initial creation of wti class (still under development)

2 files changed, 705 insertions, 0 deletions

diff --git a/wtp.c b/wtp.c
new file mode 100644
index 00000000..4bc0cd4f
--- /dev/null
+++ b/wtp.c
@@ -0,0 +1,608 @@
+/* wtp.c
+ *
+ * This file implements the worker thread pool (wtp) class.
+ * 
+ * File begun on 2008-01-20 by RGerhards
+ *
+ * There is some in-depth documentation available in doc/dev_queue.html
+ * (and in the web doc set on http://www.rsyslog.com/doc). Be sure to read it
+ * if you are getting aquainted to the object.
+ *
+ * Copyright 2008 Rainer Gerhards and Adiscon GmbH.
+ *
+ * This file is part of rsyslog.
+ *
+ * Rsyslog is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Rsyslog 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Rsyslog.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * A copy of the GPL can be found in the file "COPYING" in this distribution.
+ */
+#include "config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <signal.h>
+#include <pthread.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "rsyslog.h"
+#include "syslogd.h"
+#include "stringbuf.h"
+#include "srUtils.h"
+#include "wtp.h"
+#include "wti.h"
+#include "obj.h"
+
+/* static data */
+DEFobjStaticHelpers
+
+/* forward-definitions */
+
+/* methods */
+
+/* get the header for debug messages
+ * The caller must NOT free or otherwise modify the returned string!
+ */
+static inline uchar *
+wtpGetDbgHdr(wtp_t *pThis)
+{
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	if(pThis->pszDbgHdr == NULL)
+		return (uchar*) "wtp"; /* should not normally happen */
+	else
+		return pThis->pszDbgHdr;
+}
+
+
+
+/* Not implemented dummy function for constructor */
+static rsRetVal NotImplementedDummy() { return RS_RET_NOT_IMPLEMENTED; }
+/* Standard-Constructor for the wtp object
+ */
+BEGINobjConstruct(wtp) /* be sure to specify the object type also in END macro! */
+	int i;
+	uchar pszBuf[64];
+	size_t lenBuf;
+	wti_t *pWti;
+
+	pthread_mutex_init(&pThis->mut, NULL);
+	pthread_cond_init(&pThis->condThrdTrm, NULL);
+	/* set all function pointers to "not implemented" dummy so that we can safely call them */
+	pThis->pfChkStopWrkr = NotImplementedDummy;
+	pThis->pfIsIdle = NotImplementedDummy;
+	pThis->pfDoWork = NotImplementedDummy;
+	pThis->pfOnShutdownAdvise = NotImplementedDummy;
+	pThis->pfOnIdle = NotImplementedDummy;
+	pThis->pfOnWorkerCancel = NotImplementedDummy;
+
+	/* alloc and construct workers */
+	if((pThis->pWrkr = malloc(sizeof(wti_t*) * pThis->iNumWorkerThreads)) == NULL)
+		ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
+
+	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
+		CHKiRet(wtiConstruct(&pThis->pWrkr[i]));
+		pWti = pThis->pWrkr[i];
+		lenBuf = snprintf((char*)pszBuf, sizeof(pszBuf), "%s/w%d", wtpGetDbgHdr(pThis), i);
+		CHKiRet(wtiSetDbgHdr(pWti, pszBuf, lenBuf));
+		CHKiRet(wtiConstructFinalize(pWti));
+	}
+		
+finalize_it:
+ENDobjConstruct(wtp)
+
+
+/* Construction finalizer
+ * rgerhards, 2008-01-17
+ */
+rsRetVal
+wtpConstructFinalize(wtp_t __attribute__((unused)) *pThis)
+{
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	dbgprintf("%s: finalizing construction of worker thread pool\n", wtpGetDbgHdr(pThis));
+
+	return RS_RET_OK;
+}
+
+
+/* Destructor */
+rsRetVal
+wtpDestruct(wtp_t **ppThis)
+{
+	DEFiRet;
+	wtp_t *pThis;
+	int iCancelStateSave;
+	int i;
+
+	assert(ppThis != NULL);
+	pThis = *ppThis;
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	/* we can not be canceled, that would have a myriad of side-effects */
+	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &iCancelStateSave);
+
+	/* destruct workers */
+	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i)
+		wtiDestruct(&pThis->pWrkr[i]);
+
+	free(pThis->pWrkr);
+	pThis->pWrkr = NULL;
+
+	/* actual destruction */
+	pthread_cond_destroy(&pThis->condThrdTrm);
+	pthread_mutex_destroy(&pThis->mut);
+
+	if(pThis->pszDbgHdr != NULL)
+		free(pThis->pszDbgHdr);
+
+	/* and finally delete the queue objet itself */
+	free(pThis);
+	*ppThis = NULL;
+
+	/* back to normal */
+	pthread_setcancelstate(iCancelStateSave, NULL);
+
+	RETiRet;
+}
+
+
+/* wake up all worker threads. Param bWithDAWrk tells if the DA worker
+ * is to be awaken, too. It needs special handling because it waits on
+ * two different conditions depending on processing state.
