
 void Engine::SearchAsync()
 {
+  {
+    // Avoid many threads waiting in search mutex. One is enough.
+    threads::MutexGuard readyGuard(m_readyMutex);
+    if (m_readyThread)
+      return;
+    m_readyThread = true;
+  }
+
   // First of all - cancel previous query.
   m_pQuery->DoCancel();
 
   // Enter to run new search.
   threads::MutexGuard searchGuard(m_searchMutex);
 
+  {
+    threads::MutexGuard readyGuard(m_readyMutex);
+    m_readyThread = false;
+  }
+
   // Get current search params.
   SearchParams params;
   m2::RectD arrRects[2];
diff --git a/search/search_engine.hpp b/search/search_engine.hpp
index 3111c84aad..04b2d3f3da 100644
--- a/search/search_engine.hpp
+++ b/search/search_engine.hpp
@@ -47,7 +47,9 @@ private:
   void SetViewportAsync(m2::RectD const & viewport, m2::RectD const & nearby);
   void SearchAsync();
 
-  threads::Mutex m_searchMutex, m_updateMutex;
+  threads::Mutex m_searchMutex, m_updateMutex, m_readyMutex;
+
+  volatile bool m_readyThread;
 
   SearchParams m_params;
   m2::RectD m_viewport;