Add support for transaction multiplexing

Also delay getting a connection until after we do all the sanity
checks (e.g., that there is no active transaction). Otherwise we
are running risk of getting blocked rather than throwing an
exception.

8 files changed, 64 insertions, 39 deletions

diff --git a/odb/sqlite/connection.cxx b/odb/sqlite/connection.cxx
index ffb70a7..1e9ff6f 100644
--- a/odb/sqlite/connection.cxx
+++ b/odb/sqlite/connection.cxx
@@ -82,9 +82,6 @@ namespace odb
     transaction_impl* connection::
     begin ()
     {
-      if (transaction::has_current ())
-        throw already_in_transaction ();
-
       return new transaction_impl (
         connection_ptr (inc_ref (this)), transaction_impl::deferred);
     }
@@ -92,9 +89,6 @@ namespace odb
     transaction_impl* connection::
     begin_immediate ()
     {
-      if (transaction::has_current ())
-        throw already_in_transaction ();
-
       return new transaction_impl (
         connection_ptr (inc_ref (this)), transaction_impl::immediate);
     }
@@ -102,9 +96,6 @@ namespace odb
     transaction_impl* connection::
     begin_exclusive ()
     {
-      if (transaction::has_current ())
-        throw already_in_transaction ();
-
       return new transaction_impl (
         connection_ptr (inc_ref (this)), transaction_impl::exclusive);
     }
diff --git a/odb/sqlite/database.cxx b/odb/sqlite/database.cxx
index 6ce4621..04f788b 100644
--- a/odb/sqlite/database.cxx
+++ b/odb/sqlite/database.cxx
@@ -83,6 +83,24 @@ namespace odb
       details::options::print_usage (os);
     }
 
+    transaction_impl* database::
+    begin ()
+    {
+      return new transaction_impl (*this, transaction_impl::deferred);
+    }
+
+    transaction_impl* database::
+    begin_immediate ()
+    {
+      return new transaction_impl (*this, transaction_impl::immediate);
+    }
+
+    transaction_impl* database::
+    begin_exclusive ()
+    {
+      return new transaction_impl (*this, transaction_impl::exclusive);
+    }
+
     odb::connection* database::
     connection_ ()
     {
diff --git a/odb/sqlite/database.hxx b/odb/sqlite/database.hxx
index 13c44e6..348f236 100644
--- a/odb/sqlite/database.hxx
+++ b/odb/sqlite/database.hxx
@@ -87,7 +87,7 @@ namespace odb
       // Transactions.
       //
     public:
-      transaction_impl*
+      virtual transaction_impl*
       begin ();
 
       transaction_impl*
diff --git a/odb/sqlite/database.ixx b/odb/sqlite/database.ixx
index f78d659..e7ae208 100644
--- a/odb/sqlite/database.ixx
+++ b/odb/sqlite/database.ixx
@@ -16,23 +16,5 @@ namespace odb
       return connection_ptr (
         static_cast<sqlite::connection*> (connection_ ()));
     }
-
-    inline transaction_impl* database::
-    begin ()
-    {
-      return connection ()->begin ();
-    }
-
-    inline transaction_impl* database::
-    begin_immediate ()
-    {
-      return connection ()->begin_immediate ();
-    }
-
-    inline transaction_impl* database::
-    begin_exclusive ()
-    {
-      return connection ()->begin_exclusive ();
-    }
   }
 }
diff --git a/odb/sqlite/transaction-impl.cxx b/odb/sqlite/transaction-impl.cxx
index 772b274..b425ed8 100644
--- a/odb/sqlite/transaction-impl.cxx
+++ b/odb/sqlite/transaction-impl.cxx
@@ -14,12 +14,38 @@ namespace odb
   namespace sqlite
   {
     transaction_impl::
+    transaction_impl (database_type& db, lock l)
+        : odb::transaction_impl (db), lock_ (l)
+    {
+    }
+
+    transaction_impl::
     transaction_impl (connection_ptr c, lock l)
-        : odb::transaction_impl (c->database (), *c), connection_ (c)
+        : odb::transaction_impl (c->database (), *c),
+          connection_ (c),
+          lock_ (l)
+    {
+    }
+
+    transaction_impl::
+    ~transaction_impl ()
+    {
+    }
+
+    void transaction_impl::
+    start ()
     {
+      // Grab a connection if we don't already have one.
+      //
+      if (connection_ == 0)
+      {
+        connection_ = static_cast<database_type&> (database_).connection ();
+        odb::transaction_impl::connection_ = connection_.get ();
+      }
+
       statement_cache& sc (connection_->statement_cache ());
 
-      switch (l)
+      switch (lock_)
       {
       case deferred:
         {
@@ -39,11 +65,6 @@ namespace odb
       }
     }
 
-    transaction_impl::
-    ~transaction_impl ()
-    {
-    }
-
     void transaction_impl::
     commit ()
     {
diff --git a/odb/sqlite/transaction-impl.hxx b/odb/sqlite/transaction-impl.hxx
index 8b5687b..f0df824 100644
--- a/odb/sqlite/transaction-impl.hxx
+++ b/odb/sqlite/transaction-impl.hxx
@@ -21,10 +21,7 @@ namespace odb
   {
     class LIBODB_SQLITE_EXPORT transaction_impl: public odb::transaction_impl
     {
-    protected:
-      friend class connection;
-      friend class transaction;
-
+    public:
       typedef sqlite::database database_type;
       typedef sqlite::connection connection_type;
 
@@ -35,12 +32,16 @@ namespace odb
         exclusive
       };
 
+      transaction_impl (database_type&, lock);
       transaction_impl (connection_ptr, lock);
 
       virtual
       ~transaction_impl ();
 
       virtual void
+      start ();
+
+      virtual void
       commit ();
 
       virtual void
@@ -51,6 +52,7 @@ namespace odb
 
     private:
       connection_ptr connection_;
+      lock lock_;
     };
   }
 }
diff --git a/odb/sqlite/transaction.hxx b/odb/sqlite/transaction.hxx
index aecf8aa..b30a818 100644
--- a/odb/sqlite/transaction.hxx
+++ b/odb/sqlite/transaction.hxx
@@ -45,6 +45,11 @@ namespace odb
       static transaction&
       current ();
 
+      // Set the current thread's transaction.
+      //
+      static void
+      current (transaction&);
+
     public:
       transaction_impl&
       implementation ();
diff --git a/odb/sqlite/transaction.ixx b/odb/sqlite/transaction.ixx
index f2c9cc8..e8a6594 100644
--- a/odb/sqlite/transaction.ixx
+++ b/odb/sqlite/transaction.ixx
@@ -37,5 +37,11 @@ namespace odb
     {
       return implementation ().connection ();
     }
+
+    inline void transaction::
+    current (transaction& t)
+    {
+      odb::transaction::current (t);
+    }
   }
 }