improved statistics-gathering subsystem

... well, actually this is a first real implementation of this subsystem.
I have added a counter registry, a way to access the countres (as readable
string) and a way to define and maintem them. Also, module impstats has
been updated to utilize the new system. Finally, I added some counters. I
hope that this sets the baseline for useful future enhancements.

7 files changed, 486 insertions, 2 deletions

diff --git a/runtime/Makefile.am b/runtime/Makefile.am
index 5b2598b2..01b224e7 100644
--- a/runtime/Makefile.am
+++ b/runtime/Makefile.am
@@ -45,6 +45,8 @@ librsyslog_la_SOURCES = \
 	modules.h \
 	apc.c \
 	apc.h \
+	statsobj.c \
+	statsobj.h \
 	sync.c \
 	sync.h \
 	expr.c \
@@ -81,8 +83,8 @@ librsyslog_la_SOURCES = \
 	prop.h \
 	cfsysline.c \
 	cfsysline.h \
-       sd-daemon.c \
-       sd-daemon.h \
+	sd-daemon.c \
+	sd-daemon.h \
 	\
 	\
 	../action.h \
diff --git a/runtime/queue.c b/runtime/queue.c
index 60d17086..387c15c2 100644
--- a/runtime/queue.c
+++ b/runtime/queue.c
@@ -58,6 +58,7 @@
 #include "errmsg.h"
 #include "datetime.h"
 #include "unicode-helper.h"
+#include "statsobj.h"
 #include "msg.h" /* TODO: remove once we remove MsgAddRef() call */
 
 #ifdef OS_SOLARIS
@@ -70,6 +71,7 @@ DEFobjCurrIf(glbl)
 DEFobjCurrIf(strm)
 DEFobjCurrIf(errmsg)
 DEFobjCurrIf(datetime)
+DEFobjCurrIf(statsobj)
 
 /* forward-definitions */
 static inline rsRetVal doEnqSingleObj(qqueue_t *pThis, flowControl_t flowCtlType, void *pUsr);
@@ -1817,6 +1819,7 @@ qqueueStart(qqueue_t *pThis) /* this is the ConstructionFinalizer */
 {
 	DEFiRet;
 	uchar pszBuf[64];
+	uchar *qName;
 	size_t lenBuf;
 
 	ASSERT(pThis != NULL);
@@ -1886,6 +1889,27 @@ qqueueStart(qqueue_t *pThis) /* this is the ConstructionFinalizer */
 	qqueueAdviseMaxWorkers(pThis);
 	pThis->bQueueStarted = 1;
 
+	/* support statistics gathering */
+	qName = obj.GetName((obj_t*)pThis);
+	CHKiRet(statsobj.Construct(&pThis->statsobj));
+	CHKiRet(statsobj.SetName(pThis->statsobj, qName));
+	CHKiRet(statsobj.AddCounter(pThis->statsobj, UCHAR_CONSTANT("size"),
+		ctrType_Int, &pThis->iQueueSize));
+
+	STATSCOUNTER_INIT(pThis->ctrEnqueued, pThis->mutCtrEnqueued);
+	CHKiRet(statsobj.AddCounter(pThis->statsobj, UCHAR_CONSTANT("enqueued"),
+		ctrType_IntCtr, &pThis->ctrEnqueued));
+
+	STATSCOUNTER_INIT(pThis->ctrFull, pThis->mutCtrFull);
+	CHKiRet(statsobj.AddCounter(pThis->statsobj, UCHAR_CONSTANT("full"),
+		ctrType_IntCtr, &pThis->ctrFull));
+
+	pThis->ctrMaxqsize = 0;
+	CHKiRet(statsobj.AddCounter(pThis->statsobj, UCHAR_CONSTANT("maxqsize"),
+		ctrType_Int, &pThis->ctrMaxqsize));
+
+	CHKiRet(statsobj.ConstructFinalize(pThis->statsobj));
+
 finalize_it:
 	RETiRet;
 }
@@ -2119,6 +2143,10 @@ CODESTARTobjDestruct(qqueue)
 
 	free(pThis->pszFilePrefix);
 	free(pThis->pszSpoolDir);
+
+	/* some queues do not provide stats and thus have no statsobj! */
+	if(pThis->statsobj != NULL)
+		statsobj.Destruct(&pThis->statsobj);
 ENDobjDestruct(qqueue)
 
