1 files changed, 650 insertions, 0 deletions
diff --git a/runtime/wtp.c b/runtime/wtp.c
new file mode 100644
index 0000000..3bce02a
--- /dev/null
+++ b/runtime/wtp.c
@@ -0,0 +1,650 @@
+/* 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 https://www.rsyslog.com/doc/). Be sure to read it
+ * if you are getting aquainted to the object.
+ *
+ * Copyright 2008-2018 Rainer Gerhards and Adiscon GmbH.
+ *
+ * This file is part of the rsyslog runtime library.
+ *
+ * The rsyslog runtime library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * The rsyslog runtime 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with the rsyslog runtime library.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * A copy of the GPL can be found in the file "COPYING" in this distribution.
+ * A copy of the LGPL can be found in the file "COPYING.LESSER" 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 <atomic.h>
+#ifdef HAVE_SYS_PRCTL_H
+#  include <sys/prctl.h>
+#endif
+
+/// TODO: check on solaris if this is any longer needed - I don't think so - rgerhards, 2009-09-20
+//#ifdef OS_SOLARIS
+//#	include <sched.h>
+//#endif
+
+#include "rsyslog.h"
+#include "stringbuf.h"
+#include "srUtils.h"
+#include "wtp.h"
+#include "wti.h"
+#include "obj.h"
+#include "unicode-helper.h"
+#include "glbl.h"
+#include "errmsg.h"
+
+/* static data */
+DEFobjStaticHelpers
+DEFobjCurrIf(glbl)
+
+/* forward-definitions */
+
+/* methods */
+
+/* get the header for debug messages
+ * The caller must NOT free or otherwise modify the returned string!
+ */
+static 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_voidp_int(__attribute__((unused)) void* p1, __attribute__((unused)) int p2) {
+	return RS_RET_NOT_IMPLEMENTED; }
+static rsRetVal NotImplementedDummy_voidp_intp(__attribute__((unused)) void* p1, __attribute__((unused)) int* p2) {
+	return RS_RET_NOT_IMPLEMENTED; }
+static rsRetVal NotImplementedDummy_voidp_voidp(__attribute__((unused)) void* p1, __attribute__((unused)) void* p2) {
+	return RS_RET_NOT_IMPLEMENTED; }
+static rsRetVal NotImplementedDummy_voidp_wti_tp(__attribute__((unused)) void* p1, __attribute__((unused)) wti_t* p2) {
+	return RS_RET_NOT_IMPLEMENTED; }
+/* Standard-Constructor for the wtp object
+ */
+BEGINobjConstruct(wtp) /* be sure to specify the object type also in END macro! */
+	pthread_mutex_init(&pThis->mutWtp, NULL);
+	pthread_cond_init(&pThis->condThrdInitDone, NULL);
+	pthread_cond_init(&pThis->condThrdTrm, NULL);
+	pthread_attr_init(&pThis->attrThrd);
+	/* Set thread scheduling policy to default */
+#ifdef HAVE_PTHREAD_SETSCHEDPARAM
+	pthread_attr_setschedpolicy(&pThis->attrThrd, default_thr_sched_policy);
+	pthread_attr_setschedparam(&pThis->attrThrd, &default_sched_param);
+	pthread_attr_setinheritsched(&pThis->attrThrd, PTHREAD_EXPLICIT_SCHED);
+#endif
+	/* set all function pointers to "not implemented" dummy so that we can safely call them */
+	pThis->pfChkStopWrkr = (rsRetVal (*)(void*,int))NotImplementedDummy_voidp_int;
+	pThis->pfGetDeqBatchSize = (rsRetVal (*)(void*,int*))NotImplementedDummy_voidp_intp;
+	pThis->pfDoWork = (rsRetVal (*)(void*,void*))NotImplementedDummy_voidp_voidp;
+	pThis->pfObjProcessed = (rsRetVal (*)(void*,wti_t*))NotImplementedDummy_voidp_wti_tp;
+	INIT_ATOMIC_HELPER_MUT(pThis->mutCurNumWrkThrd);
+	INIT_ATOMIC_HELPER_MUT(pThis->mutWtpState);
+ENDobjConstruct(wtp)
+
+
+/* Construction finalizer
+ * rgerhards, 2008-01-17
+ */
+rsRetVal
+wtpConstructFinalize(wtp_t *pThis)
+{
+	DEFiRet;
+	int i;
+	uchar pszBuf[64];
+	size_t lenBuf;
+	wti_t *pWti;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	DBGPRINTF("%s: finalizing construction of worker thread pool (numworkerThreads %d)\n",
