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, 116 insertions, 67 deletions

diff --git a/odb/pgsql/connection-factory.cxx b/odb/pgsql/connection-factory.cxx
index 45d86cd..c9e758d 100644
--- a/odb/pgsql/connection-factory.cxx
+++ b/odb/pgsql/connection-factory.cxx
@@ -29,10 +29,10 @@ namespace odb
     // new_connection_factory
     //
 
-    shared_ptr<connection> new_connection_factory::
+    connection_ptr new_connection_factory::
     connect ()
     {
-      return shared_ptr<connection> (new (shared) connection (*db_));
+      return connection_ptr (new (shared) connection (*db_));
     }
 
     void new_connection_factory::
@@ -60,7 +60,7 @@ namespace odb
       }
     }
 
-    shared_ptr<connection> connection_pool_factory::
+    connection_ptr connection_pool_factory::
     connect ()
     {
       lock l (mutex_);
diff --git a/odb/pgsql/connection-factory.hxx b/odb/pgsql/connection-factory.hxx
index d90b7cb..8a7b9c8 100644
--- a/odb/pgsql/connection-factory.hxx
+++ b/odb/pgsql/connection-factory.hxx
@@ -28,7 +28,7 @@ namespace odb
     class LIBODB_PGSQL_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
@@ -92,7 +92,7 @@ namespace odb
         // @@ check min_ <= max_
       }
 
-      virtual details::shared_ptr<connection>
+      virtual connection_ptr
       connect ();
 
       virtual void
diff --git a/odb/pgsql/connection.cxx b/odb/pgsql/connection.cxx
index 36a5713..808cdbb 100644
--- a/odb/pgsql/connection.cxx
+++ b/odb/pgsql/connection.cxx
@@ -4,16 +4,19 @@
 // license   : GNU GPL v2; see accompanying LICENSE file
 
 #include <new>     // std::bad_alloc
-#include <cstring> // std::strcmp
 #include <string>
+#include <cstring> // std::strcmp
+#include <cstdlib> // std::atol
 
 #include <libpq-fe.h>
 
 #include <odb/pgsql/database.hxx>
 #include <odb/pgsql/connection.hxx>
+#include <odb/pgsql/transaction.hxx>
 #include <odb/pgsql/error.hxx>
 #include <odb/pgsql/exceptions.hxx>
 #include <odb/pgsql/statement-cache.hxx>
+#include <odb/pgsql/result-ptr.hxx>
 
 using namespace std;
 
@@ -28,7 +31,8 @@ namespace odb
   {
     connection::
     connection (database_type& db)
-        : db_ (db),
+        : odb::connection (db),
+          db_ (db),
           handle_ (0),
           statement_cache_ (new statement_cache_type (*this))
     {
@@ -65,5 +69,43 @@ namespace odb
 
       PQfinish (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)
+    {
+      // The string may not be '\0'-terminated.
+      //
+      string str (s, n);
+
+      result_ptr r (PQexec (handle_, str.c_str ()));
+      PGresult* h (r.get ());
+
+      unsigned long long count (0);
+
+      if (!is_good_result (h))
+        translate_error (*this, h);
+      else if (PGRES_TUPLES_OK == PQresultStatus (h))
+        count = static_cast<unsigned long long> (PQntuples (h));
+      else
+      {
+        const char* s (PQcmdTuples (h));
+
+        if (s[0] != '\0' && s[1] == '\0')
+          count = static_cast<unsigned long long> (s[0] - '0');
+        else
+          count = static_cast<unsigned long long> (atol (s));
+      }
+
+      return count;
+    }
   }
 }
diff --git a/odb/pgsql/connection.hxx b/odb/pgsql/connection.hxx
index 6914d5b..2e7679c 100644
--- a/odb/pgsql/connection.hxx
+++ b/odb/pgsql/connection.hxx
@@ -12,11 +12,13 @@
 #include <memory> // std::auto_ptr
 
 #include <odb/forward.hxx>
+#include <odb/connection.hxx>
 
 #include <odb/details/shared-ptr.hxx>
 
 #include <odb/pgsql/version.hxx>
 #include <odb/pgsql/forward.hxx>
+#include <odb/pgsql/transaction-impl.hxx>
 #include <odb/pgsql/pgsql-fwd.hxx> // PGconn
 
 #include <odb/pgsql/details/export.hxx>
@@ -28,7 +30,10 @@ namespace odb
     class statement;
     class statement_cache;
 
-    class LIBODB_PGSQL_EXPORT connection: public details::shared_base
+    class connection;
+    typedef details::shared_ptr<connection> connection_ptr;
+
+    class LIBODB_PGSQL_EXPORT connection: public odb::connection
     {
     public:
       typedef pgsql::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:
       PGconn*
       handle ()
       {
diff --git a/odb/pgsql/database.cxx b/odb/pgsql/database.cxx
index 721e600..050961f 100644
--- a/odb/pgsql/database.cxx
+++ b/odb/pgsql/database.cxx
@@ -4,14 +4,11 @@
 // license   : GNU GPL v2; see accompanying LICENSE file
 
