From fc70be62d8698496a20b6947d102757f426c5b3e Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 9 Nov 2015 18:14:37 +0200
Subject: Make database class move-constructible

This means it can be returned by value from a function in C++11.
---
 odb/pgsql/connection-factory.cxx | 56 ++++++++++++++--------------------------
 odb/pgsql/connection-factory.hxx | 39 +++-------------------------
 odb/pgsql/connection.cxx         | 23 ++++++++++++++---
 odb/pgsql/connection.hxx         | 42 ++++++++++++++++++++++--------
 odb/pgsql/connection.ixx         |  6 +++++
 odb/pgsql/database.hxx           |  9 +++++++
 odb/pgsql/database.ixx           | 20 ++++++++++++++
 7 files changed, 109 insertions(+), 86 deletions(-)

diff --git a/odb/pgsql/connection-factory.cxx b/odb/pgsql/connection-factory.cxx
index f35b2c8..a57fc41 100644
--- a/odb/pgsql/connection-factory.cxx
+++ b/odb/pgsql/connection-factory.cxx
@@ -15,39 +15,20 @@ namespace odb
 
   namespace pgsql
   {
-    //
-    // connection_factory
-    //
-
-    connection_factory::
-    ~connection_factory ()
-    {
-    }
-
-    //
     // new_connection_factory
     //
-
     connection_ptr new_connection_factory::
     connect ()
     {
-      return connection_ptr (new (shared) connection (*db_));
+      return connection_ptr (new (shared) connection (*this));
     }
 
-    void new_connection_factory::
-    database (database_type& db)
-    {
-      db_ = &db;
-    }
-
-    //
     // connection_pool_factory
     //
-
     connection_pool_factory::pooled_connection_ptr connection_pool_factory::
     create ()
     {
-      return pooled_connection_ptr (new (shared) pooled_connection (*db_));
+      return pooled_connection_ptr (new (shared) pooled_connection (*this));
     }
 
     connection_pool_factory::
@@ -79,7 +60,7 @@ namespace odb
           shared_ptr<pooled_connection> c (connections_.back ());
           connections_.pop_back ();
 
-          c->pool_ = this;
+          c->callback_ = &c->cb_;
           in_use_++;
           return c;
         }
@@ -89,7 +70,7 @@ namespace odb
         if (max_ == 0 || in_use_ < max_)
         {
           shared_ptr<pooled_connection> c (create ());
-          c->pool_ = this;
+          c->callback_ = &c->cb_;
           in_use_++;
           return c;
         }
@@ -105,7 +86,12 @@ namespace odb
     void connection_pool_factory::
     database (database_type& db)
     {
-      db_ = &db;
+      bool first (db_ == 0);
+
+      connection_factory::database (db);
+
+      if (!first)
+        return;
 
       if (min_ > 0)
       {
@@ -119,7 +105,7 @@ namespace odb
     bool connection_pool_factory::
     release (pooled_connection* c)
     {
-      c->pool_ = 0;
+      c->callback_ = 0;
 
       lock l (mutex_);
 
@@ -149,28 +135,26 @@ namespace odb
     //
 
     connection_pool_factory::pooled_connection::
-    pooled_connection (database_type& db)
-        : connection (db), pool_ (0)
+    pooled_connection (connection_pool_factory& f)
+        : connection (f)
     {
-      callback_.arg = this;
-      callback_.zero_counter = &zero_counter;
-      shared_base::callback_ = &callback_;
+      cb_.arg = this;
+      cb_.zero_counter = &zero_counter;
     }
 
     connection_pool_factory::pooled_connection::
-    pooled_connection (database_type& db, PGconn* handle)
-        : connection (db, handle), pool_ (0)
+    pooled_connection (connection_pool_factory& f, PGconn* handle)
+        : connection (f, handle)
     {
-      callback_.arg = this;
-      callback_.zero_counter = &zero_counter;
-      shared_base::callback_ = &callback_;
+      cb_.arg = this;
+      cb_.zero_counter = &zero_counter;
     }
 