+ * rgerhards, 2008-01-16
+ */
+static inline rsRetVal
+wtpWakeupWrks(wtp_t *pThis)
+{
+	DEFiRet;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+	pthread_cond_broadcast(pThis->pcondBusy);
+	RETiRet;
+}
+
+
+/* check if we had any worker thread changes and, if so, act
+ * on them. At a minimum, terminated threads are harvested (joined).
+ * This function MUST NEVER block on the queue mutex!
+ */
+rsRetVal
+wtpProcessThrdChanges(wtp_t *pThis)
+{
+	DEFiRet;
+	int i;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	if(pThis->bThrdStateChanged == 0)
+		FINALIZE;
+
+	/* go through all threads */
+	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
+		wtiProcessThrdChanges(pThis->pWrkr[i], LOCK_MUTEX);
+	}
+
+finalize_it:
+	RETiRet;
+}
+
+
+/* Sent a specific state for the worker thread pool.
+ * rgerhards, 2008-01-21
+ */
+rsRetVal
+wtpSetState(wtp_t *pThis, wtpState_t iNewState)
+{
+	DEFiRet;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+	pThis->wtpState = iNewState;
+	// TODO: must wakeup workers?
+
+	RETiRet;
+}
+
+
+#if 0
+/* Send a shutdown command to all workers and see if they terminate.
+ * A timeout may be specified.
+ * rgerhards, 2008-01-14
+ */
+static rsRetVal
+wtpWrkrShutdown(wtp_t *pThis)
+{
+	DEFiRet;
+	int bTimedOut;
+	struct timespec t;
+	int iCancelStateSave;
+
+	// TODO: implement
+	ISOBJ_TYPE_assert(pThis);
+	queueTellActWrkThrds(pThis, 0, tShutdownCmd);/* first tell the workers our request */
+	queueWakeupWrkThrds(pThis, 1); /* awake all workers including DA-worker */
+	/* race: must make sure all are running! */
+	queueTimeoutComp(&t, iTimeout);/* get timeout */
+		
+	/* and wait for their termination */
+dbgprintf("Queue %p: waiting for mutex %p\n", pThis, &pThis->mutThrdMgmt);
+	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &iCancelStateSave);
+	d_pthread_mutex_lock(&pThis->mutThrdMgmt);
+	pthread_cleanup_push(queueMutexCleanup, &pThis->mutThrdMgmt);
+	pthread_setcancelstate(iCancelStateSave, NULL);
+	bTimedOut = 0;
+	while(pThis->iCurNumWrkThrd > 0 && !bTimedOut) {
+		dbgprintf("Queue 0x%lx: waiting %ldms on worker thread termination, %d still running\n",
+			   queueGetID(pThis), iTimeout, pThis->iCurNumWrkThrd);
+
+		if(pthread_cond_timedwait(&pThis->condThrdTrm, &pThis->mutThrdMgmt, &t) != 0) {
+			dbgprintf("Queue 0x%lx: timeout waiting on worker thread termination\n", queueGetID(pThis));
+			bTimedOut = 1;	/* we exit the loop on timeout */
+		}
+	}
+	pthread_cleanup_pop(1);
+
+	if(bTimedOut)
+		iRet = RS_RET_TIMED_OUT;
+
+	RETiRet;
+}
+
+
+/* Unconditionally cancel all running worker threads.