 #include <sstream>
-#include <cstdlib> // std::atol
 
 #include <odb/pgsql/database.hxx>
-#include <odb/pgsql/error.hxx>
 #include <odb/pgsql/exceptions.hxx>
+#include <odb/pgsql/connection.hxx>
 #include <odb/pgsql/connection-factory.hxx>
-#include <odb/pgsql/transaction.hxx>
-#include <odb/pgsql/result-ptr.hxx>
 
 #include <odb/pgsql/details/options.hxx>
 
@@ -211,43 +208,11 @@ namespace odb
     {
     }
 
-    unsigned long long database::
-    execute (const char* s, std::size_t)
+    odb::connection* database::
+    connection_ ()
     {
-      if (!transaction::has_current ())
-        throw not_in_transaction ();
-
-      connection_type& c (transaction::current ().connection ());
-
-      result_ptr r (PQexec (c.handle (), s));
-      PGresult* h (r.get ());
-
-      unsigned long long count (0);
-
-      if (!is_good_result (h))
-        translate_error (c, h);
-      else if (PGRES_TUPLES_OK == PQresultStatus (h))
-        count = static_cast<unsigned long long> (PQntuples (h));
-      else
-      {
-        const char* s (PQcmdTuples (h));
-
-        if (s[0] != '\0' && s[1] == '\0')
-          count = static_cast<unsigned long long> (s[0] - '0');
-        else
-          count = static_cast<unsigned long long> (atol (s));
-      }
-
-      return count;
-    }
-
-    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/pgsql/database.hxx b/odb/pgsql/database.hxx
index b4917cc..d3d8f7d 100644
--- a/odb/pgsql/database.hxx
+++ b/odb/pgsql/database.hxx
@@ -20,7 +20,6 @@
 #include <odb/pgsql/forward.hxx>
 #include <odb/pgsql/connection.hxx>
 #include <odb/pgsql/connection-factory.hxx>
-#include <odb/pgsql/transaction-impl.hxx>
 
 #include <odb/pgsql/details/export.hxx>
 
@@ -28,12 +27,11 @@ namespace odb
 {
   namespace pgsql
   {
+    class transaction_impl;
+
     class LIBODB_PGSQL_EXPORT database: public odb::database
     {
     public:
-      typedef pgsql::connection connection_type;
-
-    public:
       database (const std::string& user,
                 const std::string& password,
                 const std::string& db,
@@ -82,23 +80,24 @@ namespace odb
       static void
       print_usage (std::ostream&);
 
+      // Transactions.
+      //
     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_ ();
+
     public:
       const std::string&
       user () const
diff --git a/odb/pgsql/database.ixx b/odb/pgsql/database.ixx
index a4f5040..467f765 100644
--- a/odb/pgsql/database.ixx
+++ b/odb/pgsql/database.ixx
@@ -7,10 +7,20 @@ namespace odb
 {
   namespace pgsql
   {
-    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<pgsql::connection*> (connection_ ()));
+    }
+
+    inline transaction_impl* database::
+    begin ()
+    {
+      return connection ()->begin ();
     }
   }
 }
diff --git a/odb/pgsql/forward.hxx b/odb/pgsql/forward.hxx
index 8b8ac90..046942d 100644
--- a/odb/pgsql/forward.hxx
+++ b/odb/pgsql/forward.hxx
@@ -8,12 +8,15 @@
 
 #include <odb/pre.hxx>
 
+#include <odb/forward.hxx>
+
 namespace odb
 {
   namespace pgsql
   {
     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<pgsql::connection>
+    {
+      typedef shared_base counter;
+    };
+  }
 }
 
 #include <odb/post.hxx>
diff --git a/odb/pgsql/transaction-impl.cxx b/odb/pgsql/transaction-impl.cxx
index eb93361..81aaf08 100644
--- a/odb/pgsql/transaction-impl.cxx
+++ b/odb/pgsql/transaction-impl.cxx
@@ -19,8 +19,8 @@ namespace odb
   namespace pgsql
   {
     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)
     {
       result_ptr r (PQexec (connection_->handle (), "begin"));
       PGresult* h (r.get ());
diff --git a/odb/pgsql/transaction-impl.hxx b/odb/pgsql/transaction-impl.hxx
index 9b4ec56..d3a76ce 100644
--- a/odb/pgsql/transaction-impl.hxx
+++ b/odb/pgsql/transaction-impl.hxx
@@ -24,13 +24,13 @@ namespace odb
     class LIBODB_PGSQL_EXPORT transaction_impl: public odb::transaction_impl
     {
     protected:
-      friend class database;
+      friend class connection;
       friend class transaction;
 
       typedef pgsql::database database_type;
       typedef pgsql::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_;
     };
   }
 }