+		  wtpGetDbgHdr(pThis), pThis->iNumWorkerThreads);
+	/* alloc and construct workers - this can only be done in finalizer as we previously do
+	 * not know the max number of workers
+	 */
+	CHKmalloc(pThis->pWrkr = malloc(sizeof(wti_t*) * pThis->iNumWorkerThreads));
+	
+	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",
+			(int) (sizeof(pszBuf)-6), /* leave 6 chars for \0, "/w" and number: */
+			wtpGetDbgHdr(pThis), i);
+		if(lenBuf >= sizeof(pszBuf)) {
+			LogError(0, RS_RET_INTERNAL_ERROR, "%s:%d debug header too long: %zd - in "
+					"thory this cannot happen - truncating", __FILE__, __LINE__, lenBuf);
+			lenBuf = sizeof(pszBuf)-1;
+			pszBuf[lenBuf] = '\0';
+		}
+		CHKiRet(wtiSetDbgHdr(pWti, pszBuf, lenBuf));
+		CHKiRet(wtiSetpWtp(pWti, pThis));
+		CHKiRet(wtiConstructFinalize(pWti));
+	}
+
+
+finalize_it:
+	RETiRet;
+}
+
+
+/* Destructor */
+BEGINobjDestruct(wtp) /* be sure to specify the object type also in END and CODESTART macros! */
+	int i;
+CODESTARTobjDestruct(wtp)
+	d_pthread_mutex_lock(&pThis->mutWtp); /* make sure nobody is still using the mutex */
+	assert(pThis->iCurNumWrkThrd == 0);
+
+	/* destruct workers */
+	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i)
+		wtiDestruct(&pThis->pWrkr[i]);
+
+	free(pThis->pWrkr);
+	pThis->pWrkr = NULL;
+
+	/* actual destruction */
+	d_pthread_mutex_unlock(&pThis->mutWtp);
+	pthread_cond_destroy(&pThis->condThrdTrm);
+	pthread_cond_destroy(&pThis->condThrdInitDone);
+	pthread_mutex_destroy(&pThis->mutWtp);
+	pthread_attr_destroy(&pThis->attrThrd);
+	DESTROY_ATOMIC_HELPER_MUT(pThis->mutCurNumWrkThrd);
+	DESTROY_ATOMIC_HELPER_MUT(pThis->mutWtpState);
+
+	free(pThis->pszDbgHdr);
+ENDobjDestruct(wtp)
+
+
+/* Sent a specific state for the worker thread pool. -- rgerhards, 2008-01-21
+ * We do not need to do atomic instructions as set operations are only
+ * called when terminating the pool, and then in strict sequence. So we
+ * can never overwrite each other. On the other hand, it also doesn't
+ * matter if the read operation obtains an older value, as we then simply
+ * do one more iteration, what is perfectly legal (during shutdown
+ * they are awoken in any case). -- rgerhards, 2009-07-20
+ */
+rsRetVal
+wtpSetState(wtp_t *pThis, wtpState_t iNewState)
+{
+	ISOBJ_TYPE_assert(pThis, wtp);
+	pThis->wtpState = iNewState; // TODO: do we need a mutex here? 2010-04-26
+	return RS_RET_OK;
+}
+
+/* join terminated worker threads */
+static void ATTR_NONNULL()
+wtpJoinTerminatedWrkr(wtp_t *const pThis)
+{
+	int i;
+	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
+		wtiJoinThrd(pThis->pWrkr[i]);
+	}
+}
+
+
+/* check if the worker shall shutdown (1 = yes, 0 = no)
+ * 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 bLockUsrMutex)
+{
+	DEFiRet;
+	wtpState_t wtpState;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+	/* we need a consistent value, but it doesn't really matter if it is changed
+	 * right after the fetch - then we simply do one more iteration in the worker
+	 */
+	wtpState = (wtpState_t) ATOMIC_FETCH_32BIT((int*)&pThis->wtpState, &pThis->mutWtpState);
+
+	if(wtpState == wtpState_SHUTDOWN_IMMEDIATE) {
+		ABORT_FINALIZE(RS_RET_TERMINATE_NOW);
+	} else if(wtpState == wtpState_SHUTDOWN) {
+		ABORT_FINALIZE(RS_RET_TERMINATE_WHEN_IDLE);
+	}
+
+	/* try customer handler if one was set and we do not yet have a definite result */
+	if(pThis->pfChkStopWrkr != NULL) {
+		iRet = pThis->pfChkStopWrkr(pThis->pUsr, bLockUsrMutex);
+	}
+
+finalize_it:
+	RETiRet;
+}
+
+
+PRAGMA_DIAGNOSTIC_PUSH
+PRAGMA_IGNORE_Wempty_body
+/* Send a shutdown command to all workers and see if they terminate.