+ * rgerhards, 2008-01-14
+ */
+static rsRetVal
+wtpWrkrCancel(wtp_t *pThis)
+{
+	DEFiRet;
+	int i;
+	// TODO: we need to implement peek(), without it (today!) we lose one message upon
+	// worker cancellation! -- rgerhards, 2008-01-14
+
+	ISOB_TYPE_assert(pThis);
+	/* process any pending thread requests so that we know who actually is still running */
+	queueChkWrkThrdChanges(pThis);
+
+	/* awake the workers one more time, just to be sure */
+	queueWakeupWrkThrds(pThis, 1); /* awake all workers including DA-worker */
+
+	/* first tell the workers our request */
+	for(i = 0 ; i <= pThis->iNumWorkerThreads ; ++i) {
+		if(pThis->pWrkThrds[i].tCurrCmd >= eWRKTHRD_TERMINATING) {
+			dbgprintf("Queue 0x%lx: canceling worker thread %d\n", queueGetID(pThis), i);
+			pthread_cancel(pThis->pWrkThrds[i].thrdID);
+		}
+	}
+
+	RETiRet;
+}
+
+
+/* Worker thread management function carried out when the main
+ * worker is about to terminate.
+ */
+static rsRetVal
+wtpShutdownWorkers(wtp_t *pThis)
+{
+	DEFiRet;
+	int i;
+
+	assert(pThis != NULL);
+
+	dbgprintf("Queue 0x%lx: initiating worker thread shutdown sequence\n", (unsigned long) pThis);
+
+	ISOB_TYPE_assert(pThis);
+	/* even if the timeout count is set to 0 (run endless), we still call the queueWrkThrdTrm(). This
+	 * is necessary so that all threads get sent the termination command. With a timeout of 0, however,
+	 * the function returns immediate with RS_RET_TIMED_OUT. We catch that state and accept it as
+	 * good.
+	 */
+	iRet = queueWrkThrdTrm(pThis, eWRKTHRD_SHUTDOWN, pThis->toQShutdown);
+	if(iRet == RS_RET_TIMED_OUT) {
+		if(pThis->toQShutdown == 0) {
+			iRet = RS_RET_OK;
+		} else {
+			/* OK, we now need to try force the shutdown */
+			dbgprintf("Queue 0x%lx: regular worker shutdown timed out, now trying immediate\n",
+				  queueGetID(pThis));
+			iRet = queueWrkThrdTrm(pThis, eWRKTHRD_SHUTDOWN_IMMEDIATE, pThis->toActShutdown);
+		}
+	}
+
+	if(iRet != RS_RET_OK) { /* this is true on actual error on first try or timeout and error on second */
+		/* still didn't work out - so we now need to cancel the workers */
+		dbgprintf("Queue 0x%lx: worker threads could not be shutdown, now canceling them\n", (unsigned long) pThis);
+		iRet = queueWrkThrdCancel(pThis);
+	}
+	
+	/* finally join the threads
+	 * In case of a cancellation, this may actually take some time. This is also
+	 * needed to clean up the thread descriptors, even with a regular termination.
