Add odb::connection class

This abstract class represents a connection to the database. One can
use it to start a transaction or to execute a native statement out
of a transaction.

Before we had concrete connection classes in the database runtime
libraries (e.g., odb::mysql::connection). Now these classes derive
from odb::connection.

10 files changed, 110 insertions, 71 deletions

diff --git a/odb/mysql/connection-factory.cxx b/odb/mysql/connection-factory.cxx
index 225ef9a..2da8235 100644
--- a/odb/mysql/connection-factory.cxx
+++ b/odb/mysql/connection-factory.cxx
@@ -131,12 +131,12 @@ namespace odb
     // new_connection_factory
     //
 
-    shared_ptr<connection> new_connection_factory::
+    connection_ptr new_connection_factory::
     connect ()
     {
       tls_get (mysql_thread_init_);
 
-      return shared_ptr<connection> (new (shared) connection (*db_));
+      return connection_ptr (new (shared) connection (*db_));
     }
 
     void new_connection_factory::
@@ -164,7 +164,7 @@ namespace odb
       }
     }
 
-    shared_ptr<connection> connection_pool_factory::
+    connection_ptr connection_pool_factory::
     connect ()
     {
       tls_get (mysql_thread_init_);
diff --git a/odb/mysql/connection-factory.hxx b/odb/mysql/connection-factory.hxx
index eb7380c..399fdae 100644
--- a/odb/mysql/connection-factory.hxx
+++ b/odb/mysql/connection-factory.hxx
@@ -28,7 +28,7 @@ namespace odb
     class LIBODB_MYSQL_EXPORT connection_factory
     {
     public:
-      virtual details::shared_ptr<connection>
+      virtual connection_ptr
       connect () = 0;
 
     public:
@@ -49,7 +49,7 @@ namespace odb
       {
       }
 
-      virtual details::shared_ptr<connection>
+      virtual connection_ptr
       connect ();
 
       virtual void
@@ -97,7 +97,7 @@ namespace odb
         // @@ check min_ <= max_
       }
 
-      virtual details::shared_ptr<connection>
+      virtual connection_ptr
       connect ();
 
       virtual void
diff --git a/odb/mysql/connection.cxx b/odb/mysql/connection.cxx
index 3f4a664..fe4996f 100644
--- a/odb/mysql/connection.cxx
+++ b/odb/mysql/connection.cxx
@@ -8,6 +8,7 @@
 
 #include <odb/mysql/database.hxx>
 #include <odb/mysql/connection.hxx>
+#include <odb/mysql/transaction.hxx>
 #include <odb/mysql/statement.hxx>
 #include <odb/mysql/error.hxx>
 #include <odb/mysql/exceptions.hxx>
@@ -21,7 +22,8 @@ namespace odb
   {
     connection::
     connection (database_type& db)
-        : db_ (db),
+        : odb::connection (db),
+          db_ (db),
           failed_ (false),
           handle_ (&mysql_),
           active_ (0),
@@ -72,6 +74,44 @@ namespace odb
       mysql_close (handle_);
     }
 
+    transaction_impl* connection::
+    begin ()
+    {
+      if (transaction::has_current ())
+        throw already_in_transaction ();
+
+      return new transaction_impl (connection_ptr (inc_ref (this)));
+    }
+
+    unsigned long long connection::
+    execute (const char* s, std::size_t n)
+    {
+      clear ();
+
+      if (mysql_real_query (handle_, s, static_cast<unsigned long> (n)))
+        translate_error (*this);
+
+      // Get the affected row count, if any. If the statement has a result
+      // set (e.g., SELECT), we first need to call mysql_store_result().
+      //
+      unsigned long long r (0);
+
+      if (mysql_field_count (handle_) == 0)
+        r = static_cast<unsigned long long> (mysql_affected_rows (handle_));
+      else
+      {
+        if (MYSQL_RES* rs = mysql_store_result (handle_))
+        {
+          r = static_cast<unsigned long long> (mysql_num_rows (rs));
+          mysql_free_result (rs);
+        }
+        else
+          translate_error (*this);
+      }
+
+      return r;
+    }
+
     bool connection::
     ping ()
     {
diff --git a/odb/mysql/connection.hxx b/odb/mysql/connection.hxx
index 89103c7..7db9230 100644
--- a/odb/mysql/connection.hxx
+++ b/odb/mysql/connection.hxx
@@ -12,10 +12,12 @@
 #include <memory> // std::auto_ptr
 
