From 19a457ab7dbbfee8eed09e5cffbadfb938b89daf Mon Sep 17 00:00:00 2001
From: Dennis Luxen <luxen@kit.edu>
Date: Thu, 17 Oct 2013 18:11:53 +0200
Subject: [PATCH] implement update barrier

---
 Library/OSRM.cpp                       | 26 ++++++++++++++++++++++++--
 Library/OSRM.h                         |  9 +++++++++
 Server/DataStructures/SharedBarriers.h | 18 ++++++++++++++++++
 datastore.cpp                          |  1 +
 4 files changed, 52 insertions(+), 2 deletions(-)
 create mode 100644 Server/DataStructures/SharedBarriers.h

diff --git a/Library/OSRM.cpp b/Library/OSRM.cpp
index 46d0a7fe0..601691cba 100644
--- a/Library/OSRM.cpp
+++ b/Library/OSRM.cpp
@@ -26,21 +26,36 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
 #include "OSRM.h"
-#include <boost/foreach.hpp>
 
-OSRM::OSRM( const ServerPaths & server_paths, const bool use_shared_memory ) {
+OSRM::OSRM( const ServerPaths & server_paths, const bool use_shared_memory )
+ :
+    shm(
+        boost::interprocess::open_or_create,
+        "SharedBarriers",
+        boost::interprocess::read_write
+    ),
+    use_shared_memory(use_shared_memory)
+{
     if( !use_shared_memory ) {
         SimpleLogger().Write() << "loading data into internal memory";
         query_data_facade = new InternalDataFacade<QueryEdge::EdgeData>(
             server_paths
         );
     } else {
+        region = boost::interprocess::mapped_region(
+            shm,                             //What to map
+            boost::interprocess::read_write  //Map it as read-write
+        );
+        shm.truncate( sizeof(SharedBarriers) );
+        barrier = static_cast<SharedBarriers *>( region.get_address() );
+
         SimpleLogger().Write() << "loading data from shared memory";
         query_data_facade = new SharedDataFacade<QueryEdge::EdgeData>(
             server_paths
         );
     }
 
+
     //The following plugins handle all requests.
     RegisterPlugin(
         new HelloWorldPlugin()
@@ -88,6 +103,13 @@ void OSRM::RunQuery(RouteParameters & route_parameters, http::Reply & reply) {
 
     if(plugin_map.end() != iter) {
         reply.status = http::Reply::ok;
+        if( use_shared_memory && barrier->update_ongoing ) {
+            //wait until we get the mutex and free it immediately
+            //TODO: increment semaphore of querying processes
+            boost::interprocess::scoped_lock<
+                boost::interprocess::interprocess_mutex
+            > lock(barrier->update_mutex);
+        }
         iter->second->HandleRequest(route_parameters, reply );
     } else {
         reply = http::Reply::stockReply(http::Reply::badRequest);
diff --git a/Library/OSRM.h b/Library/OSRM.h
index 6951f69a6..4b24fbad1 100644
--- a/Library/OSRM.h
+++ b/Library/OSRM.h
@@ -45,9 +45,14 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "../Util/ProgramOptions.h"
 #include "../Util/SimpleLogger.h"
 #include "../Server/BasicDatastructures.h"
+#include "../Server/DataStructures/SharedBarriers.h"
 
 #include <boost/assert.hpp>
 #include <boost/filesystem.hpp>
+#include <boost/foreach.hpp>
+#include <boost/interprocess/shared_memory_object.hpp>
+#include <boost/interprocess/mapped_region.hpp>
+#include <boost/interprocess/sync/scoped_lock.hpp>
 #include <boost/noncopyable.hpp>
 #include <boost/shared_ptr.hpp>
 #include <boost/thread.hpp>
@@ -57,7 +62,11 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 class OSRM : boost::noncopyable {
 private:
     typedef boost::unordered_map<std::string, BasePlugin *> PluginMap;
+    boost::interprocess::shared_memory_object shm;
+    boost::interprocess::mapped_region region;
+    SharedBarriers * barrier;
 
+    bool use_shared_memory;
 public:
     OSRM(
         const ServerPaths & paths,
diff --git a/Server/DataStructures/SharedBarriers.h b/Server/DataStructures/SharedBarriers.h
new file mode 100644
index 000000000..4f43403e2
--- /dev/null
+++ b/Server/DataStructures/SharedBarriers.h
@@ -0,0 +1,18 @@
+#include <boost/interprocess/sync/interprocess_mutex.hpp>
+#include <boost/interprocess/sync/interprocess_condition.hpp>
+
+struct SharedBarriers {
+
+   SharedBarriers () :  update_ongoing(false), number_of_queries(0) { }
+
+   // Mutex to protect access to the boolean variable
+   boost::interprocess::interprocess_mutex      update_mutex;
+   boost::interprocess::interprocess_mutex      query_mutex;
+
+   // Condition that no update is running
+   boost::interprocess::interprocess_condition  update_finished_condition;
+
+   // Is there any message?
+   bool update_ongoing;
+   int number_of_queries;
+};
diff --git a/datastore.cpp b/datastore.cpp
index db08496c8..a97edf18c 100644
--- a/datastore.cpp
+++ b/datastore.cpp
@@ -33,6 +33,7 @@ or see http://www.gnu.org/licenses/agpl.txt.
 
 #include <boost/integer.hpp>
 #include <boost/filesystem/fstream.hpp>
+#include <boost/interprocess/sync/interprocess_semaphore.hpp>
 
 #include <string>
 #include <vector>