libs-gsweb/GSWAdaptors/common/GSWLoadBalancing.c

/* GSWLoadBalancing.c - GSWeb: Adaptors: Load Balancing
   Copyright (C) 1999 Free Software Foundation, Inc.
   
   Written by:	Manuel Guesdon <mguesdon@sbuilders.com>
   Date: 		Jully 1999
   
   This file is part of the GNUstep Web Library.
   
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.
   
   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.
   
   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>
#include <sys/param.h>

#include "config.h"
#include "GSWUtil.h"
#include "GSWDict.h"
#include "GSWList.h"
#include "GSWString.h"
#include "GSWURLUtil.h"
#include "GSWConfig.h"
#include "GSWAppRequestStruct.h"
#include "GSWAppConnect.h"
#include "GSWHTTPRequest.h"
#include "GSWHTTPResponse.h"
#include "GSWAppRequest.h"
#include "GSWHTTPHeaders.h"
#include "GSWLoadBalancing.h"
#include "GSWLock.h"
#include "GSWApp.h"

//--------------------------------------------------------------------
BOOL GSWLoadBalancing_FindApp(GSWAppRequest* p_pAppRequest,
							  void* p_pLogServerData, GSWURLComponents* p_pURLComponents)
{
  BOOL fFound=FALSE;
  GSWApp* pApp=NULL;
  GSWLog(GSW_DEBUG,p_pLogServerData,"Start GSWLoadBalancing_FindApp");
  GSWLog(GSW_INFO,p_pLogServerData,"LoadBalance: looking for %s",
		   p_pAppRequest->pszName);
  GSWConfig_LoadConfiguration(p_pLogServerData);
  GSWLock_Lock(g_lockAppList);
  pApp = GSWConfig_GetApp(p_pAppRequest->pszName);
  if (pApp)
	{
	  GSWList* pInstancesList=GSWDict_AllKeys(&pApp->stInstancesDict);
	  unsigned int uInstancesCount=GSWList_Count(pInstancesList);
	  int iTries=uInstancesCount;
	  GSWAppInstance* pAppInstance=NULL;
	  time_t curTime = (time_t)0;
	  
	  while (!fFound && iTries-->0)
		{
		  pApp->iIndex = (pApp->iIndex+1) % uInstancesCount;
		  pAppInstance=(GSWAppInstance*)GSWDict_ValueForKey(&pApp->stInstancesDict,
															GSWList_ElementAtIndex(pInstancesList,pApp->iIndex));
		  if (pAppInstance)
			{
			  if (!pAppInstance->pApp)
				{
				  GSWLog(GSW_CRITICAL,p_pLogServerData,
						 "AppInstance pApp is null pAppInstance=%p",
						 pAppInstance);
				};
			  if (pAppInstance->timeNextRetryTime!=0)
				{
				  if (!curTime)
					time(&curTime);
				  if (pAppInstance->timeNextRetryTime<curTime)
					{
					  GSWLog(GSW_CRITICAL,
							 p_pLogServerData,
							 "LoadBalance: Instance %s:%d was marked dead for %d secs. Now resurecting !",
							 p_pAppRequest->pszName, 
							 pAppInstance->iInstance,
							 APP_CONNECT_RETRY_DELAY);
					  pAppInstance->timeNextRetryTime=0;
					};
				};
			  if (pAppInstance->timeNextRetryTime==0 && pAppInstance->fValid)
				{
				  BOOL okay = TRUE;
				  // check if refused, time to try again ?
				  if (p_pURLComponents->stRequestHandlerKey.iLength==0 || p_pURLComponents->stRequestHandlerKey.pszStart==NULL) {
					GSWAppInfo *thisAppInfo = GSWAppInfo_Find(p_pAppRequest->pszName, pAppInstance->iInstance);
					if (thisAppInfo && thisAppInfo->isRefused) {
						time_t actTime = (time_t)0;
						// this instance refuses new sessions
						time(&actTime);
						if (actTime > thisAppInfo->timeNextRetryTime) {
							thisAppInfo->isRefused = FALSE;	// try it again
						} else {
							okay = FALSE;	// try an other instance
						}
					}
				  }

			      if (okay == TRUE) {
				  	fFound = TRUE;
				  	strcpy(p_pAppRequest->pszName,pApp->pszName);
				  	p_pAppRequest->iInstance = pAppInstance->iInstance;
				  	p_pAppRequest->pszHost = pAppInstance->pszHostName;
				  	p_pAppRequest->iPort = pAppInstance->iPort;
				  	p_pAppRequest->eType = EAppType_LoadBalanced;
				  	p_pAppRequest->pAppInstance = pAppInstance;
				  	pAppInstance->uOpenedRequestsNb++;
				  }
				};
			};
		};
	  GSWList_Free(pInstancesList,FALSE);
	};
  GSWLock_Unlock(g_lockAppList);
  
  if (fFound)
	GSWLog(GSW_INFO,p_pLogServerData,"LoadBalance: looking for %s, fFound instance %d on %s:%d",
		   p_pAppRequest->pszName,
		   p_pAppRequest->iInstance,
		   p_pAppRequest->pszHost,
		   p_pAppRequest->iPort);
  else
	GSWLog(GSW_INFO,p_pLogServerData,"LoadBalance: looking for %s, Not Found",
		   p_pAppRequest->pszName);
  GSWLog(GSW_DEBUG,p_pLogServerData,"Stop GSWLoadBalancing_FindApp");
  return fFound;
};