 #include <odb/forward.hxx>
+#include <odb/connection.hxx>
 
 #include <odb/mysql/mysql.hxx>
 #include <odb/mysql/version.hxx>
 #include <odb/mysql/forward.hxx>
+#include <odb/mysql/transaction-impl.hxx>
 
 #include <odb/details/shared-ptr.hxx>
 
@@ -28,7 +30,10 @@ namespace odb
     class statement;
     class statement_cache;
 
-    class LIBODB_MYSQL_EXPORT connection: public details::shared_base
+    class connection;
+    typedef details::shared_ptr<connection> connection_ptr;
+
+    class LIBODB_MYSQL_EXPORT connection: public odb::connection
     {
     public:
       typedef mysql::statement_cache statement_cache_type;
@@ -46,6 +51,22 @@ namespace odb
       }
 
     public:
+      virtual transaction_impl*
+      begin ();
+
+      transaction_impl*
+      begin_immediate ();
+
+      transaction_impl*
+      begin_exclusive ();
+
+    public:
+      using odb::connection::execute;
+
+      virtual unsigned long long
+      execute (const char* statement, std::size_t length);
+
+    public:
       bool
       failed () const
       {
diff --git a/odb/mysql/database.cxx b/odb/mysql/database.cxx
index 31d6c7b..dc78bce 100644
--- a/odb/mysql/database.cxx
+++ b/odb/mysql/database.cxx
@@ -5,12 +5,9 @@
 
 #include <sstream>
 
-#include <odb/mysql/mysql.hxx>
 #include <odb/mysql/database.hxx>
-#include <odb/mysql/transaction.hxx>
 #include <odb/mysql/connection.hxx>
 #include <odb/mysql/connection-factory.hxx>
-#include <odb/mysql/error.hxx>
 #include <odb/mysql/exceptions.hxx>
 
 #include <odb/mysql/details/options.hxx>
@@ -211,48 +208,11 @@ namespace odb
       details::options::print_usage (os);
     }
 
-    unsigned long long database::
-    execute (const char* s, std::size_t n)
+    odb::connection* database::
+    connection_ ()
     {
-      if (!transaction::has_current ())
-        throw not_in_transaction ();
-
-      connection_type& c (transaction::current ().connection ());
-      c.clear ();
-
-      MYSQL* h (c.handle ());
-
-      if (mysql_real_query (h, s, static_cast<unsigned long> (n)))
-        translate_error (c);
-
-      // Get the affected row count, if any. If the statement has a result
-      // set (e.g., SELECT), we first need to call mysql_store_result().
-      //
-      unsigned long long r (0);
-
-      if (mysql_field_count (h) == 0)
-        r = static_cast<unsigned long long> (mysql_affected_rows (h));
-      else
-      {
-        if (MYSQL_RES* rs = mysql_store_result (h))
-        {
-          r = static_cast<unsigned long long> (mysql_num_rows (rs));
-          mysql_free_result (rs);
-        }
-        else
-          translate_error (c);
-      }
-
-      return r;
-    }
-
-    transaction_impl* database::
-    begin ()
-    {
-      if (transaction::has_current ())
-        throw already_in_transaction ();
-
-      return new transaction_impl (*this);
+      connection_ptr c (factory_->connect ());
+      return c.release ();
     }
   }
 }
diff --git a/odb/mysql/database.hxx b/odb/mysql/database.hxx
index 5e2ebc6..37b966f 100644
--- a/odb/mysql/database.hxx
+++ b/odb/mysql/database.hxx
@@ -19,7 +19,6 @@
 #include <odb/mysql/forward.hxx>
 #include <odb/mysql/connection.hxx>
 #include <odb/mysql/connection-factory.hxx>
-#include <odb/mysql/transaction-impl.hxx>
 
