Introduce caching of collation table and table engines list in connection layer. Remove that stuff from main unit and automatically clear cached stuff on disconnection.

source/createdatabase.dfm

@@ -15,7 +15,6 @@ object CreateDatabaseForm: TCreateDatabaseForm
   Position = poOwnerFormCenter
   OnClose = FormClose
   OnCreate = FormCreate
-  OnDestroy = FormDestroy
   OnShow = FormShow
   DesignSize = (
     317

source/createdatabase.pas

@@ -18,7 +18,6 @@ type
     comboCollation: TComboBox;
     lblPreview: TLabel;
     SynMemoPreview: TSynMemo;
-    procedure FormDestroy(Sender: TObject);
     procedure btnOKClick(Sender: TObject);
     procedure comboCharsetChange(Sender: TObject);
     procedure Modified(Sender: TObject);
@@ -29,7 +28,7 @@ type
     function GetCreateStatement: WideString;
   private
     { Private declarations }
-    dsCollations : TMySQLQuery;
+    CollationTable: TMySQLQuery;
     defaultCharset : String;
     currentCollation : String;
   public
@@ -53,45 +52,11 @@ var
   charset: String;
 begin
   InheritFont(Font);
-
-  try
-    dsCollations := Mainform.Connection.GetResults('SHOW COLLATION');
-    // Detect servers default charset
-    defaultCharset := Mainform.Connection.GetVar( 'SHOW VARIABLES LIKE '+esc('character_set_server'), 1 );
-  except
-    // Ignore it when the above statements don't work on pre 4.1 servers.
-    // If the list(s) are nil, disable the combobox(es), so we create the db without charset.
-  end;
-
-  // Create a list with charsets from collations dataset
-  comboCharset.Enabled := dsCollations <> nil;
-  lblCharset.Enabled := comboCharset.Enabled;
-  if comboCharset.Enabled then
-  begin
-    comboCharset.Items.BeginUpdate;
-    dsCollations.First;
-    while not dsCollations.Eof do begin
-      charset := dsCollations.Col('Charset');
-      if comboCharset.Items.IndexOf(charset) = -1 then
-        comboCharset.Items.Add(charset);
-      dsCollations.Next;
-    end;
-    comboCharset.Items.EndUpdate;
-  end;
-
-  comboCollation.Enabled := dsCollations <> nil;
-  lblCollation.Enabled := comboCollation.Enabled;
-
   // Setup SynMemoPreview
   SynMemoPreview.Highlighter := Mainform.SynSQLSyn1;
 end;
 
 
-procedure TCreateDatabaseForm.FormDestroy(Sender: TObject);
-begin
-  FreeAndNil(dsCollations);
-end;
-
 {**
   Form gets displayed: Set default values.
 }
@@ -100,8 +65,28 @@ var
   selectCharset,
   currentCharset,
   sql_create : WideString;
+  Charset: String;
   colpos: Integer;
 begin
+  CollationTable := Mainform.Connection.CollationTable;
+  // Detect servers default charset
+  defaultCharset := Mainform.Connection.GetVar( 'SHOW VARIABLES LIKE '+esc('character_set_server'), 1 );
+  comboCharset.Enabled := Assigned(CollationTable);
+  lblCharset.Enabled := comboCharset.Enabled;
+  comboCollation.Enabled := comboCharset.Enabled;
+  lblCollation.Enabled := comboCharset.Enabled;
+  if comboCharset.Enabled then begin
+    // Create a list with charsets from collations dataset
+    comboCharset.Items.BeginUpdate;
+    while not CollationTable.Eof do begin
+      Charset := CollationTable.Col('Charset');
+      if comboCharset.Items.IndexOf(Charset) = -1 then
+        comboCharset.Items.Add(Charset);
+      CollationTable.Next;
+    end;
+    comboCharset.Items.EndUpdate;
+  end;
+
   if modifyDB = '' then
   begin
     Caption := 'Create database ...';
@@ -157,21 +142,21 @@ var
   defaultCollation : String;
 begin
   // Abort if collations were not fetched successfully
-  if dsCollations = nil then
+  if not Assigned(CollationTable) then
     Exit;
 
