master: log file support

artiq/master/log.py

@@ -1,4 +1,5 @@
 import logging
+import logging.handlers
 
 from artiq.protocols.sync_struct import Notifier
 
@@ -74,23 +75,42 @@ class SourceFilter:
 
 
 def log_args(parser):
-    group = parser.add_argument_group("verbosity")
+    group = parser.add_argument_group("logging")
     group.add_argument("-v", "--verbose", default=0, action="count",
-                       help="increase logging level for the master process")
+                       help="increase logging level of the master process")
     group.add_argument("-q", "--quiet", default=0, action="count",
-                       help="decrease logging level for the master process")
+                       help="decrease logging level of the master process")
+    group.add_argument("--log-file", default="",
+                       help="store logs in rotated files; set the "
+                            "base filename")
+    group.add_argument("--log-max-size", type=int, default=1024,
+                       help="maximum size of each log file in KiB "
+                            "(default: %(default)d)")
+    group.add_argument("--log-backup-count", type=int, default=6,
+                       help="number of old log files to keep (.<n> is added "
+                            "to the base filename (default: %(default)d)")
 
 
 def init_log(args):
     root_logger = logging.getLogger()
     root_logger.setLevel(logging.NOTSET)  # we use our custom filter only
     flt = SourceFilter(logging.WARNING + args.quiet*10 - args.verbose*10)
+    full_fmt = logging.Formatter(
+        "%(levelname)s:%(source)s:%(name)s:%(message)s")
 
     handlers = []
     console_handler = logging.StreamHandler()
-    console_handler.setFormatter(logging.Formatter("%(levelname)s:%(source)s:%(name)s:%(message)s"))
+    console_handler.setFormatter(full_fmt)
     handlers.append(console_handler)
 
+    if args.log_file:
+        file_handler = logging.handlers.RotatingFileHandler(
+            args.log_file,
+            maxBytes=args.log_max_size*1024,
+            backupCount=args.log_backup_count)
+        file_handler.setFormatter(full_fmt)
+        handlers.append(file_handler)
+    
     log_buffer = LogBuffer(1000)
     buffer_handler = LogBufferHandler(log_buffer)
     buffer_handler.setFormatter(logging.Formatter("%(name)s:%(message)s"))