[Sheepdog] [PATCH v2] logger: rotate log by size, default is 500MB

[zituan at taobao.com]

From: Andy Chen <sanjie.cyg at taobao.com>

a simple patch to split log:  when log size exceed 500MB, a new
sheep.log file will be created, and old log will be renamed with
specified suffix(actually, it's the time when split happened).

the main purpose of this patch is to prevent log became too big,
which is hard to open and read.

Signed-off-by: Andy Chen <sanjie.cyg at taobao.com>
Signed-off-by: Yibin Shen <zituan at taobao.com>
---
 lib/logger.c |   47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 47 insertions(+), 0 deletions(-)

diff --git a/lib/logger.c b/lib/logger.c
index d5eb453..56da6d7 100644
--- a/lib/logger.c
+++ b/lib/logger.c
@@ -28,6 +28,7 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <sys/prctl.h>
+#include <pthread.h>
 
 #include "logger.h"
 #include "util.h"
@@ -47,10 +48,15 @@ static void dolog(int prio, const char *func, int line, const char *fmt,
 
 static struct logarea *la;
 static char *log_name;
+static char *log_nowname;
 static int log_level = SDOG_INFO;
 static pid_t pid;
 static key_t semkey;
 
+static int64_t max_logsize = 500 * 1024 * 1024;  /*500MB*/
+
+pthread_mutex_t logsize_lock = PTHREAD_MUTEX_INITIALIZER;
+
 static int logarea_init(int size)
 {
 	int shmid;
@@ -317,6 +323,29 @@ static void dolog(int prio, const char *func, int line, const char *fmt, va_list
 	}
 }
 
+static void rotate_log(void)
+{
+	int new_fd;
+
+	if (access(log_nowname, R_OK) == 0) {
+		char old_logfile[256];
+		time_t t;
+		struct tm tm;
+		time(&t);
+		localtime_r((const time_t *)&t, &tm);
+		sprintf(old_logfile, "%s.%04d-%02d-%02d-%02d-%02d",
+				log_nowname, tm.tm_year + 1900, tm.tm_mon + 1,
+				tm.tm_mday, tm.tm_hour, tm.tm_min);
+		rename(log_nowname, old_logfile);
+	}
+	new_fd = open(log_nowname, O_RDWR | O_CREAT | O_APPEND, 0644);
+	if (new_fd < 0)
+		syslog(LOG_ERR, "fail to create new log file\n");
+
+	dup2(new_fd, la->fd);
+	la->fd = new_fd;
+}
+
 void log_write(int prio, const char *func, int line, const char *fmt, ...)
 {
 	va_list ap;
@@ -369,10 +398,14 @@ static void log_sigexit(int signo)
 
 int log_init(char *program_name, int size, int is_daemon, int level, char *outfile)
 {
+	off_t offset;
+	size_t log_size;
+
 	log_level = level;
 
 	logdbg(stderr, "entering log_init\n");
 	log_name = program_name;
+	log_nowname = outfile;
 
 	semkey = random();
 
@@ -436,6 +469,20 @@ int log_init(char *program_name, int size, int is_daemon, int level, char *outfi
 
 		while (la->active) {
 			log_flush();
+
+			if (max_logsize) {
+				pthread_mutex_lock(&logsize_lock);
+				offset = lseek(la->fd, 0, SEEK_END);
+				if (offset < 0) {
+					syslog(LOG_ERR, "sheep log error\n");
+				} else {
+					log_size = (size_t)offset;
+					if (log_size >= max_logsize)
+						rotate_log();
+				}
+				pthread_mutex_unlock(&logsize_lock);
+			}
+
 			sleep(1);
 		}
 
-- 
1.7.7.3