+ * A timeout may be specified. This function may also be called with
+ * the current number of workers being 0, in which case it does not
+ * shut down any worker.
+ * rgerhards, 2008-01-14
+ */
+rsRetVal ATTR_NONNULL()
+wtpShutdownAll(wtp_t *pThis, wtpState_t tShutdownCmd, struct timespec *ptTimeout)
+{
+	DEFiRet;
+	int bTimedOut;
+	int i;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	/* lock mutex to prevent races (may otherwise happen during idle processing and such...) */
+	d_pthread_mutex_lock(pThis->pmutUsr);
+	wtpSetState(pThis, tShutdownCmd);
+	/* awake workers in retry loop */
+	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
+		wtpJoinTerminatedWrkr(pThis);
+		pthread_cond_signal(&pThis->pWrkr[i]->pcondBusy);
+		wtiWakeupThrd(pThis->pWrkr[i]);
+	}
+	d_pthread_mutex_unlock(pThis->pmutUsr);
+
+	/* wait for worker thread termination */
+	d_pthread_mutex_lock(&pThis->mutWtp);
+	pthread_cleanup_push(mutexCancelCleanup, &pThis->mutWtp);
+	bTimedOut = 0;
+	while(pThis->iCurNumWrkThrd > 0 && !bTimedOut) {
+		wtpJoinTerminatedWrkr(pThis);
+		DBGPRINTF("%s: waiting %ldms on worker thread termination, %d still running\n",
+			   wtpGetDbgHdr(pThis), timeoutVal(ptTimeout),
+			   ATOMIC_FETCH_32BIT(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd));
+
+		if(d_pthread_cond_timedwait(&pThis->condThrdTrm, &pThis->mutWtp, ptTimeout) != 0) {
+			DBGPRINTF("%s: timeout waiting on worker thread termination\n",
+				wtpGetDbgHdr(pThis));
+			bTimedOut = 1;	/* we exit the loop on timeout */
+		}
+
+		/* awake workers in retry loop */
+		for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
+			wtiWakeupThrd(pThis->pWrkr[i]);
+		}
+
+	}
+	pthread_cleanup_pop(1);
+
+	if(bTimedOut)
+		iRet = RS_RET_TIMED_OUT;
+	
+	RETiRet;
+}
+PRAGMA_DIAGNOSTIC_POP
+
+
+/* Unconditionally cancel all running worker threads.
+ * rgerhards, 2008-01-14
+ */
+rsRetVal ATTR_NONNULL()
+wtpCancelAll(wtp_t *pThis, const uchar *const cancelobj)
+{
+	DEFiRet;
+	int i;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	/* go through all workers and cancel those that are active */
+	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
+		wtiCancelThrd(pThis->pWrkr[i], cancelobj);
+	}
+
+	RETiRet;
+}
+
+
+/* this function contains shared code for both regular worker shutdown as
+ * well as shutdown via cancellation. We can not simply use pthread_cleanup_pop(1)
+ * as this introduces a race in the debug system (RETiRet system).
+ * rgerhards, 2009-10-26
+ */
+static void
+wtpWrkrExecCleanup(wti_t *pWti)
+{
+	wtp_t *pThis;
+
+	ISOBJ_TYPE_assert(pWti, wti);
+	pThis = pWti->pWtp;
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+// TESTBENCH bughunt - remove when done! 2018-11-05 rgerhards
+if(dbgTimeoutToStderr) {
+	fprintf(stderr, "rsyslog debug: %s: enter WrkrExecCleanup\n", wtiGetDbgHdr(pWti));
+}
+	/* the order of the next two statements is important! */
+	wtiSetState(pWti, WRKTHRD_WAIT_JOIN);
+	ATOMIC_DEC(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd);
+
+	/* note: numWorkersNow is only for message generation, so we do not try
+	 * hard to get it 100% accurate (as curently done, it is not).