 
@@ -2178,6 +2206,7 @@ doEnqSingleObj(qqueue_t *pThis, flowControl_t flowCtlType, void *pUsr)
 	DEFiRet;
 	struct timespec t;
 
+	STATSCOUNTER_INC(pThis->ctrEnqueued, pThis->mutCtrEnqueued);
 	/* first check if we need to discard this message (which will cause CHKiRet() to exit)
 	 */
 	CHKiRet(qqueueChkDiscardMsg(pThis, pThis->iQueueSize, pUsr));
@@ -2225,6 +2254,7 @@ doEnqSingleObj(qqueue_t *pThis, flowControl_t flowCtlType, void *pUsr)
 	      	  && pThis->tVars.disk.sizeOnDisk > pThis->sizeOnDiskMax)) {
 		DBGOPRINT((obj_t*) pThis, "enqueueMsg: queue FULL - waiting to drain.\n");
 		timeoutComp(&t, pThis->toEnq);
+		STATSCOUNTER_INC(pThis->ctrFull, pThis->mutCtrFull);
 // TODO : handle enqOnly => discard!
 		if(pthread_cond_timedwait(&pThis->notFull, pThis->mut, &t) != 0) {
 			DBGOPRINT((obj_t*) pThis, "enqueueMsg: cond timeout, dropping message!\n");
@@ -2235,6 +2265,7 @@ doEnqSingleObj(qqueue_t *pThis, flowControl_t flowCtlType, void *pUsr)
 
 	/* and finally enqueue the message */
 	CHKiRet(qqueueAdd(pThis, pUsr));
+	STATSCOUNTER_SETMAX_NOMUT(pThis->ctrMaxqsize, pThis->iQueueSize);
 
 finalize_it:
 	RETiRet;
@@ -2414,6 +2445,7 @@ BEGINObjClassInit(qqueue, 1, OBJ_IS_CORE_MODULE)
 	CHKiRet(objUse(strm, CORE_COMPONENT));
 	CHKiRet(objUse(datetime, CORE_COMPONENT));
 	CHKiRet(objUse(errmsg, CORE_COMPONENT));
+	CHKiRet(objUse(statsobj, CORE_COMPONENT));
 
 	/* now set our own handlers */
 	OBJSetMethodHandler(objMethod_SETPROPERTY, qqueueSetProperty);
diff --git a/runtime/queue.h b/runtime/queue.h
index 1c758134..38e248cd 100644
--- a/runtime/queue.h
+++ b/runtime/queue.h
@@ -29,6 +29,7 @@
 #include "wtp.h"
 #include "batch.h"
 #include "stream.h"
+#include "statsobj.h"
 
 /* support for the toDelete list */
 typedef struct toDeleteLst_s toDeleteLst_t;
@@ -165,6 +166,11 @@ struct queue_s {
 	} tVars;
 	DEF_ATOMIC_HELPER_MUT(mutQueueSize);
 	DEF_ATOMIC_HELPER_MUT(mutLogDeq);
+	/* for statistics subsystem */
+	statsobj_t *statsobj;
+	STATSCOUNTER_DEF(ctrEnqueued, mutCtrEnqueued);
+	STATSCOUNTER_DEF(ctrFull, mutCtrFull);
+	int ctrMaxqsize;
 };
 
 
diff --git a/runtime/rsyslog.c b/runtime/rsyslog.c
index a9794840..8baa2b59 100644
--- a/runtime/rsyslog.c
+++ b/runtime/rsyslog.c
@@ -82,6 +82,7 @@
 #include "ruleset.h"
 #include "parser.h"
 #include "strgen.h"
+#include "statsobj.h"
 #include "atomic.h"
 
