From a7e766e1aa77fff846d8426658befd9a01fe2861 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 11 Aug 2015 15:34:12 +0200
Subject: Share DB object between modules

---
 brep/shared-database.cxx | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 brep/shared-database.cxx

(limited to 'brep/shared-database.cxx')

diff --git a/brep/shared-database.cxx b/brep/shared-database.cxx
new file mode 100644
index 0000000..fb952d8
--- /dev/null
+++ b/brep/shared-database.cxx
@@ -0,0 +1,41 @@
+// file      : brep/shared-database.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <brep/shared-database>
+
+#include <memory>    // weak_ptr, shared_ptr, make_shared()
+#include <stdexcept> // runtime_error
+
+#include <odb/pgsql/database.hxx>
+
+using namespace std;
+using namespace odb;
+
+namespace brep
+{
+  shared_ptr<database>
+  shared_database (const string& host, unsigned int port)
+  {
+    static weak_ptr<pgsql::database> db;
+
+    // In C++11, function-static variable initialization is
+    // guaranteed to be thread-safe, thought this doesn't
+    // seem to be enough in our case (because we are re-
+    // initializing the weak pointer).
+    //
+    if (shared_ptr<database> d = db.lock ())
+    {
+      if (h != d->host () || p != d->port ())
+        throw runtime_error ("shared database host/port mismatch");
+
+      return d;
+    }
+    else
+    {
+      d = make_shared<database> ("", "", "brep", h, p);
+      db = d;
+      return d;
+    }
+  }
+}
-- 
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