Implement brep-migrate utility

1 files changed, 44 insertions, 0 deletions

diff --git a/brep/database-lock.cxx b/brep/database-lock.cxx
new file mode 100644
index 0000000..3b8ae21
--- /dev/null
+++ b/brep/database-lock.cxx
@@ -0,0 +1,44 @@
+// file      : brep/database-lock.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <brep/database-lock>
+
+#include <odb/pgsql/database.hxx>
+#include <odb/pgsql/exceptions.hxx>
+#include <odb/pgsql/transaction.hxx>
+
+namespace brep
+{
+  using namespace odb::pgsql;
+
+  database_lock::
+  database_lock (database& db)
+  {
+    // Before locking the table make sure it exists.
+    //
+    {
+      transaction t (db.begin ());
+      db.execute ("CREATE TABLE IF NOT EXISTS database_mutex ()");
+      t.commit ();
+    }
+
+    connection_ = db.connection ();
+
+    // Don't make current. Will be rolled back in destructor.
+    //
+    transaction_.reset (new transaction (connection_->begin (), false));
+
+    try
+    {
+      connection_->execute ("LOCK TABLE database_mutex NOWAIT");
+    }
+    catch (const database_exception& e)
+    {
+      if (e.sqlstate () == "55P03") // The table is already locked.
+        throw database_locked ();
+
+      throw;
+    }
+  }
+}