+	 * And, most importantly, this is needed if we have an indifitite termination
+	 * time set (timeout == 0)! -- rgerhards, 2008-01-14
+	 */
+	for(i = 0 ; i <= pThis->iNumWorkerThreads ; ++i) {
+		if(pThis->pWrkThrds[i].tCurrCmd != eWRKTHRD_STOPPED) {
+			queueJoinWrkThrd(pThis, i);
+		}
+	}
+
+	dbgprintf("Queue 0x%lx: worker threads terminated, remaining queue size %d.\n",
+		  queueGetID(pThis), pThis->iQueueSize);
+
+	RETiRet;
+}
+#endif
+
+
+
+/* check if the worker shall shutdown
+ * TODO: check if we can use atomic operations to enhance performance
+ * Note: there may be two mutexes locked, the bLockUsrMutex is the one in our "user"
+ * (e.g. the queue clas)
+ * rgerhards, 2008-01-21
+ */
+rsRetVal
+wtpChkStopWrkr(wtp_t *pThis, int bLockMutex, int bLockUsrMutex)
+{
+	DEFiRet;
+	DEFVARS_mutexProtection;
+
+	BEGIN_MTX_PROTECTED_OPERATIONS(&pThis->mut, bLockMutex);
+	if(   (pThis->wtpState == wtpState_SHUTDOWN_IMMEDIATE)
+	   || ((pThis->wtpState == wtpState_SHUTDOWN) && pThis->pfIsIdle(pThis->pUsr, bLockUsrMutex)))
+		iRet = RS_RET_TERMINATE_NOW;
+	END_MTX_PROTECTED_OPERATIONS(&pThis->mut);
+
+	/* try customer handler if one was set and we do not yet have a definite result */
+	if(iRet == RS_RET_OK && pThis->pfChkStopWrkr != NULL)
+		iRet = pThis->pfChkStopWrkr(pThis->pUsr, bLockUsrMutex);
+
+	RETiRet;
+}
+
+/* Set the Inactivity Guard
+ * rgerhards, 2008-01-21
+ */
+rsRetVal
+wtpSetInactivityGuard(wtp_t *pThis, int bNewState, int bLockMutex)
+{
+	DEFiRet;
+	DEFVARS_mutexProtection;
+
+	BEGIN_MTX_PROTECTED_OPERATIONS(&pThis->mut, bLockMutex);
+	pThis->bInactivityGuard = bNewState;
+	END_MTX_PROTECTED_OPERATIONS(&pThis->mut);
+
+	RETiRet;
+}
+
+
+/* cancellation cleanup handler for executing worker
+ * decrements the worker counter
+ * rgerhards, 2008-01-20
+ */
+void
+wtpWrkrExecCancelCleanup(void *arg)
+{
+	wtp_t *pThis = (wtp_t*) arg;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+	pThis->iCurNumWrkThrd--;
+
+	dbgprintf("%s: thread CANCELED with %d workers running.\n", wtpGetDbgHdr(pThis), pThis->iCurNumWrkThrd);
+
+}
+
+
+/* wtp worker shell. This is started and calls into the actual
+ * wti worker.
+ * rgerhards, 2008-01-21
+ */
+static void *
+wtpWorker(void *arg)
+{
+	DEFiRet;
+	DEFVARS_mutexProtection;
+	wti_t *pWti = (wti_t*) arg;
+	wtp_t *pThis;
+	sigset_t sigSet;
+
+	ISOBJ_TYPE_assert(pWti, wti);
+	pThis = pWti->pWtp;
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	sigfillset(&sigSet);
+	pthread_sigmask(SIG_BLOCK, &sigSet, NULL);
+
+	BEGIN_MTX_PROTECTED_OPERATIONS(&pThis->mut, LOCK_MUTEX);
+
+	/* do some late initialization */
+
+	pthread_cleanup_push(wtpWrkrExecCancelCleanup, pThis);
+
+	// TODO: review code below - if still needed (setState yes!)? 