 #include <odb/details/shared-ptr.hxx>
 
@@ -29,12 +28,11 @@ namespace odb
 {
   namespace mysql
   {
+    class transaction_impl;
+
     class LIBODB_MYSQL_EXPORT database: public odb::database
     {
     public:
-      typedef mysql::connection connection_type;
-
-    public:
       // In MySQL, NULL and empty string are treated as the same value
       // for all the arguments except passwd and socket.
       //
@@ -159,23 +157,21 @@ namespace odb
       }
 
     public:
-      using odb::database::execute;
-
-      virtual unsigned long long
-      execute (const char* statement, std::size_t length);
-
-    public:
-      virtual transaction_impl*
+      transaction_impl*
       begin ();
 
     public:
-      details::shared_ptr<connection_type>
+      connection_ptr
       connection ();
 
     public:
       virtual
       ~database ();
 
+    protected:
+      virtual odb::connection*
+      connection_ ();
+
     private:
       std::string user_;
       std::string passwd_str_;
diff --git a/odb/mysql/database.ixx b/odb/mysql/database.ixx
index 5791222..399fbdc 100644
--- a/odb/mysql/database.ixx
+++ b/odb/mysql/database.ixx
@@ -7,10 +7,20 @@ namespace odb
 {
   namespace mysql
   {
-    inline details::shared_ptr<database::connection_type> database::
+    inline connection_ptr database::
     connection ()
     {
-      return factory_->connect ();
+      // Go through the virtual connection_() function instead of
+      // directly to allow overriding.
+      //
+      return connection_ptr (
+        static_cast<mysql::connection*> (connection_ ()));
+    }
+
+    inline transaction_impl* database::
+    begin ()
+    {
+      return connection ()->begin ();
     }
   }
 }
diff --git a/odb/mysql/forward.hxx b/odb/mysql/forward.hxx
index 75aeff0..94b175b 100644
--- a/odb/mysql/forward.hxx
+++ b/odb/mysql/forward.hxx
@@ -8,12 +8,15 @@
 
 #include <odb/pre.hxx>
 
+#include <odb/forward.hxx>
+
 namespace odb
 {
   namespace mysql
   {
     class database;
     class connection;
+    typedef details::shared_ptr<connection> connection_ptr;
     class connection_factory;
     class transaction;
     class query;
@@ -29,6 +32,15 @@ namespace odb
     template <typename T>
     class container_statements;
   }
+
+  namespace details
+  {
+    template <>
+    struct counter_type<mysql::connection>
+    {
+      typedef shared_base counter;
+    };
+  }
 }
 
 #include <odb/post.hxx>
diff --git a/odb/mysql/transaction-impl.cxx b/odb/mysql/transaction-impl.cxx
index 659dc56..86cccbe 100644
--- a/odb/mysql/transaction-impl.cxx
+++ b/odb/mysql/transaction-impl.cxx
@@ -14,8 +14,8 @@ namespace odb
   namespace mysql
   {
     transaction_impl::
-    transaction_impl (database_type& db)
-        : odb::transaction_impl (db), connection_ (db.connection ())
+    transaction_impl (connection_ptr c)
+        : odb::transaction_impl (c->database (), *c), connection_ (c)
     {
       if (mysql_real_query (connection_->handle (), "begin", 5) != 0)
         translate_error (*connection_);
diff --git a/odb/mysql/transaction-impl.hxx b/odb/mysql/transaction-impl.hxx
index a15ac8b..a8aa491 100644
--- a/odb/mysql/transaction-impl.hxx
+++ b/odb/mysql/transaction-impl.hxx
@@ -24,13 +24,13 @@ namespace odb
     class LIBODB_MYSQL_EXPORT transaction_impl: public odb::transaction_impl
     {
     protected:
-      friend class database;
+      friend class connection;
       friend class transaction;
 
       typedef mysql::database database_type;
       typedef mysql::connection connection_type;
 
-      transaction_impl (database_type&);
+      transaction_impl (connection_ptr);
 
       virtual
       ~transaction_impl ();
@@ -45,7 +45,7 @@ namespace odb
       connection ();
 
     private:
-      details::shared_ptr<connection_type> connection_;
+      connection_ptr connection_;
     };
   }
 }