Delphi7 send email in different thread and unit - delphi

Question

I want to send email in other unit with different thread with indy10.0.52
I have source code
unit ThreadEmail;
interface
uses Classes, SysUtils, IdGlobal, IdMessage, IdIOHandler, IdIOHandlerSocket,
IdSSLOpenSSL, IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient,
IdMessageClient, IdSMTP, IdExplicitTLSClientServerBase, IdSMTPBase,
IdIOHandlerStack, IdSSL, ExtCtrls;
type
TThreadEmail = class(TThread)
private
run : boolean;
counter : Integer;
target : Integer;
IdSMTP: TIdSMTP;
IdSSLIOHandlerSocketOpenSSL: TIdSSLIOHandlerSocketOpenSSL;
Messages : Array [0..10] of TIdMessage;
procedure checkRun();
protected
procedure Execute; override;
public
constructor Create(timerInS:Integer;host:string;port:integer;username,password:String;readTimeout : integer = 0);reintroduce;
function expressSend(recipients,subject,body:string;from:String='';replayTo:String='') :boolean;
function makeEmail(recipients,subject,body:string;from:String='';replayTo:String=''): boolean;
procedure SendAllEmail();
end;
implementation
constructor TThreadEmail.Create(timerInS:Integer;host:string;port:integer;username,password:String;readTimeout : integer = 0);
var b: byte;
begin
inherited Create(False);
Priority:= tpNormal;
FreeOnTerminate:= True;
IdSMTP := TIdSMTP.Create;
IdSSLIOHandlerSocketOpenSSL := TIdSSLIOHandlerSocketOpenSSL.Create();
for b:=low(Messages) to high(messages) do Messages[b] := nil;
IdSMTP.IOHandler := IdSSLIOHandlerSocketOpenSSL;
IdSMTP.UseTLS := utUseImplicitTLS;
IdSMTP.Host := host;
IdSMTP.Port := port;
IdSMTP.Username := username;
IdSMTP.Password := password;
IdSSLIOHandlerSocketOpenSSL.DefaultPort := 0;
IdSSLIOHandlerSocketOpenSSL.Destination := host+':'+inttostr(port);
IdSSLIOHandlerSocketOpenSSL.Host := host;
IdSSLIOHandlerSocketOpenSSL.MaxLineAction := maException;
IdSSLIOHandlerSocketOpenSSL.Port := port;
IdSSLIOHandlerSocketOpenSSL.ReadTimeout := readTimeout;
IdSSLIOHandlerSocketOpenSSL.SSLOptions.Method := sslvSSLv3;
IdSSLIOHandlerSocketOpenSSL.SSLOptions.Mode := sslmClient;
run:=true;
//target := timerInS*10;
end;
function TThreadEmail.expressSend(recipients,subject,body:string;from:String='';replayTo:String='') : boolean;
var IdMessage: TIdMessage;
begin
Result := false;
IdMessage := TIdMessage.Create();
IdMessage.Recipients.EMailAddresses := recipients;
IdMessage.Subject := subject;
IdMessage.Body.Text := body;
if from <> '' then IdMessage.From.Address := from;
if replayTo <> '' then IdMessage.ReplyTo.EMailAddresses := from;
try
IdSMTP.Connect();
IdSMTP.Send(IdMessage);
Result := true;
finally
IdSMTP.Disconnect();
end;
end;
function TThreadEmail.makeEmail(recipients,subject,body:string;from:String='';replayTo:String='') : boolean;
var b: byte;
begin
Result := false;
for b:=low(Messages) to high(messages) do
if Messages[b] = nil then
begin
Result := true;
Messages[b]:= TIdMessage.Create();
Messages[b].Recipients.EMailAddresses := recipients;
Messages[b].Subject := subject;
Messages[b].Body.Text := body;
if from <> '' then Messages[b].From.Address := from;
if replayTo <> '' then Messages[b].ReplyTo.EMailAddresses := from;
end;
if not(result) then
begin
SendAllEmail();
makeEmail(recipients,subject,body,from,replayTo);
end;
end;
procedure TThreadEmail.SendAllEmail();
var b: byte;
begin
try
IdSMTP.Connect();
for b:=low(Messages) to high(messages) do
if run and (Messages[b] <> nil) then
begin
try
IdSMTP.Send(Messages[b]);
finally
Messages[b].Free;
Messages[b] := nil;
end
end;
finally
IdSMTP.Disconnect();
end;
end;
procedure TThreadEmail.checkRun();
begin
Dec(counter);
if counter <= 0 then SendAllEmail();
end;
procedure TThreadEmail.Execute;
var b: byte;
begin
while run do
begin
sleep(100);
checkRun();
end;
IdSMTP.Free;
IdSSLIOHandlerSocketOpenSSL.Free;
for b:=low(Messages) to high(messages) do
if Messages[b] <> nil then Messages[b].Free;
end;
end.
and in mainfrom that i create
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ThreadEmail;
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
var ThreadEmail : TThreadEmail;
begin
ThreadEmail := ThreadEmail.Create(10,'smtp.gmail.com',465,'xxx.gmail.com','xxx',2000);
ThreadEmail.expressSend('xxx#yahoo.com','TES','TES');
end;
When button1 clicked, it always "create access violation error", Why it happend? can anyone help me? as a info, i sucesed send a email before, but i want to make a singgle unit that can run alone.
thanks

Answer 1

ThreadEmail := ThreadEmail.Create(10,'s....
this should be :
ThreadEmail := TThreadEmail.Create(10,'s....
Not sure if that's just a typo? It will definitely cause an AV if not.
In any case, ThreadEmail.expressSend will not run in your TThread's thread the way you are calling it. When you run a TThread the code in its Execute method will run in a separate thread. Any of the public member methods, however, can be called on an instance just like public methods of any class and they are executed on the thread that calls them.
To get this to work you need to have the Execute method performing the calls to send the email message. The UI thread needs to trigger action in the Execute method and not perform the action itself; this can be done by any number of means (having Execute synchronize with WaitForSingleObject, via message passing, etc).
The rest of your code looks rather broken. Your Execute code is not really going to work as it is - this loop :
while run do
begin
sleep(100);
checkRun();
end;
will never terminate as it seems you don't set run to false anywhere. Furthermore, counter does not seem to get set anywhere (nor do I really understand its purpose) so this will just SendAllEmail() every 100ms or so.
The makeEmail function will never terminate (stack overflow) since it calls itself recursively with the original arguments and the logic guarantees re-entry on each pass. It also looks like it will send whatever message eleven times on each recursion (since all 11 elements of Messages will be nil after initialization and after each call to SendAllEmail().
Even if you fix this - if you are calling makeEmail externally (ie: from the UI or another thread) then this will likely end up with all sorts of cross-thread errors since both Execute and the calling thread will be trying to call SendAllEmail at the same time. This code will need some work.