+	 */
+	const int numWorkersNow = ATOMIC_FETCH_32BIT(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd);
+	DBGPRINTF("%s: Worker thread %lx, terminated, num workers now %d\n",
+		wtpGetDbgHdr(pThis), (unsigned long) pWti, numWorkersNow);
+	if(numWorkersNow > 0) {
+		LogMsg(0, RS_RET_OPERATION_STATUS, LOG_INFO,
+			"%s: worker thread %lx terminated, now %d active worker threads",
+			wtpGetDbgHdr(pThis), (unsigned long) pWti, numWorkersNow);
+	}
+}
+
+
+/* cancellation cleanup handler for executing worker decrements the worker counter.
+ * rgerhards, 2009-07-20
+ */
+static void
+wtpWrkrExecCancelCleanup(void *arg)
+{
+	wti_t *pWti = (wti_t*) arg;
+	wtp_t *pThis;
+
+	ISOBJ_TYPE_assert(pWti, wti);
+	pThis = pWti->pWtp;
+	ISOBJ_TYPE_assert(pThis, wtp);
+	DBGPRINTF("%s: Worker thread %lx requested to be cancelled.\n",
+		  wtpGetDbgHdr(pThis), (unsigned long) pWti);
+
+	wtpWrkrExecCleanup(pWti);
+
+	pthread_cond_broadcast(&pThis->condThrdTrm); /* activate anyone waiting on thread shutdown */
+}
+
+
+/* wtp worker shell. This is started and calls into the actual
+ * wti worker.
+ * rgerhards, 2008-01-21
+ */
+PRAGMA_DIAGNOSTIC_PUSH
+PRAGMA_IGNORE_Wempty_body
+static void *
+wtpWorker(void *arg) /* the arg is actually a wti object, even though we are in wtp! */
+{
+	wti_t *pWti = (wti_t*) arg;
+	wtp_t *pThis;
+	sigset_t sigSet;
+#	if defined(HAVE_PRCTL) && defined(PR_SET_NAME)
+	uchar *pszDbgHdr;
+	uchar thrdName[32] = "rs:";
+#	endif
+
+	ISOBJ_TYPE_assert(pWti, wti);
+	pThis = pWti->pWtp;
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	/* block all signals except SIGTTIN and SIGSEGV */
+	sigfillset(&sigSet);
+	sigdelset(&sigSet, SIGTTIN);
+	sigdelset(&sigSet, SIGSEGV);
+	pthread_sigmask(SIG_BLOCK, &sigSet, NULL);
+
+#	if defined(HAVE_PRCTL) && defined(PR_SET_NAME)
+	/* set thread name - we ignore if the call fails, has no harsh consequences... */
+	pszDbgHdr = wtpGetDbgHdr(pThis);
+	ustrncpy(thrdName+3, pszDbgHdr, 20);
+	if(prctl(PR_SET_NAME, thrdName, 0, 0, 0) != 0) {
+		DBGPRINTF("prctl failed, not setting thread name for '%s'\n", wtpGetDbgHdr(pThis));
+	}
+	dbgOutputTID((char*)thrdName);
+#	endif
+
+// TESTBENCH bughunt - remove when done! 2018-11-05 rgerhards
+if(dbgTimeoutToStderr) {
+	fprintf(stderr, "rsyslog debug: %s: worker %p started\n", wtpGetDbgHdr(pThis), pThis);
+}
+	/* let the parent know we're done with initialization */
+	d_pthread_mutex_lock(&pThis->mutWtp);
+	wtiSetState(pWti, WRKTHRD_RUNNING);
+	pthread_cond_broadcast(&pThis->condThrdInitDone);
+	d_pthread_mutex_unlock(&pThis->mutWtp);
+
+	pthread_cleanup_push(wtpWrkrExecCancelCleanup, pWti);
+
+	wtiWorker(pWti);
+	pthread_cleanup_pop(0);
+	d_pthread_mutex_lock(&pThis->mutWtp);
+	pthread_cleanup_push(mutexCancelCleanup, &pThis->mutWtp);
+	wtpWrkrExecCleanup(pWti);
+
+	pthread_cond_broadcast(&pThis->condThrdTrm); /* activate anyone waiting on thread shutdown */
+	pthread_cleanup_pop(1); /* unlock mutex */
+	if(dbgTimeoutToStderr) {
+		fprintf(stderr, "rsyslog debug: %p: worker exiting\n", pWti);
+	}
+	pthread_exit(0);
+	return NULL; /* To suppress warning */
+}
+PRAGMA_DIAGNOSTIC_POP
+
+/* start a new worker */
+static rsRetVal ATTR_NONNULL()