+	/* finally change to RUNNING state. We need to check if we actually should still run,
+	 * because someone may have requested us to shut down even before we got a chance to do
+	 * our init. That would be a bad race... -- rgerhards, 2008-01-16
+	 */
+	//if(qWrkrGetState(pWrkrInst) == eWRKTHRD_RUN_INIT)
+		wtiSetState(pWti, eWRKTHRD_RUNNING, MUTEX_ALREADY_LOCKED); /* we are running now! */
+
+	do {
+		END_MTX_PROTECTED_OPERATIONS(&pThis->mut);
+
+		iRet = wtiWorker(pWti); /* just to make sure: this is NOT protected by the mutex! */
+
+		BEGIN_MTX_PROTECTED_OPERATIONS(&pThis->mut, LOCK_MUTEX);
+	} while(pThis->iCurNumWrkThrd == 1 && pThis->bInactivityGuard == 1);
+	/* inactivity guard prevents shutdown of all workers while one should be running due to race
+	 * condition. It can lead to one more worker running than desired, but that is acceptable. After
+	 * all, that worker will shutdown itself due to inactivity timeout. If, however, none were running
+	 * when one was required, processing could come to a halt. -- rgerhards, 2008-01-21
+	 */
+
+	pthread_cleanup_pop(0);
+	pThis->iCurNumWrkThrd--;
+
+	dbgprintf("%s: Worker thread %lx, terminated, num workers now %d\n",
+		  wtpGetDbgHdr(pThis), (unsigned long) pWti, pThis->iCurNumWrkThrd);
+
+	END_MTX_PROTECTED_OPERATIONS(&pThis->mut);
+
+	pthread_exit(0);
+}
+
+
+/* start a new worker */
+static rsRetVal
+wtpStartWrkr(wtp_t *pThis, int bLockMutex)
+{
+	DEFiRet;
+	DEFVARS_mutexProtection;
+	wti_t *pWti;
+	int i;
+	int iState;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	wtpProcessThrdChanges(pThis);
+
+	BEGIN_MTX_PROTECTED_OPERATIONS(&pThis->mut, bLockMutex);
+
+	pThis->iCurNumWrkThrd++;
+
+	/* find free spot in thread table. If we find at least one worker that is in initialization,
+	 * we do NOT start a new one. Let's give the other one a chance, first.
+	 */
+	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
+		// TODO: sync!
+		if(pThis->pWrkr[i]->tCurrCmd == eWRKTHRD_STOPPED) {
+			break;
+		}
+	}
+
+dbgprintf("%s: after thrd search: i %d, max %d\n", wtpGetDbgHdr(pThis), i, pThis->iNumWorkerThreads);
+	if(i == pThis->iNumWorkerThreads)
+		ABORT_FINALIZE(RS_RET_NO_MORE_THREADS);
+
+	pWti = pThis->pWrkr[i];
+	wtiSetState(pWti, eWRKTHRD_RUN_CREATED, LOCK_MUTEX); // TODO: thuink about mutex lock
+	iState = pthread_create(&(pWti->thrdID), NULL, wtpWorker, (void*) pWti);
+	dbgprintf("%s: started with state %d, num workers now %d\n",
+		  wtpGetDbgHdr(pThis), iState, pThis->iCurNumWrkThrd);
+
+	/* we try to give the starting worker a little boost. It won't help much as we still
+ 	 * hold the queue's mutex, but at least it has a chance to start on a single-CPU system.
+ 	 */
+	pthread_yield();
+
+	/* indicate we just started a worker and would like to see it running */
+	wtpSetInactivityGuard(pThis, 1, MUTEX_ALREADY_LOCKED);
+
+finalize_it:
+	END_MTX_PROTECTED_OPERATIONS(&pThis->mut);
+	RETiRet;
+}
+
+
+/* set the number of worker threads that should be running. If less than currently running,
+ * a new worker may be started. Please note that there is no guarantee the number of workers
+ * said will be running after we exit this function. It is just a hint. If the number is
+ * higher than one, the "busy" condition is also signaled to awake a worker.
