b89349715

Denis Vlasenko

2007-01-04

FAILED Duration: 3s

Subject

syslogd: stop doing open/fstat/lseek/close on _every_ write (still doing it if more than a second passed in between). Costs ~40 bytes.

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

sysklogd/syslogd.c +65 -52

sysklogd/syslogd.c+65 -52

@@ -29,6 +29,7 @@ static char *dev_log_name;

	/* Path for the file where all log messages are written */
	static const char *logFilePath = "/var/log/messages";
+	static int logFD = -1;

	/* interval between marks in seconds */
	static int markInterval = 20 * 60;
@@ -41,9 +42,11 @@ static char localHostName[64];

	#if ENABLE_FEATURE_ROTATE_LOGFILE
	/* max size of message file before being rotated */
-	static int logFileSize = 200 * 1024;
+	static unsigned logFileSize = 200 * 1024;
	/* number of rotated message files */
-	static int logFileRotate = 1;
+	static unsigned logFileRotate = 1;
+	static unsigned curFileSize;
+	static smallint isRegular;
	#endif

	#if ENABLE_FEATURE_REMOTE_LOG
@@ -256,7 +259,10 @@ void log_to_shmem(const char *msg);
	/* Print a message to the log file. */
	static void log_locally(char *msg)
	{
-	int fd, len = strlen(msg);
+	static time_t last;
+
+	struct flock fl;
+	int len = strlen(msg);

	#if ENABLE_FEATURE_IPC_SYSLOG
	if ((option_mask32 & OPT_circularlog) && shbuf) {
@@ -264,62 +270,69 @@ static void log_locally(char *msg)
	return;
	}
	#endif
-
-	again:
-	fd = device_open(logFilePath, O_WRONLY \| O_CREAT
+	if (logFD >= 0) {
+	time_t cur;
+	time(&cur);
+	if (last != cur) {
+	last = cur; /* reopen log file every second */
+	close(logFD);
+	goto reopen;
+	}
+	} else {
+	struct stat statf;
+	reopen:
+	logFD = device_open(logFilePath, O_WRONLY \| O_CREAT
	\| O_NOCTTY \| O_APPEND \| O_NONBLOCK);
-	if (fd >= 0) {
-	struct flock fl;
+	if (logFD < 0) {
+	/* cannot open logfile? - print to /dev/console then */
+	int fd = device_open(_PATH_CONSOLE, O_WRONLY \| O_NOCTTY \| O_NONBLOCK);
+	if (fd < 0)
+	fd = 2; /* then stderr, dammit */
+	full_write(fd, msg, len);
+	if (fd != 2)
+	close(fd);
+	return;
+	}
+	#if ENABLE_FEATURE_ROTATE_LOGFILE
+	isRegular = (fstat(logFD, &statf) == 0 && (statf.st_mode & S_IFREG));
+	/* bug (mostly harmless): can wrap around if file > 4gb */
+	curFileSize = statf.st_size;
+	#endif
+	}

-	fl.l_whence = SEEK_SET;
-	fl.l_start = 0;
-	fl.l_len = 1;
-	fl.l_type = F_WRLCK;
-	fcntl(fd, F_SETLKW, &fl);
+	fl.l_whence = SEEK_SET;
+	fl.l_start = 0;
+	fl.l_len = 1;
+	fl.l_type = F_WRLCK;
+	fcntl(logFD, F_SETLKW, &fl);

	#if ENABLE_FEATURE_ROTATE_LOGFILE
-	if (logFileSize) {
-	struct stat statf;
-	int r = fstat(fd, &statf);
-	if (!r && (statf.st_mode & S_IFREG)
-	&& (lseek(fd, 0, SEEK_END) > logFileSize)
-	) {
-	if (logFileRotate) { /* always 0..99 */
-	int i = strlen(logFilePath) + 3 + 1;
-	char oldFile[i];
-	char newFile[i];
-	i = logFileRotate - 1;
-	/* rename: f.8 -> f.9; f.7 -> f.8; ... */
-	while (1) {
-	sprintf(newFile, "%s.%d", logFilePath, i);
-	if (i == 0) break;
-	sprintf(oldFile, "%s.%d", logFilePath, --i);
-	rename(oldFile, newFile);
-	}
-	/* newFile == "f.0" now */
-	rename(logFilePath, newFile);
-	fl.l_type = F_UNLCK;
-	fcntl(fd, F_SETLKW, &fl);
-	close(fd);
-	goto again;
-	}
-	ftruncate(fd, 0);
+	if (logFileSize && isRegular && curFileSize > logFileSize) {
+	if (logFileRotate) { /* always 0..99 */
+	int i = strlen(logFilePath) + 3 + 1;
+	char oldFile[i];
+	char newFile[i];
+	i = logFileRotate - 1;
+	/* rename: f.8 -> f.9; f.7 -> f.8; ... */
+	while (1) {
+	sprintf(newFile, "%s.%d", logFilePath, i);
+	if (i == 0) break;
+	sprintf(oldFile, "%s.%d", logFilePath, --i);
+	rename(oldFile, newFile);
	}
+	/* newFile == "f.0" now */
+	rename(logFilePath, newFile);
+	fl.l_type = F_UNLCK;
+	fcntl(logFD, F_SETLKW, &fl);
+	close(logFD);
+	goto reopen;
	}
-	#endif
-	full_write(fd, msg, len);
-	fl.l_type = F_UNLCK;
-	fcntl(fd, F_SETLKW, &fl);
-	close(fd);
-	} else {
-	/* cannot open logfile? - print to /dev/console then */
-	fd = device_open(_PATH_CONSOLE, O_WRONLY \| O_NOCTTY \| O_NONBLOCK);
-	if (fd < 0)
-	fd = 2; /* then stderr, dammit */
-	full_write(fd, msg, len);
-	if (fd != 2)
-	close(fd);
+	ftruncate(logFD, 0);
	}
+	#endif
+	curFileSize += full_write(logFD, msg, len);
+	fl.l_type = F_UNLCK;
+	fcntl(logFD, F_SETLKW, &fl);
	}

	static void parse_fac_prio_20(int pri, char *res20)