changed imudp to utilize epoll(), where available.

This shall provide slightly better performance (just slightly because we called
select() rather infrequently on a busy system).

3 files changed, 105 insertions, 21 deletions

diff --git a/ChangeLog b/ChangeLog
index 0e36da85..89195390 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,9 @@ Version 5.3.0  [DEVEL] (rgerhards), 2009-08-??
 - begun to add simple GUI programs to gain insight into running rsyslogd
   instances and help setup and troubleshooting (active via the
   --enable-gui ./configure switch)
+- changed imudp to utilize epoll(), where available. This shall provide
+  slightly better performance (just slightly because we called select()
+  rather infrequently on a busy system)
 - added new config option $ActionWriteAllMarkMessages
   this option permites to process mark messages under all circumstances,
   even if an action was recently called. This can be useful to use mark
diff --git a/configure.ac b/configure.ac
index c32e8674..9d1f7593 100644
--- a/configure.ac
+++ b/configure.ac
@@ -107,7 +107,7 @@ AC_TYPE_SIGNAL
 AC_FUNC_STAT
 AC_FUNC_STRERROR_R
 AC_FUNC_VPRINTF
-AC_CHECK_FUNCS([flock basename alarm clock_gettime gethostbyname gethostname gettimeofday localtime_r memset mkdir regcomp select setid socket strcasecmp strchr strdup strerror strndup strnlen strrchr strstr strtol strtoul uname ttyname_r epoll_wait getline malloc_trim prctl])
+AC_CHECK_FUNCS([flock basename alarm clock_gettime gethostbyname gethostname gettimeofday localtime_r memset mkdir regcomp select setid socket strcasecmp strchr strdup strerror strndup strnlen strrchr strstr strtol strtoul uname ttyname_r getline malloc_trim prctl epoll_create1])
 
 # Check for MAXHOSTNAMELEN
 AC_MSG_CHECKING(for MAXHOSTNAMELEN)
diff --git a/plugins/imudp/imudp.c b/plugins/imudp/imudp.c
index 0a8920f5..f1a720bc 100644
--- a/plugins/imudp/imudp.c
+++ b/plugins/imudp/imudp.c
@@ -32,6 +32,9 @@
 #include <errno.h>
 #include <unistd.h>
 #include <netdb.h>
+#if HAVE_SYS_EPOLL_H
+#	include <sys/epoll.h>
+#endif
 #include "rsyslog.h"
 #include "dirty.h"
 #include "net.h"
@@ -113,7 +116,7 @@ static rsRetVal addListner(void __attribute__((unused)) *pVal, uchar *pNewVal)
 		} else {
 			/* we need to add them */
 			if((tmpSocks = malloc(sizeof(int) * (1 + newSocks[0] + udpLstnSocks[0]))) == NULL) {
-				dbgprintf("out of memory trying to allocate udp listen socket array\n");
+				DBGPRINTF("out of memory trying to allocate udp listen socket array\n");
 				/* in this case, we discard the new sockets but continue with what we
 				 * already have
 				 */
@@ -205,7 +208,7 @@ processSocket(int fd, struct sockaddr_storage *frominetPrev, int *pbIsPermitted,
 				DBGPRINTF("INET socket error: %d = %s.\n", errno, errStr);
 				errmsg.LogError(errno, NO_ERRCODE, "recvfrom inet");
 			}
-			ABORT_FINALIZE(RS_RET_ERR);
+			ABORT_FINALIZE(RS_RET_ERR); // this most often is NOT an error, state is not checked by caller!
 		}
 
 		/* if we reach this point, we had a good receive and can process the packet received */
@@ -267,22 +270,19 @@ finalize_it:
 }
 