   // Fill pulldown with fitting collations
   comboCollation.Items.BeginUpdate;
   comboCollation.Items.Clear;
-  dsCollations.First;
+  CollationTable.First;
-  while not dsCollations.Eof do begin
+  while not CollationTable.Eof do begin
-    if dsCollations.Col('Charset') = comboCharset.Text then
+    if CollationTable.Col('Charset') = comboCharset.Text then
     begin
-      comboCollation.Items.Add( dsCollations.Col('Collation'));
+      comboCollation.Items.Add(CollationTable.Col('Collation'));
-      if dsCollations.Col('Default') = 'Yes' then
+      if CollationTable.Col('Default') = 'Yes' then
-        defaultCollation := dsCollations.Col('Collation');
+        defaultCollation := CollationTable.Col('Collation');
     end;
-    dsCollations.Next;
+    CollationTable.Next;
   end;
 
   // Preselect default or current collation

source/main.pas

@@ -708,9 +708,6 @@ type
     EditVariableForm           : TfrmEditVariable;
     FileNameSessionLog         : String;
     FileHandleSessionLog       : Textfile;
-    dsShowEngines,
-    dsHaveEngines,
-    dsCollations,
     FSelectedTableColumns,
     FSelectedTableKeys         : TMySQLQuery;
     FilterPanelManuallyOpened  : Boolean;
@@ -824,7 +821,6 @@ type
     procedure ActivateFileLogging;
     procedure DeactivateFileLogging;
     procedure TrimSQLLog;
-    procedure TableEnginesCombo(var Combobox: TCombobox);
     function GetTreeNodeType(Tree: TBaseVirtualTree; Node: PVirtualNode): TListNodeType;
     function GetFocusedTreeNodeType: TListNodeType;
     procedure RefreshTree(DoResetTableCache: Boolean; SelectDatabase: WideString = '');
@@ -850,7 +846,6 @@ type
     function GetRegKeyTable: String;
     procedure SaveListSetup( List: TVirtualStringTree );
     procedure RestoreListSetup( List: TVirtualStringTree );
-    function GetCollations(Items: TWideStrings = nil): TMySQLQuery;
     procedure SetEditorTabCaption(Editor: TFrame; ObjName: WideString);
     procedure ResetSelectedTableStuff;
     procedure SetWindowCaption;
@@ -1662,18 +1657,11 @@ begin
   ClearAllTableLists;
   FreeAndNil(AllDatabases);
   FreeAndNil(InformationSchemaTables);
-  FreeAndNil(dsShowEngines);
-  FreeAndNil(dsHaveEngines);
-  FreeAndNil(dsCollations);
   FreeAndNil(FDataGridSelect);
   ResetSelectedTableStuff;
   SynMemoFilter.Clear;
   SetLength(FDataGridSort, 0);
 
-  // Free forms which use session based datasets, fx dsShowEngines
-  FreeAndNil(TableEditor);
-  FreeAndNil(CreateDatabaseForm);
-
   // Closing connection
   if Assigned(Connection) then
     FreeAndNil(Connection);
@@ -5783,81 +5771,6 @@ begin
 end;
 