 /* forward definitions */
@@ -150,6 +151,8 @@ rsrtInit(char **ppErrObj, obj_if_t *pObjIF)
 		 * class immediately after it is initialized. And, of course, we load those classes
 		 * first that we use ourselfs... -- rgerhards, 2008-03-07
 		 */
+		if(ppErrObj != NULL) *ppErrObj = "statsobj";
+		CHKiRet(statsobjClassInit(NULL));
 		if(ppErrObj != NULL) *ppErrObj = "prop";
 		CHKiRet(propClassInit(NULL));
 		if(ppErrObj != NULL) *ppErrObj = "glbl";
diff --git a/runtime/rsyslog.h b/runtime/rsyslog.h
index 34eaedca..7b2655b0 100644
--- a/runtime/rsyslog.h
+++ b/runtime/rsyslog.h
@@ -150,6 +150,8 @@ typedef struct parser_s parser_t;
 typedef struct parserList_s parserList_t;
 typedef struct strgen_s strgen_t;
 typedef struct strgenList_s strgenList_t;
+typedef struct statsobj_s statsobj_t;
+typedef struct statsctr_s statsctr_t;
 typedef rsRetVal (*prsf_t)(struct vmstk_s*, int);	/* pointer to a RainerScript function */
 typedef uint64 qDeqID;	/* queue Dequeue order ID. 32 bits is considered dangerously few */
 