+wtpStartWrkr(wtp_t *const pThis, const int permit_during_shutdown)
+{
+	wti_t *pWti;
+	int i;
+	int iState;
+	DEFiRet;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+// TESTBENCH bughunt - remove when done! 2018-11-05 rgerhards
+if(dbgTimeoutToStderr) {
+	fprintf(stderr, "%s: worker start requested, num workers currently %d\n",
+		wtpGetDbgHdr(pThis),
+		ATOMIC_FETCH_32BIT(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd));
+}
+	const wtpState_t wtpState = (wtpState_t) ATOMIC_FETCH_32BIT((int*)&pThis->wtpState, &pThis->mutWtpState);
+	if(wtpState != wtpState_RUNNING && !permit_during_shutdown) {
+		DBGPRINTF("%s: worker start requested during shutdown - ignored\n", wtpGetDbgHdr(pThis));
+		if(dbgTimeoutToStderr) {
+			fprintf(stderr, "rsyslog debug: %s: worker start requested during shutdown - ignored\n",
+				wtpGetDbgHdr(pThis));
+		}
+		return RS_RET_ERR; /* exceptional case, but really makes sense here! */
+	}
+
+	d_pthread_mutex_lock(&pThis->mutWtp);
+
+	wtpJoinTerminatedWrkr(pThis);
+	/* find free spot in thread table. */
+	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
+		if(wtiGetState(pThis->pWrkr[i]) == WRKTHRD_STOPPED) {
+			break;
+		}
+	}
+
+	if(i == pThis->iNumWorkerThreads)
+		ABORT_FINALIZE(RS_RET_NO_MORE_THREADS);
+
+	if(i == 0 || pThis->toWrkShutdown == -1) {
+		wtiSetAlwaysRunning(pThis->pWrkr[i]);
+	}
+
+	pWti = pThis->pWrkr[i];
+	wtiSetState(pWti, WRKTHRD_INITIALIZING);
+	iState = pthread_create(&(pWti->thrdID), &pThis->attrThrd, wtpWorker, (void*) pWti);
+	ATOMIC_INC(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd); /* we got one more! */
+
+// TESTBENCH bughunt - remove when done! 2018-11-05 rgerhards
+if(dbgTimeoutToStderr) {
+	fprintf(stderr, "%s: wrkr start initiated with state %d, num workers now %d\n",
+		wtpGetDbgHdr(pThis), iState,
+		ATOMIC_FETCH_32BIT(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd));
+}
+	DBGPRINTF("%s: started with state %d, num workers now %d\n",
+		wtpGetDbgHdr(pThis), iState,
+		ATOMIC_FETCH_32BIT(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd));
+
+	/* wait for the new thread to initialize its signal mask and
+	 * cancellation cleanup handler before proceeding
+	 */
+	do {
+		d_pthread_cond_wait(&pThis->condThrdInitDone, &pThis->mutWtp);
+	} while((iState = wtiGetState(pWti)) == WRKTHRD_INITIALIZING);
+	DBGPRINTF("%s: new worker finished initialization with state %d, num workers now %d\n",
+		wtpGetDbgHdr(pThis), iState,
+		ATOMIC_FETCH_32BIT(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd));
+// TESTBENCH bughunt - remove when done! 2018-11-05 rgerhards
+if(dbgTimeoutToStderr) {
+	fprintf(stderr, "rsyslog debug: %s: started with state %d, num workers now %d\n",
+		wtpGetDbgHdr(pThis), iState,
+		ATOMIC_FETCH_32BIT(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd));
+}
+
+finalize_it:
+	d_pthread_mutex_unlock(&pThis->mutWtp);
+	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, and no worker is started, the "busy" condition is signaled to awake a worker.
+ * So the caller can assume that there is at least one worker re-checking if there is "work to do"
+ * after this function call.