     bool connection_pool_factory::pooled_connection::
     zero_counter (void* arg)
     {
       pooled_connection* c (static_cast<pooled_connection*> (arg));
-      return c->pool_ ? c->pool_->release (c) : true;
+      return static_cast<connection_pool_factory&> (c->factory_).release (c);
     }
   }
 }
diff --git a/odb/pgsql/connection-factory.hxx b/odb/pgsql/connection-factory.hxx
index a0009ff..0ee2197 100644
--- a/odb/pgsql/connection-factory.hxx
+++ b/odb/pgsql/connection-factory.hxx
@@ -25,42 +25,17 @@ namespace odb
 {
   namespace pgsql
   {
-    class LIBODB_PGSQL_EXPORT connection_factory
-    {
-    public:
-      virtual connection_ptr
-      connect () = 0;
-
-    public:
-      typedef pgsql::database database_type;
-
-      virtual void
-      database (database_type&) = 0;
-
-      virtual
-      ~connection_factory ();
-    };
-
     class LIBODB_PGSQL_EXPORT new_connection_factory: public connection_factory
     {
     public:
-      new_connection_factory ()
-          : db_ (0)
-      {
-      }
+      new_connection_factory () {}
 
       virtual connection_ptr
       connect ();
 
-      virtual void
-      database (database_type&);
-
     private:
       new_connection_factory (const new_connection_factory&);
       new_connection_factory& operator= (const new_connection_factory&);
-
-    private:
-      database_type* db_;
     };
 
     class LIBODB_PGSQL_EXPORT connection_pool_factory:
@@ -86,7 +61,6 @@ namespace odb
             min_ (min_connections),
             in_use_ (0),
             waiters_ (0),
-            db_ (0),
             cond_ (mutex_)
       {
         // max_connections == 0 means unlimited.
@@ -111,8 +85,8 @@ namespace odb
       class LIBODB_PGSQL_EXPORT pooled_connection: public connection
       {
       public:
-        pooled_connection (database_type&);
-        pooled_connection (database_type&, PGconn*);
+        pooled_connection (connection_pool_factory&);
+        pooled_connection (connection_pool_factory&, PGconn*);
 
       private:
         static bool
@@ -121,11 +95,7 @@ namespace odb
       private:
         friend class connection_pool_factory;
 
-        shared_base::refcount_callback callback_;
-
-        // NULL pool value indicates that the connection is not in use.
-        //
-        connection_pool_factory* pool_;
+        shared_base::refcount_callback cb_;
       };
 
       friend class pooled_connection;
@@ -152,7 +122,6 @@ namespace odb
       std::size_t in_use_;  // Number of connections currently in use.
       std::size_t waiters_; // Number of threads waiting for a connection.
 
-      database_type* db_;
       connections connections_;
 
       details::mutex mutex_;
diff --git a/odb/pgsql/connection.cxx b/odb/pgsql/connection.cxx
index a39f6a8..dcc841b 100644
--- a/odb/pgsql/connection.cxx
+++ b/odb/pgsql/connection.cxx
@@ -28,9 +28,10 @@ namespace odb
   namespace pgsql
   {
     connection::
-    connection (database_type& db)
-        : odb::connection (db), db_ (db), failed_ (false)
+    connection (connection_factory& cf)
+        : odb::connection (cf), failed_ (false)
     {
+      database_type& db (database ());
       handle_.reset (PQconnectdb (db.conninfo ().c_str ()));
 
       if (handle_ == 0)
@@ -42,8 +43,8 @@ namespace odb
     }
 
     connection::
-    connection (database_type& db, PGconn* handle)
-        : odb::connection (db), db_ (db), handle_ (handle), failed_ (false)
+    connection (connection_factory& cf, PGconn* handle)
+        : odb::connection (cf), handle_ (handle), failed_ (false)
     {
       init ();
     }
@@ -117,5 +118,19 @@ namespace odb
 
       return count;
     }
+
+    // connection_factory
+    //
+    connection_factory::
+    ~connection_factory ()
+    {
+    }
+
+    void connection_factory::
+    database (database_type& db)
+    {
+      odb::connection_factory::db_ = &db;
+      db_ = &db;
+    }
   }
 }
diff --git a/odb/pgsql/connection.hxx b/odb/pgsql/connection.hxx
index 78d8cd5..0f1d78c 100644
--- a/odb/pgsql/connection.hxx
+++ b/odb/pgsql/connection.hxx
@@ -27,6 +27,7 @@ namespace odb
   namespace pgsql
   {
     class statement_cache;
+    class connection_factory;
 
     class connection;
     typedef details::shared_ptr<connection> connection_ptr;
@@ -40,14 +41,11 @@ namespace odb
       virtual
       ~connection ();
 