diff --git a/runtime/statsobj.c b/runtime/statsobj.c
new file mode 100644
index 00000000..e1a89cf4
--- /dev/null
+++ b/runtime/statsobj.c
@@ -0,0 +1,315 @@
+/* The statsobj object.
+ *
+ * This object provides a statistics-gathering facility inside rsyslog. This
+ * functionality will be pragmatically implemented and extended.
+ *
+ * Copyright 2010 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 <stdarg.h>
+#include <pthread.h>
+#include <errno.h>
+#include <assert.h>
+
+#include "rsyslog.h"
+#include "unicode-helper.h"
+#include "obj.h"
+#include "statsobj.h"
+#include "sysvar.h"
+#include "srUtils.h"
+#include "stringbuf.h"
+
+
+/* externally-visiable data (see statsobj.h for explanation) */
+int GatherStats = 0;
+
+/* static data */
+DEFobjStaticHelpers
+
+/* doubly linked list of stats objects. Object is automatically linked to it
+ * upon construction. Enqueue always happens at the front (simplifies logic).
+ */
+static statsobj_t *objRoot = NULL;
+static statsobj_t *objLast = NULL;
+
+static pthread_mutex_t mutStats;
+
+/* ------------------------------ statsobj linked list maintenance  ------------------------------ */
+
+static inline void
+addToObjList(statsobj_t *pThis)
+{
+	pthread_mutex_lock(&mutStats);
+	pThis->prev = objLast;
+	if(objLast != NULL)
+		objLast->next = pThis;
+	objLast = pThis;
+	if(objRoot == NULL)
+		objRoot = pThis;
+	pthread_mutex_unlock(&mutStats);
+}
+
+
+static inline void
+removeFromObjList(statsobj_t *pThis)
+{
+	pthread_mutex_lock(&mutStats);
+	if(pThis->prev != NULL)
+		pThis->prev->next = pThis->next;
+	if(pThis->next != NULL)
+		pThis->next->prev = pThis->prev;
+	if(objLast == pThis)
+		objLast = pThis->prev;
+	if(objRoot == pThis)
+		objRoot = pThis->next;
+	pthread_mutex_unlock(&mutStats);
+}
+
+
+static inline void
+addCtrToList(statsobj_t *pThis, ctr_t *pCtr)
+{
+	pthread_mutex_lock(&pThis->mutCtr);
+	pCtr->prev = pThis->ctrLast;
+	if(pThis->ctrLast != NULL)
+		pThis->ctrLast->next = pCtr;
+	pThis->ctrLast = pCtr;
+	if(pThis->ctrRoot == NULL)
+		pThis->ctrRoot = pCtr;
+	pthread_mutex_unlock(&pThis->mutCtr);
+}
+
+/* ------------------------------ methods ------------------------------ */
+
+
+/* Standard-Constructor
+ */
+BEGINobjConstruct(statsobj) /* be sure to specify the object type also in END macro! */
+	pthread_mutex_init(&pThis->mutCtr, NULL);
+	pThis->ctrLast = NULL;
+	pThis->ctrRoot = NULL;
+ENDobjConstruct(statsobj)
+
+
+/* ConstructionFinalizer
+ */
+static rsRetVal
+statsobjConstructFinalize(statsobj_t *pThis)
+{
+	DEFiRet;
+	ISOBJ_TYPE_assert(pThis, statsobj);
+	addToObjList(pThis);
+	RETiRet;
+}
+
+
+/* set name. Note that we make our own copy of the memory, caller is
+ * responsible to free up name it passes in (if required).
+ */
+static rsRetVal
+setName(statsobj_t *pThis, uchar *name)
+{
+	DEFiRet;
+	CHKmalloc(pThis->name = ustrdup(name));
+finalize_it:
+	RETiRet;
+}
+
+
+/* add a counter to an object
+ * ctrName is duplicated, caller must free it if requried
+ */
+static rsRetVal
+addCounter(statsobj_t *pThis, uchar *ctrName, statsCtrType_t ctrType, void *pCtr)
+{
+	ctr_t *ctr;
+	DEFiRet;
+
+	CHKmalloc(ctr = malloc(sizeof(ctr_t)));
+	ctr->next = NULL;
+	ctr->prev = NULL;
+	CHKmalloc(ctr->name = ustrdup(ctrName));
+	ctr->ctrType = ctrType;
+	switch(ctrType) {
+	case ctrType_IntCtr:
+		ctr->val.pIntCtr = (intctr_t*) pCtr;
+		break;
+	case ctrType_Int:
+		ctr->val.pInt = (int*) pCtr;
+		break;
+	}
+	addCtrToList(pThis, ctr);
+
+finalize_it:
+	RETiRet;
+}
+
+
+/* get all the object's countes together with object name as one line.
+ */
+static rsRetVal
+getStatsLine(statsobj_t *pThis, cstr_t **ppcstr)
+{
+	cstr_t *pcstr;
+	ctr_t *pCtr;
+	DEFiRet;
+
+	CHKiRet(cstrConstruct(&pcstr));
+	rsCStrAppendStr(pcstr, pThis->name);