+ * rgerhards, 2008-01-21
+ */
+rsRetVal
+wtpAdviseMaxWorkers(wtp_t *pThis, int nMaxWrkr)
+{
+	DEFiRet;
+	DEFVARS_mutexProtection;
+	int nMissing; /* number workers missing to run */
+	int i;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	if(nMaxWrkr == 0)
+		FINALIZE;
+
+	BEGIN_MTX_PROTECTED_OPERATIONS(&pThis->mut, LOCK_MUTEX);
+
+	nMissing = nMaxWrkr - pThis->iCurNumWrkThrd;
+	if(nMissing > pThis->iNumWorkerThreads)
+		nMissing = pThis->iNumWorkerThreads;
+	else if(nMissing < 0)
+		nMissing = 0;
+
+	dbgprintf("%s: high activity - starting %d additional worker thread(s).\n", wtpGetDbgHdr(pThis), nMissing);
+	/* start the rqtd nbr of workers */
+	for(i = 0 ; i < nMissing ; ++i) {
+		CHKiRet(wtpStartWrkr(pThis, MUTEX_ALREADY_LOCKED));
+	}
+	
+	END_MTX_PROTECTED_OPERATIONS(&pThis->mut);
+
+finalize_it:
+	RETiRet;
+}
+
+
+/* some simple object access methods */
+DEFpropSetMeth(wtp, toWrkShutdown, long);
+DEFpropSetMeth(wtp, wtpState, wtpState_t);
+
+
+/* set the debug header message
+ * The passed-in string is duplicated. So if the caller does not need
+ * it any longer, it must free it. Must be called only before object is finalized.
+ * rgerhards, 2008-01-09
+ */
+rsRetVal
+wtpSetDbgHdr(wti_t *pThis, uchar *pszMsg, size_t lenMsg)
+{
+	DEFiRet;
+
+	ISOBJ_TYPE_assert(pThis, wti);
+	assert(pszMsg != NULL);
+	
+	if(lenMsg < 1)
+		ABORT_FINALIZE(RS_RET_PARAM_ERROR);
+
+	if(pThis->pszDbgHdr != NULL) {
+		free(pThis->pszDbgHdr);
+		pThis->pszDbgHdr = NULL;
+	}
+
+	if((pThis->pszDbgHdr = malloc(sizeof(uchar) * lenMsg + 1)) == NULL)
+		ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
+
+	memcpy(pThis->pszDbgHdr, pszMsg, lenMsg + 1); /* always think about the \0! */
+
+finalize_it:
+	RETiRet;
+}
+
+/* Initialize the stream class. Must be called as the very first method
+ * before anything else is called inside this class.
+ * rgerhards, 2008-01-09
+ */
+BEGINObjClassInit(wtp, 1)
+ENDObjClassInit(wtp)
+
+/*
+ * vi:set ai:
+ */
diff --git a/wtp.h b/wtp.h
new file mode 100644
index 00000000..45fa2b8d
--- /dev/null
+++ b/wtp.h
@@ -0,0 +1,97 @@
+/* Definition of the worker thread pool (wtp) object.
+ *
+ * Copyright 2008 Rainer Gerhards and Adiscon GmbH.
+ *
+ * This file is part of rsyslog.
+ *
+ * Rsyslog is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Rsyslog 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Rsyslog.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * A copy of the GPL can be found in the file "COPYING" in this distribution.