 
-{**
-  Fetch table engines from server
-  Currently used in tbl_properties and createtable
-}
-procedure TMainForm.TableEnginesCombo(var Combobox: TCombobox);
-var
-  engineName, defaultEngine, engineSupport : String;
-  HaveEngineList : TStrings;
-begin
-  Combobox.Items.BeginUpdate;
-  Combobox.Items.Clear;
-
-  // Cache datasets
-  if dsShowEngines = nil then begin
-    FreeAndNil(dsShowEngines);
-    try
-      dsShowEngines := Connection.GetResults('SHOW ENGINES');
-    except
-      // Ignore errors on old servers
-    end;
-  end;
-  if dsHaveEngines = nil then begin
-    FreeAndNil(dsHaveEngines);
-    dsHaveEngines := Connection.GetResults('SHOW VARIABLES LIKE ''have%''');
-  end;
-
-  if Assigned(dsShowEngines) then begin
-    dsShowEngines.First;
-    while not dsShowEngines.Eof do begin
-      engineName := dsShowEngines.Col('Engine');
-      engineSupport := LowerCase(dsShowEngines.Col('Support'));
-      // Add to dropdown if supported
-      if engineSupport <> 'no' then
-        Combobox.Items.Add(engineName);
-      // Check if this is the default engine
-      if engineSupport = 'default' then
-        defaultEngine := engineName;
-      dsShowEngines.Next;
-    end;
-  end
-  else begin
-    // Manually fetch available engine types by analysing have_* options
-    // This is for servers below 4.1 or when the SHOW ENGINES statement has
-    // failed for some other reason
-
-    // Add default engines which will not show in a have_* variable:
-    Combobox.Items.CommaText := 'MyISAM,MRG_MyISAM,HEAP';
-    defaultEngine := 'MyISAM';
-    // Possible other engines:
-    HaveEngineList := TStringList.Create;
-    HaveEngineList.CommaText := 'ARCHIVE,BDB,BLACKHOLE,CSV,EXAMPLE,FEDERATED,INNODB,ISAM';
-    dsHaveEngines.First;
-    while not dsHaveEngines.Eof do begin
-      engineName := copy(dsHaveEngines.Col(0), 6, Length(dsHaveEngines.Col(0)) );
-      // Strip additional "_engine" suffix, fx from "have_blackhole_engine"
-      if Pos('_', engineName) > 0 then
-        engineName := copy(engineName, 0, Pos('_', engineName)-1);
-      engineName := UpperCase(engineName);
-      // Add engine to dropdown if it's a) in HaveEngineList and b) activated
-      if (HaveEngineList.IndexOf(engineName) > -1)
-        and (LowerCase(dsHaveEngines.Col(1)) = 'yes') then
-        Combobox.Items.Add(engineName);
-      dsHaveEngines.Next;
-    end;
-  end;
-
-  Combobox.Sorted := True;
-
-  // Select default
-  Combobox.ItemIndex := Combobox.Items.IndexOf(defaultEngine);
-
-  Combobox.Items.EndUpdate;
-end;
-
-
 {**
   A row in the process list was selected. Fill SynMemoProcessView with
   the SQL of that row.
@@ -8215,28 +8128,6 @@ begin
 end;
 
 
-function TMainform.GetCollations(Items: TWideStrings = nil): TMySQLQuery;
-begin
-  // Return cached collation list, used in several places, e.g. table editor
-  if dsCollations = nil then try
-    dsCollations := Connection.GetResults('SHOW COLLATION');
-  except
-    // Ignore errors on old servers
-  end;
-  if Assigned(dsCollations) then begin
-    dsCollations.First;
-    if Assigned(Items) then begin
-      while not dsCollations.Eof do begin
-        Items.Add(dsCollations.Col('Collation'));
-        dsCollations.Next;
-      end;
-      dsCollations.First;
-    end;
-  end;
-  Result := dsCollations;
-end;
-
-
 procedure TMainForm.PlaceObjectEditor(Which: TListNodeType);
 var
   frm: TFrame;