+	rsCStrAppendStrWithLen(pcstr, UCHAR_CONSTANT(": "), 2);
+
+	/* now add all counters to this line */
+	pthread_mutex_lock(&pThis->mutCtr);
+	for(pCtr = pThis->ctrRoot ; pCtr != NULL ; pCtr = pCtr->next) {
+		rsCStrAppendStr(pcstr, pCtr->name);
+		cstrAppendChar(pcstr, '=');
+		switch(pCtr->ctrType) {
+		case ctrType_IntCtr:
+			rsCStrAppendInt(pcstr, *(pCtr->val.pIntCtr)); // TODO: OK?????
+			break;
+		case ctrType_Int:
+			rsCStrAppendInt(pcstr, *(pCtr->val.pInt));
+			break;
+		}
+		cstrAppendChar(pcstr, ' ');
+	}
+	pthread_mutex_unlock(&pThis->mutCtr);
+
+	CHKiRet(cstrFinalize(pcstr));
+	*ppcstr = pcstr;
+
+finalize_it:
+	RETiRet;
+}
+
+
+/* this function can be used to obtain all stats lines. In this case,
+ * a callback must be provided. This module than iterates over all objects and
+ * submits each stats line to the callback. The callback has two parameters:
+ * the first one is a caller-provided void*, the second one the cstr_t with the
+ * line. If the callback reports an error, processing is stopped.
+ */
+static rsRetVal
+getAllStatsLines(rsRetVal(*cb)(void*, cstr_t*), void *usrptr)
+{
+	statsobj_t *o;
+	cstr_t *cstr;
+	DEFiRet;
+
+	for(o = objRoot ; o != NULL ; o = o->next) {
+		CHKiRet(getStatsLine(o, &cstr));
+		CHKiRet(cb(usrptr, cstr));
+		rsCStrDestruct(&cstr);
+	}
+
+finalize_it:
+	RETiRet;
+}
+
+
+/* Enable statistics gathering. currently there is no function to disable it
+ * again, as this is right now not needed.
+ */
+static rsRetVal
+enableStats()
+{
+	GatherStats = 1;
+	return RS_RET_OK;
+}
+
+
+/* destructor for the statsobj object */
+BEGINobjDestruct(statsobj) /* be sure to specify the object type also in END and CODESTART macros! */
+	ctr_t *ctr, *ctrToDel;
+CODESTARTobjDestruct(statsobj)
+	removeFromObjList(pThis);
+
+	/* destruct counters */
+	ctr = pThis->ctrRoot;
+	while(ctr != NULL) {
+		ctrToDel = ctr;
+		ctr = ctr->next;
+		free(ctrToDel->name);
+		free(ctrToDel);
+	}
+
+	pthread_mutex_destroy(&pThis->mutCtr);
+	free(pThis->name);
+ENDobjDestruct(statsobj)
+
+
+/* debugprint for the statsobj object */
+BEGINobjDebugPrint(statsobj) /* be sure to specify the object type also in END and CODESTART macros! */
+CODESTARTobjDebugPrint(statsobj)
+	dbgoprint((obj_t*) pThis, "statsobj object, currently no state info available\n");
+ENDobjDebugPrint(statsobj)
+
+
+/* queryInterface function
+ */
+BEGINobjQueryInterface(statsobj)
+CODESTARTobjQueryInterface(statsobj)
+	if(pIf->ifVersion != statsobjCURR_IF_VERSION) { /* check for current version, increment on each change */
+		ABORT_FINALIZE(RS_RET_INTERFACE_NOT_SUPPORTED);
+	}
+
+	/* ok, we have the right interface, so let's fill it
+	 * Please note that we may also do some backwards-compatibility
+	 * work here (if we can support an older interface version - that,
+	 * of course, also affects the "if" above).
+	 */
+	pIf->Construct = statsobjConstruct;
+	pIf->ConstructFinalize = statsobjConstructFinalize;
+	pIf->Destruct = statsobjDestruct;
+	pIf->DebugPrint = statsobjDebugPrint;
+	pIf->SetName = setName;
+	pIf->GetStatsLine = getStatsLine;
+	pIf->GetAllStatsLines = getAllStatsLines;
+	pIf->AddCounter = addCounter;
+	pIf->EnableStats = enableStats;
+finalize_it:
+ENDobjQueryInterface(statsobj)
+
+
+/* Initialize the statsobj class. Must be called as the very first method
+ * before anything else is called inside this class.
+ */
+BEGINAbstractObjClassInit(statsobj, 1, OBJ_IS_CORE_MODULE) /* class, version */
+	/* request objects we use */
+
+	/* set our own handlers */
+	OBJSetMethodHandler(objMethod_DEBUGPRINT, statsobjDebugPrint);
+	OBJSetMethodHandler(objMethod_CONSTRUCTION_FINALIZER, statsobjConstructFinalize);
+
+	/* init other data items */
+	pthread_mutex_init(&mutStats, NULL);
+
+ENDObjClassInit(statsobj)
+
+/* Exit the class.