+ */
+
+#ifndef WTP_H_INCLUDED
+#define WTP_H_INCLUDED
+
+#include <pthread.h>
+#include "obj.h"
+
+/* commands and states for worker threads. */
+typedef enum {
+	eWRKTHRD_STOPPED = 0,	/* worker thread is not running (either actually never ran or was shut down) */
+	eWRKTHRD_TERMINATING = 1,/* worker thread has shut down, but some finalzing is still needed */
+	/* ALL active states MUST be numerically higher than eWRKTHRD_TERMINATED and NONE must be lower! */
+	eWRKTHRD_RUN_CREATED = 2,/* worker thread has been created, but not yet begun initialization (prob. not yet scheduled) */
+	eWRKTHRD_RUN_INIT = 3,	/* worker thread is initializing, but not yet fully running */
+	eWRKTHRD_RUNNING = 4,	/* worker thread is up and running and shall continue to do so */
+	eWRKTHRD_SHUTDOWN = 5,	/* worker thread is running but shall terminate when wtp is empty */
+	eWRKTHRD_SHUTDOWN_IMMEDIATE = 6/* worker thread is running but shall terminate even if wtp is full */
+	/* SHUTDOWN_IMMEDIATE MUST alsways be the numerically highest state! */
+} qWrkCmd_t;
+
+
+/* possible states of a worker thread pool */
+typedef enum {
+	wtpState_RUNNING = 0,		/* runs in regular mode */
+	wtpState_SHUTDOWN = 1,		/* worker threads shall shutdown when idle */
+	wtpState_SHUTDOWN_IMMEDIATE = 2	/* worker threads shall shutdown ASAP, even if not idle */
+} wtpState_t;
+
+
+/* the worker thread pool (wtp) object */
+typedef struct wtp_s {
+	BEGINobjInstance;
+	wtpState_t wtpState;
+	int 	iNumWorkerThreads;/* number of worker threads to use */
+	int 	iCurNumWrkThrd;/* current number of active worker threads */
+	struct wti_s **pWrkr;/* array with control structure for the worker thread(s) associated with this wtp */
+	int	toWrkShutdown;	/* timeout for idle workers in ms, -1 means indefinite (0 is immediate) */
+	int	bInactivityGuard;/* prevents inactivity due to race condition */
+	rsRetVal (*pConsumer)(void *); /* user-supplied consumer function for dewtpd messages */
+	/* synchronization variables */
+	pthread_mutex_t mut; /* mutex for the wtp's thread management */
+	pthread_cond_t condThrdTrm;/* signalled when threads terminate */
+	int bThrdStateChanged;	/* at least one thread state has changed if 1 */
+	/* end sync variables */
+	/* user objects */
+	void *pUsr;		/* pointer to user object */
+	pthread_mutex_t *pmutUsr;
+	pthread_cond_t *pcondBusy; /* condition the user will signal "busy again, keep runing" on (awakes worker) */
+	rsRetVal (*pfChkStopWrkr)(void *, int);
+	rsRetVal (*pfIsIdle)(void *, int);
+	rsRetVal (*pfDoWork)(void *, int);
+	rsRetVal (*pfOnShutdownAdvise)(void *, int);
+	rsRetVal (*pfOnIdle)(void *, int);
+	rsRetVal (*pfOnWorkerCancel)(void *);
+	/* end user objects */
+	uchar *pszDbgHdr;	/* header string for debug messages */
+} wtp_t;
+
+/* some symbolic constants for easier reference */
+
+
+/* prototypes */
+rsRetVal wtpConstruct(wtp_t **ppThis);
+rsRetVal wtpConstructFinalize(wtp_t *pThis);
+rsRetVal wtpDestruct(wtp_t **ppThis);
+rsRetVal wtpAdviseMaxWorkers(wtp_t *pThis, int nMaxWrkr);
+rsRetVal wtpProcessThrdChanges(wtp_t *pThis);
+rsRetVal wtpSetInactivityGuard(wtp_t *pThis, int bNewState, int bLockMutex);
+rsRetVal wtpChkStopWrkr(wtp_t *pThis, int bLockMutex, int bLockUsrMutex);
+rsRetVal wtpSetState(wtp_t *pThis, wtpState_t iNewState);
+PROTOTYPEObjClassInit(wtp);
+PROTOTYPEpropSetMeth(wtp, toWrkShutdown, long);
+PROTOTYPEpropSetMeth(wtp, wtpState, wtpState_t);
+#define wtpGetID(pThis) ((unsigned long) pThis)
+
+#endif /* #ifndef WTP_H_INCLUDED */