source/mysql_connection.pas

@@ -83,6 +83,10 @@ type
       FServerVersionUntouched: String;
       FLastQueryStart, FLastQueryEnd: Cardinal;
       FIsUnicode: Boolean;
+      FTableEngines: TStringList;
+      FTableEngineDefault: String;
+      FCollationTable: TMySQLQuery;
+      FCollationsUnavailable: Boolean;
       function GetActive: Boolean;
       procedure SetActive(Value: Boolean);
       procedure SetDatabase(Value: WideString);
@@ -93,8 +97,12 @@ type
       function GetServerVersionStr: String;
       function GetServerVersionInt: Integer;
       function GetLastQueryDuration: Cardinal;
+      function GetTableEngines: TStringList;
+      function GetCollationTable: TMySQLQuery;
+      function GetCollationList: TStringList;
       procedure Log(Category: TMySQLLogCategory; Msg: WideString);
       procedure DetectCapabilities;
+      procedure ClearCache;
     public
       constructor Create(AOwner: TComponent); override;
       destructor Destroy; override;
@@ -119,6 +127,10 @@ type
       property RowsAffected: Int64 read FRowsAffected;
       property LastQueryDuration: Cardinal read GetLastQueryDuration;
       property IsUnicode: Boolean read FIsUnicode;
+      property TableEngines: TStringList read GetTableEngines;
+      property TableEngineDefault: String read FTableEngineDefault;
+      property CollationTable: TMySQLQuery read GetCollationTable;
+      property CollationList: TStringList read GetCollationList;
     published
       property Active: Boolean read GetActive write SetActive default False;
       property Hostname: String read FHostname write FHostname;
@@ -196,6 +208,7 @@ end;
 destructor TMySQLConnection.Destroy;
 begin
   if Active then Active := False;
+  ClearCache;
   inherited Destroy;
 end;
 
@@ -290,8 +303,10 @@ end;
 
 function TMySQLConnection.GetActive: Boolean;
 begin
-  if FActive and (mysql_ping(FHandle) <> 0) then
+  if FActive and (mysql_ping(FHandle) <> 0) then begin
     Active := False;
+    ClearCache;
+  end;
   Result := FActive;
 end;
 
@@ -616,6 +631,93 @@ begin
 end;
 
 
+function TMySQLConnection.GetTableEngines: TStringList;
+var
+  ShowEngines, HaveEngines: TMySQLQuery;
+  engineName, engineSupport: String;
+  PossibleEngines: TStringList;
+begin
+  if not Assigned(FTableEngines) then begin
+    FTableEngines := TStringList.Create;
+    try
+      ShowEngines := GetResults('SHOW ENGINES');
+      while not ShowEngines.Eof do begin
+        engineName := ShowEngines.Col('Engine');
+        engineSupport := LowerCase(ShowEngines.Col('Support'));
+        // Add to dropdown if supported
+        if engineSupport <> 'no' then
+          FTableEngines.Add(engineName);
+        // Check if this is the default engine
+        if engineSupport = 'default' then
+          FTableEngineDefault := engineName;
+        ShowEngines.Next;
+      end;
+    except
+      // Ignore errors on old servers and try a fallback:
+      // Manually fetch available engine types by analysing have_* options
+      // This is for servers below 4.1 or when the SHOW ENGINES statement has
+      // failed for some other reason
+      HaveEngines := GetResults('SHOW VARIABLES LIKE ''have%''');
+      // Add default engines which will not show in a have_* variable:
+      FTableEngines.CommaText := 'MyISAM,MRG_MyISAM,HEAP';
+      FTableEngineDefault := 'MyISAM';
+      // Possible other engines:
+      PossibleEngines := TStringList.Create;
+      PossibleEngines.CommaText := 'ARCHIVE,BDB,BLACKHOLE,CSV,EXAMPLE,FEDERATED,INNODB,ISAM';
+      while not HaveEngines.Eof do begin
+        engineName := copy(HaveEngines.Col(0), 6, Length(HaveEngines.Col(0)));
+        // Strip additional "_engine" suffix, fx from "have_blackhole_engine"
+        if Pos('_', engineName) > 0 then
+          engineName := copy(engineName, 0, Pos('_', engineName)-1);
+        engineName := UpperCase(engineName);
+        // Add engine to list if it's a) in HaveEngineList and b) activated
+        if (PossibleEngines.IndexOf(engineName) > -1)
+          and (LowerCase(HaveEngines.Col(1)) = 'yes') then
+          FTableEngines.Add(engineName);
+        HaveEngines.Next;
+      end;
+    end;
+  end;
+  Result := FTableEngines;
+end;
+
+
+function TMySQLConnection.GetCollationTable: TMySQLQuery;
+begin
+  if (not Assigned(FCollationTable)) and (not FCollationsUnavailable) then try
+    FCollationTable := GetResults('SHOW COLLATION');
+  except
+    // Ignore errors on old servers
+    FCollationsUnavailable := True;
+  end;
+  if Assigned(FCollationTable) then
+    FCollationTable.First;
+  Result := FCollationTable;
+end;
+
+
+function TMySQLConnection.GetCollationList: TStringList;
+var
+  c: TMySQLQuery;
+begin
+  c := CollationTable;
+  Result := TStringList.Create;
+  if not FCollationsUnavailable then while not c.Eof do begin
+    Result.Add(c.Col('Collation'));
+    c.Next;
+  end;
+end;
+
+
+procedure TMySQLConnection.ClearCache;
+begin
+  // Free cached lists and results. Called when the connection was closed and/or destroyed
+  FreeAndNil(FCollationTable);
+  FCollationsUnavailable := False;
+  FreeAndNil(FTableEngines);
+  FTableEngineDefault := '';
+end;
+
 
