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(*
@Example: `event_and_thread`.
@Description: Use event-driven for usual requests and threads to slowly requests.
@Authors: Silvio Clecio and Gilson Nunes
*)
program event_and_thread;
// Shows `event_and_thread` details on Linux:
//
// $ ps axo pid,ppid,rss,vsz,nlwp,cmd | grep 'event_and_thread'
//
// But if you prefer to see only the number of thread of `event_and_thread`:
//
// $ ps axo nlwp,cmd | grep 'event_and_thread'
{$mode objfpc}{$H+}
{$MACRO ON}
{$DEFINE DEBUG}
{.$DEFINE WAIT_CLIENTS_DISCONNECT}
{$DEFINE TIMEOUT := 10}
{.$DEFINE CONTINGENCY_CONTROL}
{$IF DEFINED(CONTINGENCY_CONTROL)}
{$DEFINE MAX_THREAD_COUNT := 2}
{$ENDIF}
uses
{$IFDEF UNIX}
cthreads, BaseUnix,
{$ELSE}
Sockets,
{$ENDIF}
Classes, SysUtils, cutils, libmicrohttpd;
procedure MHD_socket_close(fd: cint);
begin
{$IFDEF UNIX}
FpClose(fd);
{$ELSE}
CloseSocket(fd);
{$ENDIF}
end;
const
PORT = 8888;
var
_threads: TFPList;
_mutex: TRTLCriticalSection;
type
{ TConnectionHandler }
TConnectionHandler = packed record
Connection: PMHD_Connection;
Url: Pcchar;
end;
{ TSlothThread }
TSlothThread = class(TThread)
private
FHandler: TConnectionHandler;
protected
procedure Execute; override;
public
constructor Create(AHandler: TConnectionHandler);
destructor Destroy; override;
end;
{ TSlothThread }
constructor TSlothThread.Create(AHandler: TConnectionHandler);
begin
inherited Create(True);
FreeOnTerminate := True;
FHandler := AHandler;
end;
destructor TSlothThread.Destroy;
begin
_threads.Remove(Self);
inherited Destroy;
end;
procedure TSlothThread.Execute;
const
page: AnsiString =
'<html><body>I''m a sloth, and my URL is "%s". T: %s</body></html>';
var
i: Byte;
s: AnsiString;
response: PMHD_Response;
begin
for i := 1 to TIMEOUT do
begin
if Terminated then
Break;
Sleep(1000);
end;
if not Terminated then
begin
s := Format(page, [FHandler.Url, DateTimeToStr(Now)]);
response := MHD_create_response_from_buffer(Length(s), Pointer(s),
MHD_RESPMEM_MUST_COPY);
MHD_queue_response(FHandler.Connection, MHD_HTTP_OK, response);
MHD_resume_connection(FHandler.Connection);
MHD_destroy_response(response);
end;
end;
{ daemon }
function RequestHandler(cls: Pointer; connection: PMHD_Connection;
url: Pcchar; method: Pcchar; version: Pcchar; upload_data: Pcchar;
upload_data_size: Psize_t; ptr: PPointer): cint; cdecl;
const
page = '<html><body>Hello world! T: %s</body></html>';
{$IF DEFINED(CONTINGENCY_CONTROL)}
busy_page: Pcchar = '<html><body>The server is busy. :-(</body></html>';
{$ENDIF}
var
s: string;
ret: cint;
thr: TThread;
response: PMHD_Response;
handler: TConnectionHandler;
begin
if method <> 'GET' then
Exit(MHD_NO);
{ By Gilson Nunes:
"The connection state for first call is `MHD_CONNECTION_HEADERS_PROCESSED`
and `MHD_CONNECTION_FOOTERS_RECEIVED` for the next, so the flag below
ensures that the response will be delivered to the client after `MHD`
