datasnap xe连接池_DataSnap数据库连接池，数据集对象池的应用

传统的应用服务器的开发往往是在ServerMethods单元中拖放一堆TDataSet, TDaTaSetProvider控件，这是一个最简单粗暴的开发方向，往往会造成服务端程序文件的臃肿、服务运行期间内存资源消耗过大的问题。因此这种往应用服务器中拖放一堆TDataSet, TDaTaSetProvider控件的做法，非常的笨拙。

当然了，如果我们的系统采用的是以短连接的方式的话，那就可以每次直接TDataSet.Create(nil);然后Free;但是这种方法对服务器的开销很大，因为每执行一个服务都需要重复开辟内存空间，销毁内存空间等。

为此，我们可以通过使用对象池方法来改进之。

一、数据库连接池：TConnection对象池

unit DSServerContainer;

interface

uses

SysUtils, Classes,

DSTCPServerTransport,

DSServer, DSCommonServer, DSAuth, DB, ADODB, Generics.Collections, DSService,

DBXDataSnap, DBXCommon, DSHTTPLayer, DBXinterbase, Forms;

type

TServerContainer1 = class(TDataModule)

DSServer1: TDSServer;

DSTCPServerTransport1: TDSTCPServerTransport;

DSServerClass1: TDSServerClass;

procedure DSServerClass1GetClass(DSServerClass: TDSServerClass;

var PersistentClass: TPersistentClass);

procedure DataModuleCreate(Sender: TObject);

procedure DSServer1Disconnect(DSConnectEventObject: TDSConnectEventObject);

private

{ Private declarations }

ListofConnection : TDictionary;

public

function getConnection : TAdoConnection;

end;

var

ServerContainer1: TServerContainer1;

implementation

uses Windows, ServerMethodsUnit1,uConst;

{$R *.dfm}

procedure TServerContainer1.DataModuleCreate(Sender: TObject);

begin

ListofConnection := TDictionary.Create;

end;

procedure TServerContainer1.DSServer1Disconnect(

DSConnectEventObject: TDSConnectEventObject);

begin

if getConnection <> nil then

getConnection.Close;

end;

procedure TServerContainer1.DSServerClass1GetClass(

DSServerClass: TDSServerClass; var PersistentClass: TPersistentClass);

begin

PersistentClass := ServerMethodsUnit1.TServerMethods1;

end;

function TServerContainer1.getConnection: TAdoConnection;

var

dbconn : TAdoConnection;

begin

if ListofConnection.ContainsKey(TDSSessionManager.GetThreadSession.Id) then

Result := ListofConnection[TDSSessionManager.GetThreadSession.Id]

else

begin

if ListofConnection.Count <= g_MaxPoolSize then

begin

dbconn := TadoConnection.Create(Self);

dbconn.Name := 'con'+ IntToStr(TDSSessionManager.GetThreadSession.Id);

dbconn.LoginPrompt := false;

dbconn.ConnectionString := 'FILE NAME=' + extractfilepath(application.ExeName) + 'connect.udl';

ListofConnection.Add(TDSSessionManager.GetThreadSession.Id, dbconn);

Result := dbconn;

end;

end;

end;

end.

二、数据集对象池：TDataSet和TDataSetProvider的池化

unit ServerMethodsUnit1;

interface

uses

SysUtils, Classes, DSServer, DB, Generics.Collections, DSService, Provider,

ADODB;

type

TServerMethods1 = class(TDSServerModule)

procedure DSServerModuleCreate(Sender: TObject);

private

{ Private declarations }

ListofQuery : TDictionary;

ListofProvider : TDictionary;

function _GetQuery(sql: string; exeNo: Integer) : TAdoquery;

function _GetPrv(sql: string; exeNo: Integer) : TDatasetProvider;

public

{ Public declarations }

function GetProviderName(sql: string; exeNo: Integer): string;

end;

implementation

{$R *.dfm}

uses StrUtils, DSServerContainer, uConst;

procedure TServerMethods1.DSServerModuleCreate(Sender: TObject);

begin

Listofquery := TDictionary.Create;

Listofprovider := TDictionary.Create;

end;

function TServerMethods1._GetPrv(sql: string; exeNo: Integer): TDatasetProvider;

var

dbprv : Tdatasetprovider;

begin

if ListofProvider.ContainsKey(exeNo) then

Result := ListofProvider[exeNo]

else

begin

if ListofProvider.Count <= g_MaxPoolSize then

begin

dbprv := TDataSetProvider.Create(Self);

dbprv.Name := 'dsp'+ IntToStr(exeNo);

dbprv.DataSet := _GetQuery(sql, exeNo);

ListofProvider.Add(exeNo, dbprv);

Result := dbprv;

end;

end;

end;

function TServerMethods1._GetQuery(sql: string; exeNo: Integer): TAdoQuery;

var

qry : TADOQuery;

begin

if Listofquery.ContainsKey(exeNo) then

Result := ListofQuery[exeNo]

else

begin

if ListofQuery.Count <= g_MaxPoolSize then

begin

qry := TADOQuery.Create(Self);

with qry do

begin

Connection := ServerContainer1.getConnection;

Name := 'qry'+ IntToStr(exeNo);

close;

sql.Clear;

sql.Text := sql;

open;

end;

ListofQuery.Add(exeNo, qry);

Result := qry;

end;

end;

end;

function TServerMethods1.GetProviderName(sql: string; exeNo: Integer): string;

begin

Result := _GetPrv(sql, exeNo).Name;

end;

end.

版权声明：本文为博主原创文章，未经博主允许不得转载。