 
 { TMySQLQuery }

source/table_editor.dfm

@@ -343,7 +343,7 @@ object frmTableEditor: TfrmTableEditor
         TabOrder = 0
         OnChange = editNumEditChange
       end
-      object comboCollation: TTntComboBox
+      object comboCollation: TComboBox
         Left = 354
         Top = 3
         Width = 119

source/table_editor.pas

@@ -36,7 +36,7 @@ type
     memoUnionTables: TTntMemo;
     comboInsertMethod: TComboBox;
     lblCollation: TLabel;
-    comboCollation: TTNTComboBox;
+    comboCollation: TComboBox;
     lblEngine: TLabel;
     comboEngine: TComboBox;
     treeIndexes: TVirtualStringTree;
@@ -302,9 +302,9 @@ begin
   // Start with "basic" tab activated when just called
   if FAlterTableName <> AlterTableName then
     PageControlMain.ActivePage := tabBasic;
-  Mainform.TableEnginesCombo(comboEngine);
+  comboEngine.Items := Mainform.Connection.TableEngines;
-  comboCollation.Items.Clear;
+  comboEngine.ItemIndex := comboEngine.Items.IndexOf(Mainform.Connection.TableEngineDefault);
-  Mainform.GetCollations(comboCollation.Items);
+  comboCollation.Items := Mainform.Connection.CollationList;
   FAlterTableName := AlterTableName;
   listColumns.BeginUpdate;
   FColumns.Clear;
@@ -688,8 +688,8 @@ begin
   if comboInsertMethod.Enabled and (comboInsertMethod.Tag = ModifiedFlag) and (comboInsertMethod.Text <> '') then
     Specs.Add('INSERT_METHOD='+comboInsertMethod.Text);
   if chkCharsetConvert.Checked then begin
-    Results := Mainform.GetCollations;
+    Results := Mainform.Connection.CollationTable;
-    while not Results.Eof do begin
+    if Assigned(Results) then while not Results.Eof do begin
       if Results.Col('Collation') = comboCollation.Text then begin
         Specs.Add('CONVERT TO CHARSET '+Results.Col('Charset'));
         break;
@@ -1409,7 +1409,7 @@ begin
     8: begin // Collation pulldown
       EnumEditor := TEnumEditorLink.Create(VT);
       EnumEditor.ValueList := TWideStringList.Create;
-      Mainform.GetCollations(EnumEditor.ValueList);
+      EnumEditor.ValueList.Text := Mainform.Connection.CollationList.Text;
       EnumEditor.ValueList.Insert(0, '');
       EditLink := EnumEditor;
       end;