From a051c451c178152dc0b37bf955bf60022d226843 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Thu, 12 Sep 2013 13:01:49 +0200
Subject: Optimize schema version access for default schema

---
 odb/database.cxx | 33 +++++++++++++++++++++++++++++++++
 odb/database.hxx | 20 +++++++++++++++-----
 odb/database.ixx | 39 ++++++++++-----------------------------
 3 files changed, 58 insertions(+), 34 deletions(-)

diff --git a/odb/database.cxx b/odb/database.cxx
index ad71b4f..c9692ba 100644
--- a/odb/database.cxx
+++ b/odb/database.cxx
@@ -4,6 +4,8 @@
 
 #include <odb/database.hxx>
 
+using namespace std;
+
 namespace odb
 {
   database::
@@ -17,4 +19,35 @@ namespace odb
     connection_type& c (transaction::current ().connection ());
     return c.execute (st, n);
   }
+
+  const database::schema_version_info& database::
+  schema_version_migration_ (const string& name) const
+  {
+    schema_version_map::const_iterator i (schema_version_map_.find (name));
+    const schema_version_info& svi (
+      i != schema_version_map_.end () && i->second.version != 0
+      ? i->second
+      : load_schema_version (name));
+
+    if (default_schema_version_ == 0 && name.empty ())
+      default_schema_version_ = &svi;
+
+    return svi;
+  }
+
+  void database::
+  schema_version_migration (const schema_version_migration_type& svm,
+                            const string& name)
+  {
+    schema_version_info& svi (schema_version_map_[name]);
+    if (svi.version != svm.version || svi.migration != svm.migration)
+    {
+      svi.version = svm.version;
+      svi.migration = svm.migration;
+      schema_version_seq_++;
+    }
+
+    if (default_schema_version_ == 0 && name.empty ())
+      default_schema_version_ = &svi;
+  }
 }
diff --git a/odb/database.hxx b/odb/database.hxx
index c7c4598..7ddbecb 100644
--- a/odb/database.hxx
+++ b/odb/database.hxx
@@ -339,24 +339,29 @@ namespace odb
     typedef odb::schema_version_migration schema_version_migration_type;
 
     schema_version_type
-    schema_version (const std::string& schema_name = "") const;
+    schema_version (const std::string& schema_name = std::string ()) const;
 
     bool
-    schema_migration (const std::string& schema_name = "") const;
+    schema_migration (const std::string& schema_name = std::string ()) const;
 
+    // Note that there is code that relies on the returned reference
+    // being valid until the version is changed or the database instance
+    // is destroyed.
+    //
     const schema_version_migration_type&
-    schema_version_migration (const std::string& schema_name = "") const;
+    schema_version_migration (
+      const std::string& schema_name = std::string ()) const;
 
     // Set schema version and migration state manually.
     //
     void
     schema_version_migration (schema_version_type,
                               bool migration,
-                              const std::string& schema_name = "");
+                              const std::string& schema_name = std::string ());
 
     void
     schema_version_migration (const schema_version_migration_type&,
-                              const std::string& schema_name = "");
+                              const std::string& schema_name = std::string ());
 
     // Set default schema version table for all schema names. The table
     // name should already be quoted if necessary.
@@ -386,6 +391,10 @@ namespace odb
     virtual const schema_version_info&
     load_schema_version (const std::string& schema_name) const = 0;
 
+  private:
+    const schema_version_info&
+    schema_version_migration_ (const std::string& schema_name) const;
+
     // Database id.
     //
   public:
@@ -478,6 +487,7 @@ namespace odb
 
     std::string schema_version_table_;
     mutable schema_version_map schema_version_map_;
+    mutable const schema_version_info* default_schema_version_; // Cached.
     unsigned int schema_version_seq_;
   };
 }
diff --git a/odb/database.ixx b/odb/database.ixx
index 3de5bbc..378a376 100644
--- a/odb/database.ixx
+++ b/odb/database.ixx
@@ -11,7 +11,10 @@ namespace odb
 {
   inline database::
   database (database_id id)
-      : id_ (id), tracer_ (0), schema_version_seq_ (1)
+      : id_ (id),
+        tracer_ (0),
+        default_schema_version_ (0),
+        schema_version_seq_ (1)
   {
   }
 
@@ -36,14 +39,11 @@ namespace odb
   inline const database::schema_version_migration_type& database::
   schema_version_migration (const std::string& name) const
   {
-    // Note that there is code that relies on the returned reference
-    // being valid until the version is changed or the database instance
-    // is destroyed.
-    //
-    schema_version_map::const_iterator i (schema_version_map_.find (name));
-    return i != schema_version_map_.end () && i->second.version != 0
-      ? i->second
-      : load_schema_version (name);
+    return name.empty () &&
+      default_schema_version_ != 0 &&
+      default_schema_version_->version != 0
+      ? *default_schema_version_
+      : schema_version_migration_ (name);
   }
 
   inline void database::
@@ -51,26 +51,7 @@ namespace odb
                             bool m,
                             const std::string& name)
   {
-    schema_version_info& svi (schema_version_map_[name]);
-    if (svi.version != v || svi.migration != m)
-    {
-      svi.version = v;
-      svi.migration = m;
-      schema_version_seq_++;
-    }
-  }
-
-  inline void database::
-  schema_version_migration (const schema_version_migration_type& svm,
-                            const std::string& name)
-  {
-    schema_version_info& svi (schema_version_map_[name]);
-    if (svi.version != svm.version || svi.migration != svm.migration)
-    {
-      svi.version = svm.version;
-      svi.migration = svm.migration;
-      schema_version_seq_++;
-    }
+    schema_version_migration (schema_version_migration_type (v, m), name);
   }
 
   inline void database::
-- 
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