Make multi-processing optional for feed_dns

feed_dns.py

@@ -29,20 +29,37 @@ FUNCTION_MAP: typing.Any = {
 
 class Writer(multiprocessing.Process):
     def __init__(self,
-                 recs_queue: multiprocessing.Queue,
+                 recs_queue: multiprocessing.Queue = None,
                  autosave_interval: int = 0,
                  ip4_cache: int = 0,
                  ):
+        if recs_queue:  # MP
             super(Writer, self).__init__()
-        self.log = logging.getLogger(f'wr')
             self.recs_queue = recs_queue
+        self.log = logging.getLogger(f'wr')
         self.autosave_interval = autosave_interval
         self.ip4_cache = ip4_cache
+        if not recs_queue:  # No MP
+            self.open_db()
 
-    def run(self) -> None:
+    def open_db(self) -> None:
         self.db = database.Database()
         self.db.log = logging.getLogger(f'wr')
         self.db.fill_ip4cache(max_size=self.ip4_cache)
+
+    def exec_record(self, record: Record) -> None:
+        self.db.enter_step('exec_record')
+        select, write, updated, name, value = record
+        try:
+            for source in select(self.db, value):
+                write(self.db, name, updated, source=source)
+        except (ValueError, IndexError):
+            # ValueError: non-number in IP
+            # IndexError: IP too big
+            self.log.exception("Cannot execute: %s", record)
+
+    def run(self) -> None:
+        self.open_db()
         if self.autosave_interval > 0:
             next_save = time.time() + self.autosave_interval
         else:
@@ -54,17 +71,7 @@ class Writer(multiprocessing.Process):
 
             record: Record
             for record in block:
-
+                self.exec_record(record)
-                select, write, updated, name, value = record
-                self.db.enter_step('feed_switch')
-
-                try:
-                    for source in select(self.db, value):
-                        write(self.db, name, updated, source=source)
-                except (ValueError, IndexError):
-                    # ValueError: non-number in IP
-                    # IndexError: IP too big
-                    self.log.exception("Cannot execute: %s", record)
 
             if next_save > 0 and time.time() > next_save:
                 self.log.info("Saving database...")
@@ -81,28 +88,36 @@ class Writer(multiprocessing.Process):
 class Parser():
     def __init__(self,
                  buf: typing.Any,
-                 recs_queue: multiprocessing.Queue,
+                 recs_queue: multiprocessing.Queue = None,
-                 block_size: int,
+                 block_size: int = 0,
+                 writer: Writer = None,
                  ):
-        super(Parser, self).__init__()
+        assert bool(writer) ^ bool(block_size and recs_queue)
         self.buf = buf
         self.log = logging.getLogger('pr')
         self.recs_queue = recs_queue
+        if writer:  # No MP
+            self.prof: database.Profiler = writer.db
+            self.register = writer.exec_record
+        else:  # MP
             self.block: typing.List[Record] = list()
             self.block_size = block_size
             self.prof = database.Profiler()
             self.prof.log = logging.getLogger('pr')
+            self.register = self.add_to_queue
 
-    def register(self, record: Record) -> None:
+    def add_to_queue(self, record: Record) -> None:
         self.prof.enter_step('register')
         self.block.append(record)
         if len(self.block) >= self.block_size:
             self.prof.enter_step('put_block')
+            assert self.recs_queue
             self.recs_queue.put(self.block)
             self.block = list()
 
     def run(self) -> None:
         self.consume()
+        if self.recs_queue:
             self.recs_queue.put(self.block)
         self.prof.profile()
 
@@ -205,6 +220,10 @@ if __name__ == '__main__':
         '-a', '--autosave-interval', type=int, default=900,
         help="Interval to which the database will save in seconds. "
         "0 to disable.")
+    args_parser.add_argument(
+        '-s', '--single-process', action='store_true',
+        help="Only use one process. "
+        "Might be useful for single core computers.")
     args_parser.add_argument(
         '-4', '--ip4-cache', type=int, default=0,
         help="RAM cache for faster IPv4 lookup. "
@@ -213,6 +232,15 @@ if __name__ == '__main__':
         "be a memory-heavy process, even without the cache.")
     args = args_parser.parse_args()
 
+    parser_cls = PARSERS[args.parser]
+    if args.single_process:
+        writer = Writer(
+            autosave_interval=args.autosave_interval,
+            ip4_cache=args.ip4_cache
+        )
+        parser = parser_cls(args.input, writer=writer)
+        parser.run()
+    else:
         recs_queue: multiprocessing.Queue = multiprocessing.Queue(
             maxsize=args.queue_size)
 
@@ -222,7 +250,10 @@ if __name__ == '__main__':
                         )
         writer.start()
 
-    parser = PARSERS[args.parser](args.input, recs_queue, args.block_size)
+        parser = parser_cls(args.input,
+                            recs_queue=recs_queue,
+                            block_size=args.block_size
+                            )
         parser.run()
 
         recs_queue.put(None)