From f8d6e4750a6c609e01c4697bb2b1a12ee1715319 Mon Sep 17 00:00:00 2001
From: karenzshea <karenzshea@gmail.com>
Date: Thu, 12 Apr 2018 15:53:43 +0200
Subject: [PATCH] log err instead of throwing when no shmem regions found

---
 include/storage/shared_monitor.hpp | 11 +++++++++++
 src/tools/store.cpp                |  9 ++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/include/storage/shared_monitor.hpp b/include/storage/shared_monitor.hpp
index 7c79b0ee9..c9e901902 100644
--- a/include/storage/shared_monitor.hpp
+++ b/include/storage/shared_monitor.hpp
@@ -117,6 +117,17 @@ template <typename Data> struct SharedMonitor
 #endif
 
     static void remove() { bi::shared_memory_object::remove(Data::name); }
+    static bool exists() {
+        try
+        {
+            bi::shared_memory_object shmem_open = bi::shared_memory_object(bi::open_only, Data::name, bi::read_only);
+        }
+        catch (const bi::interprocess_exception &exception)
+        {
+            return false;
+        }
+        return true;
+    }
 
   private:
 #if USE_BOOST_INTERPROCESS_CONDITION
diff --git a/src/tools/store.cpp b/src/tools/store.cpp
index 7289eaa22..16a9dba4d 100644
--- a/src/tools/store.cpp
+++ b/src/tools/store.cpp
@@ -27,7 +27,11 @@ void deleteRegion(const storage::SharedRegionRegister::ShmKey key)
 
 void listRegions()
 {
-
+    if (!storage::SharedMonitor<storage::SharedRegionRegister>::exists())
+    {
+        osrm::util::Log() << "No shared memory regions found. Try running osrm-datastore";
+        return;
+    }
     storage::SharedMonitor<storage::SharedRegionRegister> monitor;
     std::vector<std::string> names;
     const auto &shared_register = monitor.data();
@@ -105,8 +109,7 @@ bool generateDataStoreOptions(const int argc,
          boost::program_options::value<bool>(&list_datasets)
              ->default_value(false)
              ->implicit_value(true),
-         "Name of the dataset to load into memory. This allows having multiple datasets in memory "
-         "at the same time.") //
+         "List all OSRM datasets currently in memory") //
         ("only-metric",
          boost::program_options::value<bool>(&only_metric)
              ->default_value(false)