-      connection (database_type&);
-      connection (database_type&, PGconn* handle);
+      connection (connection_factory&);
+      connection (connection_factory&, PGconn* handle);
 
       database_type&
-      database ()
-      {
-        return db_;
-      }
+      database ();
 
     public:
       virtual transaction_impl*
@@ -135,11 +133,6 @@ namespace odb
       friend class transaction_impl; // invalidate_results()
 
     private:
-      // Needed to break the circular connection-database dependency
-      // (odb::connection has the odb::database member).
-      //
-      database_type& db_;
-
       auto_handle<PGconn> handle_;
       bool failed_;
 
@@ -148,6 +141,33 @@ namespace odb
       //
       details::unique_ptr<statement_cache_type> statement_cache_;
     };
+
+    class LIBODB_PGSQL_EXPORT connection_factory:
+      public odb::connection_factory
+    {
+    public:
+      typedef pgsql::database database_type;
+
+      virtual void
+      database (database_type&);
+
+      database_type&
+      database () {return *db_;}
+
+      virtual connection_ptr
+      connect () = 0;
+
+      virtual
+      ~connection_factory ();
+
+      connection_factory (): db_ (0) {}
+
+      // Needed to break the circular connection_factory-database dependency
+      // (odb::connection_factory has the odb::database member).
+      //
+    protected:
+      database_type* db_;
+    };
   }
 }
 
diff --git a/odb/pgsql/connection.ixx b/odb/pgsql/connection.ixx
index f549dd4..92ce453 100644
--- a/odb/pgsql/connection.ixx
+++ b/odb/pgsql/connection.ixx
@@ -6,6 +6,12 @@ namespace odb
 {
   namespace pgsql
   {
+    inline database& connection::
+    database ()
+    {
+      return static_cast<connection_factory&> (factory_).database ();
+    }
+
     template <typename T>
     inline prepared_query<T> connection::
     prepare_query (const char* n, const char* q)
diff --git a/odb/pgsql/database.hxx b/odb/pgsql/database.hxx
index 6ad1ba9..bf77397 100644
--- a/odb/pgsql/database.hxx
+++ b/odb/pgsql/database.hxx
@@ -12,6 +12,7 @@
 #include <iosfwd> // std::ostream
 
 #include <odb/database.hxx>
+#include <odb/details/config.hxx> // ODB_CXX11
 #include <odb/details/unique-ptr.hxx>
 #include <odb/details/transfer-ptr.hxx>
 
@@ -78,6 +79,12 @@ namespace odb
                 details::transfer_ptr<connection_factory> =
                   details::transfer_ptr<connection_factory> ());
 
+      // Move-constructible but not move-assignable.
+      //
+#ifdef ODB_CXX11
+      database (database&&);
+#endif
+
       static void
       print_usage (std::ostream&);
 
@@ -470,6 +477,8 @@ namespace odb
       }
 
     private:
+      // Note: remember to update move ctor if adding any new members.
+      //
       std::string user_;
       std::string password_;
       std::string db_;
diff --git a/odb/pgsql/database.ixx b/odb/pgsql/database.ixx
index ab65be0..591a090 100644
--- a/odb/pgsql/database.ixx
+++ b/odb/pgsql/database.ixx
@@ -2,12 +2,32 @@
 // copyright : Copyright (c) 2009-2015 Code Synthesis Tools CC
 // license   : GNU GPL v2; see accompanying LICENSE file
 
+#include <utility> // move()
+
 #include <odb/pgsql/transaction.hxx>
 
 namespace odb
 {
   namespace pgsql
   {
+#ifdef ODB_CXX11
+    inline database::
+    database (database&& db) // Has to be inline.
+        : odb::database (std::move (db)),
+          user_ (std::move (db.user_)),
+          password_ (std::move (db.password_)),
+          db_ (std::move (db.db_)),
+          host_ (std::move (db.host_)),
+          port_ (db.port_),
+          socket_ext_ (std::move (db.socket_ext_)),
+          extra_conninfo_ (std::move (db.extra_conninfo_)),
+          conninfo_ (std::move (db.conninfo_)),
+          factory_ (std::move (db.factory_))
+    {
+      factory_->database (*this); // New database instance.
+    }
+#endif
+
     inline connection_ptr database::
     connection ()
     {
-- 
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