 
-/* This function is called to gather input.
- * Note that udpLstnSocks must be non-NULL because otherwise we would not have
- * indicated that we want to run (or we have a programming error ;)). -- rgerhards, 2008-10-02
- * rgerhards, 2008-10-07: I have implemented a very simple, yet in most cases probably
- * highly efficient "name caching". Before querying a name, I now check if the name to be
- * queried is the same as the one queried in the last message processed. If that is the
- * case, we can simple re-use the previous value. This algorithm works quite well with
- * few sender, especially if they emit messages in bursts. The more sender and the
- * more intermixed messages arrive, the less this algorithm works, but the overhead
- * is so minimal (a simple memory compare and move) that this does not hurt. Even
- * with a real name lookup cache, this optimization here is useful as it is quicker
- * than even a cache lookup).
+/* This function implements the main reception loop. Depending on the environment,
+ * we either use the traditional (but slower) select() or the Linux-specific epoll()
+ * interface. ./configure settings control which one is used.
+ * rgerhards, 2009-09-09
  */
-BEGINrunInput
+#if HAVE_EPOLL_CREATE1
+#define NUM_EPOLL_EVENTS 10
+rsRetVal rcvMainLoop()
+{
+	DEFiRet;
 	int maxfds;
 	int nfds;
+	int efd;
 	int i;
 	fd_set readfds;
 	struct sockaddr_storage frominetPrev;
@@ -290,16 +290,82 @@ BEGINrunInput
 	uchar fromHost[NI_MAXHOST];
 	uchar fromHostIP[NI_MAXHOST];
 	uchar fromHostFQDN[NI_MAXHOST];
-CODESTARTrunInput
+	struct epoll_event *udpEPollEvt = NULL;
+	struct epoll_event currEvt[NUM_EPOLL_EVENTS];
+	char errStr[1024];
+
+RUNLOG_STR("ZZZ: imudp epoll startup");
 	/* start "name caching" algo by making sure the previous system indicator
 	 * is invalidated.
 	 */
 	bIsPermitted = 0;
 	memset(&frominetPrev, 0, sizeof(frominetPrev));
-	/* this is an endless loop - it is terminated when the thread is
-	 * signalled to do so. This, however, is handled by the framework,
-	 * right into the sleep below.
+
+	CHKmalloc(udpEPollEvt = calloc(udpLstnSocks[0], sizeof(struct epoll_event)));
+
+	efd = epoll_create1(EPOLL_CLOEXEC);
+	if(efd < 0) {
+		DBGPRINTF("epoll_create1() could not create fd\n");
+		// TODO: "good" error message
+		ABORT_FINALIZE(RS_RET_IO_ERROR);
+	}
+
+	/* fill the epoll set - we need to do this only once, as the set
+	 * can not change dyamically.
+	 */
+	maxfds = 0;
+	FD_ZERO (&readfds);
+
+	/* Add the UDP listen sockets to the list of read descriptors. */
+	for (i = 0; i < *udpLstnSocks; i++) {
+		if (udpLstnSocks[i+1] != -1) {
+			udpEPollEvt[i].events = EPOLLIN | EPOLLET;
+			udpEPollEvt[i].data.fd = udpLstnSocks[i+1];
+			if(epoll_ctl(efd, EPOLL_CTL_ADD,  udpLstnSocks[i+1], &(udpEPollEvt[i])) < 0) {
+				rs_strerror_r(errno, errStr, sizeof(errStr));
+				errmsg.LogError(errno, NO_ERRCODE, "epoll_ctrl failed on fd %d with %s\n",
+					udpLstnSocks[i+1], errStr);
+			}
+		}
+	}
+
+RUNLOG_STR("ZZZ: done setting up epoll interface");
+	while(1) {
+		/* wait for io to become ready */
+		nfds = epoll_wait(efd, currEvt, NUM_EPOLL_EVENTS, -1);
+		DBGPRINTF("imudp: epoll_wait() returned with %d fds\n", nfds);
+
+		for(i = 0 ; i < nfds ; ++i) {
+dbgprintf("ZZZ: imudp processing fd %d\n", currEvt[i].data.fd);
+			processSocket(currEvt[i].data.fd, &frominetPrev, &bIsPermitted,
+				      fromHost, fromHostFQDN, fromHostIP);
+		}
+	}
+
+finalize_it:
+	RETiRet;
+}
+#else /* #if HAVE_EPOLL_CREATE1 */
+/* this is the code for the select() interface */
+rsRetVal rcvMainLoop()
+{
+	DEFiRet;
+	int maxfds;
+	int nfds;
+	int i;
+	fd_set readfds;
+	struct sockaddr_storage frominetPrev;
+	int bIsPermitted;
+	uchar fromHost[NI_MAXHOST];
+	uchar fromHostIP[NI_MAXHOST];
+	uchar fromHostFQDN[NI_MAXHOST];
+
+	/* start "name caching" algo by making sure the previous system indicator
+	 * is invalidated.
 	 */
+	bIsPermitted = 0;
+	memset(&frominetPrev, 0, sizeof(frominetPrev));
+
 	while(1) {
 		/* Add the Unix Domain Sockets to the list of read
 		 * descriptors.
@@ -342,7 +408,22 @@ CODESTARTrunInput
 	       /* end of a run, back to loop for next recv() */
 	}
 
-	return iRet;
+	RETiRet;
+}
+#endif /* #if HAVE_EPOLL_CREATE1 */
+
+/* This function is called to gather input.
+ * Note that udpLstnSocks must be non-NULL because otherwise we would not have
+ * indicated that we want to run (or we have a programming error ;)). -- rgerhards, 2008-10-02
+ */
+BEGINrunInput
+CODESTARTrunInput
+	/* this is an endless loop - it is terminated when the thread is
+	 * signalled to do so. This, however, is handled by the framework,
+	 * right into the sleep below.
+	 */
+RUNLOG_STR("ZZZ: imudp startup");
+	iRet = rcvMainLoop();
 ENDrunInput