finish all the request processing." }
if not Assigned(ptr^) then
begin
ptr^ := Pointer(1);
Exit(MHD_YES);
end;
ptr^ := nil;
if (strcomp(url, '/sloth1') = 0) or (strcomp(url, '/sloth2') = 0) then
begin
{$IF DEFINED(CONTINGENCY_CONTROL)}
if _threads.Count = MAX_THREAD_COUNT then
begin
response := MHD_create_response_from_buffer(Length(busy_page),
busy_page, MHD_RESPMEM_PERSISTENT);
ret := MHD_queue_response(connection, MHD_HTTP_OK, response);
MHD_destroy_response(response);
Exit(ret);
end;
{$ENDIF}
MHD_suspend_connection(connection);
handler.Connection := connection;
handler.Url := url;
thr := TSlothThread.Create(handler);
EnterCriticalsection(_mutex);
try
_threads.Add(thr);
finally
LeaveCriticalsection(_mutex);
end;
thr.Start;
Result := MHD_YES;
end
else
begin
s := Format(page, [DateTimeToStr(Now)]);
response := MHD_create_response_from_buffer(Length(s), Pointer(s),
MHD_RESPMEM_MUST_COPY);
ret := MHD_queue_response(connection, MHD_HTTP_OK, response);
MHD_destroy_response(response);
Result := ret;
end;
end;
var
_daemon: PMHD_Daemon;
procedure StopServer;
var
i: Integer;
thr: TThread;
sckt: MHD_socket;
connections: PMHD_DaemonInfo;
begin
sckt := MHD_quiesce_daemon(_daemon);
{$IFDEF MSWINDOWS}
if LongWord(sckt) <> MHD_INVALID_SOCKET then
{$ELSE}
if sckt <> MHD_INVALID_SOCKET then
{$ENDIF}
MHD_socket_close(sckt);
EnterCriticalsection(_mutex);
try
WriteLn('Threads: ', _threads.Count);
for i := Pred(_threads.Count) downto 0 do
begin
thr := TThread(_threads[i]);
WriteLn('Finishing thread $', HexStr(thr), ' ...');
if Assigned(thr) then
thr.Terminate;
end;
while _threads.Count > 0 do
Sleep(500);
finally
LeaveCriticalsection(_mutex);
end;
connections := MHD_get_daemon_info(_daemon, MHD_DAEMON_INFO_CURRENT_CONNECTIONS);
if Assigned(connections) then
begin
WriteLn('Connections: ', connections^.num_connections);
{$IFDEF WAIT_CLIENTS_DISCONNECT}
while True do
begin
if connections^.num_connections = 0 then
Break;
Sleep(500);
end;
{$ENDIF}
end;
MHD_stop_daemon(_daemon);
WriteLn('Bye!');
end;
procedure SigProc(sig: cint); cdecl;
begin
WriteLn;
StopServer;
FreeAndNil(_threads);
Halt;
end;
begin
InitCriticalSection(_mutex);
_threads := TFPList.Create;
try
_daemon := MHD_start_daemon(MHD_USE_SELECT_INTERNALLY or
MHD_USE_SUSPEND_RESUME or MHD_USE_DEBUG,
PORT, nil, nil, @RequestHandler, nil,
{$IF DEFINED(CONTINGENCY_CONTROL)}
MHD_OPTION_THREAD_POOL_SIZE, cuint(MAX_THREAD_COUNT),
{$ENDIF}
MHD_OPTION_CONNECTION_TIMEOUT, cuint(TIMEOUT + 1),
MHD_OPTION_END);
if not Assigned(_daemon) then
Halt(1);
signal(SIGINT, @SigProc);
{$IFDEF MSWINDOWS}
signal(SIGBREAK, @SigProc);
{$ELSE}
signal(SIGTERM, @SigProc);
{$ENDIF}
WriteLn('HTTP server running. Press [Ctrl+C] to stop the server ...');
while Assigned(_daemon) do
Sleep(100);
finally
FreeAndNil(_threads);
DoneCriticalsection(_mutex);
end;
end.
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