+ * Parameter "permit_during_shutdown" if true, permits worker starts while the system is
+ * in shutdown state. The prime use case for this is persisting disk queues in enqueue only
+ * mode, which is activated during shutdown.
+ */
+rsRetVal ATTR_NONNULL()
+wtpAdviseMaxWorkers(wtp_t *const pThis, int nMaxWrkr, const int permit_during_shutdown)
+{
+	DEFiRet;
+	int nMissing; /* number workers missing to run */
+	int i, nRunning;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+
+	if(nMaxWrkr == 0)
+		FINALIZE;
+
+	if(nMaxWrkr > pThis->iNumWorkerThreads) /* limit to configured maximum */
+		nMaxWrkr = pThis->iNumWorkerThreads;
+
+	nMissing = nMaxWrkr - ATOMIC_FETCH_32BIT(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd);
+
+	if(nMissing > 0) {
+		if(ATOMIC_FETCH_32BIT(&pThis->iCurNumWrkThrd, &pThis->mutCurNumWrkThrd) > 0) {
+			LogMsg(0, RS_RET_OPERATION_STATUS, LOG_INFO,
+				"%s: high activity - starting %d additional worker thread(s), "
+				"currently %d active worker threads.",
+				wtpGetDbgHdr(pThis), nMissing,
+				ATOMIC_FETCH_32BIT(&pThis->iCurNumWrkThrd,
+					&pThis->mutCurNumWrkThrd) );
+		}
+		/* start the rqtd nbr of workers */
+		for(i = 0 ; i < nMissing ; ++i) {
+			CHKiRet(wtpStartWrkr(pThis, permit_during_shutdown));
+		}
+	} else {
+		/* we have needed number of workers, but they may be sleeping */
+		for(i = 0, nRunning = 0; i < pThis->iNumWorkerThreads && nRunning < nMaxWrkr; ++i) {
+			if (wtiGetState(pThis->pWrkr[i]) != WRKTHRD_STOPPED) {
+				pthread_cond_signal(&pThis->pWrkr[i]->pcondBusy);
+				nRunning++;
+			}
+		}
+	}
+
+	
+finalize_it:
+	RETiRet;
+}
+
+
+/* some simple object access methods */
+DEFpropSetMeth(wtp, toWrkShutdown, long)
+DEFpropSetMeth(wtp, wtpState, wtpState_t)
+DEFpropSetMeth(wtp, iNumWorkerThreads, int)
+DEFpropSetMeth(wtp, pUsr, void*)
+DEFpropSetMethPTR(wtp, pmutUsr, pthread_mutex_t)
+DEFpropSetMethFP(wtp, pfChkStopWrkr, rsRetVal(*pVal)(void*, int))
+DEFpropSetMethFP(wtp, pfRateLimiter, rsRetVal(*pVal)(void*))
+DEFpropSetMethFP(wtp, pfGetDeqBatchSize, rsRetVal(*pVal)(void*, int*))
+DEFpropSetMethFP(wtp, pfDoWork, rsRetVal(*pVal)(void*, void*))
+DEFpropSetMethFP(wtp, pfObjProcessed, rsRetVal(*pVal)(void*, wti_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(wtp_t *pThis, uchar *pszMsg, size_t lenMsg)
+{
+	DEFiRet;
+
+	ISOBJ_TYPE_assert(pThis, wtp);
+	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(lenMsg + 1)) == NULL)
+		ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
+
+	memcpy(pThis->pszDbgHdr, pszMsg, lenMsg + 1); /* always think about the \0! */
+
+finalize_it:
+	RETiRet;
+}
+
+/* dummy */
+static rsRetVal wtpQueryInterface(interface_t __attribute__((unused)) *i) { return RS_RET_NOT_IMPLEMENTED; }
+
+/* exit our class
+ */
+BEGINObjClassExit(wtp, OBJ_IS_CORE_MODULE) /* CHANGE class also in END MACRO! */
+CODESTARTObjClassExit(nsdsel_gtls)
+	/* release objects we no longer need */
+	objRelease(glbl, CORE_COMPONENT);
+ENDObjClassExit(wtp)
+
+
+/* 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, OBJ_IS_CORE_MODULE)
+	/* request objects we use */
+	CHKiRet(objUse(glbl, CORE_COMPONENT));
+ENDObjClassInit(wtp)