//--------------------------------------------------------------------
BOOL GSWLoadBalancing_FindInstance(GSWAppRequest *p_pAppRequest,void* p_pLogServerData, GSWURLComponents* p_pURLComponents)
{
  BOOL fFound=FALSE;
  GSWApp* pApp=NULL;
  int i=0;
  GSWLog(GSW_DEBUG,p_pLogServerData,"Start GSWLoadBalancing_FindInstance");
  GSWConfig_LoadConfiguration(p_pLogServerData);
  GSWLock_Lock(g_lockAppList);
  pApp = (GSWApp*)GSWConfig_GetApp(p_pAppRequest->pszName);
  if (pApp)
	{
	  GSWAppInstance* pAppInstance=NULL;
	  char szInstanceNum[50]="";
	  sprintf(szInstanceNum,"%d",p_pAppRequest->iInstance);
	  pAppInstance=(GSWAppInstance*)GSWDict_ValueForKey(&pApp->stInstancesDict,szInstanceNum);
	  if (pAppInstance)
		{
		  GSWLog(GSW_DEBUG,p_pLogServerData,"Instance Found");
		  if (pAppInstance->fValid)
			{
				  BOOL okay = TRUE;
				  // check if refused, time to try again ?
				  if (p_pURLComponents->stRequestHandlerKey.iLength==0 || p_pURLComponents->stRequestHandlerKey.pszStart==NULL) {
					GSWAppInfo *thisAppInfo = GSWAppInfo_Find(p_pAppRequest->pszName, pAppInstance->iInstance);
					if (thisAppInfo && thisAppInfo->isRefused) {
						time_t actTime = (time_t)0;
						// this instance refuses new sessions
						time(&actTime);
						if (actTime > thisAppInfo->timeNextRetryTime) {
							thisAppInfo->isRefused = FALSE;	// try it again
						} else {
							okay = FALSE;	// try an other instance
						}
					}
				  }

			    if (okay == TRUE) {

			  		fFound=TRUE;
			  		p_pAppRequest->iInstance = pAppInstance->iInstance;
			  		p_pAppRequest->pszHost = pAppInstance->pszHostName;
			  		p_pAppRequest->iPort = pAppInstance->iPort;
			  		p_pAppRequest->eType = EAppType_LoadBalanced;
			  		p_pAppRequest->pAppInstance = pAppInstance;
			  		pAppInstance->uOpenedRequestsNb++;		
			  		GSWLog(GSW_DEBUG,p_pLogServerData,"Instance is valid");
				}
			}
		  else
			{
			  GSWLog(GSW_DEBUG,p_pLogServerData,"Instance is not valid");
			};
		};
	};
  GSWLock_Unlock(g_lockAppList);
  GSWLog(GSW_DEBUG,p_pLogServerData,"Stop GSWLoadBalancing_FindInstance");
  return fFound;
};

//--------------------------------------------------------------------
void GSWLoadBalancing_MarkNotRespondingApp(GSWAppRequest* p_pAppRequest,
										   void* p_pLogServerData)
{
  GSWAppInstance* pAppInstance;
  time_t now;
  time(&now);
  pAppInstance =p_pAppRequest->pAppInstance;
  pAppInstance->uOpenedRequestsNb--;
  pAppInstance->timeNextRetryTime=now+APP_CONNECT_RETRY_DELAY;
  GSWLog(GSW_WARNING,p_pLogServerData,"Marking %s unresponsive",p_pAppRequest->pszName);
  if (!pAppInstance->fValid)
	{
	  if (GSWAppInstance_FreeIFND(pAppInstance))
		pAppInstance=NULL;
	};
};

//--------------------------------------------------------------------
void GSWLoadBalancing_StartAppRequest(GSWAppRequest* p_pAppRequest,
									  void* p_pLogServerData)
{
  GSWAppInstance* pAppInstance=p_pAppRequest->pAppInstance;
  if (pAppInstance->timeNextRetryTime!=0)
	{
	  pAppInstance->timeNextRetryTime=0;
	  GSWLog(GSW_WARNING,p_pLogServerData,"Marking %s as alive",p_pAppRequest->pszName);
	};
}

//--------------------------------------------------------------------
void GSWLoadBalancing_StopAppRequest(GSWAppRequest *p_pAppRequest,
									 void* p_pLogServerData)
{
  GSWAppInstance* pAppInstance=p_pAppRequest->pAppInstance;
  GSWLock_Lock(g_lockAppList);
  pAppInstance->uOpenedRequestsNb--;
  if (!pAppInstance->fValid)
	{
	  if (GSWAppInstance_FreeIFND(pAppInstance))
		pAppInstance=NULL;
	};
  GSWLock_Unlock(g_lockAppList);
  p_pAppRequest->pAppInstance = NULL;
};