Protect updating of router when rotating.

When rotating, all state variables of router are now updated while
protected by the router->binlog_lock lock.

server/modules/include/blr.h

@@ -48,6 +48,7 @@
 #define BINLOG_FNAMELEN		255
 #define BLR_PROTOCOL		"MySQLBackend"
 #define BINLOG_MAGIC		{ 0xfe, 0x62, 0x69, 0x6e }
+#define BINLOG_MAGIC_SIZE	4
 #define BINLOG_NAMEFMT		"%s.%06d"
 #define BINLOG_NAME_ROOT	"mysql-bin"
 

server/modules/routing/binlog/blr_file.c

@@ -189,20 +189,17 @@ blr_file_rotate(ROUTER_INSTANCE *router, char *file, uint64_t pos)
  * binlog files need an initial 4 magic bytes at the start. blr_file_add_magic()
  * adds them.
  *
- * @param router	The router instance
  * @param fd            file descriptor to the open binlog file
- * @return		Nothing
+ * @return              True if the magic string could be written to the file.
  */
-static void
-blr_file_add_magic(ROUTER_INSTANCE *router, int fd)
+static bool
+blr_file_add_magic(int fd)
 {
-unsigned char	magic[] = BINLOG_MAGIC;
+    static const unsigned char magic[] = BINLOG_MAGIC;
 
-	write(fd, magic, 4);
-	router->current_pos = 4;			/* Initial position after the magic number */
-	router->binlog_position = 4;			/* Initial position after the magic number */
-	router->current_safe_event = 4;
-	router->last_written = 0;
+    ssize_t written = write(fd, magic, BINLOG_MAGIC_SIZE);
+
+    return written == BINLOG_MAGIC_SIZE;
 }
 
 
@@ -216,32 +213,53 @@ unsigned char	magic[] = BINLOG_MAGIC;
 static int
 blr_file_create(ROUTER_INSTANCE *router, char *file)
 {
-char		path[PATH_MAX + 1] = "";
-int		fd;
+    int created = 0;
+    char err_msg[STRERROR_BUFLEN];
+
+    char path[PATH_MAX + 1] = "";
 
     strcpy(path, router->binlogdir);
     strcat(path, "/");
     strcat(path, file);
 
-	if ((fd = open(path, O_RDWR|O_CREAT, 0666)) != -1)
-	{
-		blr_file_add_magic(router,fd);
-	}
-	else
-	{
-		char err_msg[STRERROR_BUFLEN];
+    int fd = open(path, O_RDWR|O_CREAT, 0666);
 
-		MXS_ERROR("%s: Failed to create binlog file %s, %s.",
-                          router->service->name, path, strerror_r(errno, err_msg, sizeof(err_msg)));
-		return 0;
-	}
-	fsync(fd);
+    if (fd != -1)
+    {
+        if (blr_file_add_magic(fd))
+        {
             close(router->binlog_fd);
             spinlock_acquire(&router->binlog_lock);
             strncpy(router->binlog_name, file, BINLOG_FNAMELEN);
             router->binlog_fd = fd;
+            router->current_pos = BINLOG_MAGIC_SIZE;     /* Initial position after the magic number */
+            router->binlog_position = BINLOG_MAGIC_SIZE;
+            router->current_safe_event = BINLOG_MAGIC_SIZE;
+            router->last_written = 0;
             spinlock_release(&router->binlog_lock);
-	return 1;
+
+            created = 1;
+        }
+        else
+        {
+            MXS_ERROR("%s: Failed to write magic string to created binlog file %s, %s.",
+                      router->service->name, path, strerror_r(errno, err_msg, sizeof(err_msg)));
+            close(fd);
+
+            if (!unlink(path))
+            {
+                MXS_ERROR("%s: Failed to delete file %s, %s.",
+                          router->service->name, path, strerror_r(errno, err_msg, sizeof(err_msg)));
+            }
+        }
+    }
+    else
+    {
+        MXS_ERROR("%s: Failed to create binlog file %s, %s.",
+                  router->service->name, path, strerror_r(errno, err_msg, sizeof(err_msg)));
+    }
+
+    return created;
 }
 
 /**
@@ -273,7 +291,15 @@ int		fd;
 	router->current_pos = lseek(fd, 0L, SEEK_END);
 	if (router->current_pos < 4) {
 		if (router->current_pos == 0) {
-			blr_file_add_magic(router, fd);
+			if (blr_file_add_magic(fd))
+			{
+				router->current_pos = BINLOG_MAGIC_SIZE;
+				router->binlog_position = BINLOG_MAGIC_SIZE;
+				router->current_safe_event = BINLOG_MAGIC_SIZE;
+				router->last_written = 0;
+			} else {
+			    MXS_ERROR("%s: Could not write magic to binlog file.", router->service->name);
+			}
 		} else {
 			/* If for any reason the file's length is between 1 and 3 bytes
 			 * then report an error. */

server/modules/routing/binlog/blr_master.c

@@ -1196,7 +1196,11 @@ int			n_bufs = -1, pn_bufs = -1;
 						ptr = ptr + 5;	// We don't put the first byte of the payload
 								// into the binlog file
 						if (hdr.event_type == ROTATE_EVENT)
+						{
+							spinlock_acquire(&router->binlog_lock);
 							router->rotating = 1;
+							spinlock_release(&router->binlog_lock);
+						}
 
 						/* current event is being written to disk file */
 						if (blr_write_binlog_record(router, &hdr, ptr) == 0)
@@ -1358,7 +1362,9 @@ int			n_bufs = -1, pn_bufs = -1;
 						ptr += 5;
 						if (hdr.event_type == ROTATE_EVENT)
 						{
+							spinlock_acquire(&router->binlog_lock);
 							router->rotating = 1;
+							spinlock_release(&router->binlog_lock);
 							if (!blr_rotate_event(router, ptr, &hdr))
 							{
 								/*
@@ -1474,6 +1480,7 @@ blr_extract_header(register uint8_t *ptr, register REP_HEADER *hdr)
  * @param router	The instance of the router
  * @param ptr		The packet containing the rotate event
  * @param hdr		The replication message header
+ * @return 		    1 if the file could be rotated, 0 otherwise.
  */
 static int
 blr_rotate_event(ROUTER_INSTANCE *router, uint8_t *ptr, REP_HEADER *hdr)
@@ -1505,17 +1512,20 @@ char		file[BINLOG_FNAMELEN+1];
 
 	strcpy(router->prevbinlog, router->binlog_name);
 
+	int rotated = 1;
+
 	if (strncmp(router->binlog_name, file, slen) != 0)
 	{
 		router->stats.n_rotates++;
 		if (blr_file_rotate(router, file, pos) == 0)
 		{
-			router->rotating = 0;
-			return 0;
+			rotated = 0;
 		}
 	}
+	spinlock_acquire(&router->binlog_lock);
 	router->rotating = 0;
-	return 1;
+	spinlock_release(&router->binlog_lock);
+	return rotated;
 }
 
 /**