+ */
+BEGINObjClassExit(statsobj, OBJ_IS_CORE_MODULE) /* class, version */
+	/* release objects we no longer need */
+	pthread_mutex_destroy(&mutStats);
+ENDObjClassExit(statsobj)
diff --git a/runtime/statsobj.h b/runtime/statsobj.h
new file mode 100644
index 00000000..1ab02182
--- /dev/null
+++ b/runtime/statsobj.h
@@ -0,0 +1,124 @@
+/* The statsobj object.
+ *
+ * Copyright 2010 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.
+ */
+#ifndef INCLUDED_STATSOBJ_H
+#define INCLUDED_STATSOBJ_H
+
+#include "atomic.h"
+
+/* The following data item is somewhat dirty, in that it does not follow
+ * our usual object calling conventions. However, much like with "Debug", we
+ * do this to gain speed. If we finally come to a platform that does not
+ * provide resolution of names for dynamically loaded modules, we need to find
+ * a work-around, but until then, we use the direct access.
+ * If set to 0, statistics are not gathered, otherwise they are.
+ */
+extern int GatherStats;
+
+/* our basic counter type -- need 32 bit on 32 bit platform. 
+ * IMPORTANT: this type *MUST* be supported by atomic instructions!
+ */
+typedef uint64 intctr_t;
+
+/* counter types */
+typedef enum statsCtrType_e {
+	ctrType_IntCtr,
+	ctrType_Int
+} statsCtrType_t;
+
+
+/* helper entity, the counter */
+typedef struct ctr_s {
+	uchar *name;
+	statsCtrType_t ctrType;
+	union {
+		intctr_t *pIntCtr;
+		int *pInt;
+	} val;
+	struct ctr_s *next, *prev;
+} ctr_t;
+
+/* the statsobj object */
+struct statsobj_s {
+	BEGINobjInstance;		/* Data to implement generic object - MUST be the first data element! */
+	uchar *name;
+	pthread_mutex_t mutCtr;		/* to guard counter linked-list ops */
+	ctr_t *ctrRoot;			/* doubly-linked list of statsobj counters */
+	ctr_t *ctrLast;
+	/* used to link ourselves together */
+	statsobj_t *prev;
+	statsobj_t *next;
+};
+
+
+/* interfaces */
+BEGINinterface(statsobj) /* name must also be changed in ENDinterface macro! */
+	INTERFACEObjDebugPrint(statsobj);
+	rsRetVal (*Construct)(statsobj_t **ppThis);
+	rsRetVal (*ConstructFinalize)(statsobj_t *pThis);
+	rsRetVal (*Destruct)(statsobj_t **ppThis);
+	rsRetVal (*SetName)(statsobj_t *pThis, uchar *name);
+	rsRetVal (*GetStatsLine)(statsobj_t *pThis, cstr_t **ppcstr);
+	rsRetVal (*GetAllStatsLines)(rsRetVal(*cb)(void*, cstr_t*), void *usrptr);
+	rsRetVal (*AddCounter)(statsobj_t *pThis, uchar *ctrName, statsCtrType_t ctrType, void *pCtr);
+	rsRetVal (*EnableStats)(void);
+ENDinterface(statsobj)
+#define statsobjCURR_IF_VERSION 1 /* increment whenever you change the interface structure! */
+
+
+/* prototypes */
+PROTOTYPEObj(statsobj);
+
+
+/* macros to handle stats counters
+ * These are to be used by "counter providers". Note that we MUST
+ * specify the mutex name, even though at first it looks like it
+ * could be automatically be generated via e.g. "mut##ctr". 
+ * Unfortunately, this does not work if counter is e.g. "pThis->ctr".
+ * So we decided, for clarity, to always insist on specifying the mutex
+ * name (after all, it's just a few more keystrokes...).
+ */
+#define STATSCOUNTER_DEF(ctr, mut) \
+	intctr_t ctr; \
+	DEF_ATOMIC_HELPER_MUT(mut)
+
+#define STATSCOUNTER_INIT(ctr, mut) \
+	INIT_ATOMIC_HELPER_MUT(mut); \
+	ctr = 0;
+
+#define STATSCOUNTER_INC(ctr, mut) \
+	if(GatherStats) \
+		ATOMIC_INC(&ctr, mut);
+
+#define STATSCOUNTER_DEC(ctr, mut) \
+	if(GatherStats) \
+		ATOMIC_DEC(&ctr, mut);
+
+/* the next macro works only if the variable is already guarded
+ * by mutex (or the users risks a wrong result). It is assumed 
+ * that there are not concurrent operations that modify the counter.
+ */
+#define STATSCOUNTER_SETMAX_NOMUT(ctr, newmax) \
+	if(GatherStats && ((newmax) > (ctr))) \
+		ctr = newmax;
+
+#endif /* #ifndef INCLUDED_STATSOBJ_H */